Genomic analysis reveals depression due to both individual and maternal inbreeding in a free-living mammal population

There is ample evidence for inbreeding depression manifested as a reduction in fitness or fitness-related traits in the focal individual. In many organisms, fitness is not only affected by genes carried by the individual, but also by genes carried by their parents, for example if receiving parental care. While maternal effects have been described in many systems, the extent to which inbreeding affects fitness directly through the focal individual, or indirectly through the inbreeding coefficients of its parents, has rarely been examined jointly. The Soay sheep study population is an excellent system in which to test for both effects, as lambs receive extended maternal care. Here, we tested for both maternal and individual inbreeding depression in three fitness-related traits (birthweight and weight and hindleg length at 4 months of age) and three fitness components (first-year survival, adult annual survival and annual breeding success), using either pedigree-derived inbreeding or genom...已有充分证据显示，近交衰退（inbreeding depression）会导致目标个体的适合度（fitness）或与适合度相关的性状出现下降。在多数生物类群中，个体适合度不仅受自身携带的基因调控，还会受到亲本携带基因的影响——在存在亲本抚育行为的类群中，这一点尤为明显。尽管诸多研究体系中均已报道了母体效应（maternal effects），但目前极少有研究同时检验近交衰退是通过目标个体直接影响适合度，还是通过其亲本的近交系数（inbreeding coefficients）间接发挥作用的两种路径。索艾羊（Soay sheep）研究种群是同时检验这两类效应的理想体系，因为该种群的羔羊会接受时长较长的母体抚育。本研究针对3项与适合度相关的性状（出生体重、4月龄体重及后肢长度）以及3项适合度组分（第一年存活率、成年个体年存活率与年度繁殖成功率），分别采用系谱推导的近交系数或基因组（genom……）相关数据，检验了母体及个体层面的近交衰退效应。