Effects of natural selection on genetic diversity of freshwater insect Stenopsyche marmorata populations

Abstract

 Environmental heterogeneity among habitats may be one of the factors causing adaptive genetic divergence in wild populations. We examined the effect of natural selection on genetic diversity of Stenopsyche marmorata population in middle of Miyagi, Japan. Eight microsatellites were employed to draw genetic structure and tested for their neutrality. Three microsatellites were estimated to be presumably under the selection and 4 microsatellites were nuetrall. Genetic diversity at selective loci showed significant positive partial correlations with food condition (SS, FPOM, chlorophyll a within surface biofilm, FBOM) and riverbed heterogeneity (average size of pebbles, uniform coefficient of sediment). It support that linked geanes with lower fitness could exist under habitats with abundand foods and variable sediments. This results suggest a risk of decrease of genetic diversity by artificial environment disruption.