DISSERTATION RESEARCH: The Evolutionary Genomics of Facultative Social Behavior in a Tropical Sweat Bee

摘要：热带汗蜂兼性社会行为的进化基因组学自达尔文时代以来，人们一直在寻找利他主义的进化解释，但许多研究者仍未达成一致。在群居昆虫群体中，合作是最极端的，其中一个或几个成员（蚁后）繁殖，而大多数群体成员（工蜂）放弃繁殖而专注于其他任务。社会进化的一种解释是基于群居昆虫工蚁行为和母体生殖特征之间的相似性。工人阶级可能起源于一个孤独的祖先，当一个突变的雌性在分散之前表现出母性行为。这将导致以兄弟姐妹为导向的照顾，而不是以后代为导向的照顾。如果这一理论是正确的，那么在独居祖先的整个生殖周期中，活跃的基因在工蚁和群居后代的蚁后中应该受到不同的调节。这一假设的理想测试需要了解社会和祖先孤独状态代表的基因表达模式。幸运的是，在大翅蜂中也存在类似的情况，在同一个种群中同时发现了群居和独居的个体。为了分析不同的基因表达，将创建一个定制的微阵列（一个包含探针的幻灯片，对应大约5000个基因在M. genalis大脑中表达）。由于大叶蝉的社会性是灵活的和季节性的，这一建议代表了一个更好的控制和更多信息的研究，而不是迄今为止研究过的任何物种。这些结果将突出进化压力对群居性起源的重要性，并在理解社会环境如何影响生殖行为方面具有变革性作用。这项工作的广泛影响：在这项提议中创建的新的大规模基因组资源将是公开的，对许多科学学科的其他研究人员都很有用。拟议的实验室工作将通过加州大学洛杉矶分校正在进行的旨在增加少数民族参与科学研究的项目，为本科生提供尖端分子技术的培训。

ABSTRACT PI Nonacs CoPI Wayne Proposal #IOS-0808256THE EVOLUTIONARY GENOMICS OF FACULTATIVE SOCIAL BEHAVIOR IN A TROPICAL SWEAT BEEEvolutionary explanations for altruism have been sought since the time of Darwin, and are still not agreed upon by many researchers. Cooperation is most extreme within social insect colonies, in which one or a few members (queens) reproduce, and most colony members (workers) forego reproduction to specialize in other tasks. One explanation for social evolution is based on the similarities between social insect worker behavior and maternal reproductive traits. The worker caste may have originated in a solitary ancestor when a mutant female exhibited maternal behavior prior to dispersal. This would have resulted in sibling-directed, instead of offspring-directed care. If this theory is correct, genes active throughout the reproductive cycle of solitary ancestors should be differentially regulated in workers and queens of social descendants. An ideal test of this hypothesis requires knowledge of gene expression patterns in representatives of the social and ancestral solitary state. Fortunately an analogous condition exists in Megalopta genalis bees, where both social and solitary individuals are found simultaneously within the same population. To analyze differential gene expression, a custom microarray, (a slide containing probes corresponding to approximately 5,000 genes expressed in the M. genalis brain) will be created. Because sociality in M. genalis is flexible and aseasonal, this proposal represents a better controlled and more informative study than is possible in any species studied to date. The results will highlight evolutionary pressures consistently important to the origin of eusociality, and have a transformative role in understanding how the social environment affects reproductive behavior. Broader impacts of the work: The new large-scale genomic resource created within this proposal will be publicly available, and useful to other researchers from many scientific disciplines. The proposed laboratory work will provide training in cutting edge molecular techniques to undergraduate students through an ongoing UCLA program aimed at increasing minority participation in scientific research.