What happens after extinction?

Resumen

 The situation after an extinction is considered. An important post-extinction event is diversification and three main aspects concerning this must be taken into account: a) ecological aspects; b) natural selection, adaptation and morphogenesis, and e) macroevolutionary aspects. Adaptive radiations come usually after a mass extinction. The first point deals with ecology; morphological novelties and a suitable internal structure of ecosystems are as important as good physical environments for diversification. A second point considered is how natural selection works in the case of dealing with constrained or unconstrained developmental systems. The third point considers the action of non adaptive macroevolutionary processes at the beginning of diversification and later, strong natural selection if ecological niches are gradually filled. Chance as a macroevolutionary factor is also considered.