What area of study does population ecology focus on?

Population ecology focuses on how populations of organisms interact with their environment, including factors that affect population density, distribution, and growth. This field examines aspects such as resource availability, predation, competition, and habitat destruction, all of which can influence the dynamics of populations over time.

For instance, population ecologists might study how food supply impacts the growth of a particular species or how environmental changes affect migration patterns. This understanding is essential for conservation efforts and managing species populations in natural habitats, making it a crucial area within ecology.

The other options address related biological concepts but are distinct areas of study. Genetic variation is a core focus in population genetics, ecosystems are the realm of ecosystem ecology, and evolutionary relationships pertain to phylogenetics and systematics. Each of these areas contributes to the broader understanding of biology but does not fall under the umbrella of population ecology specifically.