Microsatellite Analysis of Genetic Variation in Intraspecific Hybrids and Self-Breds of Steelhead Trout and Golden Rainbow Trout

Abstract

Genetic diversity of the hybrids and inbreds of Steelhead trout and golden rainbow trout, altogether four populations, was studied based on 15 polymorphic microsatellite locus. Two hundred and forty individuals (sixty individuals per one population) were collected from the Yudu hill aquaculture experimental station of Beijing Fisheries Research Institute, Beijing, China. The genetic variation of the hybrids and inbreds of Steelhead trout and golden rainbow trout were all relatively high. The mean observed heterozygosity value of YJ, YY, JJ and JY were respectively 0.6600, 0.7733, 0.7822, and 0.6533. The mean Fis and Fit value were respectively (-0.5065, -0.6037, -0.5728, -0.4620) and (-0.3857, -0.5272, -0.4987, -0.4069), showing an average excess of heterozygote proportion. The mean Fst value was respectively 0.0802, 0.0477, 0.0471, and 0.0376. The mean genetic distance between JJ and YY was the closest (0.0097), next to YJ and YY (0.0655), and that between JY and YY was the most distant (0.1096). The dendrogram showed JY and YJ firstly clustered together, and then they clustered together with the inbred offspring (JJ and YY). Duo to Fst (little genetic differentiation) and Nm (the Nm values of 15 locus > 1), JY was a finer variety the two hybrids of Steelhead trout and golden rainbow trout. Our data offer supporting evidence that inbreeding depression of Steelhead trout and golden rainbow trout involves multiple related genes, favoring partial dominance over dominance.