Sperm performance in conspecific and heterospecific female fluid

摘要: Divergent sexual selection within allopatric populations may result in divergent phenotypes, which can act as reproductive barriers between upon secondary contact. This hypothesis has been most tested on traits involved precopulatory selection, with less work focusing that after copulation and before fertilization (i.e., postcopulatory prezygotic traits), particularly internally fertilizing vertebrates. However, species also drive trait divergence, resulting reduced performance of heterospecific sperm the female tract. Such incompatibilities, arising a by-product allopatry, represent barriers, analogous to species-assortative mating preferences. Here, we for three pairs taxa diverged phenotypes moderate-to-high opportunity (barn swallows Hirundo rustica versus sand martins Riparia riparia, two subspecies bluethroats, Luscinia svecica L. s. namnetum, great tits Parus major blue Cyanistes caeruleus). We swimming fluid from outer tract females, because greatest reduction number birds occurs swim across vagina. Contrary our expectations, swam equally well conspecific suggesting do not these taxon pairs, at this stage fertilization. therefore suggest divergence allopatry is insufficient cause widespread form impaired passerine birds.