Pierrick Bourrat

There is a tension between, on the one hand, the view that natural selection produces adaptations, and on the other hand, the theoretical results showing that the links between natural selection are weakened in different evolutionary scenarios such as situations of (negative) frequency-dependent selection or more generally in situations where fitnesses are not constant. If these results are taken at face value, in the absence of alternative explanations to natural selection for adaptation, the existence of most complex biological structures appear as mysterious.
In this paper, I provide an analysis of this problem. I show that the theoretical framework establishing only weak links between natural selection and adaptation refers to what I call local populations. In contrast, I argue that assessing such links should be regarded from the perspective of global populations, that is populations of local populations which, in some cases, can be constituted of more than one taxonomic group. When natural selection on a trait is looked at from the perspective of a global population, I show that it can be considered as frequency-independent selection, which restores a strong link between natural selection and adaptation.
I show the adequacy of characterizing natural selection at that global level of description when one aims at explaining adaptations.