Genomic and fitness consequences of inbreeding in an endangered carnivore

Reduced fitness through genetic drift and inbreeding is a major threat to
small and isolated populations. Although previous studies have generally
used genetically verified pedigrees to document effects of inbreeding and
gene flow, these often fail to capture the whole inbreeding history of the
species. By assembling a draft arctic fox (Vulpes lagopus) genome and
re-sequencing complete genomes of 23 additional foxes born before and
after a well-documented immigration event in Scandinavia, we here look
into the genomic consequences of inbreeding and genetic rescue. We found a
difference in genome-wide diversity, with 18% higher heterozygosity and
81% lower FROH in immigrant F1 compared to native individuals. However,
more distant descendants of immigrants (F2, F3) did not show the same
pattern. We also found that foxes with lower inbreeding had higher
probability to survive their first year of life. Our results demonstrate
the important link between genetic variation and fitness as well as the
transient nature of genetic rescue. Moreover, our results have
implications in conservation biology as they demonstrate that inbreeding
depression can effectively be detected in the wild by a genomic approach.