Crucial for the long-term survival of wild populations is their ability to fight diseases. Disease outbreaks can lead to severe population size reductions, which makes endangered and reintroduced species especially vulnerable. In vertebrates, the major histocompatibility complex (MHC) plays an important role in determining the immune response. Species which went through severe bottlenecks, often show very low levels of genetic diversity at the MHC. Due to the known link between the MHC and immune response, such species are expected to be at particular risk in case of disease outbreaks. However, so far, only few studies have shown that low MHC diversity is correlated with increased disease susceptibility in species after severe bottlenecks. We investigated genetic variation at the MHC and its correlations with disease resistance and other fitness related traits in Alpine ibex (Capra ibex), a wild goat species that underwent a strong bottleneck in the last century and that is known to have extremely low genetic variability, both genome-wide and at the MHC. We studied MHC variation in male ibex of Gran Paradiso National Park, the population used as source for all post-bottleneck reintroductions. We found that individual MHC heterozygosity (based on six microsatellites) was not correlated with genome-wide neutral heterozygosity. MHC heterozygosity, but not genome-wide heterozygosity, was positively correlated with resistance to infectious kerato-conjunctivitis and with body mass. Our results show that genetic variation at the MHC plays an important role in disease resistance and, hence, should be taken into account for successfully managing species conservation.

heterozygosity-fitnessthe file contains Standardized multilocus heterozygosity calculated at 37 putatively neutral markers as well as at 6 MHC-linked markers and fitness data of 147 male Alpine ibex of Gran Paradiso National Park (Italy). Please note that fitness data were only available for a subset of the genotyped individuals. The heterozygosity-fitness correlations were therefore based only on 147 out of the 247 individuals in file "genotypes_PNGP". The full dataset was however used for the calculations of diversity measures and also for the Standardized multilocus heterozygosity that was calculated for each individual as the ratio of its heterozygosity to the mean heterozygosity in the population of the loci at which the individual was genotyped (Coltman et al., 1999).genotypes_PNGPThe file contains microsatellite genotype data. 6 MHC-linked and 37 putatively neutral markers.heterozygosity-IKCThe file contains individual kerato conjunctivitis dataset.