Island Population of Feral Horses: Origin and Genetic Diversity

For the first time, using the methods of genetic analysis, the origin of feral horse population (Equus caballus), living in the Rostovsky State Nature Biosphere Reserve (Rostov oblast, Russia), from Don breed, with possible contribution of Budyonny breed genome, was determined. Quantitative assessment of the population genetic parameters and their comparative analysis with data on other horse breeds raised in Russia were performed. It was found that island population was characterized by reduced values of allelic diversity, including the number of effective alleles (Ne = 2.97, Na = 4.59), reduced level of observed heterozygosity (Ho = 0.59), and the pronounced genetic homogeneity, indicating high degree of isolation and inbreeding. The key factors limiting the population genetic diversity are the limited founder pool, geographic isolation restricting gene flow, low effective population size, and repeated demographic bottlenecks throughout its historical dynamics. The data obtained highlight the influence of long-term isolation and stochastic processes (genetic drift, founder effect) on the formation of a unique genetic structure of island populations.