Biology 2F03: Lecture 1
Chapter 2: Life on Land
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Labs start on the Sept 17
Why horses and cattle help restore Guanacaste forest of Costa Rica? o This forest was in decline for thousands of years, when Indians colonized central
America, it caused its decline. o Its regenerated when the Europeans came with the cattle o The trees only produce a new plant after processes: the fallen fruit has to be eaten by a larger animal (mule, or horse or cow) à it has to pass through the body and ends up in a pile of fertilizer only then it can regenerate and produce a tree o Why did it evolve to be depended to this process?
§ There must be animals there in the past, in the past it was a camel (llama, alpaca). When the Indians came from asia (50000 years ago) these animals went extinct and the tree lost its major dispersal system
What is the most obvious foundation of life on land? o Is landà soil
Climate defines biomes, the ‘shapes’ of vegetation o Defines the major types of land on earth o Temperature and precipitation to be specific
Soils in turn greatly affect the aspects (roots, water, nutrient) à rentention, root attachment, etc. Soil typically form layers (horizontal) retaining a range of physical and chemical layers: o Classification of soil: O= organic, A, B, C
Soil horizons: description o O: organic, litter on top, fine litter deeper (gets broken down, hence fine), pollen, dead organisms o A: mineral soil, some organic matter. Clay, iron, aluminum, silicates, and soluble organics leach out gradually o B: depositional. Materials leached from A settle in B. Deposits may form banding patterns. o C: weathered parent material: rock fragment o Particulate to dissolved material gradient, organic to purely mineral
Soils: warm and humid climate à breakdown faster than in colder climate à large organic waste o Tropicsà very wet climate, organic waste produced falls and since oxygen is lacking, organic waste is stored as a whole o Soil horizons result from interactions between climate, vegetation, animal activities, and geology. Horizons change gradually. o Any pattern you see reflects recent (scale of 10^2- 10^3 yrs) history
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o Change vegetation, climate or animals and the soil will change; differently in different habitats
North of the equator is the Sahara, south of the equator is the Kalahari
Earth rotation effects prevailing winds and ocean currents. Earth rotates from the west to the east à clockwise
Where is the movement of earth the fastest? The equator is moving faster
Coriolis force: the inertia that is associated from fast lane to slow lane
Ocean current north to south, slow lane to fast lane, wind from south to north
Equator you travel for 12 hrs to reach the middle o For 60 N it also takes 12 hrs but less distance o If you move from slow to fast lane you will be falling behind o If you move north then you move ahead of everything in that area if you move south then you lag behind everything in that area
Wind and water travelling towards the equator will be (left behind) west and those travelling away Mean temperature, water and variation of both
Climate diagrams captures variation of temperature and water o Allow to infer water availability to plants o Climate diagram: temperature in Celsius, mm and months o Monthly measurements o Mean precipitation and temperature per month o Red pink area is above freezing o Blue area is continuous it means that there is enough water given the temperature à there is never a drought that limits species in that area
Different Biomes: Tropical wet climateà little variation, hot and wet
Shaded gold means that temperature is above the precipitation line, indication dry conditions o Dry, hot condition for the plants o Arizona desert
Tropical rainforest: continuously wet, limited seasonality, and equatorial precipitation 100 mm of rain each month. Slight variation o Between tropic of cancer and tropic of Capricorn.
Excessive water: do not need to be in the ground they can grow anywhere o Nutrients from air or animals
Tropical dry forest: distribution: between savannah and rain forests o Great variation in precipitation and temp
Which biome is favoured by people? o Moist and dry (most favoured) are favoured o Reasonable precipitation and seasonal o Great difference in density o Great difference in damage
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Deserts distribution: Lowest mean precipitation, droughts during the summers
Islands on land: mountains have climate and conditions different from the area where they arise à engines were new species are created due to isolation (evolutionary path) o Mountain effect the regional climate o Orientation: Americas mountains are oriented north to south à plate tectonics movements o Compressed physical gradient of conditions: tropical rain forest at the bottom à 30 km up its very cold equivalent to Antarctica. o Isolation: many species cannot reach the top of the mountain and can only be colonized by certain species.
Boreal forest: tundra: 2-4 months of frost free time
For each biomes you should know: location in space and relative to others o Whether its temperature is strongly seasonal and involves regularly negative temperatures o Typical precipitations patterns relative to others o Types of soil need mentioning o Characteristic vegetation o Signature animals o Adaptations to its conditions

Chapter 3: Water
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What is different? o Density, oxygen, light, no H2O shortage, pressure o Fish who lose water due to osmotic water, salinity outside is higher than the salinity in the tissue, then the water is sucked out and so they need to drink water!
Are chemical and physical conditions in the ocean similar to different latitudes? o Temperature differs, warm equator to cold polar
§ Density of water, salinity of water, etc. o Longitudes: yes they do differ because they are obstacles for water and their temperatures Latitude and Longitudes o Winds influence currents; currents bring cold or warm water, they have an impact along longitude regions even though the primary activity is related to latitude
Oceanic zones: lose light (no sunlight below 30 m) and drop in oxygen (it comes from the atmosphere and algae, and it caught in top layer) o Epipelagic zone: productive zone, life being produced, most oxygen, as life dies it sinks and decomposes o Open water very little life o Bottom habitat; receives a rain of particles, diversified life
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o Zones: intertidal (difference between lowest and highest tide), neritic (photosynthetic activity conducted effectively), epipelagic, mesopelagic (200- 1000m decreasing light and temperature, penetration of light), bathypelagic (deep dark but open ocean), abyssal (deepest and coolest)
Vents and chemosynthesis: rocks and metals are instantly melted, due to the heat
Adaptations: to deep water and limited food o Angler fish: uses its bait (light) to attract other fish. o Number and size of fins and skeletal system reduced o Male= a sperm producing appendage of female
Finding food may be a problem but would being found be a problem too? o Defense strategies: spines, body shape, translucence
Diversity
o Phytoplankton: produce sugars, fix carbon o Zooplankton: predatory animals that eat phytoplankton o Larger predators (whales, fish, squid, crabs) o Benthos: organisms associated with the bottom, fish that crawl on the bottom, mussels, crustaceans. o Corals o Algae (kelp) swim near the surface of the ocean, also attached to rocks at the bottom of the oceans o Invertebrates phyla
Vertebrates are phylum: land 10 phylum+, marine approx 30. o Endemic means unique to the location eg. Lemurs endemic to Madagascar o Marine have a lot of endemic organisms o Land: velvet worms are endemic to land only
Kelp uses vessels to stand in a vertical position in water o Large algae (10- 50 m tall), form habitat that looks like a forest o Produce food that is eaten by a variety of organisms and attracts a variety of organism
(fish, seal, sea otters, whales, sharks)
What are corals? o Why are they green? They can corporate algae into their tissues, and they photosynthesis and protect algae from being predated.
§ Coral being an animal produced nitrogen fertilizer and algae uses nitrogen to produce sugar
§ They sometimes crab zooplankton and grab the nitrogen o How fast do they grow? 2-3 cm a year o When damaged takes long time to repair o Why are they important? They are the foundation of coral reefs (tropics) oceanic food is being produced

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o Coral bleaching? Once they are stressed by pollution or temperature, they expel algae and due to that they lose their colour and pale (bleached), they cut the branch on which they sit, it is a defensive responsive.
§ Once detached it is infected and the skeletons and taken by organisms
What is an atoll? o A island in the Pacific ocean which looks like a ring, there is a lagoon and inside is a lake. o How does an atoll form?
§ Coral reefs forms around the island formed by volcano in shallow waters, volcano stops growing and moves away (island doesn’t grow and therefore, erodes) § Island disappears but the ring of reefs doesn’t. The coral reefs was there in the first place because it was growing and continues to grow, the coral adjust itself to the ocean. o Reefs provide food, recreation and nutrients. The reefs protects the island from erosion and rising sea level.
Corals: tropics, warm currents, no silt
Kelp: temperature, cold currents, rocky shores
Tidal zone: when ocean means the shore o Supratidal fringe: exposed to air when oceans moves out, marine organisms used to exposure to air. o Middle intertidal zone: starfish, mussels o Lower intertidal zone: crabs, anenemes
Tidal zone: Starfish and sea urchins
Can trees grow in the ocean? o Mangrove trees grow in the ocean o In Indonesia they cause the sediment to settle and this allows them to move further and further down the ocean (up to 100 km) o They are productive (sunlight), microorganisms, fish o Removal of these mangroves means erosion on the shores o They live in the muddy areas, therefore, their roots develop pores which they can breathe through o Provide shelter, spawning and breeding for many fish and invertebrates o Provide foot in forms of leaves (crabs love these leaves)
Salt marshes: mostly subtropics to polar regions o The tides retreat and come back a lot and this causes channels to be carved o It is the most productive environment based on the biomass o It is exported by tides to oceans, this allows for fishes to feed on them. o Creeks, marsh flats, salt pans, secondary low marsh, microhabitat
Why carnivorous plants are commonly found in freshwater bog habitats?
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What type of freshwater wetlands you have heard of?
Estuary: Where the rivers comes to become an ocean o Since the salt water is denser, at the bottom the salt water flows in the river. o When it moves from river to ocean it causes river water to float on top of the ocean water o Lower salinity, low density river water flows over the top of the higher salinity ocean water o Strong gradients in salinity: sedimentsà filter feeding organisms, highly productive; o Daily fluctuations, like on rocky shores, salt marshes, mangroves due to tides.
Riparian vegetation: vegetation that grows on the side of the river
When a river slows down, it is a pool (moves in circles or is still)
Riffle water moving
Wetted channel; water is always there
Active channel: water is seasonally there phreatic zone: groundwater under the river
Do tropical rivers flow differently from the temperature ones? o Temperate water flow is fairly stable, tropical river is very unstable and fluctuating o Min to max flow for temperate and then tropical o 1:3 vs 1:50 o Greater impact on sediments and bottoms in the tropics o Uneven flow due to: extra precipitation, overcoming of surrounding landscape, weather and watershed
Do desert rivers differ in nutrients from rivers draining wetter areas?
Chemistry of rivers depends on land and climate: o Amazon (Tropical) Rio Negros 10 mg/L salinity o BC (Temperate) Columbia River 120 mg/L salinity o New Mexico (Desert) Pecos River 5000 mg/L salinity o Few minerals enter tropical rivers, in the Pecos river a lot of minerals enter the river causing the salinity o Nutrients that are in the amazon are captured by the nature (plants, trees)
River continuum concept: o Turbulence, temperature differences, higher location to lower locations, picks up minerals as it goes along, oxygen will be upstream, salts will be downstream o Leaves fall into the river, animals (shredders) chop the leaves into smaller pieces à open the internal structure of the leaf to the bacteria and fungi
§ Cellulose, other fibers are going to be converted to bacterial biomass and fungi biomass
§ Lower section is fed by what happens in the higher section
§ Particles taken downstream, colonized by microorganisms
§ Food for the next batch of vertebrates
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Grazer take the algae and feed on them, further down = more minerals= more algae § Changes in functional groups: shredders, predators, filter beaters (earth worms, mussels)
§ Stergents will be downstream because they feel on mussels and cray fish o Forest feeds the stream, the next section of the steam relies more on the stream and more on the microorganisms that are up the stream.
Life in standing freshwaters: glaciers created several lakes, they are characterized by light penetration, these waters don’t mix, less oxygen in deep water. o Sunlight penetrates and warms the water and full of oxygen
§ Photosynthesis is were accurate o Eplimnion, Metalimnion, and hypolimnion o Hypolimnion: organisms that require less oxygen o Too much production in water means you die due to oxygen levels
Diversity: vegetations adapts to the variety of water that we have
Temperate lakes: Water is dense at 4 degrees and it sinks to the bottom, o Whenever the lakes reaches 4 degrees, the water will cycle and bottom and top water are mixed together o Enough time for the winds to mix the water thoroughly, oxygen are taken from top to bottom and nutrients from bottom to top.
Lakes form a gradient form Oligotrophic to Eutrophic o Small lakes have relatively high production because they receive a lot of nutrients in a small volume. o Warm and cold species cannot survive because the lake will freeze over and the species will die. There will be a lot of oxygen production and consumption required by the warm water o Lakes that have little nutrients are good o Eutrophic lakes are very fertile lake, they store enough oxygen during the winters, and get replenished during fall and spring o Oligotrohpic: nutrient poor, clear water, deep, high oxygen, unique life, thin littoral vegetation o Eutrophic: nutrient right, green water, shallow, low oxygen below ice or thermocline, common species, extensive march areas
Which country has the greatest expanses of wetlands in the world? o Canada

