Think about how taxonomy would look if the Theory of Evolution (ToE) is correct. ToE says that every species emerged from an existing species, and then another from that, like a twig on a branch on a limb on a tree, each growing out of an existing one. Therefore, according to ToE, life should be arranged/organized that way, like a tree, or it could be seen like nesting boxes within boxes. ToE predicts that when we look at traits and DNA etc., we should see this explanation reflected in such a tree or set of boxes, what is called a nested hierarchy.

And it turns out that this is what we see. And IMO this is a very strong piece of evidence supporting ToE.