Already at the bottom? Demographic declines are unlikely further to undermine genetic diversity of a large Arctic ungulate: muskox, Ovibos moschatus (Artiodactyla: Bovidae)

• Published in: Biological Journal of the Linnean Society
• Main Authors: Prewer, Erin, Kutz, Susan, Leclerc, Lisa Marie, Kyle, Christopher J
• Other Authors: Natural Sciences and Engineering Research Council of Canada
• Format: Article in Journal/Newspaper
• Language: English
• Published: Oxford University Press (OUP) 2019
• Subjects: Ecology, Evolution, Behavior and Systematics; Arctic; muskox; ovibos moschatus; Victoria Island
• Online Access: http://dx.doi.org/10.1093/biolinnean/blz175; http://academic.oup.com/biolinnean/article-pdf/129/2/459/32292781/blz175.pdf

Abstract Low genetic diversity is associated with low fitness and evolutionary potential, yet the demographic and life-history traits of some species contribute to low genetic diversity, without empirical evidence of negative impacts on fitness. Modelling past and future trajectories of genetic diversity under different demographic scenarios can provide insight into how genetic variation might impact population fitness. The muskox is an Arctic species that has undergone multiple population bottlenecks and, although populations have rebounded repeatedly, two large populations have recently declined by > 50%. It is unclear how these demographic patterns influence muskox genetic diversity and fitness. We compared the genetic diversity of Canadian muskox populations undergoing opposing population trends. Genotyping 84 mainland and 244 Victoria Island individuals at ten microsatellite loci revealed low genetic variation (Victoria Island, mean allelic richness 1.66, expected heterozygosity 0.16; mainland, mean allelic richness 2.58, expected heterozygosity 0.41), with no evidence of further reductions in diversity subsequent to recent demographic declines. Bayesian modelling showed that a 1900s bottleneck contributed to the lack of diversity in contemporary populations, and forward-in-time simulations suggested little effect on genetic diversity over the next 100 years. Muskoxen might have reached a genetic diversity minimum, and additional research will be needed to determine their capacity to adapt to rapid changes in selective pressures in a rapidly changing Arctic.