Temperature: Chapter 5 o Temperature effects organisms by: directly affecting metabolism
§ Indirectly by changing the habitat
§ Availability of food
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§ Causing currents
§ Stratifying the lake
§ Freezing water (cold drought)
§ Drying the soil
Can plants regulate their temperature? o Temperature as a ‘resource’ o Dryas flowers keep tracking the sun for several hours each day, sunlight reflects from parabolic shaped flowers to heat an insect
If plants can regulate their own temperature can they affect their environment, too? o Shading and can warm up the environment o In the winter, trees around the house increase the temperature and in the summer, the trees make the house cooler o Soil temperature decreases underneath the plants, less loss of water to the air o Plants modify their microhabitat by: shading, accumulating litter or organic matter
(helps retain water), accumulating O horizon (retains more water)
Different habitats have thermal regimes; o Why does black sand appear black? Because it is wetter o Often the arithmetic mean is the same but variation differs
§ Aquatic habitats are less variable
§ Shallow riffle: varies 3rd most
§ Aquatic reed bed: 2nd most variation, near the shore
§ Deep pool has the least variation in temperature o Heat capacity of water is very high, allowing the temperature underwater to be less variable How does stream temperature affect Chinook salmon reproduction and survival? o Green box chapter 5
Can organisms optimize their physiology and growth for the typical range of temperatures? o YES! o Plants photosynthesize best at different temperatures o Migration of insects, and animals
Acclimation
o Organisms can adjust and optimize performance for different temperatures o Experiment with cuttings of a desert shrub grown in cold and hot chambers
Thermal regulations: main terms
No or poor regulation: poikilotherms
External sources of warmth: ectotherms
Internal sources of warmth: endotherms
Heat gains and losses: o Metabolic heat- internally generated o Conduction- direct transfer from other things
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o Convection- lost or gain to moving air or H2O o Radiation heat- electromagnetic radiation o Evaporation- lost during evaporation
Body Temperature o Methods used by piokilotherms may involve:
§ Coloration change (eg. Grasshoppers can adjust their body colour to capture more radiated heat)
§ Hairs (keep up from losing metabolic heat, reduces conduction loss)
§ Waxes- stop evaporation
§ Antifreezes (eg. Fish and aquatic invertebrates have complex sugars that reduce temperature under which they can survive)
§ Clustering to form cushioning
Behavioral methods o Basking (Grasshoppers) o Stilting (Beetles)
Are all mammals equally capable of regulating their body temperature? o Mammals differ in their ability to thermo-regulate depending on where they live o Tropical species maintain a constant metabolic rate over a narrow range of temperature Can insects be endotherms as well as poikilotherms? o They can shiver to warm up
Regulation: experimento Figure out steps needed to show that moths regulate their body temperature o Measure the temperature of the thorax o Measure the temperature of the abdomen of a dead moth

Water essentials: Chapter 6

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o Gradient of water potential o Terrestrial plants and animals balance water loss against water intake o Marine and freshwater animals regulate water and salt diffusion depending on osmotic pressure o Precipitation and its timing and humidity define biomes in N. America
Cicada puzzle o Sonoran desert: Air Temp= 46 degrees (deadly) o Ground= 70 degrees o Secadas sit on trees, they make a lot of noise while on trees à they remain active by they manage to sing to indicate they are single à only when they are alone (no predators) 9

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o Physics: Temperature vs. saturation of water vapour in atmosphere à saturation means that you cannot put any more water in the air à hot humid days sweating doesn’t help because it doesn’t evaporate
§ Recall water precipitation in air circulation cells (when it cools)
§ Highest saturation is at high temperature à you can put more grams of water in the atmosphere
§ Cool down the air à return the water back, into liquid, move down the curve
§ Evaporation cools (energy used), this energy rips h2o molecules out and puts it into the air
§ H2O lost as vapour must be replenished (drinking, absorption)
§ In 100% relative humidity, evaporation cannot take place and thus no cooling
§ To cool Cicada must lose water which water?
• They live underground and chew on roots and tubers and organic living plants
§ At 39 degrees Cicada felt uncomfortable and felt the need to cool down à when raised to 41 degrees rocketed rate of water release
§ Cicada fracture the bark and take water from the tree
Beetles- lives on sand à it gets water on the legs by fathering fog water on their bodies
(morning) and let it drip to the mouth o Evaporated water is released in the air when the air cools at night and morning à
Beetles capture this and drink it
Beetle water budget o Water is important to beetles- food has water à you can eat starch and convert it to water o Beetles obtain most of their water by drinking condensed fog o Food contributes a moderate amount to water gains o Water mainly lost due to evaporation and a little bit due to secretions
What causes water to move? o Water potential
Water potential- water moves from area of more water to area of less water o = Capacity of water to do work (it involves a variety of physical processes) o More water in the ground than in the air à water moves from the ground to the air due to water potential
§ Trees are intermediates o A gradient of water concentration form soil to air allows for its movement o A gradient of salt concentration can also affect water movement à jar with salt has more water than jar without salt (water flows from more salt to less salt) o The steeper the gradient the fast the water flows
Some adaptations: more extensive roots help replenish water lost to dry air o Some plants on two different sites (dry sites longer roots then wet lands)
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FIND 9 MECHANISMS to keep or gain H2O!
Is water easier to manage when you are an aquatic organism? o Is this different in fresh and salt water?
Water in water o Isosmotic: equals concentration of salts and water
§ Define which direction water is moving
§ Hagfish o Hyperosmotic- higher concentration of salts, lower of water: absorbs water
§ Catfish- absorb water from water à in order to stop absorbing water it uses its kidneys to expel water
§ Kidneys pick up salts while doing it
§ Absorb water they don’t want and expel water and retain salt o Hypoosmotic- lower concentration of salt relative to the surroundings: loses water
§ Marine fish (mandarin fish)- lose water
§ Drink water remove salt
Sharks are different: hypoosmotic organisms often drink water o Must replenish that lost to the outside o Problem: need to get rid of salts too o Only slightly hyperosmotic thus?
§ More like fresh water fish, absorbs water unwillingly and retain salts in the process In freshwater o Fish lose extra water through urine à lose salts à replenish salts by food o Water enters water through gills

