Parental guarding behaviour affects the evolution of egg shapes

When females guard clutches on substrates against predators with a straddling posture, eggs located in the peripheral area of such clutches experience high predation pressure.Thus, selection may favor compact clutches composed of longitudinally elongated eggs.We tested this hypothesis using shield bugs.Our phylogenetic comparative analyses revealed that eggs were more elongated in caring than in non-caring species, although this difference was obscured in species with large eggs.Reconstructed ancestral states of egg shape and maternal care suggested that the enhanced elongation of eggs occurred after the establishment of maternal care.当雌性以跨坐姿态在产卵基质上守护卵块以抵御捕食者时，位于该卵块外围区域的卵会承受较高的捕食压力。据此，自然选择可能更青睐由纵向伸长的卵构成的紧凑卵块。我们以盾蝽为实验类群验证了这一假说。系统发育比较分析结果显示，存在母性抚育行为的物种，其卵的纵向伸长程度高于无育幼行为的物种，但这一差异在卵体型较大的物种中被掩盖。对卵形与母性抚育的祖先状态重建结果表明，卵的纵向伸长增强是在母性抚育行为确立之后演化出现的。