GENETIC-VARIATION OF MAJOR HISTOCOMPATIBILITY COMPLEX AND MICRCOSATELLITE LOCI - A COMPARISON IN BIGHORN SHEEP

Examining and comparing genetic variation for major histocompatibility complex (MHC) and microsatellite (MS) loci in the same individuals pr ovides an opportunity to understand the forces influencing genetic var iation. We examined five MHC and three MS loci in 235 bighorn sheep (O vis canadensis) from 14 populations and found that both types of loci were highly variable and were in Hardy-Weinberg proportions. Mean F-ST values for both markers were very similar and MHC and MS genetic vari ability was predominantly distributed within rather than among populat ions. However, analyses of genetic distances and tree topologies revea led different spatial patterns of variation for the two types of loci. Collectively, these results indicated that neutral forces substantial ly influenced MS and MHC variation, and they provided limited evidence for selection acting on the MHC.