Chapter 7: Energy and Nutrients
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Sources of energy: light, organic and inorganic molecules
Rate of energy acquisition is limited
Optimal foraging theory helps explains choice and location of food items
How on Earth life is being fed?
Energy use and kingdoms o Energy is obtained by: heterotrophic: uses organic matter, photosynthetic uses light, and chemotrophic uses chemicals o Who captures the most? Bacteria captures all three, Protists captures hetero and photo, plants captures hetero and photo, fungi captures hetero, and animals capture hetero and photo (only a little bit because they don’t use this energy directly, they use symbiotic algae in their tissue and use the energy that they synthesize). o What is PAR? Photosynthetically active radiation
§ Kind of energy that pigments can use to convert to organic matter, generally measured by photons flux
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§ Photon flux: number of photons striking 1m^2/ second
§ Visible light (400-700 nm) carries 45% solar energy at sea level o Three pathways for using this energy:
§ 1. C3 photosynthesis- C3 plants
§ 2. C4 plants
§ 3. Cam plants (crassulacean acid)
C3 vs C4 plants o C4 uses lower concentration of CO2:
§ Can afford to open stomata less than C3 plants
§ Conserve water
§ Do better in climate where water is limited, plants but not trees in deserts because they don’t have C4
§ The two pathways involve different number of carbon atoms in the initial photosynthate (3 vs 4)
§ C4 plants are moving further north due to warmer temperatures o CAM plants combine day and night phases with C3 pathway very efficient water use, using as less water as possible and absorbing as much CO2 as possible
§ Taking oxygen means that you lose water
§ CAM plants open their stomata and take in CO2 at night when temperatures are lower and humidity higher à store CO2
§ Water potential between air and plants is less and so they lose less water during the night
§ They use the CO2 during the day to photosynthesize
Needs for nitrogen are different between plants and animals? o Yes because animals need more proteins due to movement (muscles) o Nitrogen is a crucial limiting element
§ Animals get it from plants, animals can eat other animals ( easier then eating just plants)
§ C:N ratios show that plants are relatively rich in carbon and poor in nitrogen
(plants) because plants are not rich in proteins
§ Animals, fungi and bacteria: low C:N ratios shows that animals and fungi and bacteria are relatively rich in nitrogen
C:N ratio tells us if the biomass is rich in protein o Since animals, bacteria, and fungi have low C:N rations, they must obtain much more nitrogen per unit of biomass (or C)
§ Eating plants or each other is a solution
§ Some plants material is of low value o Plants are good for vitamins, nutrients and fibers o Needles and herbecues have high nutritional benefit, low C:N ratio
Predation shapes plant chemistry
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o Both marine and terrestrial plants are more defended in the tropics o Tropical plants are better defended than temperate plants
§ On average, higher proportion of tropical plants species bear toxic alkaloids, a potent defence against potential herbivores
§ Why?
• More consistent and diverse attacks on plants in the tropics, greater diversity of plants species, plants also have to figure out different ways to defend themselves
• Positive feedback due to other plants having strong defence
§ Result: a suite of anti-predatory defenses
Flexibility in resource use o Because nutritional values of various preys is similar, it allows predators to match their diet to what is locally available o European otter diet changes from north to south; note the fish is in blue o Diets of river otters in the Shetlands islands are dominated by fish and crustaceans o England dominated by fish but several other prey o Portugal have a wide variety of different foods
Chemical energy o Tube worms are related to earth worms and they depend on chemical energy à typically found in the undersea vents (thermal vents) at that temperature water dissolves minerals that are not easily dissolvable à metals o Hydrogen sulfate comes in abundance (H2S) à red tissue surrounding the worm is filled with bacteria à that combine H2S with O2 and the S and O burn and produce energy o Energy can be used to metabolize à organic tissues o This is symbiosis
Does the amount of food consumed changed depending on how much is available? o Is this change regular or can it take different forms?
Functional responses o How much a predator eats depends on prey density o But it does not depend in the same way
§ Three types of response:
§ Shapes: Linear (mechanical), gradually saturating (glutton), slow to start
(connoisseur)
o Tell us how an animal handles prey
Optimal foraging theory o Is based on balancing the energy invested and energy gained (optimization) o Process between cost vs. benefits is done between energy, risk or other necessities o Can be applied to plants; helps predict the best way of using water and nutrients o Low prey capture rate and high search effort are bad news
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§ Sometimes you have to eat what you don’t like in order to refuel
Root length changes in response to water availability? o Same applies to other nutrients- plants optimize resource allocation o Nutrient availability determines how deep the roots are, therefore you water everyday, short roots, once a week- longer roots o Plant decision making can be done through: size of roots vs above ground structure
(root to Shoot ratio)
§ A measure of relative importance of above and below ground parts o More nitrogen à less roots because you do not need structures that acquire more nitrogen o Root: shoot ratio decreases are nitrogen increases
Can a simple theoretical index (C:N ratio) help with management of environmental problems? o Carbon provides fuel, physiological structures while nitrogen provides cell structure and proteins
Applying C:N ratio Knowledge o Cyanide, CN, removed from gold mine ore o Ore contains much N (1:1 ratio) but not much carbon o Bacteria eating CN have C:N= 5, so they will be short of carbon if they only feed off
CN
o When sucrose was added to CN, bacteria degraded the CN completely (100%)
§ This was 10 C: 1N
Organisms use three sources of energy: light, organic, and inorganic molecules o Only a fraction of energy contained in the three sources can effectively be used o Optimum foraging theory helps to understand how costs and benefits of energy acquisition affects organisms o Knowledge of these nutrient requirements aids in technologies (sewage, toxic compounds) Chapter 10: Populations- distributions and abundance
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Does habitat quality determine geographical distribution of species?
Distribution of kangaroo species o Macropus Giganteus- where precipitation varies little from season to season but rain is not rare o Where the winter reason dominates o M. Rufus- where conditions are hot and dry
Distribution and climate often match: the case of a tiger beetle o Unlike some other species, its temperature preference is constant o The beetle only operates at temperatures of 35 degrees, areas where temperature does not reach this, they are not found
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When related species (Encelia), have different T and water requirements, they are differently distributed o E. californica confined to a narrow zone along the coast; cool and moist in the north and cool and dry south o E. actoni lives further inland; drier and warmer areas o E. farinosa and frutescens live in much hotter islands
§ How do they manage?
Can difference between adjacent microhabitat make a difference? o Microhabitat- scale relevant to an organism
Encelia species differ in light absorbance o Some of them receive a lot of light and some of them are protected from too much light o Nonpubscent leaves of E.frutescens absorb approx. 80% of incident photosynthetically active radiation o Pubescent leaves of E.farinosa absorbs less than 40%
Distribution of two barnacles within the intertidal zone
Barnacles are shrimp, but they build skeletons and are sedentary o They capture plankton
Balanus: larvae can settle anywhere, adults are limited to the high neap tide and low neap tide
Chthamalus: larvae- settle in upper areas, adults settle only in very high zones
When compared adults to adults: the two are able to prevent from overlap
Barnacle mortality in the upper intertidal zone o Warm weather and calm seas produced much higher mortality among Balanus
Balanoides than among Chthamalus stellatus in the upper intertidal zone o C survives longer in warm weather without wave spray o This explains why it remains in higher intertidal zones
Does a pattern of distribution provide information on what individuals do?
Microscale distribution can reveal species interactions o An individual has an equal probability of occurring anywhere in an area à in agreement to a random pattern
§ Neutral interactions between individuals and between individuals and the environment o Regular interaction: individual are uniformly spaced through the environment
§ Antagonistic interaction between individuals or local depletion of resources o Clumped: individuals live in areas of high local abundance which are separated by areas of low abundance
§ Attraction between individuals or attraction of individuals to a common resource
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Regular and random distributions of stingless bee colonies in the tropical dry forests o Colonies of the stingless bee which interact aggressively and distributed regularly across this tract of forest o From rival colonial battled daily for possession of nectar and potential nest
Less intereactive stingless bee, T. dorsalis is distributed randomly across the same tract of forest à random distribution
Interactions may change over time, with growth of individuals (shrubs in the hypothetical situation below) o Small shrubs establish in high densities and produce a clumped distribution o Mortality as the shrubs grow reduces clumping and produces a random distribution among medium shrubs o Competition enforces a regular distribution among large shrubs
Creosote bush root distributions: hypothetical vs actual root overlap o The root systems of 32 creosote bushes were mapped o If excavated shrubs had circular root systems 20% of the areas would include extensive overlap of four or more shrubs (shaded area) o The actual root systems were not circular and overlapped extensively in only
4% of the area
§ Note the scientific method here: null model
Abundance of three tree species on a moisture gradient in Smoky Mountains o Table mountain pine, red maple, hemlock o Table mountain pines are most abundant on drier upper slope o Red maples at midslope o Hemlocks on moist valley bottoms o Once species replaces another as you move up the slope o Note the greatest abundance in about the middle of each species distributions
(the bell shape)
Which are more numerous mice or deer? o The bigger the body mass the less the density of herbivores o Factors responsible for loss of dinosaurs, the density was less due to their large body size à probability of extinction was much larger o Herbivorous mammals of North America o If they are smaller their density will be higher
Animal size and population density (all animals) o Aquatic vertebrates have a higher density for body size then terrestrial o Mammals have greater density then birds o Birds need more energy to fly then for mammals to stay on the ground à since birds aren’t no more efficient are finding food, there will be less birds
Distribution, habitat tolerance, population size o Commonness, rarity and vulnerability to extinction
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Chapter 11 Populations: Structure
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Survivorship
Age distribution
Life tables
Dispersal
A population of tunicates: colonial relatives of vertebrates
Do all individuals born have the same probability of survival? o They have the same probability when they are born but it differs once they start aging
Dall Sheep (mountain sheep) o Investigations used wolves to collect data o Determine gender from skulls- using this data they were able to analyze the population of sheeps o You use a cohort to track the population, either by 3, 4 5 years o Dall Sheep follow Type 1 survivorship curve o Their mortality is the highest at: o Life table for dull sheep
Other organisms may have similar survivorship curves o A rotifer (1mm worm)- their survivorship curve is initially high and then it decreases slowly, the old rotifers (7 days and older) die much faster
§ This is typical of Dall Sheep and Humans o Two birds (white crowned sparrow and American robin)
§ Here mortality is unrelated to age
§ Linear decreasing curve, same proportion of the population that dies o Plants- start with 1Million seedlings and they die very rapidly, and between
50- 100 seedlings survive first year and then the survivorship increases, the rest can live up to 60 years
§ Concave down curve
§ Numerous offspring often means low survivorship at early life
§ In a population of C. droserifolia only 39 plants survive to 1 years of age of each 1 million seeds o Common in fish, and other plants o Sharks have the same survival chances as humans
Type 1: Juvenile survival high, mortality mostly among old individuals
Type II: Individuals die at equal rates, irrespective of age
Type III: great loss of individuals at early age, good survivorship later in life
Can we use the survival curve to infer the state of a species?
Difference in dying and surviving lead to difference in numbers of old and young individuals 17

This population of white oaks is dominated by young individuals
Type III survivorship
Oak population is biased towards population of young oak trees
Last 50 years, there have been an increase in Oaks (they have been seeded and they are growing) o This age structure shows that older trees are being replaced by young ones
Cottonwood
o A cohort of 20 o There are very few young individuals and a lot of middle age individuals and very few old individuals o Fewer and fewer individuals have been successfully seeding and growing o This might lead to extinction- a dying population o Insufficient replacement
Cactus finch ( Galapagos) o Age structure allows reconstructing population history and predicting its future o Population tracked from 1977- 1987 and its age structure for 1987
Life tables can also include births per individual, which permits; o Calculation of Ro- the new reproductive rate per individuals
§ How many new individuals adds on balance o And finding lambda- the geometric rate of increase (of population) o A ratio of new population to old population o lambda= Nt+1/ Nt o Size of the population at two different times to get the rate o r= ln Ro/ T(generation time)
Ro is calculated from life tables
T, the generation time is also calculated from life tables
The two can be used to calculate per capita increase of population, r
Ro only tells how much a population increase from generation to generation (which may be short or long)
“r” is very important parameter as it allows to forecast population ahead of time
What is the sex ratio?
Why is the ratio of male to female ratio is often close to 1?
Do individuals that are born and survive always stay near where they were born?
Dispersal
o Affects population density (emigration)
§ If you population in one generation doubles, its good to move away because the number of resources become scarce o Involves a variety of mechanisms
§ Direct thinking assessment o o o o

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§ Signal to starve (not enough food) o The windblown seeds of dandelions can be disperse long distances o As can the waterborne larvae of barnacles o Juvenile spiders disperse by spinning a silken thread that catches the wind
Unwelcoming dispersal o Organisms that come from other parts of the world cause ecological damage to the foreign countries o African bees introduced to Brazil to breed with honey bees and make them a better species
§ Africanised bees- when they broke from human containment
§ They started spreading and move very fast across the continent
§ Mechanism: active dispersal of swarms , compete with native, they continue to move until they find the right environment and climate and they reproduce and move on
Plants may respond to climate change o Maple spread North after glaciers retreated à when the glaciers melted the maple kept moving northward and they can still move further north but it stopped 6000 years ago when the climate stabilized o It took more time for the maple trees (8000 years) while bees did a larger distance in 20-30 years
Do all species disperse with equal ease (same distances, speed, numbers)?
What factors may be responsible for differences? o Availability of resources o Wind o Active dispersal o Hitch hiking (used by recent colonizer Clam that came from the Sea, and it colonized the Great Lakes
§ Introduced great modification to local ecosystems à both plant fisheries and other fisheries
§ They larva may be attached to wheels and they might be taken to the next lake and so on, they may also have used rivers
Rate of dispersal differ o Early humans are thought to disperse at 10 km a year o Dispersal may be a response to food supple, climate change, random rodents and others
Food Availability o Density of predators, owls and kestrels changes as vole density changes- why?
§ Kestrel and owl densities closely follow variation in vole densities in western Finland
§ Due to dispersal, not mortality
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Drift requires upstream dispersal o In the colonization cycle, upstream and downstream dispersal and reproduction have major influences on stream populations o Fish and invertebrates cannot resist water movement
§ Organisms that live in streams have special adaptation that allow them to move back to the areas upstream in order to re-establish population
§ They follow the polarization of light, smell and chemistry o Fish are much more migratory- breed in the upper portions of the stream and move down as they increase in size

