Final answer:
Population ecology studies the size and distribution of species populations and how factors such as environmental changes affect them. Examples include the federally endangered Karner blue butterfly's dependence on wild lupine and the effects of predator reduction in deer populations. It goes hand in hand with community ecology, which looks at the interactions between different species and how they impact their populations.
Step-by-step explanation:
Population Ecology and the Impact of Biotic Factors on Populations
A population refers to a group of interbreeding organisms that are members of the same species living in the same area at the same time. For instance, a group of grizzly bears in a park symbolizes a population, as they are conspecifics residing within a specific geographical location. Population ecologists study the dynamics of populations, such as their size and distribution, and how environmental factors including human activities, like wildfire suppression, affect these populations. An example is the federally endangered Karner blue butterfly, which relies on the wild lupine plant for survival. The loss of wild lupine due to human development has had a significant impact on the butterfly's population.
Additionally, population ecology extends to understanding the effects of predator reduction on prey species. For example, fewer cougars in Utah have led to an explosion of the deer population, which in turn affects the local ecosystem including stream paths and biodiversity. In Africa, the reduction in lion and leopard populations is correlated with an increase in olive baboons, and consequently, an increased transmission of intestinal parasites to humans.
It is also important to recognize community ecology, which includes all the different species within an area and their interactions. These interactions shape the ecosystem and can have significant effects on the populations within it. For example, in Kibale National Park, the density of blue monkeys has decreased due to logging, whereas black and white colobus populations have increased in regrowth forests.