1. The Great Oxygenation Event was the first major extinction event. Since the Cambrian explosion five further major mass extinctions have significantly exceeded the background extinction rate. The latest, the Cretaceous Paleogene extinction event, which occurred approximately 66 million years ago was a large-scale mass extinction of animal and plant species in a geologically short period of time.
2. .
a. Population size: The number of individual organisms alive. Extinctions come from decline in population.
b. Population density: Higher density makes it easier for organisms to find a mate and reproduce, but it also leads to competition over space and food
c. Spatial distribution: 3 Types
1. Random Distribution: Individuals are located …show more content…
It is a symbiotic relationship in which two different species interact with and in some cases, totally rely on one another for survival. Example: Common mutualistic associations occur between organisms in which one organism obtains nutrition, while the other receives some type of service.
4. A keystone species is a plant or animal that plays a crucial role in the way anecosystem works. Without keystone species, the ecosystem would be very different or not even exist at all. All species in an ecosystem depend on others. The contributions of a keystone species are huge compared to the species' prevalence in the habitat. A low amount of keystone species can have a big impact on the environment. A keystone species is usually the predator. Without the keystone species, new animals or plants may also come into the habitat and push out the native species.
5. Forests, grasslands, and deserts. The boreal coniferous forest, ortaiga, is a northern biome occurring in wet climates with cold winters. The boreal forest is full of conifers, which are trees that bear cones such as fir, larch, spruce, and pin. Some broad-leaved trees are also in the boreal forest. Most boreal forests are subject to occasional emergencies, such as wildfires and attacks by