Chapter 12: Population Growth
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Quelea form flock and move from move site to another
Populations can grow at geometric (exponential rates) o Rates that continuously accelerate in growth
When limited, they grown logistically
Growth is limited by environment’s influence on birth and death rates
Small organisms have higher rates of increase
Can we figure out what population size will be in the future?
Is there a simple answer?
Anatomy of Geometric growth; o Nt= N0(lambda^t) o Lambda: average number of offspring left by an individual one time interval
(b-d)
o Nt: Number at some t
Exponential growth; o Define: r= net (b-d) rate of per capita increase; (speed). Thus;
§ dN/dt= rN à population change (rate)
§ this is exponential growth curve o Phlox plant: exponential growth
§ Plenty of space, nutrients and resources weren’t limited as population increase Continuous growth: calculating N o Nt=N0(e^rt) o Nt= number at some time t o N0= the initial number times e raised to the power rt o R= per capita rate of increase (b-d) o T= number of time intervals
Example: collared dove
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o Exponential growth for 15 years after colonization of British Isles o Population increase rapidly after colonization o Growing but slower after that- a question emerges:
§ What slowed it down? Predators (slow, spend time on ground), food is scarce Geometric and exponential models predict an accelerated growth of numbers but is it possible? o If not how do we find out what future size of a population will be?
Answer: Logistic growth o Population cannot grow infinitely. A population can not exceed a certain maximum or carrying capacity o Carrying capacity= the number of individual that the environment can keep o K= carrying capacity (max N). Thus if there is a limit. This acts like a ceiling for population o dN/dt= rN((K-N)/K) o when N is small population can grow according to exponential, when N is larger, the population slows down compared to exponential o Environmental resistance: surviving and reproducing becomes harder and harder Logistic growth: example o Paramecium grown rapidly for 10 days- then the population levels off (food, metabolites, both?)
§ Population grew slowly for 5 days, then population grew rapidly for 5 days, and then it levels off
§ Carrying capacity, the population declines to return to it, they overshoot and then starve and then population crashed below carrying capacity and environment becomes optimal again and the population overshoots § Crash and leveling off o Yeast cells initially grow fast (until sugar is exhausted)
§ Low densities the yeast population grows at a high rate
§ At higher densities growth slows and then levels off
§ The organisms can change carrying capacity (ie. Medow produces enough grass for 100 cows, if you keep 100 cows, the soil become more compact and the production of grass decreases and carrying capacity for cows decreases.
§ Yeast keep producing alcohol, and once they have too much they stop o Rm is the reduced by N

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Maximum rate at which population can grow assumed that conditions are optimal (ie. Resources are unlimited, encouragement to reproduce, space) § As organisms accumulate à the space is constraint, resources are constraint and rate decreases
§ Logistic equation on N and K; dN/dt= rmN((K-N)/K) o Rm is the max rate of per capita growth, the maximum rate of increase rm, occurs at very low population size
§ If NK, r is negative and the population declines
Example: Daphnia pulex o Daphnia is kept at different densities (water flies) o They graze on algae à reproduce fairly fast o Reproduction per individual is recorded o Each point is a separate population o They reproduce asexually o R declines with N à population of high density can be predicted to grow at low rate o When they went over 16- 24 individuals they started declining
Carrying capacity may fluctuate o With the conditions of the environment o Population size in a ground finsh changed in response to rain (à vegetation, à insect food) o Wheat production has been less this year than previous years à an example of how carrying capacity can change, therefore if we all depended on wheat then the entire carrying capacity of human population may change by 10% o Rain means better vegetation which means more insects à finches can be protein and energy, when there is few insects they switch to plant material which is not as efficient or good for them
Drought (1976-1977) led to high mortality
Good rains (1983)
Additional data o Density of caterpillar depends on weather
§ Number of caterpillars counted in 5 mins, in year 1981 (dry year) its 56 times less than in year 1983 (wet year) o Number of young produced by finches depends on caterpillars, number of young in 1981 was less than in 1983
In dry years the number of egg clutches is small, number of egg clutches (per pair) is correlated with annual rainfall (mm).
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o During years of low rainfall cactus finches produce one or no clutches o During years of high rainfall they produce 4-6 clutches
Finches damage cactus o As finches population fluctuate in response to rain, so does damage they inflict on the cactus, Opuntia o Number of flowers, when the flows are abundant damage by finches is low (in dry year) , damage increase when flows abundance is low (in the year that it was wet) o Here the number of flowers and the weather modulate the amount of damage by finches, when a lot of flowers they can exploit it, when there aren’t a lot of flowers o Importantly the effects propagate onto the organisms
Bio Notes Written
40 Qs, 2 questions are Short Answers rest is MC
Human population- distribution o Remember clumped distribution?
§ Great variation in human densities between and within continents
(more or less matches habitat suitability)
§ Canada very cold, deserts (cold and hot deserts), dry places
§ Human population grows at different rates in different places, where population is growing fast might be related to environment, cultural or historical factors
Can we figure out where the population is heading?
Lithuania- you cannot have more individuals born than the middle aged groups, has a declining population because less infants then middle aged o Can be due to ecological or economical factors?
Rwanda: each cohort is greater than the one before it, and do the population is increasing at an accelerated rate
If b,d (=r) are constant, the populations of Lithuania, hungary and Rwanda will change; Human population changes its own carrying capacity: imported energy (metals, lands), also at the cost of the environment o Finite resources and so it will become more and more expensive, preventing the it from being able to hold large populations

Chapter 13: Competition
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Would all species have the same carrying capacity, K when they live in the same habitat/place? Population density, soil nitrogen and grass size o Nitrogen is a limiting nutrient for the grass S.nutans
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Limiting nutrient inhibits population growth first
S. nutans was grown at high and low densities on a gradient of nitrogen availability
§ Low densities became large, high densities (despite high nutrients) would not become larger à with the addition of increasing nitrogen
§ Plants fail ot gain size when grown at density with respect to nutrients availability § Intraspecific competition- competition within the same species
If intraspecific competition matters, what would be its ecological outcome, particularly among plants?
Self-thinning in plant populations o Many of the small and crowded plants die
§ They cannot grow, they are weak and they are wimps
§ Consequence population will move to lower density
§ Population will be losing population but will be gaining biomass
§ Loss of individuals means gain of biomass by the remaining individuals à which is often seen in forests o The self-thinning rule: predicts plants density to decrease and the total biomass of all others increase
Self-thinning in alfalfa populations o Initially plants planted at high density o Mortality thinned the surviving alfalfa population as the remaining plants grew Would competition affect health and survival of animals in way comparable to plants? o They may be competition for; food, water or life
Population density and survival (isopods) o Crustaceans; provided with abundant food and you compare the survival of isopods in low density vs. high densities o When they are placed in high density they only survive 50% while in the other situation they survive 70% o They interfere with each other; eat each other, too close, stronger starts chewing on closer o Interference competition differs from resource competition
The niche concept o Summarizes the environmental factors influencing species performance o The frequency of seed consumption will reach a peak and it will successively decline o It is a kind of ecological signature of a species; o An n-dimensional volume (each variable forms another dimensions)
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§ Ecological space that the species is using à differs per species o Fundamental niche: range of physical conditions a species can live with in the absence of other species o Realized niche: actually occupies
What is the link between the niche of a species its morphology? o Regional niche relate to how we look, north (stocky, shorter hands and legs) o Southern: lighter, dark skin o People in hot climate tend to be taller and slimmer, less sun exposure than stocky Body size and seed size o Are correlated o The small ground finch eats mainly small seeds, the medium ground finch eats mainly medium seeds, and large ground finch eats mainly large seeds.
§ Depends on beak depth
§ Here frequency of large seeds consumed increase with beak size o The bigger seeds are larger consumer also increase with beak size
Seed depletion and average seed hardness o Supply of soft seed changes over time o When population goes up, seeds go out and the availability of seeds and environment changes o As G. fortis depleted the seed supply, the average hardness of the remaining seeds increase, then average seed hardness declined as new supplies were produced in 1978
§ Low seed numbers due to drought caused a shift in consumption and back § Side effects: droughtà finch (sometimes it picks more seeds from one plant and sometimes from the other) predation differs and so does production Selection for larger body size during drought o Eg. Food is far enough that you don’t get food if you can’t walk far enough, then you will not be able to reproduce o During the drought of 1977 larger birds capable of cracking hard seeds survived at higher rate. Consequently the population was dominated by larger birds at the end of the drought o Weak beaks die out big ones survive on o Here competition modulates body size in a population
If carrying capacity differ among species, what consequences that may have for their numbers/densities? o Maximum number of individual that an environment can support

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o If the carrying capacity is higher the population to reach it will still be higher
(greater mean will still be higher)
Population growth and K densities o Gause experimented with paramecium o Half strength medium, both reached a carrying capacity, K= 105 and K=64 o When put in a full strength medium (more food and resources), carrying capacity doubles o When grown separately max density depends on food alone; although the species differ o Maximum density= higher carrying capacity o When you put both of them together, the paramecium that had lower carrying capacity goes extinct
Is competitive superiority fixed for any pair of species that we compare? o What may affect it?
Flower beetles when grown separately do well (34C and 70% humidity)
When separate at 24C and 30% humidity, red does poorly (roles reverse)
There two species respond differently to different environments then, it pre-disposes one of the species to doing worse already
When together, red does even worse interspecific competition
Remember the distribution of two barnacles species within the intertidal zone? o If a parasite enter the environment then it affects the population and lowers their carrying capacity (it can be anything that affects their resources) o Absence of balanus was due to poor larval survival in the dry zone
Competition experiment with barnacles o Removing the Balanus in the upper intertidal zone has little effect o Chthamalus (dry land barnacle) is not because it cannot live thereà it does very well there, but instead its due to the Balanus because of its competitiveness o Not due to physical conditions but due to competition
Competition Theory o Lotka and Volterra developed a mathematical approach to modelling competition o The approach stimulated quantitative research in ecology (because it predicts specific outcomes)
Logistic growth o In a finite environment population follows a growth pattern where the population reaches a carrying capacity
What happens when two species must share a limiting resource (one that defines K)?
Would growth of one affect K of the other?

