Maternal care shapes an aposematic display and provides lifelong protection against predators

Parental care can improve early offspring survival against predators by providing protection and resources. However, we have little knowledge of how its effects shape predator-prey interactions later in life. We investigated this with the burying beetle Nicrophorus vespilloides, which provides care for offspring and carries warning colouration to advertise its chemical defences to predators. Warning displays by prey are selected by predators for uniformity and to reliably advertise the extent to which individuals are chemically defended. We investigated whether the strength of the correlation between the conspicuousness of the warning display and the potency of the chemical defences depends on levels of care received during development by manipulating the level of maternal care received by larvae and tracking the effects into adulthood. We found that individuals who received limited care developed into smaller adults with less conspicuous warning displays. The correlation between the visual display and the chemical defence was also weaker when broods received little care as larvae. We conclude that maternal care received by burying beetles modulates the information content of aposematic defence: less care makes signals less reliable. Our results further suggest that the prey’s social environment could constrain the response to selection from predators on warning signal reliability.

双亲抚育可通过提供保护与资源，提升子代早期抵御捕食者的存活率。然而目前我们对其效应如何在生命后期调控捕食者与猎物的种间互作仍知之甚少。本研究以斑埋葬甲（Nicrophorus vespilloides）为实验对象，该物种会对后代提供抚育，并通过警戒色（warning colouration）向捕食者展示其化学防御（chemical defences）能力。捕食者会对猎物的警戒展示进行选择，以维持其一致性，并可靠地传递个体化学防御能力的强弱程度。我们通过调控幼虫阶段获得的母本抚育水平，并追踪其对成虫阶段的影响，探究警戒展示的醒目程度与化学防御效力之间的相关强度是否会随发育过程中获得的抚育水平发生变化。研究发现，抚育不足的个体发育为成虫后体型更小，警戒展示的醒目程度也更低。当幼虫群获得的抚育较少时，视觉展示与化学防御之间的相关强度同样较弱。本研究结论表明，斑埋葬甲获得的母本抚育会调控其警戒防御（aposematic defence）的信息含量：抚育不足会降低信号的可靠性。本研究结果进一步表明，猎物所处的社会环境可能会限制捕食者对警戒信号可靠性的选择响应。