Ecology Exam 1 Study Guide
Lecture 1- Introduction 1. Ecology is a science of interactions and multiple causal factors 2. Evolutionary history constrains ecological processes and systems 3. Ecological systems are open but resource limited 4. Biotic-biogeochemical cycling coupled through stoichiometry 5. Biotic-biophysical processes coupled through energy budgets 6. Ecological processes and systems are scale dependent
*An ecological system (or ecosystem) will have more trophic levels if there is more primary production

Lecture 2- Research
Scientific Method:
Observation/Research Question->Hypothesis->Experimental/Observational Study->Prediction

Observation:
Graph: Increasing the amount of CO2 in the atmosphere will influence plant production

Null Hypothesis: Higher CO2 concentrations have no effect on plant production
Alternate Hypothesis: Higher CO2 concentrations increases plant production
Observational Study: Collect data (observe) on phenomenon of interest and analyze patterns
Experimental Study: Collect data after modifying the environment with a treatment and control, determining if the manipulation effect the phenomenon of interest
Prediction: Qualitative Models- Rule based, Quantitative Models- Empirical, process-based Models Used: * To evaluate future scenarios * To evaluate how well we understand the processes * For both purposes * For neither purposes

Lecture 4- Climate & Soils
*Climate is the most important driver of global vegetation patterns
*The earth’s surface receives more radiation in the form of solar radiation than long wave radiation High Altitudes- light strikes earth at a lower angle, spreads over greater area Equator- sun is closer to the perpendicular, shines directly on earth’s surface Lower Angle= Greater Area, Higher Angle= Smaller Area

*Regions near oceans are characterized by smaller ranges in annual temperatures when compared to regions in the middle of the continent
Soils- form from bedrock weather Factors Influencing Formation (Hans Jenny) * Climate * Organisms/Vegetation * Relief/Topography * Parent Material * Time
*Soils are important for plant production in terrestrial ecosystems because they are a source of mineral nutrients for plants
Soil Horizons:

Soil Texture/Size: Sand>Silt>Clay Fertility * Nutrient Cycling * Mineralization from soil organic matter * Inputs of carbon and decomposition rates * Cation Exchange Capacity (CEC) * Mineral nutrient retention in soils * CEC depends on soil texture organic matter

*Soils with a deeper A horizon will be more fertile based on soil organic matter content
*Fertility of the soil is influenced by mineralization rates from soil organic matter and CEC, but will also depend on: * Fertilization management * Atmospheric deposition of nutrients * Parent material

Lecture 5- Light, Energy & Primary Production
*Solar radiation causes the following when it reaches the earth’s surface: * Evaporation of water * Increases the temperature of organisms and other objects * Drives primary production

Photosynthetically Active Radiation (PAR) Photosynthesis: 6CO2 + 6H2O + Photons Magic C6H12O6 + 6O2

*Which type of photosynthetic pathway is most adaptive for an arid environment? * Crassulacean Acid Metabolism (CAM)

*Respiration releases chemical energy from organic molecules

Primary Production: the production of organic compounds from atmospheric or aquatic carbon dioxide mainly through the process of photosynthesis

*A plant is taking up a total of 1000g CO2 cm-2 leaf area day-1 and respiring at a rate of 200g CO2 cm-2 leaf area day-1. What is the daily GPP? * 1000g CO2 cm-2 leaf area day-1

Lecture 6- Water & Nutrients
*Water is important for nutrient supply because: * Of its capacity to dissolve inorganic compounds