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o Yes! As resources decrease for one due to consumption from other, it also decreases its carrying capacity
Two species o Take a finite resource and two species ‘consuming’ it with one species and no competition o Individuals would use all the resources o First: Carrying capacity is 13. Population cannot increase o Second: species can fit 65 species o A green could replace 5 red individuals. The red thus= 1/5 of green individual and the green= 5 red trees. o Small species have greater carrying capacity then the larger species o We know that increase in N limits further growth
§ If you increase green, less room for the red. Vice versa
Competiton coefficient is the measure of the inhibitory effect of species on one another Two species equation o Two species logistic growth function for species 1:
§ dN/dt= r1N1(K1-N2- a12N2)/K1
§ Read: increase in population size of species 1 is a function of its r, N, and numbers of species 2, N2. o We cannot use this to predict anything but you can determine the effect of growth rate from species 1 on species 2.
Do you want to do the calculations using the two population growth equations?
Analysis: these equation can either be solved or examined visually o Lets see what happens when both species stop growing (say, all space is filled) due to competition o Mathematically this means that the rate of population change is 0 for each other them: o Then r1 or N1 or (K1- N1- a12N2) must be 0
Isoclines
o Recall K1-N2- a12N2 = 0 and consider the absence of the other species (N1 or
N2 = 0) o When N1=0 then N2= K1/a o Species 1 cannot grow beyond K1 and beyond K1/a of species 2
Lotka- Volterra model predicts; o Species will coexist where intra-specific competition is stronger than interspecific

Chapter 14: Exploitation (Predation, Herbivory, Parasitism, Disease)

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Exploitation weaves species into complex webs à multiple edges both negative and positive, controlling excessive populations
Predators, parasites and pathogens affect abundance and distribution of species
Adaptation: refuges and fled
Life Cycle of P.Cylindraceus o Predation and parasitism combined: as example o Worm’s eggs in the bird intestine; released with feces o The dropping of the bird falls on the ground à where insects seek and be attracted to the organic matter (sugars, nitrogen) eg. Isopods and scrubs and release eggs o The isopods eats feces; eggs develop into worms o Isopod forage and move on the ground o Starling consume the isopods; worms infect the bird o Birds are weakened by having parasitic worms
Starling predation on isopod, A.vulgare o Observations: infected isopods at much more preyed upon then uninfected isopods, this benefits the parasite o Those that are infects are less sensitive to exposure, infected isopods shelter less, do not see humid habitats, walk happily on light colour substrates o Conclusion: worms alter behaviour of isopods thus predation intensity in order to parasitize birds and disperse better o Fungi may modify plants on infects on plants
Does predation affect the size of the prey population or just means an accident happened to the affected individual?
Biomass of algae and grazing caddisfly o Stone case of the caddisfly larva- insect hides itself and protects itself from being eaten o They go into stone covered with algae and eat it à scrape them o Predation may strongly affect target population o Example: algal biomass responds strongly to colonization of ceramic tiles by a grazing caddisfly
§ Algae biomass decreases as the grazer (caddisfly) increases
How effective is parasitism?
Biological control of prickly pear, Opuntia o Parasitism may affect target population- invasive pest in Australia
§ Example: introduced Cactoblastis destroyed prickly pear (reduction from 12000/ha to 27/ha)
§ Its larvae begin to chew on the tissues of plants à causing the reduction in plants

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In principle the predator becomes less effective as the prey becomes thinner and thinner. In mechanism is singular, these moths do not like to fly, if they successfully lay eggs on one plant and there is no other plant on site, they cannot fly 20m to find another plant. They just die with the plant they live on. It becomes harder and harder to destroy plants § The prickly bear does not increase because as soon as it does, the moth increases in population and the plant decreases in size again
Foxes and mountain hares in Sweden o Time series may indicate causes: o There is a cycle where the number of foxes affect the number of mountain hares that exist, as the number of foxes increase, the number of hares decrease o Foxes exposed to disease which causes the loss of hair and this causes the population of hares to increase rapidly o The hare population crashes because resources are depleted o The foxes were responsible for the vulnerability of the hare populations
Predation dynamic relationships o Returning to the tropic of predation, parasitism, and disease from a theoretical angle o Focus on the dynamics of predator- prey model
Lynx vs Snowshoe Hare o Catching hares and lynx for pallet was a very economical activity à they sold them to the Hudson Bay Company o The cycle between the snowshoe hare and lynx populations o The hare would have a lower population during the winter and therefore the lynx population also falls and then when the hare population increases again, they lynx population increases as well o Causes: price fluctuation (hunters do not have incentives due to price), sun spots (11 year cycle), bad weather for hunting, food supply (for hares) or food quality o Answer: food quality, weather and predation add up to create this pattern à it is not about how much food is there in the summer, but the amount of food that accumulates over the summer and isn’t covered by snow (hares do well), hares need food storage for winter. o Hares are doing well, increasing number and eat more and more food during the summers à less and less food during the winter time
§ The lynx population starts eating more and more of the hares
§ The hare population goes down during the winter and the lynx population also decreases o Bad weather exaggerates this effect
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Lotka-Volterra equations o For prey species o dN/dt= rhNh – pNhNp o the rate of prey population change equals the exponential rate of increase by prey population minus p- the number killed by 1 predators
Predator equation o dNp/dt= cpNhNp-dpNp o rate of predator population change equals the rate, cp, at which prey are converted to predators (offspring) o cp= hot to predator conversion rate o dp= predator death rate o determines how the predator population will grow in relation to the prey, and how the prey population will grow due to its losses to predation
Plot prey and predator against time and each other. o Prey N vs Predator N à forms an entire circle o Predator and prey N vs time à as prey increase, predator decreases and vice versa o Outcome: oscillations in time can be viewed as cycling of two populations
§ If the environment changes the graphs will not be as smooth as they are § Finches= drought bigger beaks and rainfall selects for smaller beaks
§ Add noise and the path will be widen
How one could test the model predictions? o Experimental approach to retrieve data because not all info collected are directly the result of prey and predators
Laboratory populations of hot and parasite o Parasite kill the weevil beetles (they eat plants), wasps lay larvae inside the beetle and it eats the beetle from the inside o Weevil beetle and parasitoid wasp o The peaks rarely overlap, therefore the peaks and dips of the two species do not generally overlap
Refuges and persistence of predator-prey oscillation o Paramecium and Didinium: in the absence of refuges and immigration o When they are placed together, the number of predators and preys o The prey increases the predator, gets exhausted and both die o With a refuge, prey persists predator loses -à population of paramecium does well after the predator dies o With immigrations both prey and predators persist and oscillate o As you decrease the density of prey, the territory of predator increases (fight for space and food)
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Environmental complexity and oscillations o 120 oranges were placed with jelly barriers, partially protected from predators, prey can ‘fly’ o Mites are relatives of spiders without the waists o When both populations were enleashed in that environment, the two regular cycles. § Predators don’t have wings but they produce a web and since they are so small they are lifted to another orange by wind
§ If one declines to zero so will the other and the prey and predators will be lost completely, once they hit zero they cannot reform
Cicadas: they live underground around 11 years and once the egg hatches and feeds on plant saps and roots, they all come out at the same time, this gives difficulty to birds and therefore, the birds learn to replace their diet and when all the cicadas come out there is an excess of food o Predators satiation (prey escapes from predation through numbers) o Wildebest lay their babies at the same time, and therefore hyhenas and lions cannot have a significant impact on the population because they cannot handle the excess of food
Cicadas populations density and mortality o Cicada density increases , the fractions of population killed by predators decreases o The first few were eaten about 25% chance o Then as more and more cicadas started coming out, the fraction of population killed by predators was almost 0 o When the number of the cicadas drop, the number of cicadas being eaten increases exponentially o Many predators (birds, rodents, squirrels and bats), they need to cue in, as the season progresses there are more bird offsprings to feed
Large mussels are eaten infrequently; escape from predation by size o Changing size allows of escaping predation o Paine experimented with predation by starfish on mussels on the rocky shores of Pacific o Small starfish tend of eat muscles 4-5 cm in length o Bigger 20cm starfish eat muscles 10 cm in length o This forms a linear correlations between the size of the predator and prey o Big starfish above cm in size don’t bother with small muscles o If beyond 24 cm, you no longer eat muscles that are small
Posturing by ephemerellid mayfly o Other defensive mechanism- bugs put their tails over their heads like scorpions. 31

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By assuming a “scorpion” posture they are able to prevent themselves from being eaten by scorpions

Mimicry o Resemble something else: Mullerian mimicry- trying to resemble someone that is unpleasant o Batesian mimicry- resemble the same o Cryptic- look like the background of the environment that you live in, camouflage § Birds eat a disproportionate number of the conspicuous members of a peppered moth population
§ The moths took up darker colour to match the darker bark to prevent from being spotted by birds
§ Yellow and black and red combinations have been adopted as not being eatable à tell other organisms that they are harmful
• Mimics try to look like them to deceive the potential predator
Seahorse that resembles algae, they live on pink corals and they look like pink corals
Parasite Schistosoma o Female lies in the grove of the male o The male sticks to blood vessel in different parts of the body and sucks on blood and tissues o They live in our bodies
Life cycle of Schistosoma o Debilitating parasite, complex life cycle, easy re-infection o An egg ends up in the water and it passes through the body o The larvae attacks the snail and penetrates the snail skin and make more of themselves o Then they break out of the snail and come out as a form of cercaries à is swims in the water column o It can drill through human skin and enter the body and infect humans o They are a mm long o They can cause swelling in the abdomen, they have been discovered in
Egyptian mummies o Millions of people are affected, and very difficult to get rid of
Distribution of snail hosts and crayfish o Introduced American crayfish eats the snail, host of flukes o Cray fish did not survive in all the ponds of Africa but where they did it was only the crayfish o Only a few ponds have both organisms o Most ponds have either snails or crayfish not both o Crayfish put selective pressure on the snails
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If the crayfish produces well, it can put significant pressure on the snails and decreases the probability of the Schistosoma cycle by 10 times
Behaviour is the most common way of resisting predators

