Dissertation Research: Population Genetic Aspects of Philopatry and Effective Population Size

霍尔泽9972743种群遗传学领域的两个基本预测尚未在自然动物种群中得到令人满意的检验。第一种预测是，亲缘关系(社会物种普遍存在的一种趋势，即个体在出生地附近定居和繁殖)导致当地个体的遗传相似性增加，不同地区的个体之间的遗传差异更大。第二个预测是，繁殖成功率的高度差异(这是许多社会物种常见的另一种趋势，即一些个体产生的后代多于他们所分享的后代，而许多其他个体则没有后代)也增加了当地种群中个体的遗传相似性。合作繁殖是在一些鸟类和哺乳动物身上看到的一种社会性；与非合作物种相比，合作繁殖者的特点是更具亲和力，繁殖成功的差异也更大。这项研究使用了两种澳大利亚鸟类--合作繁殖的棕树栖鸟(气候鸟)和不合作繁殖的白喉树栖鸟(Cormobates Leucophaea)来验证上述预测。研究人员将收集这两个物种目前的亲缘关系水平和繁殖成功的差异的数据，同时分析从地方到景观等不同空间尺度的遗传数据。与以前的研究不同，这项研究利用最近轻型无线电发射器的改进来监测个体的运动，以及最近开发的遗传标记(微卫星DNA)，用于评估个体之间的遗传相似和差异。以上详细的预测构成了群体遗传学的两个基石，但这项研究将是第一个在实验室外对它们进行批判性评估的研究。这样做将提高对一个物种的生态、行为和遗传学如何在种群水平上相互作用以产生如此惊人的各种社会制度的理解。具体地说，这些数据将被用来测试关于一般利他行为进化的替代理论，特别是合作繁殖的进化理论。这项研究将解释为什么一个物种变得高度社会化，表现出许多合作行为，而另一个密切相关的物种保持相对非社会性，表现出主要的自私行为。此外，这项研究将促进更好地理解一个物种的社会性和合作性水平如何影响进一步进化变化的可能性。

Hoelzer 9972743Two fundamental predictions from the field of population genetics have yet to be satisfactorily tested in natural animal populations. The first prediction is that philopatry (the tendency, common to social species, for individuals to settle and breed close to their place of birth) leads to increased genetic similarity of individuals in local areas and greater genetic differences between individuals from different localities. The second prediction is that high variance in reproductive success (another tendency common to many social species, whereby some individuals produce more than their share of offspring while many others produce none) also increases the genetic similarity of individuals within a local population. Cooperative breeding is a type of sociality seen in some birds and mammals; cooperative breeders are characterized by both greater philopatry and high variance in reproductive success relative to non-cooperative species. This study uses two Australian bird species, the cooperatively breeding Brown Treecreeper (Climacteris picumnus) and the non-cooperative White-throated Treecreeper (Cormobates leucophaea), to test the predictions stated above. The investigators will collect data on current levels of philopatry and variance in reproductive success in the two species, while simultaneously analyzing genetic data at varying spatial scales, ranging from local to landscape levels. Unlike previous studies, this study takes advantage of recent improvements in lightweight radio transmitters to monitor individual movements, as well as recently developed genetic markers (microsatellite DNA) for assessing genetic similarities and differences between individuals. The predictions detailed above form two of the cornerstones of population genetics, yet this study will be the first to critically evaluate them outside of the laboratory. Doing so will improve understanding of how the ecology, behavior, and genetics of a species interact at the population level to produce such an astonishing variety of social systems. Specifically, these data will be used to test alternative theories regarding the evolution of altruistic behavior in general, and of cooperative breeding in particular. The research will illuminate why one species becomes highly social, exhibiting many cooperative behaviors, while another closely related species remains relatively asocial, exhibiting predominately selfish behaviors. Further, this study will promote a better understanding of how levels of sociality and cooperation in a species might affect the potential for further evolutionary change.