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，或对卵与子代开展抚育行为，提升子代的适合度。尽管学界对卵大小与亲代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）开展亲代移除实验，以检验孵化后亲代抚育是否会掩盖卵大小对子代适合度的影响。正如实验预期，我们发现亲代的存在与否对幼虫体重具有显著的主效应，而未检测到卵大小的独立显著效应。进一步分析显示，在亲代缺失的情境下，卵大小对子代体重存在显著的正向影响；但在亲代存在的条件下，卵大小对子代体重无显著关联。上述结果支持了“孵化后亲代抚育对子代生长的更强效应，掩盖了卵大小的较弱效应”这一推测。我们未发现卵的数量与大小之间存在相关性。然而，在亲代存在的条件下，幼虫体重与窝仔数呈负相关，而在亲代缺失的情况下则无此关联。这些研究结果表明，子代数量与大小之间的生活史权衡，已从卵阶段转移至亲代抚育期结束阶段，且孵化后亲代抚育会在一定程度上缓解这一权衡。