Mutualism Chapter 15
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Hummingbirds during the night, they go into torpor à where they do not maintain their body temperature and cool down significantly o Otherwise they wont survive because the nectar can only last them 5 minutes or so
Moose- symbiotic relationship with microorganisms to help digest their food for them
Fungus root symbiotic relationship- many larger plants grow roots in to the soil, roots do not necessarily absorb nutrients and water, its usually the fungi that grows on the roots that does this
Are there species that do not engage in mutualism or how common mutualism is?
Plant performance and mycorrhizal fungi o Fossil record à mycorrhizae arose early in evolution of land plants, perhaps as long as 400 M years ago o Mutualism between plant and fungi
Lead water potential o Water concentration in the leaves vs. the water potential in the air o If the water potential in the leave is higher than the air then you are getting water otherwise it will die o Apropyron with mycorrhizae maintain higher leaf water potential throughout hot summer days
§ Water potential in MPa, plants with mycorrhizae have more water potential then plants without mycorrhizae
§ Specially during midday à they have twice the amount of water potential o With increased performance plants can afford to invest less in root biomass and divert resources to the green shoot à less seed less fruit, may not be able to compete with other plants à essential sterile
Plant performance and mycorrhizal fungi o Mycorrhizal fungi provide plants with greater access to inorganic nutrients while feeding off root sugars o Plant allows to absorb sugar from the roots and in return delivers nutrients and release enzymes that make insoluble substances soluble in water which they can absorb o Which other organisms do that?
§ Nitrogen absorbing bacteria
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o Increase plant access to phosphorus and other immobile nutrients (nutrients that do not move freely through soil) such as copper and zinc as well as nitrogen and water. o An arbuscule (little tree) a fungal structure for exchange of minerals with parts of the host
Ants and bullshorn Acacia o Swollen thorn acacias: 2-3 cm in diameter, they are very hard on the surface, the ants find a little hole and excavate it o One relative of ants can occupy one acacia o Benefits for ants: always produces leaves, nutrients all year around o Leaves not only serve the plants but also the ants à foliar nectarinesà source of sugar and liquid to the ants
Leaflet tip modified into concentrated food sources Beltian bodies à source of oils and protein
Why does the plant need ants? o Fast and agile runners o Good vision o Forage independently o Benefit : larger colony size if supplemented with food o Ants eat other animals small and large (birds, insects, lizards and etc.)
Newly mated queens find unoccupied seedlings or shoots of bullshorn acacia o Ants from time to time ants go on a date with the queen and the queen produces larvae which the sister ants take care of o A young queen excavates entrance in one green thorn à lays first eggs in thorn à begins to forage o The queen begins much bigger o Gets nectar for herself and developing larvae from the foliar nectaries and the
Beltain bodies o Colony grows (workers) à actively take up chores of colony o Queen shifts to reproductive function à abdomen is too large and cannot go out to forage anymore
Benefits for plants o Ants and the abundance of hervivorous insects on bullshorn acacia
§ This does not necessarily mean that acacia is protected, fewer organisms eat acacia with ants then acacia without ants
§ Acacia shoots without ants have much larger numbers of herbivorous insects o 8 times different in the presence or absence of ants on acacia o Ants have similar arrangement with our native trees (aspen where they tend aphids which obtain sugar from the plant)
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o Aphids are very tiny bugs and puncture tissues of plants, they obtain sugar where they puncture the tree, the ants come and tickle these aphids and the ants receive a drop of sugar and in return the ants don’t eat aphids o In Indonesia species of ants that uses heteroptians they tap into the sugar flow of the plants and release a bit of sugar at the other end and ants take it
§ The ants take them to another plant the next day and place them in the most optimal spot and then the insects retrieve the sugar for ants and the next day the cycle continues o Treehoppers, aphids, and bugs have two blades that can puncture the tissue and a tube sucks in the fluid o The ants are restricted to the plant and so if the plant have less insects visiting or less sugar then they have to suffer
Benefits for plants o Survival of acacia shoots with and without residents ants o Survival of the young acacia with and without ants is different: with ants the survival is higher then without ants
Growth of acacia with and without resident ants o For acacia with ants the growth rate is much better then plants without ants o Without ants: leaves lose photosynthetic potential, and leaves and affected by disturbance Acacia- ant mutualism overview o In exchange for food and shelter, ants protect acacias from attack by herbivores and competition from other plants o Ants even chase tongues of giraffe’s tongues when the tongue comes out to extract the leaves from the plants
Acacia talk to each other, they release chemicals saying that there are a bunch of giraffes comes and the acacia pump special defensive chemicals into their leaves and protects the acacia from the giraffes
Workers will attack, bite and sting all insects or large herbivores
Workers kill any vegetation encroaching on the host tree o Ants are types of wasps so they can sting
Workers keep acacia free from competition for water, light, nutrients by other trees, shrubs and vines
Therefore, the host plants and ants benefit in many ways
How flexible are mutualistic relationship? o Are they inherently beneficial?
Temperate systems à alpine aspen sunflowers o Aspen sunflowers attract ants by producing nectar at extrafloral nectaries structures outside of the flowers o Extrafloral nectar rich in sucrose and high concentrations of amino acids
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o Similar to swollen thorn acacia
Other actors do matter o Sunflowers benefits from ants o Grey sunflower seed weevil o Banded sunflower moths o They both attack seeds of sunflowers and that’s a major investment of the plant and determines reproductive success o In the central rocky mountains a variety of seed predators attack aspen sunflowers o Seed predators damaged over 90% of seeds produced and when the ants are present the seeds are protected
Relationship between sunflower and ants is facultative is conditional, not mandatory and optional depending on the circumstances o The relationship between ants and acacia is obligate. Why not obligate on aspen sunflowers? o Long-term study: every few years the flower heads of aspen sunflowers are skilled by late frosts à timing of the flowering such that late frost may kill the sunflower and so the ants must be able to survive even if the sunflower cant provide for them o In obligate mutualism with aspen sunflower ants would occasionally have no food and go extinct o Mutualism evolves if benefits are greater than costs o You do not need to study the equations o Another kind of mutualism: farming an ant taking care of scale insects o Ants are the only species that do things similar to other species like what humans do
What about the aquatic organisms?
Coral reefs: they provide habitat for fish and food o Corals modify the landscape in the ocean o Species richness on coral reefs 0.5 million à coral reef productivity is among the highest of any natural ecosystem o Where coral reefs are present the water is very poor, all the nutrients are kept in living things and they are very quickly moved between living things without going into the water column and going away
Sea slug can be poisonous and eel o Exceptional productive results in diversity occurs o Corals are the key- green algae sit inside the corals, the algae are small creatures that are being consumed by zooplanktons but algaes in corals are protects because corals eat zooplanktons, corals provides nitrogen for algae, it

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helps rebuilt proteins, corals get these nitrogen from organisms that they consume § Algae: light, protection and nitrogen
§ Corals: energy, plants have access to solar energy in forms of organic compounds o Corals induce zooxanthellae to release organic compounds using signal compounds à alter permeability of zooxanthellae cell membrane
§ Organic compounds released constitute up to 99% of algal production o Tank containing corals without zooxanthellae and with zooxanthellae, corals with zooanxthellae excrete ammonium into the environment, in contrast corals with zooanxthellae absorb ammonium from the environment
How complicated can things become? o Pocillopora- victim o Acropora- victims o Corals are become food for pilot fish, starfish and sponges eat them because they are soft and produce soo much food o Pistol shrimp- defends the corals
Coral species with crustacean have less predation rates corals pay back trapezia crab by giving food by releasing mucus (with nutrients) corals give nitrogen to algae, algae give carbon to corals, carbon to shrimp through the coral these provide defeence and corals provide shelter cleaning stations, small fish or shrimp pick up parasites from groupers or other large fish o they remove parasites, wounds, dead skin and etc. shrimp cleaning and depending the coral, the gobi defending the sponge
Gobi has big eyes but shrimp doesn’t have eyes but catches the gobi with one antennae, the blind creature digs the hole and the gobi notices the predator first and he goes into the hole and shrimp does the same thing o Gobi is poor swimmer and digger and so needs the shrimp to dig the hole
Mutualism contribute to coral reef growth o Colonize and dissolve rocks o Form major geographical regions that interact with the shoreline, may serve humans, protects shoreline from ocean o lichens are needs to eat organic compounds but releases enzymes that break down rocks
Mutualist- pollination, flowering plants rely on animals for pollination o What organisms would appear in the absence of pollination?

Chapter 16: Species abundance and Diversity

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Species differ in their abundance some are rare; few are very abundance most are moderately abundant
Diversity- a combination of the number of species and their abundance o Species richness
Species diversity is higher in complex environments or in environments with modest
(intermediate) level of recurring disturbance
Is there any order to the commonness and rarity of species?
Lognormal distribution: number of individual (x-axis) vs. number of species o Take a community of species living together, count their individuals:
§ Few species are rare (7 species had 1-2 individual)
§ Few species are very common
§ The number of species with the intermediate density are the most (630 individuals) o This is a common pattern, depends on sample size à the conclusion is that the greatest number of species have intermediate abundance
Community metrics o Richness- the number of species, S o Evenness – the degree of equality among abundances, E o Example- two communities with equal number of individuals and species
Rank abundance curves o Abundance rank vs population abundance o Community B had more even distribution of species, community A has one abundant species and all other are represented by 1 o Community A is much more uneven than community B o Community A is dominated by one species, due to environmental conditions or due to suppression of others o To compare such situation; diversity indices are used o Where: H’ is a Shannon-Wiener diversity index o S is the number of species o o P is the proportion of the population
Rank abundance: example o Habitats and taxa differ in the number of species an equitability of their abundances o If you have more ranks then you have more species, mountain steam has 4 times more species then in costal ponds o Logarithmic scale, for costal species, most abundant species is 80% of all species o In mountain streams the most abundant species is only 10% of all species
Question: which factors cause such differences?
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Spatial complexity o Field observations (warblers in maine) : they looked at the vertical complexity of the environment because on the floor there isn’t much complexity o As you move form simpler habitat (simpler 3D structure) you would see more species o Simple 2-4 species of warblers in short vegetation o 4-5 species and a greater total number of individuals in tall vegetation
Spatial complexity o Height of vegetation indicates greater 3D complexity o A survey of a number of forests produced this picture: the bird species diversity was increasing with the foliage height diversity (height of the trees)
Can some of the explanations be cast in terms of niche?
Niches and heterogeneity o Remember C/N ratio and the effect of adding sugar? o Similar limitations can be produced by Si/P ratio
§ Most algae want phosphorus, nitrogen and some algae that build glass skeleton need silicate o Asterionelle dominant (phosphorus limited) à star structure
§ Cyclotella dominant (silicate limited) à round structure o Asterionelle need lots of silica
§ 1000:1, Si/P o Cyclotella Si/P equals 1 o In the middle neither species will win because they have nutrient limitation
§ Two coexist where each is limited by a different nutrient
Nutrient complexity o Colors show different concentrations of nutrient, NO3 and SiO2 in a lake o The concentration of NO3 varies more than fourfold across Pyramid Lake o Distribution is uneven for silicate as well and allow the diversity of different species living together o Greatest diversity of algae in an area but there is no nutrients at all o Silicate concentrations also vary substantially across the lake, different nutrients are different distributed and the cominations of 2 or 3 nutrients create different conditions for species to grow and thrive
Terrestrial Heterogeneity o Nitrate concentrations and soil humidity also vary at small scale o This will differentiate plant performance and allow coexistence of several species o Both NO3 concentration and soil moisture show great heterogeneity over short distances o Dynamic mosaic and species can keep avoiding each other and do OK!
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Main channel Oxbows (areas of channels cut off) as the sediment accumulate, they form habitat à diversity of conditions
Small scale habitat differences translate into diverse vegetation in Amazon forest o Changes in soil type and depth to groundwater produce differences in vegetation over short distances
Real systems: middle island grow by themselves and biologicall driven, the plant absorb water from surrounding ponds, and the ponds deposit nutrients near the islands o Very rich texture of lands o Micro-texture of the landscape
If no nutrients present no species could exist. o The more nutrients you have the more species you should have? o Soil fertility affects plants S
§ Highest fertility has the lowest number of species
§ At high fertility there is an abundance of a single species and therefore, no other species cannot grow
§ One species will suppress all others o If you remove the major item over which all plants go and the plant that grows the fastest will shift the competition towards its way and therefore making it harder for other species to grow
Effect of fertilization o To improve the agriculture in late 1800s, they started on a regime of treatments to show how they can produce the best food. o For many years they collected sample of soil because they wanted to know how the composition of soil also changes in different conditions, they figured out in the 1970s, there is a detectable level of radioactive material in the soil
(due to the atomic bomb testing) à lead to the prevention of nuclear tests in the atmosphere. o Grasslands fertilized for about 100 years, started very diverse (green). o These rank-abundance curves show that plant diversity had progressively declined since the beginning of longterm fertilizing in 1856 o The abundance of species declined from 49 species to 3 species and therefore due to the addition of fertilization repeatedly, they abundance of a single species increased and diversity decreased. o The whole meadow became homogenous (one species) o Provides direct evidence for effect of nutrient availability (negative impact)
§ We actually fertilize more now than we did before, the excessive nutrients is going to lakes and rivers and causes problems in the aquatic ecosystems
§ Fertilizers improve crops but they lead to homogeneity
However, how does this agree with the Paramecium experiments where high resource levels led to a speedier decline of the competitor?
Productivity richness hypothesis o Fertilization is often bad o Biomass (fertility) vs, species richness o The greatest diversity is at some level of productivity peak and then declines regardless of the increase in nutrients
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Along what other gradient you might expect richness first to rise and then decline?
(recall 1m03) o Disturbance
Intermediate disturbance hypothesis predicts highest S at intermediate intensity o The hypothesis predicts that species diversity will be highest at intermediate levels of disturbance o Highest level of disturbance reduces disturbance o Low level of disturbance allow competition to reduce diversity
§ Imagine a homogenous habitat one species and a fire that damages it but allows another species to use the burned areas o Example: rocky shore boulders are disturbed (overturned) at different rates by waves. Their algae and inverts suffer o Most highly disturbed boulders had usually one species (max 5)
§ One species of boulders dominates o Typical number of species was 4 on boulders with intermediate disturbance
(max 7)
§ All boulders were approximately equal o Typical number of species was 2 on little disturbed boulders (max 6)
§ Low disturbance o Low disturbance- the all interactions that cause the reductions, if there is no physical impacts on some individual then the only way they can be eliminated is through competition or predation, since competitors and predators are not disturbed then they do more damage to species diversity
Prairie dog example o Prairie dogs live in patches (clumped) o The colonies compete with each other and therefore there is equal distribution o Their grazing create different plant associations o Since they can be seen from far distance, and they have so many predators, they cannot go very from where they live
§ Where they forage is in immediate distance of their burrows
§ They change the environment
§ They also fertilize the soil by releasing nitrogen into the soil o Richness of these associations conforms to IDH
§ Plant species diversity is highest at intermediate levels of disturbance which allows a high diversity
Intermediate condition create other environmental opportunities so that species can exist there that would normally be out competed or strongly predated
Pollen record: Panama o Lake cores, count the proportion of pollen, pollen is specific to the looks of the plants it comes from and you can identify how common the plant was by looking at the proportion of the pollen present o Species composition and abundance change
§ Pollen and charcoal in lake Wodehouse indicate a human presence and agriculture around the lake beginning 3900 BP
§ Pollen and spores of plants associated with disturbance increases after
3900 BP
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§ Corn pollen appears in sediments after 3900 BP
§ Particulate carbon also increases substantially after 3900 BP o Human disturbance: increase in cecropia, corn and soot
§ When humans came along they started changing the environment
§ Filicales corresponding to the loss of cecropia, these are ferns, that correlated with the corn reduction
Summary
o Common (few), rare (few) and moderately abundant species o Quantification via diversity indices o Diversity is higher in environments that are: complex, nutrient poor, moderately disturbed o Species composition and abundance change over time

