Extreme in Every Way: Exceedingly Low Genetic Diversity in Snow Leopards Due to Persistently Small Population Size

Abstract

Snow leopards (Panthera uncia) serve as an umbrella species whose conservation benefits their high-elevation Asian habitat. Their numbers are believed to be in decline due to numerous Anthropogenic threats; however, their conservation is hindered by numerous knowledge gaps. They are the least studied genetically of all big cat species and little is known about their historic population size and range, current population trends, or connectivity across their range. Here, we use whole genome sequencing data for 41 snow leopards (37 newly sequenced) to assess population connectivity, historic population size, and current levels of genetic diversity. Among our samples, we find evidence of a primary genetic divide between the northern and southern part of the range around the Dzungarian Basin and a secondary divide south of Kyrgyzstan around the Taklamakan Desert. However, we find evidence of gene flow, suggesting that barriers between these groups are permeable. Perhaps most noteworthy, we find that snow leopards have the lowest genetic diversity of any big cat species, likely due to a persistently small population size throughout their evolutionary history. Without a large population size or ample standing genetic variation to help buffer them from any forthcoming Anthropogenic challenges, snow leopard persistence may be more tenuous than currently appreciated.