GENETIC-VARIATION WITHIN AND RELATIONSHIPS AMONG POPULATIONS OF ASIANWATER-BUFFALO (BUBALUS-BUBALIS)

Genetic variation at 53 protein-coding loci (25 polymorphic) was analy sed for 17 water buffalo populations - 12 swamp, three Lankan and two of the Murrah breed (river type), to determine the magnitude of geneti c differentiation and the genetic relationships among the populations. In accord with previous cytological studies, the Lankan buffalo clear ly are river type. Significant deviations from Hardy-Weinberg equilibr ium were shown for a number of locus-population combinations, with all populations but one showing significant heterogeneity in these deviat ions among loci. By contrast, heterogeneity among populations for each locus was much less, indicating locus-specific deviations, which sugg est selection affecting allele frequencies at some loci. There was sig nificant genetic differentiation among populations of both the swamp a nd river types. The differentiation among the swamp populations may re flect the geography of south-east Asia and the presumed spread of the swamp buffalo through this region. Phylogenies derived from pairwise g enetic distance estimates show the clear separation of swamp and river types, but the topology of the swamp populations shows rather poor co nsistency with their geographic locations. For at least one population (Australia), it is clear that bottleneck effects have distorted the p hylogenetic topology. Average genetic distances for both the swamp and river types, as compared with previous studies of livestock breeds, s how that the genetic differentiation of each of these sets of populati ons is of the same order of magnitude as that among well-recognized an d established breeds of other species.