Chapter 17: Food Webs
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A food web is a summary of the feeding interaction in a community of species
A few keystone species may control the structure of a community
Exotic predators may simplify the structure
Feeding relations o Network of connections between species o Arrow from predators to prey or prey to predators o To simplify description, graphic representations called food web are used o Example: A simple Antarctic food web o Krill as animals are the foundation of the entire food web of the antarctic
§ Diatoms, build shells out of silica, they love cold water and common in lakes in the spring à primary producer (algae)
§ Krills are secondary producers
On the opposite pole o Food web of bear island, Arctic à involves animals that are also on land, aquatic invertebrates o On land you have grasses that involve lemmings (signature animal of that environment) and insects and midgets o You have birds due to the huge amount of food that is available in the short season à lots of insects o They have plenty of food for the offspring, minor climatic variations birds fails to reproduce significantly o Arctic foxes feed on nesting birds (goslings)
Commonalities: body size tends to increase as you move from primary consumers towards herbivores to carnivores o Density of the animal increases as the body size declines o Arrows are pointing up to show the movement of energy from bottom to up
Are all the links all the same? o The species are different, the densities are different and they need different amounts of food and therefore there will be consequences which determine who effects who.
Tropical stream
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Cano volcan in Costa Rica and its food webs (these are fishes)
10 most common fish species and their food iteams: the web is v. complex
Weak links removed: food becomes simpler to analyze
Only strong interactions are left, they are arbitrarily set based on the consequences of one species to another
What may influence food web properties in space and time?
Two food web comparison o Costal, rocky shore interactions o In the tropics the snails, barnacles and brachiopods at the bottom and other snails are higher in the picture
§ We start with snails that feed on plant material and then there are predators of these snails and then predators of predators
§ This food web has more intermediate species and who the shape of the food web changes o Temperate narrow because less intermediate
§ Segmented mollusc, limpids (cling to rocks), clams, barnacles
§ Predator snails that feeds on clams, limphids and barnacles
§ And then a top predator that feeds on everything
§ Prey à feed on algae, organic material or anything that is in small pieces and floats in water o Many more predators in the tropical food web; greater diversity o Greater diversity: everything is more diverse then in warm climate then in cold climate o Does this prove that predation increases diversity?
Keystone species experiment o Starfish removal: removing starfish acting as top predator in intertidal food web reduced and number of species both in Mukkaw Bay, Washington and
New Zealand o Following starfish removal at Mukkaw Bay, the number of species fell from
15 to 8. o There was a pretty good loss of species à almost half of the species were lost o Even though starfish does damage on every species is predates on, overall, it helps the community
§ Having many species ensures that there is a redundancy that ensures that the community is stabilized over a long period of time. o One diversity declines then you cannot get it back
§ Food webs are easy to disrupt and cause decline in species
Do top predators determine the rest of the community? o Do they play a role in the defining the number of species in a community that are not preyed by them?
Steam web and fish keystone species o Natural arrangement: the players are steelhead (trout), large roach (small omnivorous species) o Stickleback fry (small fish) o Midgets (tuft-weaving chironomids)
Question: does steelhead control this structure o o o o

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o If you are big and can eat a lot of animals then you will eat it because you will be more successful
Experiment: protect algal communities on stone (where insects live) by using cages
(meshed) or add fishes to some cages o Depending on whether fish was included or exluded, # of algae changed o When fish present the number of algae increased
§ The reason is that insect predators were decimated and algae eating insects multiplied à predators that kept algae in check were excluded so now midgets were uncontrolled and kept eating
§ excluding fish reduces algal biomass
• there are a cascade of effects
Exclosure- enclosure contrasts o Enclosing fish led to increasing densities of herbivorous chironomids
§ Predatory insects increase in exclosure because fish were not there to eat them, and in enclosure they were kept on check and decreased
§ The algae in exclosure went down and in enclosure algae went up o Young roach and sticklebacks were completely gone in enclosures but in exclosure they were present à eaten by predators
Depending on what you allow to expend on numbers you can control what is eliminated Are there more ways in which species matter
Exclosure- enclosure contrasts
Are there more ways in which species matter, i.e. influence strongly the communities they are members of? o Keystone species have greater impact for the same biomass of the species o Dominant species have less impact for higher biomass o Keystone species have large impact on community structure; disproportionate to their biomass or numbers
Lake Victoria: invaders o Original food web included 400 species of fish o Nile perch introduced to provide larger and game fish opportunity o Now dominated by 2 species: Nile perch, Nile tilapia, and Omena o Yellow perch, Eric, Nile perch in lake Victoria was massive
Are humans a keystone species or an important species?
Humans
o Traditionally, humans hunted animals o Native hunters in Amazonia (peru) hunt 18% of available mammal species
(game)
§ Game mammals are 17.9% o These mammals constitute 75% of available mammal biomass o Such hunting pattern may have a great impact o Forests deprived of large animals (humans action) begin to develop different generation patterns—create appearance of
Summary
o A food web provides an effective summary of feeding relationships o Feeding by a few keystone species may shape community structure
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§ They have a regulatory role in the environment
§ They are capable of deciding which species can increase or decrease
§ Having a keystone species is a good thing
§ They are usually controlled by the natural environment o Exotic predators may collapse and simplify community structure o Humans even with traditional life styles may act as a keystone species or important species
§ Australians routinely employed fires, they moved from area to area after they cleared out the game in the area
§ The same has been done in Africa
§ The change in vegetation by introduction of fire.
Chapter 18: Primary Production and Energy Flow
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Terrestrial primary production is primarily limited by temperature and moisture
Aquatic primary production is generally limited by nutrient availability
Consumers affect the primary production rates
If you eat more cows then your herd is producing each year and your herd will get smaller and smaller each year and then go extinct
Energy losses limit the number of trophic levels in ecosystems o At each level organisms lose some energy as heat o Therefore energy is reduced at each level
Primary production- definition o Primary production- energy fixed (biomass produced) by autotrophs (plants, algae, chemosynthetic microbes) o Rate of primary production- the amount of energy (biomass) fixed over a time interval o Gross primary production- the total amount of energy fixed
§ Including all the energy that will be burned a few minutes later to produce energy o Net primary production- the amount of energy left after autotrophs met their energetic needs o Trophic level- a position in the food web determined by the number of energy transfers from primary producers
What are the main controls of primary production?
Productivity vs water and temperature o Defined the number of organisms we have o Actual evapotranspiration, AET, and net aboveground primary productionvarious ecosystems o Terrestrial primary production increases with actual evapotranspiration o More water passes through the plant, the more production you have
Nutrient also affect productivity o Experimental addition of several nutrients (tundra)
§ Adding fertilizers nearly doubled primary production in these tundra study plots

