Intrinsic and Extrinsic Factors Modulating the Shift from Paternal Care to Filial Cannibalism

许多动物为幼崽提供照顾，这对早期发育至关重要，但这种关系的中断可能会导致忽视、遗弃和后代死亡。在一些物种中，父母甚至可以采取极端的措施，吃掉自己的幼崽。自相残杀的后代长期以来一直令科学家们着迷，但人们对引发这种行为的环境因素或决定照顾或吃掉幼崽的生理变化知之甚少。回答这些问题将提供对成年人如何以及为什么在广泛的物种中终止父母照料的见解。这项研究将在一个引人入胜的研究系统--东部地狱之滨--中考察从父母照料到同类相食的转变。这些大火蜥蜴曾经在美国东部的溪流中很常见，但在过去的30年里，它们的大部分范围内的数量都经历了急剧的下降。与许多物种不同的是，雄性地狱鸟会在更长的时间内(7个月)专门照顾他们的幼崽。然而，在某些情况下，男性地狱弯曲者不再提供照顾，而是吃掉他们所有的后代。这项研究将在不同栖息地特征的溪流中使用水下巢箱，以确定是什么荷尔蒙触发了这种行为变化，以及什么环境因素促进了吃人行为。这不仅将提高父母照料的知识，而且这项研究还将聘请高中科学教师进行综合推广工作，以保护世界上最大、最迷人的两栖动物之一。父母照料是许多动物生活史的一个基本方面。自相矛盾的是，在一些无脊椎动物和脊椎动物中，提供照顾的父母(S)参与了孝道自相残杀，消耗自己的后代。亲子相食的适应基础仍然是一个尚未解决的进化难题，野生动物的这种行为的生理基础也没有被探索过。此外，很少有研究考虑到这样一种可能性，即在某些情况下，孝道自相残杀可能是不适应的，或者在一个物种中，可能有多个孝道自相残人的驱动因素。这些关键的知识差距的存在，至少部分是由于缺乏可同时识别这一生活史决定的环境和生理方面的易驯服的野生动物模型。地狱蜥蜴既表现出父性的照顾，也表现出孝顺的食人主义，并拥有一系列特征，使它们成为解决与这一迷人的生活史决定的调节相关的先前未经检验的假设的理想系统。这项研究使用一个高度综合的框架，包括在河流中部署的水下巢箱，跨越栖息地质量和寄生虫的梯度，再加上对整个育儿季节从个体收集的血清成分的遗传分析和分析，本研究将：1)确定影响父母决定照顾或蚕食幼崽的生理调节因素(即激素、血清成分)；2)确定影响这种权衡的关键因素(即人均资源/身体状况、多个父亲身份和寄生虫)；以及3)决定栖息地退化是否会增加自相残杀的频率。该奖项是由综合组织系统分部内的动物行为和综合生态生理学项目共同资助的。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Nontechnical descriptionMany animals provide care for their young that is critical for early development, but disruption of this relationship can lead to neglect, abandonment, and death of offspring. In some species, parents can even take the extreme step of eating their own young. Cannibalism of offspring has long fascinated scientists, but little is known about the environmental factors that provoke this behavior or the physiological changes that underlie the decision to care for or eat one's young. Answering these questions will provide insights into how and why adults terminate parental care in a broad range of species. This study will examine the switch from parental care to cannibalism in a fascinating study system, the eastern hellbender. These giant salamanders were once common in streams across the eastern U.S., but have experienced drastic population declines across much of their range in the last 30 years. Unlike many species, male hellbenders provide exclusive care for their young for an extended period (7 months). In some circumstances, however, male hellbenders cease providing care and consume all of their young. This study will employ underwater nest boxes in streams across a gradient of habitat characteristics to determine what hormones trigger this switch in behaviors and what environmental factors promote cannibalism. Not only will this advance knowledge of parental care, but the study will also employ high school science teachers in an integrated outreach effort to conserve of one of the largest and most fascinating amphibians in the world. Technical descriptionParental care is a fundamental aspect of the life history of many animals. Paradoxically, in some invertebrates and vertebrates the parent(s) providing care engage in filial cannibalism, the consumption of one's own viable young. The adaptive basis for filial cannibalism remains an unresolved evolutionary conundrum, and the physiological basis for the behavior is unexplored in wild animals. In addition, few studies have considered the possibility that filial cannibalism may be maladaptive in some contexts or that there could be multiple drivers of filial cannibalism within a species. These critical knowledge gaps exist, at least in part, due to a scarcity of tractable wild animal models for simultaneously identifying environmental and physiological aspects of this life history decision. Hellbender salamanders exhibit paternal care as well as filial cannibalism and possess a suite of characteristics that make them an ideal system for addressing previously untested hypotheses related to the modulation of this fascinating life-history decision. Using a highly integrative framework that includes underwater nest boxes deployed in streams across a gradient of habitat quality and parasitism, coupled with genetic analyses and analysis of serum components collected from individuals throughout the paternal care season, this study will: 1) Identify the physiological modulators (i.e., hormones, serum components) that underlie the decision by a parent to either care for or cannibalize one's young, 2) Determine what key factors (i.e., per capita resources/body condition, multiple paternity, and parasites) influence this trade-off, and 3) Determine if habitat degradation increases the frequency of filial cannibalism. This award was co-funded by the Animal Behavior and the Integrative Ecological Physiology Programs within the Division of Integrative Organismal Systems.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.