Populations of a Connecticut River midge structured by geological history and downstream gene flow.

摘要: Connecticut River midges in the genus Axarus are constrained to semi-isolated populations associated with submerged clay exposures, and gene flow between is restricted. I sampled larval from fifteen spatially separated sites determined karyotypes for 3111 larvae two closely related species. In one of these species, an undescribed species referred as varvestris, 5chromosomal rearrangements were present polymorphisms. Four paracentric inversions, fifth a terminal insertion or deletion. used chromosomal rearrangement frequencies calculate Nei’s genetic distance measures all pairwise population comparisons constructed neighbor-joining phenetic tree using distances. Genetic A. sp. varvestris increases geographic separation, structure indicates that restricted only occurs downstream direction. The effect unidirectional (downstream)gene on riverine described here first time. A break apparent 12 000-year-ol sediments originating different ancient lakes. geological lakes also coincides composition