What defines a population in biological terms?

The defining characteristic of a population in biological terms is a group of individuals that belong to the same species and inhabit a specific geographical area at the same time. This unique collective shares certain genetic, behavioral, and ecological traits, which enable them to interbreed. For instance, these individuals interact with one another, compete for resources, and contribute to the gene pool of that species within their localized environment.

In contrast, other options focus on different aspects of biological communities. A group of different species in an area pertains to a community rather than a population, reflecting more on biodiversity rather than species-specific interactions. The total number of organisms in an ecosystem describes an ecological framework rather than the specific dynamics of a single species' population. Meanwhile, a collection of species that can interbreed typically refers to a species complex but does not define a population since it involves multiple species rather than a singular species group.

By understanding that a population inherently includes factors like species specificity and geographical boundaries, it becomes clear why the focus is narrowed down to a single, species-based entity living within a defined location.