Data from: Maternal effects alter the severity of inbreeding depression in the offspring

A maternal effect is a causal influence of the maternal phenotype on the offspring phenotype over and above any direct effects of genes. There is abundant evidence that maternal effects can have a major impact on offspring fitness. Yet, no previous study has investigated the potential role of maternal effects in influencing the severity of inbreeding depression in the offspring. Inbreeding depression is a reduction in the fitness of inbred offspring relative to outbred offspring. Here, we tested whether maternal effects due to body size alter the magnitude of inbreeding depression in the burying beetle Nicrophorus vespilloides. We found that inbreeding depression in larval survival was more severe for offspring of large females than offspring of small females. This might be due to differences in how small and large females invest in an inbred brood because of their different prospects for future breeding opportunities. To our knowledge, this is the first evidence for a causal effect of the maternal phenotype on the severity of inbreeding depression in the offspring. In natural populations that are subject to inbreeding, maternal effects may drive variation in inbreeding depression and therefore contribute to variation in the strength and direction of selection for inbreeding avoidance.

母体效应（maternal effect）指的是母体表型对子代表型产生的因果性影响，且该影响独立于基因的直接遗传效应。已有大量研究证据表明，母体效应对子代适合度具有显著影响。然而，此前尚无研究探讨母体效应在影响子代近交衰退（inbreeding depression）严重程度方面的潜在作用。近交衰退指的是近交子代相较于远交子代，其适合度出现下降的现象。本研究以埋葬甲虫（Nicrophorus vespilloides）为实验对象，探究体型相关的母体效应是否会改变其子代的近交衰退程度。研究结果显示，相较于小型雌性的子代，大型雌性子代的幼虫存活相关近交衰退程度更为显著。该现象可能源于小型与大型雌性因未来繁殖机会不同，而对近交子代群的投入策略存在差异。据我们所知，本研究首次证实了母体表型对子代近交衰退严重程度的因果性影响。在存在近交现象的自然种群中，母体效应可能会导致近交衰退程度产生变异，进而影响近交规避选择的强度与方向。