Dissertation Research: Cooperation and the Covariance between Genetic Monogamy and Limited Dispersal

许多动物，包括人类，生活在大家庭群体中，父母和成熟的后代共同承担照顾幼崽的责任。这种类型的社会制度被称为合作繁育，通常与各种动物群体的一夫一妻制有关。这种关联被认为是因为一夫一妻制群体中的帮助者平均有50%的基因与他们的完全兄弟姐妹共享--他们与自己的后代共享相同的比例。因此，从基因的角度来看，当帮助者可以帮助抚养完整的兄弟姐妹时，帮助可以和独立繁殖一样好。尽管在某些情况下，留在家中提供帮助可能是有益的，但如果帮助者发现自己在与近亲争夺资源，而他们没有离开出生地，那么合作的好处可能会减少，甚至被抵消。这个项目调查了合作和竞争发生的背景，以确定动物是否可以通过分散行为来平衡这些成本和收益。这项建议还对观察到的一夫一妻制和合作之间的联系进行了一种新的替代解释，询问这种关系是否可能是由于环境因素造成的，环境因素同样影响配偶忠诚度和帮助行为。兄弟姐妹关系在合作进化中的作用是行为进化领域的主要兴趣，这里提出的研究可能会对我们对以家庭为基础的合作社会的理解产生深远的影响，例如我们自己的社会。该项目还将为研究生和本科生提供多种现代科学技能方面的培训机会，包括使用最尖端的DNA测序技术。这项工作将通过社区科学节和科学插图课与公众分享。这项研究以合作的甲虫为模式生物，研究了交配系统和社会制度之间的关系。首先，将对细微规模的种群结构进行评估，以检验这样一个假设，即甲虫在它们高度相关的家庭群体内进行局部合作，然后分散到全球与无关的个体竞争，使它们能够避免与亲戚竞争的成本，同时最大化与亲戚合作的好处。这项研究的第二个目标将检验这一新的假设，即某些环境可能同时有利于一夫一妻制和合作，导致交配和社会制度之间的关联是结果而不是因果的。从概念上讲，这一假设表明，哈密尔顿规则(RB-C0)中的术语在某些环境中可能会发生变化。具体地说，这项研究将测试一个单一的生态因素，低资源密度，是否降低了帮助成本(C)(通过增加分散成本)，同时通过减少额外的配对父亲关系，增加了帮助者与他们兄弟姐妹之间的联系(R)。为了评估这种可能性，将调查自然种群和实验种群的资源密度对父子关系和扩散的影响。这项研究的结果可能表明，哈密尔顿-S规则中的术语不是模块化的，而是在特定条件下相互变化的，改变了我们理解社会系统和交配系统的相关进化以及关系和合作之间的联系的方式。

Many animals, including humans, live in extended family groups where both parents and mature offspring share the responsibility of caring for young. This type of social system, called cooperative breeding, is frequently associated with monogamy across a diversity of animal groups. This association is thought to result from the fact that helpers in monogamous groups share on average 50% of their genes with their full siblings - the same proportion they share with their own offspring. Therefore, from a gene's eye view, helping can be as good a strategy as reproducing independently when helpers can assist in rearing full siblings. Although staying near home to help can be beneficial in some circumstances, the benefits of cooperating could be reduced or even cancelled out if helpers find themselves competing with close relatives for resources when they do not disperse from the area where they were born. This project investigates the contexts in which cooperation and competition occur to determine if animals can balance these costs and benefits through dispersal behavior. This proposal also tests a novel alternative explanation for the observed association between monogamy and cooperation, asking whether this relationship could be due to environmental factors that similarly influence both mate fidelity and helping behavior. The role of sibling relatedness in the evolution of cooperation is of major interest in the field of behavioral evolution, and the studies proposed here could have profound influences on our understanding of family-based cooperative societies, such as our own. The project will also provide multiple training opportunities for graduate and undergraduate students in a range of modern scientific skills, including the use of the most cutting edge DNA sequencing techniques. The work will be shared with the public through a community science festival and scientific illustration classes.This research investigates the relationship between mating systems and social systems using cooperative bess beetles as a model organism. First, fine-scale population structure will be assessed to test the hypothesis that beetles cooperate locally within their highly related family group before dispersing to compete globally with unrelated individuals, allowing them to avoid the costs of competing with kin while maximizing the benefits of cooperating with relatives. The second objective in this study will test the novel hypothesis that certain environments may favor both monogamy and cooperation simultaneously, leading to a correlation between mating and social system that is consequential rather than causal. Conceptually, this hypothesis suggests that the terms in Hamilton's Rule (rB-C0) may covary in certain environments. Specifically, this study will test whether a single ecological factor, low resource density, reduces the costs (C) of helping (by increasing the costs of dispersal) while simultaneously increasing the relatedness between helpers and their siblings (r) by reducing extra-pair paternity. To assess this possibility, paternity and dispersal will be investigated in response to resource density in both natural and experimental populations of bess beetles. The results of this study could suggest that the terms in Hamilton?s Rule are not modular, but rather covary under certain conditions, changing the way we understand both the correlated evolution of social and mating systems as well as the association between relatedness and cooperation.