High levels of inbreeding with spatial and host-associated structure in lice of an endangered freshwater seal

Host-specialist parasites of endangered large vertebrates are in many cases more endangered than their hosts. In particular, low host population densities and reduced among-host transmission rates are expected to lead to inbreeding within parasite infrapopulations living on single host individuals. Furthermore, spatial population structures of directly-transmitted parasites should be concordant with those of their hosts. Using population genomic approaches, we investigated inbreeding and population structure in a host-specialist seal louse (Echinophthirius horridus) infesting the Saimaa ringed seal (Phoca hispida saimensis), which is endemic to Lake Saimaa in Finland and is one of the most endangered pinnipeds in the world. We conducted genome resequencing of pairs of lice collected from 18 individual Saimaa ringed seals throughout the Lake Saimaa complex. Our analyses showed high genetic similarity and inbreeding between lice inhabiting the same individual seal host, indicating low amo...

寄生于濒危大型脊椎动物的宿主特异性寄生虫（host-specialist parasites），在多数情况下比其宿主面临更高的灭绝风险。具体而言，宿主种群密度偏低、宿主间传播率下降，预计可导致寄生于单个宿主体内的寄生物亚种群（infrapopulation）发生近交现象。此外，直接传播型寄生虫的空间种群结构应与其宿主的空间种群结构保持一致。本研究采用种群基因组学方法，对一种寄生于塞马环斑海豹（Phoca hispida saimensis）的宿主特异性海虱（Echinophthirius horridus）的近交与种群结构展开分析；塞马环斑海豹为芬兰塞马湖特有物种，同时也是全球最为濒危的鳍足目动物之一。我们对覆盖塞马湖流域的18头塞马环斑海豹个体上采集的成对海虱样本开展了基因组重测序。分析结果显示，寄生于同一海豹宿主的海虱间存在极高的遗传相似性与近交程度，这表明低 amo...