What''s wrong with "development of isolating mechanims"? (and its special case in form of "reinforcement")
Examined are the conceptual grounds of the "reinforcement" model that play an important role in explanatory schemes of the theory of evolution. According to the current views, reinforcement (of obstacles for crossing under natural selection when there occurs a repeated contact with hybridization between two substantially divergent forms, up to the level where started hybridization is terminated and the forms become unable to cross) should be a common or even frequent phenomenon. In fact, reinforcement turns out to be a rare event needed to be specially searched for, all such events are dubious, etc. Here, empirical data on reinforcement pro and contra are analyzed, using mostly ornithological (and some other zoological) materials. It is shown that in most cases where the theory predicts reinforcement to occur, it does not happen. On the contrary, something quite opposite is observed - selection for non-crossing enhancement does not stop up the leaks in gene pools of the forms that are due to their hybridization within the zone of a repeated contact, but instead the stable hybrid zone is established which serve as a conduit for gene exchange between the forms. Through hybridization, those forms can adopt strange genes, remaining, at that, their isolation at the level of separate species. This is achieved through the system of self-non-self recognition in population system of both forms being in contact. Within the zone of a repeated contact, conditions are usually such that individuals repeatedly make mistakes forming mixed pairs and producing hybrids, i.e., at the level of individuals, self-non-self recognition is often inefficient, especially at the range edges, in zone of repeated contact and such. Efficient recognition, that ensures species separ