Studying the Correlation Between MHC Microsatellites and Susceptibility to Mange in the Yellowstone Gray Wolf (Canis lupus)

Abstract

Since the reintroduction of the Yellowstone Gray wolf (Canis lupus) to Yellowstone National Park some 13 years ago, multiple diseases and parasites have been found to hamper the reintroduction effort. Tightly knit social formation within packs and behavioral patterns allow for parasites like the Sarcoptes scabiei to easily sweep through the population. Recently, particular emphasis has been put on discovering the patterns to susceptibility to Sarcoptes scabiei, which is the root cause of sarcoptic mange. Current study shows that the population within Yellowstone appears to be highly variable with respect to the risk, severity, and duration of infection (Almberg et al. 2012). A study by Wu (2016) revealed several phenotypic/behavioral categories contribute to patterns of individuals having higher susceptibility to mange infection. This study expands upon previous studies by attempting to find a genetic pattern to susceptibility to mange. This was done by genotyping 163 individuals at 24 MHC loci. Also, the data was used to investigate the level of genetic diversity within YNP. Along with finding an extremely high level of genetic diversity at MHC loci, GLM analysis revealed that the heterozygote allele at ABCF1_DOWN1 locus may provide the individual that carries it with some type of increased fitness. Statistically, individuals that had the heterozygous form decreased their odds of having mange by 83%. It is suggested that this could display a heterozygote advantage, however, the locus appears to remain in Hardy-Weinberg equilibrium. Possible reasons for the locus remaining in HWE could be due to the fact that selection for the heterozygote isn’t as strong because any lowered fitness within homozygotes may be mitigated by social aspects of group living. Other selection factors such as evolutionary time and the possibility that selection doesn’t act on the entire population are discussed as possible explanations for this observation.