Water Intake vs. Loss * Water flows through ingestion and egestion in animals
Water flows across energy gradients * Water Potential * Gibb’s Free Energy
Water Balance in Terrestrial Plants * Flows from Soil-Plant-Atmosphere * Ѱ= ѱO + ѱm + ѱp ѱO: osmotic potential, ѱm: matric potential, ѱp: mechanical pressure * Water Potential in Soil: * Largely driven by matric potential * More surface area has lower water potential
*What happens to a plant if the water potential of the soil is more negative than the plant? * The plant will eventually wilt
*Conduct an experiment in which you place a plant in a pot with sandy soil and another plant in a pot with clayey soil. Add same amount of water to each pot. Amount of soil is same in both pots. Plant roots reach bottom in each pot. Which plant(s) will wilt first? * Plant in clayey soil pot: Clayey soil has more (-) water potential due to surface area- stronger hold on water making it hard for the plant to absorb it
*Osmotic potential will be more negative on which side of the semipermeable membrane? * Side A, due to the ions

Water potential in a plant is driven largely by osmotic pressure and mechanical pressure

Water potential in atmosphere driven largely by vapor pressure deficit (VPD) * VPD= saturation Water Vapor Pressure – Actual Water Pressure * Low Temperature: air saturated by low quantities of water vapor, water vapor pressure is low * Higher Temperature: saturation water vapor pressure increases
*Water balance in aquatic organisms is largely controlled by ingestion/egestion of water and: * Osmotic Potential

Nutrients & Organisms * Limiting resource for growth and reproduction of animals, plants, and microbial organisms * Basis for competitive interactions * Can evolve in response to nutrient availability: * Improve nutrient acquisition, growth and reproduction rates to lower/higher nutrient availability
*Would A. stolonifera or A. canina have higher C:N ratio (hint: assume that plant biomassof both species is 45% C by plant weight and both take up the same proportion of N from the soil)? * A. stolonifera: more weight- carbon diluted, higher ratio

Lecture 7- Niche Concept
*Habitat is: * The environment in which an organism exists providing food, water, shelter, and space
Niche- Range of biological and physical conditions in which an organism can grow and reproduce * Multidimensional: considered the functional role of a species in the environment
*Two species of plants can exist across the same range of thermal and water regimes in addition to having the same range of requirements for nutrients and light, but actually exist in different parts of a habitat within a smaller range of these conditions. Why? * The two plant species have different biotic interactions
Niche Types:
Fundamental- limits to a species physiological acclimation, behavioral adaptations, etc. to abiotic conditions
Realized- Limits also include biotic interactions *Which of the following, A, B, C, or D, is the realized niche of Planaria species A? * C

Resource-Based Competition * Resources are central to niche concept * Resource-Based competition model * Assumptions: * Species deplete the supply of available resources * Survivors are those that tolerate the smallest level of resources * Assumes exploitative competition is the dominant type of competition * Mortality is a constant

Pop. Dies<-|->Pop. Grows
Pop. Dies<-|->Pop. Grows

*If regions 1, 2, and 3 represent resource availability in three different habitats, which species will be the superior competitor in Region 1? * Neither Species, both populations will decline

*If regions 1, 2, 3, 4 represent resource availability in four different habitats, which species will be the superior competitor in Region 4? * Species B

Species co-exist in the same habitat by: * Niche/Resource Partitioning * Both Spatial & Temporal

Niche Partitioning Example 1- The impact of native competitors on an alien invasive: temporal niche shifts to avoid interspecific aggression?

*What type of niche partitioning has occurred between the American Mink and Native Otter along the River Thames? * Temporal Partitioning, Mink normally nocturnal- became active during day, Otter became active at night

Niche Partitioning Example 2- Niche complementarity due to plasticity in resource use: plant partitioning of chemical N forms

*Which model was supported by the data? - B

*Could Tillman’s resource-based competition model explain niche partitioning in a single habitat? * Yes

*A non-native frog species is accidentally introduced to an island and becomes the dominant frog species after two years while the number of native frogs drastically declines to near extinction. Both the non-native and native frog species have the same fundamental niche. What does the decline in population size imply about the niche of the native species? * Realized niche has become smaller

Realized Niche Expansion * Realized niche increases in size in the absence of a competitor (ie. Competitive release)

*Which barnacle species would undergo a realized niche expansion in the absence of the other species in the intertidal zone? * Chthamalus