Linkage analysis of seventeen loci in poeciliid fish (genus Poeciliopsis).

Electrophoretic surveys of genetic variation reveal considerable levels of polymorphism in most species. Only rarely, however, are loci polymorphic in natural populations examined for their linkage relationships. Using inter-and intraspecific crosses, the linkage relationships of 17 loci were examined in four species of fish in the genus Poeciliopsis. Five loci are in one linkage group; two loci are in a second group. The remaining 10 loci assort independently. Finding five of 17 loci in a single linkage group is unexpected since there is no reason to expect polymorphic loci would be clustered in an organism with a large number of chromosomes in the haploid set. Comparisons of the genetic map of Poeciliopsis with the maps in the related genera Xiphophorus and Poecilia indicate the above linkage relationships have been conserved during the divergence of three genera of poeciliid fish.