Sex-specific impact of inbreeding on pathogen load in the striped dolphin

The impact of inbreeding on fitness has been widely studied and provides
consequential inference about adaptive potential and the impact on survival for
reduced and fragmented natural populations. Correlations between heterozygosity
and fitness are common in the literature, but they rarely inform about the likely
mechanisms. Here we investigate a pathology with clear impact on health in striped
dolphin hosts (a nematode infection that compromises lung function). Dolphins
varied with respect to their parasite burden of this highly pathogenic lung nematode
(Skrjabinalius guevarai). Genetic diversity revealed by high resolution restriction
associated DNA (43,018 RADseq SNPs) analyses showed a clear association
between heterozygosity and pathogen load, but only for female dolphins, for which
the more heterozygous individuals had lower Skrjabinalius guevarai burden. One
locus identified by RADseq was a strong outlier in association with parasite load
(heterozygous in all uninfect...