Data from: MHC variability in an isolated wolf population in Italy

Small, isolated populations may experience increased extinction risk due
to reduced genetic variability at important functional genes, thus
decreasing the population’s adaptive potential. The major
histocompatibility complex (MHC), a key immunological gene cluster,
usually shows high variability maintained by positive or balancing
selection in response to challenges by pathogens. Here we investigated for
the first time, the variability of 3 MHC class II genes (DRB1, DQA1, and
DQB1) in 94 samples collected from Italian wolves. The Italian wolf
population has been long isolated south of the Alps and is presently
recovering from a recent bottleneck that decreased the population to less
than 100 individuals. Despite the bottleneck, Italian wolves show
remarkable MHC variability with 6–9 alleles per locus, including 2
recently described alleles at DRB1. MHC sequences show signatures of
historical selective pressures (high d N/d S ratio, ω > 1.74) but
no evidence of ongoing selection. Variation at the MHC genes and 12
background microsatellite loci were not apparently affected by the recent
bottleneck. Although MHC alleles of domestic dog origin were detected in 8
genetically admixed individuals, these alleles were rare or absent in
nonadmixed wolves. Thus, despite known hybridization events between
domestic dogs and Italian wolves, the Italian wolf population does not
appear affected by deep introgression of domestic dog MHC alleles.