Conflict, Cooperation and the Evolution of Conditional Social Behaviors in Colonial Marine Invertebrates

冲突与合作之间的紧张关系推动着社会行为的进化，偶尔会导致社会组织的永久性转变。然而，更常见的是，这种紧张关系导致了同族之间短暂的社会联系的演变，这种联系在不同的地方、一代又一代之间形成、解体和改革。在这些短暂的联系背后是一系列可塑的行为——有些是利他的，有些是自私的——其表现取决于通过相互作用提供的社会环境。当前的社会进化理论建立在亲缘选择的基本作用之上，同时承认社会环境的其他方面影响着利他和自私行为的成本和收益，因此也影响着利他和自私行为表现的条件。在其他条件相同的情况下，个体应该将利他（或合作）行为指向亲属，而将自私行为远离亲属。个体也应该根据当时的社会环境和自身的个体发育状态来调节利他和自私行为的表达。最后，不同物种所经历的社会环境的变化应该会促进社会行为的多样化。尽管这些条件行为在涉及捕食者、竞争者和配偶的生态相互作用的调节中无处不在，并且在理论上具有重要意义，但实际上我们对社会环境如何影响它们的表达和进化一无所知，特别是在海洋生物中。该研究项目将测试和扩展社会进化理论的基本预测，使用一组殖民地海洋刺胞动物（水螅虫），这些刺胞动物表现出戏剧性的，依赖于环境的行为，包括基因型间融合（和嵌合体形成）和侵略，并经历了广泛的社会环境。通过从生态学、遗传学和系统发育的角度考察社会环境介导的选择如何影响这种行为和社会多样性的水螅动物群体中融合和攻击的表达和进化，本研究将为理解条件行为的进化、其表达的线索及其在种群和群落水平上的广泛影响奠定基础。

Grosberg 9906741The tension between conflict and cooperation drives the evolution of social behavior, occasionally leading to permanent transitions in social organization. More commonly, however, the tension results in the evolution of transitory social liaisons among conspecifics that form, disintegrate and reform from place to place and generation to generation. Underlying many of these transient associations is a spectrum of plastic behaviors -some altruistic, some selfish - whose expression depends on the social environment provided by interacting conspecifics. Current theories of social evolution build on the fundamental role of kin selection, while acknowledging that other facets of the social environment influence the costs and benefits of altruistic and selfish behaviors, hence the conditions under which they should be expressed. All else being equal, individuals should direct altruistic (or cooperative) behaviors toward relatives, and selfish behaviors away from relatives. Individuals should also modulate the expression of altruistic and selfish behaviors according to the prevailing social environment and their own ontogenetic state. Finally, changes in the social environment experienced by different species should promote the diversification of social behavior.Despite the ubiquity and theoretical importance of these conditional behaviors in the regulation of ecological interactions involving predators, competitors, and mates, virtually nothing is known about how the social environment affects their expression and evolution, especially in marine organisms. This research project will test and extend the basic predictions of social evolutionary theory using a group of colonial marine cnidarians (the hydractiniids) that exhibit dramatic, context-dependent behaviors, including intergenotypic fusion (and chimera formation) and aggression, and that experience a broad range of social environments. By examining from ecological, genetic, and phylogenetic perspectives how selection mediated by the social environment influences the expression and evolution of fusion and aggression in this behaviorally and socially diverse group of hydrozoans, this research will build a general foundation for understanding the evolution of conditional behaviors, the cues underlying their expression, and their widespread effects at the level of the population and community.