Persistent genetic connectivity in caribou may buffer against inbreeding effects
Abstract
The Mulchatna Caribou Herd (MCH) in southwest Alaska has undergone significant demographic fluctuations, with a 94% decline over the past three decades, reducing the population from an estimated 200,000 to 13,000 individuals. This decline, coupled with radio-telemetry studies, reveals female fidelity to one of two spatially distinct calving grounds within the MCH range (designated east and west), an attribute typically used to define individual herds in Alaska. To assess the genetic consequences of the population decline, we analyzed genotyping-by-sequencing data from 121 adult female caribou. We found no strong genetic differentiation between east and west subgroups, suggesting that the herd currently functions as a single genetic population despite observed spatial structuring. In addition, we found no significant levels of inbreeding, likely due to the previously large population size. Overall, our results support the idea that the movement of caribou is best characterized by a metapopulation structure where connectivity between migratory and nonmigratory groups occurs over a large geographic range.