What term describes the variety of species within an ecosystem?

Biodiversity is the term that describes the variety of species within an ecosystem. It encompasses not only the number of different species (species richness) but also the genetic diversity among individuals of those species and the variety of ecosystems themselves. High biodiversity typically indicates a healthy and resilient ecosystem, as it can better withstand environmental changes and pressures.

Population density refers to the number of individuals of a species per unit area, which does not necessarily reflect the variety of species present. Species richness is a component of biodiversity that specifically counts the number of different species in an area, but it does not encompass genetic variance or ecosystem variety. Community structure describes how various species in an ecosystem interact and are organized but does not directly indicate the diversity of species. Therefore, biodiversity is the most comprehensive term that captures the variety of species within an ecosystem.