Just a short note, since I posted on a different branch in detail: what matters isn't the absolute magnitude of diversity within the group itself, but the difference in magnitude of the differences within and the differences between the groups you compare.

I disagree. For example, imagine that Group A is Loxodonta Africana Africana and Group B is "worms"

It's both meaningful and true to assert that members of Group A are larger than members of Group B.