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...近交（inbreeding）对生物适合度（fitness）的影响已得到广泛研究，可为种群缩减且片段化的自然种群的适应潜力（adaptive potential）及其存活效应提供重要推断依据。现有文献中常报道杂合性（heterozygosity）与适合度间的相关性，但此类关联往往难以揭示其潜在作用机制。本研究聚焦于一种对条纹海豚（striped dolphin）宿主健康具有显著危害的病害——一种会损害肺功能的线虫感染。受试条纹海豚的该高致病性肺线虫（highly pathogenic lung nematode）*Skrjabinalius guevarai*感染负荷存在显著个体差异。借助高分辨率限制性酶切位点相关DNA测序（restriction associated DNA sequencing, RADseq）分析得到的43018个单核苷酸多态性（SNPs）位点所揭示的遗传多样性显示，杂合性与病原体负荷之间存在显著关联，但该关联仅存在于雌性条纹海豚中：此类个体的杂合度越高，其*Skrjabinalius guevarai*感染负荷越低。通过RADseq鉴定得到的一个位点在与寄生虫负荷的关联分析中呈现极强的离群特征（所有未感染个体均为杂合子……