Mass extinctions have occurred five times in Earth’s history. The end Permian and Cretaceous extinctions were responsible for removing a large percentage of organisms from the planet. How do these extinctions contribute to the biodiversity we see today? A. Species that have gone extinct are able to re-evolve from the ancestors that survived the extinction. B. Species that remain after the extinction are able to radiate, new adaptations arise, and these produce the diversity seen today. C. Species that remain after the extinction are unable to speciate, therefore the number of species on Earth today is lower than just before either extinction. D. Species that remain after the extinction represent all of the lineages that were present before the extinction event, therefore diversity of lineages is not changed by extinction.

Mass extinctions have a great contribution to nowadays biodiversity because news forms of life are able to arise, given that new conditions on the environment are available. So species that remain and survive extinction have new ways to suffer selection from their new environment and what we observe on nature on the present are the result of millions of years of natural, and in some cases as well artificial selection.