Which term measures both the number and relative abundance of species in a community?

The term that measures both the number of species and their relative abundance in a community is known as species diversity. This concept combines two key components: the richness of the species, which refers to the total number of different species present, and the evenness, which pertains to how uniformly individuals are distributed among those species. By incorporating both aspects, species diversity provides a comprehensive understanding of the biological complexity of an ecosystem.

In contrast, ecosystem diversity refers to the variety of ecosystems within a given area but does not specifically address the individual species within those ecosystems. Conservation biology focuses on the protection and management of biodiversity, while genetic diversity pertains to the variety of genetic information within a species or among populations of a species. Therefore, species diversity uniquely captures the necessary elements of both species number and abundance.