Characteristic of Przewalski horses population from Askania-Nova reserve based on genetic markers

Abstract

Przewalski horses are considered the last living population of wild horses, however, they are secondarily feral offspring of herds domesticated about 5000 years ago by the Botai culture. After Przewalski horses were almost extinct at the beginning of the 20th century, their population is about 2500 individuals worldwide, with one of the largest breeding centers in the Askania-Nova Biosphere Reserve (Ukraine). The research aimed to analyse the genetic structure of Przewalski horses population maintained in the Askania-Nova Reserve, as well as establish maternal ancestry based on whole hypervariable mitochondrial DNA region profiling, analysis of Y chromosome single nucleotide polymorphism unique for Przewalski horses, and coat color markers - MC1R (‘fox’), TBX3 (Dun). The mtDNA hypervariable region analysis in 23 Przewalski horses allowed assigning them to three distinctly different haplotypes, showing the greatest similarity to the Equus caballus reference, the Equus przewalskii reference, and to extinct species - Haringtonhippus. The Y chromosome analysis using fluorescently labelled assays (FAM and VIC) differentiated horses in terms of polymorphism (MH341179.1, g731821T>C) characteristic of the species Equus caballus and Equus przewalskii. All 13 male individuals presented genotype C characteristics for Przewalski horses. The polymorphisms within genes related coat color confirmed the presence of primitive genetic variants in Przewalski horses: polymorphism of MC1R gene (ECA3g.36259552C>T) assigned all horses to the genotype with C/C alleles; the two TBX3 polymorphisms (chr8:18,227,267+1,066G>T, chr8:18,226,905A>G) assigned all horses to the genotype with G/G alleles in both loci; and in the third TBX3 1.6 kb in/del polymorphism (chr8:18,227,267) deletions were not observed.