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o No! all biomes are limited by nutrients in a similar fashion but evapotranspiration exerts dominant control o Adding fertilizer leads to higher production o Also the range for all ecosystems is: 50- 3200 o Are evapotranspiration and nutrients also the main controls in the aquatic systems? § Aquatic plants have to figure out different mechanisms for moving
CO2 and nutrients in their tissues à done by diffusion through cells
§ They use internal network of channels for that as well à for plants that migrated from land to sea
Aquatic systems o In most freshwater ecosystems one nutrient limited primary production
§ Phosphorus- needed in greater [] than nitrogen and it is not available as much as nitrogen
§ Higher phosphorus concentrations are associated with greater algal biomass o Since 70s we do not have soaps with phosphorus because they are harmful to freshwater species o If you recall Si:P ratio and competition among diatoms, you could predict where the greatest diversity is going to be o The highest diversity tends to be in the middle of the graph à at the lower range would do better
Causes of high algal biomass o Why are algae are abundant at high Phosphorus?
§ Algae might not be limited by P
§ Algal biomass and rate of primary production are linked (in temperate lakes) § As algal biomass increases so does the rate of primary production à they also keep growing really fast o Possible alternative: longevity of cells combined with the absence of grazing
(accumulation)
Experimental evidence o A whole lake experiment demonstrates the effect of nutrient additions on phytoplankton biomass
§ Investigator put plastic blanket to prevent the transfer of nutrients from one part to the other and fertilized one part of the lake
§ Before fertilizing the two lakes the two lakes were similar in biomass of phytoplankton
§ After fertilization phytoplankton biomass increased in the experimental lake
§ When fertilizing stopped phytoplankton biomass decreases in the experimental lake due to flushing or disappearing of the phosphorus, each year the phosphorus disappears into the sediments o In the winter, due to decomposition (not very aerobic) it becomes more and more acidic and dissolve nutrients locked in the sediments during the summer
§ Mixing of the lake brings those nutrients up
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Therefore, where should one expect greatest productivity in the oceans? o In the oceans that are fertilized (more dense the oceans are fertilized) near the land o Sediments in the ocean are definitely not available o Greatest productivity of fish à coast of chili and peru, this is because the deep water current is upwelling and the nutrients are brought back up
Geographic variation in marine primary production o Highest rates of production are on continental shelf and in shallow seas o Canada overfished cod fish and the population is so reduced that it did not increase very much after fishing was prohibited
If you recall the effects of steelhead on algae in a stream, do you think they represent a rule or an exception?
Trophic cascade hypothesis o The trophic cascade hypothesis proposes that feeding by piscivores and planktivores affects rates of primary production in lakes
Specific predictions: the operational hypothesis o Trophic cascade model predicts that manipulating piscivore biomass
(numbers) will lead to changes in biomass and production of planktivores, herbivores and phytoplankton
Are terrestrial communities and ecosystems similar in their response to change of the top predator
Predators can restore forests o Canadian wolves were re-introduced to Yellowstone. The diagram below summaries their impacts:
§ Wolves started hunting elk à lowered elk population and make them more scared, they cannot graze anywhereà reduced grazing ability
§ Which improves willows and aspect
§ Much more vegetation, which restores population of beavers
Is consumption of plants always bad for plants (it is for animals, right?) o Experiment: wildebeests are excluded from some areas. Comepnsatory growth occurs where they graze o Biomass increases on grazed areas, but decreases on ungrazed areas
§ Grazed grass was growing and ungrazed grass was decreasing
Grazing and primary production: Serengeti o Compensatory growth is highest at intermediate level of grazing, little grazing allows for compensatory growth à stimulates growth o Low-intensity grazing is associated with low production o Areas grazed at medium intensity have the highest production o Highest intensity grazing is associated with low production o Light grazing insufficient to stimulate o Heavy grazing stresses plants o Grazing has great impact on impact of production o Improved water balance, lower respiration, self-shading, saliva
§ It’s the mechanical action of the grazers on the grass that causes the change in growth of the grass
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Could metabolic demands of organisms translate into ecosystem structure consequences? Annual production by tropic level into two lakes o Usually 85-95% of energy is used at a given trophic level for respiration (or just decays)
§ Only 5-15% makes it to the next trophic level
§ 10% golden rule, from one level to another o Energy losses at each trophic level, and at each transfer of energy between trophic levels, produce a pyramid-shaped distribution of production

Missed One Lecture Here (November 15, 2012)
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What is nitrogen needed for? o Which organisms can obtain nitrogen directly from air?
Plants get nitrogen through roots, the root system is good at bringing whatever is dissolved in water in the soil
Nitrogen: main pathways and storage o Needed for amino acids, RNA, DNA, Chlorophyll, hemoglobin o The main storage of nitrogen is in the atmosphere (70% of atmosphere) o From air à soluble compounds: nitrate, ammonia à plants à animals à elements (inorganic) à denitrification brings it back to the air
Organisms which are responsible for bringing more nitrogen into the soils are N fixers (bacteria free and symbiotic, blue-green algae), lightning, synthetic fertilizers o Lightning is so hot that it burns nitrogen and mixers it with oxygen, reduced to ammonia, or forms nitrates o Denitrification (free bacteria) o Mean biotic life of bacteria is 600 years, it is not as easily let go by the bacteria Nitrogen: Main Pathways o Additional chemical details:
Bloom due to nitrogen (2000) o Remote sensing of green pigments permits tracking of algal blooms in the ocean o Such blooms result from land originated nutrients, mostly N o If you produce a lot of algae, they die and sink to the bottom and decompose and remove all the oxygen
Which element most abundantly used? o How do we lose carbon?
§ Its through CO2
Carbon Cycle: main points o Building material of life: lost via respiration o Cycles fast in organic molecules and CO2
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o Exists in many forms: in water:carbonate-exchanges with plants and atmosphere o In rocks it is bound of calcium (calcium carbonate) o It is the marine creatures that capture calcium carbonate and burry it into the sediments of the ocean
§ Slow recycling via volcanic activating, uplifting and erosion o Humans add a lot: from fossil fuels, processing of plants and animals; accelerated rock weathering (through acidifying rain)
Decomposition
o Re-use of P, N, C by a new batch of creatures requires decomposition (or respiration) o Decomposition depends on water availability o ‘litter bags’ – capture and burry the same bag into the earth and see how much is being decomposed (bag is netting to allow bacteria in and out)
§ After 24 months 40% of the leaf mass was left in dry forest
§ In wet forest less than 10% of leaf mass was lost
Question:
o Different species decompose different aspects of the organic matter o Aliveness- how active these organisms are o Oxygen- they all require oxygen to do so o Moisture
Regional differences o In the tropics annual leaf mass loss (of dead leaves) is 3 times that of temperate forest o Annual mass loss in tropical forest is faster then in termperate forests o This allows for fast nutrient recycling and high production
§ Nutrients in temperature accumulates
§ Nutrients in the tropical forests decompose completely à almost no carbon left over
Streams are supplied by leaves o Do leaves have different lives?
§ It affects for fast they will be decomposed o Leaves with higher lignin content decomposed at a much slower rate à litter bag experiments o Thus streams with different riparian vegetation will deal with different problems and at different speeds o Leaves cannot be decomposed unless they are penetrated by bacterial and fungi and if they are hard then they wont be able to penetrate the leaves easily

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o If you change forest composition may lead to destruction of stream communities and ecosystem, because the diversity of species eating the leaves will decrease
Nutrient spiraling o Transport of nutrients is slowed by nutrient uptake by benthos o In streams each particle as its cycles it also moves downstream hence it spirals o Retention in living tissues and current velocity determine how long a nutrient particle stays in the stream
Pocket gophers moves great amounts of soil o Activities of animals may create great herteogeneity in distribution of nitrogen light, temperature and humidity o They have dedicated locations called letrines close to the burrows where they go to the water
§ this causes the fertilization of the soil near these letrines o some plants say bingo to gopher latrines o animal activity actually stimulates plant growth
Gopher: chain of effects o Decomposition of nitrogen leads to better growth of grasses o Grasses near gophers mounds have also more nitrogen in their tissues o Grasses growing on praries dog colonies have higher average nitrogen content o Grasses near gopher mounds invite intensive grazing by bison o Bison grazing stimulates growth of young grass
Effects of animal grazing on nutrient cycling o Large grazers speed up nutrient cycling on Serengeti ecosystem o Biomass turnover refers to replacement time for the current vegetation
§ Also affects the nutrient movement, nutrient movement is a function of how much biomass is produced o In ungrazed plots, several years are required to turn over plant biomass, when substantial proportion of annual production is consumed plant biomass turns over in less than 1 year o Turnover time decreases with the intensity of grazing: production is both accelerated and consumed transferred to animals o Low nutrient systems are quite diverse
In fynbos: plants play a role of their own o Acacia is an introduce species
§ Can synthesize their own nitrogen fertilizer
§ Nitrogen content under acacia is much higher
§ Acacia litter contains approximately 10 times more nitrogen than litter of Leucospermum

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o By adding one species that changes the nutrient budget of the environment it out competes others species
How about humans affect nutrient budgets?
Hubbard Brook experimental watershed o Change in vegetation cover (clear cutting) led to different concentration of nitrogen in steam water meaning?
§ Clear cutting the experimental basin increase losses of nitrates by more than 10 times
§ Nitrogen got washed from surrounding area to the stream o There was a delay between the time when the forest was cut and the time when the nutrient started coming into the stream in high concentrations
§ Fauna died and plants died, it took a bit of time for the nitrogen to be trained Weather interacts with stream nutrients o The relationship of nutrient transport as a function of stream flow o If the imports and exports are the same then =1 o Exports imports greater than 1 o During years of low flow Bear Brook stores phosphorus à it stores it in a near lake
§ During years of high flow Bear Brook exports phosphorus
Human impacts are like rain o No matter what measures are taken, when there are more people and more technology, nitrate exports increase o As the human density increases the nitrate export from river basins increases
§ Rivers that have lack of flow near high human settlement, have high export of nitrates o This nitrogen always ends up in the coastal waters and fertilizes the ocean
Humans- the same story again o Human density and landscape use intensity are correlated with phosphorus exports § Phosphorus increases as land use intensifies o Excessive P in freshwater resources

Chapter 18: Succession
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Community changes include increases in species diversity and changes in species composition Ecosystem changes include increases in biomass, primary production, respiration and nutrient retention
Mechanisms of succession include facilitation, tolerance and inhibition
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Community stability may be due to lack of disturbance
Definitions
o Succession- gradual accumulation and change in plant and animal communities in an open area o Primary- succession on newly exposed geological substrates o Secondary- succession following disturbance that does not destroy all life o Climax community- late successional stage remains stable until disrupted by disturbance. Glacier Bay Primary succession o Glacier melting back, leaving new soil exposed over time o Reiner et al. found that total number of plant species increase with plot age.
Species richness increased rapidly in early years of succession and more slowly during later stages. Not all groups of plants increased in density throughout o The number of plant species increased rapidly at first (200 years) and then began to level off
§ The first 200-250 years the species rised really fast
§ Different plant forms reach greatest diversity at different stages of succession § Trees, tall shrubs and mosses, liverworts and lichens attained maximum density in about one century
§ Low shrub and herb diversity continued to increase through 1500 years of succession
Succession and nutrients o Hubbard brook deforestation lead to nutrient loss o Plant biomass increases with succession o Vegetation starts to recover (biomass accumulates) o Exports of calcium, potassium and nitrate decline to the pre-disturbance levels o Succession and accumulation of biomass leads to protects the soil from losing the fertilizers
Succession in temperate forests o Number of woody plant species begins to level off after about 100-150 years o Patterns of diversity similar to Glacier bay for plants and birds o Number of birds species leveled off after 50-100 years of forest succession o In relation to the number of plants in the forests o All the connection between birds diversity and habitat complexity

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