EXTENSIVE PROTEIN AND MICROSATELLITE VARIABILITY IN AN ISOLATED, CYCLIC UNGULATE POPULATION

We investigated polymorphism at protein and microsatellite DNA loci in an isolated, unmanaged and cyclic population of Soay sheep on the isl and of Hirta, St. Kilda. Extensive molecular variation was revealed at both protein loci (mean heterozygosity 7.78 per cent) and microsatell ite loci (mean heterozygosity 50.93 per cent). Typically, large mammal s possess limited protein variation and we were surprised to observe s uch a level of protein heterozygosity, particularly considering the ge netic history of the Hirta population. Indeed, compared to other mamma ls, Soay sheep lie within the top 17 per cent of the distribution of a verage protein heterozygosities. We discuss the level of protein heter ozygosity in the context of other mammalian species, other breeds of s heep and the genetic history of Soay sheep. Possible explanations for a large average and interlocus variance in protein heterozygosity are proposed. Although little data are available from other studies to com pare with microsatellite DNA variability in this population, we discus s the potential application of microsatellite markers to interpopulati on and interspecific genetic studies.