Dissertation Research: Genetic Determination of Parentage in Cooperative Groups

12年来，PI们一直在研究委内瑞拉实行合作繁殖的几个种群的白鹭(Camylorhynchus Griseus)。这些鸟以大家庭的形式生活在永久的公共领地上，这一习性在热带鸟类中很普遍。这些种群是上述关于合作的进化思想的一个特别有启发性的测试案例，因为它如此有效地增加了可以产生的幼崽的数量。在两种不同的栖息地类型中，该物种的85组(超过700个标记个体)的系谱可用。利用新开发的DNA指纹技术，PI将确定假定的繁殖者是否是这些家庭群体中唯一繁殖的鸟类，以及假定的非繁殖助手是否在帮助抚养兄弟姐妹。这项测试现在将基于来自遗传物质本身的确凿证据，而不是基于行为观察的错误推断。他们将记录在群体内和群体之间的亲子关系共享的程度，分析模型和计算机模拟将量化在社会群体中超出主要配对的亲子关系的潜在重要性。他们将继续进行野外实验，研究争夺生产性繁殖地位和群体防御捕食者的过程，这是群体繁殖优势的可疑机制。他们还将利用限制性片段长度多态性(RFLP)分析和我们关于种群间扩散趋势差异的长期数据，探索短距离扩散对种群遗传结构和区分性的影响。

For twelve years the PIs have studied several populations of wrens (Campylorhynchus griseus) that practice cooperative breeding in Venezuela. These birds live in extended family groups on permanent communal territories, a habit that is widespread among tropical birds. These populations are an especially revealing test case of the above evolutionary ideas about cooperation because it so effectively increases the number of young that can be produced. Genealogies are available for 85 groups (more than 700 marked individuals) of this species in two distinct habitat types. Using newly-developed DNA fingerprinting techniques, the PIs will establish whether the presumed breeders are the only birds reproducing in these family groups, and whether putative nonbreeding helpers are aiding in rearing siblings. This test will now be based on conclusive evidence from the genetic material itself rather than on fallible inferences based on behavioral observation. They will document the extent to which parentage is shared within and between groups, and analytical models and computer simulations will quantify the potential importance of parentage shared beyond a principal pair in social groups. They will continue field experiments examining the processes of competition for productive breeding positions and group defense against predators, the suspected mechanism of the advantage of breeding in a group. They will also explore the implications of short-distance dispersal for the genetic structure and distinctness of populations, using restriction- fragment-length polymorphism (RFLP) analyses and our long-term data on differences in dispersal tendencies between populations.