Post zygotic hybridization isolation mechanisms

The study of the patterns of reproductive isolation in relation to species divergence is critical for the understanding of the process of speciation.Comparative  analyses  of  this  kind  were previously  conducted  in  Drosophila,  Lepidoptera,  and  frogs,  ducks,  and  birds‟ .In  general. Information analyzed from the literatures, hybrid inviability in relation to species divergence in pigeons and doves. Four main patterns arose from this analysis as in the other groups studied, F1 hybrid  inviability  gradually  increases  as  species  diverge,  the  time  needed  to  reach  total inviability  being  higher  in  birds  than  in  the  other  groups;    as  expected,  the  presence  of geographic overlap does not influence the evolution of postzygotic isolation; the percentage of unhatched eggs does not differ between hybrids of the first generation and the backcrosses, but it increases in the second hybrid generation; and   pigeons and doves follow Haldane‟s rule, as found in the other groups studied so far. The similarity between the results of previous different studies contributes to the growing evidence suggesting that the patterns of the evolution of postzygotic isolation, and the process of speciation in general, are shared among animal groups.The hypothesis that reinforcement accounts for behavioral isolation in sympatry assumes that hybridization and postzygotic isolation are present. Here, genomic and morphological data used to demonstrate that hybridization is ongoing between orange throat and rainbow darters and used hybrids collected from nature to measure postzygotic barriers across two hybrid generations.