Answer
Biodiversity does not only refer to diversity of species.
Work Step by Step
Biodiversity constitutes diversity in species, genetic information, and systemic relationships throughout an ecosystem. A loss of species through extinction is indeed one part of the crisis, but there are other components.
Diminishing individual populations contribute to a loss of genetic diversity and the destruction of ecosystems long before that species actually becomes extinct. A loss of genetic diversity and ecosystem disruption interferes with a population's ability to adapt and thrive, causing a negative impact to their overall health and well-being. As different species interact and rely on one another within an ecosystem, this impact ripples outwards from any individual affected population.