Data from: Post-hatching parental care masks the effects of egg size on offspring fitness: a removal experiment on burying beetles

Parents can increase the fitness of their offspring by allocating nutrients to eggs and/or providing care for eggs and offspring. Although we have a good understanding of the adaptive significance of both egg size and parental care, remarkably little is known about the co-evolution of these two mechanisms for increasing offspring fitness. Here, we report a parental removal experiment on the burying beetle Nicrophorus vespilloides in which we test whether post-hatching parental care masks the effect of egg size on offspring fitness. As predicted, we found that the parent’s presence or absence had a strong main effect on larval body mass, while there was no detectable effect of egg size. Furthermore, egg size had a strong and positive effect on offspring body mass in the parent’s absence, while it had no effect on offspring body mass in the parent’s presence. These results support the suggestion that the stronger effect of post-hatching parental care on offspring growth masks the weaker effect of egg size. We found no correlation between the number and size of eggs. However, there was a negative correlation between larval body mass and brood size in the parent’s presence, but not in its absence. These findings suggest that the trade-off between number and size of offspring is shifted from the egg stage towards the end of the parental care period, and that post-hatching parental care somehow moderates this trade-off.

双亲可通过向卵内分配营养物质，以及/或对卵与子代开展抚育行为，提升子代的适合度（fitness）。尽管学界对于卵大小与双亲抚育的适应性意义已有较为充分的认知，但对于这两种提升子代适合度的机制的协同演化，目前仍知之甚少。本研究针对埋葬甲（Nicrophorus vespilloides）开展双亲移除实验，以此验证孵化后双亲抚育是否会掩盖卵大小对子代适合度的影响。正如研究预期，我们发现双亲的存在与否对幼虫体重存在显著主效应，而卵大小未检测到显著影响。进一步分析显示，在双亲缺失的情境下，卵大小对子代体重存在显著正向影响；而在双亲存在的情境下，卵大小对子代体重无显著影响。上述结果支持了这一假说：孵化后双亲抚育对子代生长的较强效应，掩盖了卵大小的较弱效应。本研究未发现卵的数量与大小之间存在相关性。但在双亲存在的情境下，幼虫体重与窝子代数量（brood size）呈负相关，而在双亲缺失的情境下未出现该相关性。上述研究结果表明，子代数量与大小之间的权衡关系，已从卵期转移至双亲抚育期的末期，且孵化后双亲抚育会在一定程度上缓解这一权衡。