Conflict resolution and direct benefits in kin-selected conflicts in social groups

亲属选择理论是解释生物体社会行为进化的主要理论。该理论基于自然选择理论对影响社会行为的基因的应用，其中社会行为包括合作和冲突。它提出，个体之间的价值与他们的遗传相关性成正比，因为相关性衡量的是他们共享影响社会行为的基因的机会。由于它的基本基础，以及解释动物社会性复杂性的需要，研究亲属选择是进化生态学家的主要兴趣。这一理论在解释社会现象的某些方面非常成功，但在其他方面则不然。人们提出了这个理论失败的两个一般性原因。首先，社会互动是由尚未充分研究的理论方面来解决的，即在社会冲突中，不同群体的相对权力，和/或冲突行为对社会群体的总体成本。第二种解释是，个人的社会行为是由直接利益（个人繁殖的收益）驱动的，而不是亲属选择的利益。我们建议使用熊蜂作为我们的研究生物来测试这两个想法。在社会性的水翅目（蚂蚁、蜜蜂和黄蜂）中，亲属选择预测，根据殖民地的亲缘结构，蚁后或工蚁（如果能繁殖，只会产生儿子）应该垄断成年雄性后代的生产。但实际的工人再生产水平往往远低于预测。这是B中的情况。terrestris。在这个物种中，理论预测工蜂应该生产大部分的成年雄性，但我们的数据显示，事实上它们只生产c。5%。我们建议测试两个假设之间缺乏适合的男性亲子关系的数据和亲属选择理论的预测在B。terrestris。这些假设分别来自冲突解决（通过不平等的权力分配）和直接利益的想法。它们是：（1）大多数工蜂产下的卵被蜂王或其他工蜂选择性地摧毁，这在很大程度上决定了雄蜂的亲子关系;（2）工蜂的繁殖并不像亲缘选择理论所认为的那样由工蜂与巢友的亲缘关系决定，而是工蜂种内社会寄生能力的副产品。这些假设来自两组观察结果。第一种是工人在B产蛋。蚁后或其他工蜂经常吃土生蚁，但这种情况的严重程度从未被量化。第二个是我们最近发现B。terrestris工蜂进入它们自己物种的其他殖民地，然后在那里它们产生作为生殖“漂流者”（种内社会寄生虫）的儿子。我们将通过观察、实验和遗传亲子关系分析（基于微卫星标记）来检验假设1，以确定B中工人产蛋的主要消费者是否是工人。terrestris是女王，生殖工人，或工人作为一个整体。我们将使用相同的技术来测试假设2，以确定是否与居民工人的繁殖最多的殖民地是那些出口最具生殖力的漂流工人，和/或是否生殖漂流者在与居民工人的优势战斗中失败。我们还将测量频率的生殖漂流工人在外地殖民地和巢聚集漂流行为的影响。我们计划的工作是新颖的，因为它解决了新的现象和未回答的研究问题。它的影响将是广泛的，因为研究的基本性质，对社会进化的广泛兴趣，以及结果将导致对长期存在的概念进行重新评估的可能性。它应该大大推进我们对社会行为进化生态学的理解。

Kin selection theory is the leading theory for explaining the evolution of social behaviour in organisms. The theory is based on the application of natural selection theory to the genes that influence social behaviour, where social behaviour includes both cooperation and conflict. It proposes that individuals value one another in proportion to their genetic relatedness, since relatedness measures the chance they share the genes influencing the social behaviour. Because of its fundamental basis, and the need to explain the complexity of animal sociality, investigating kin selection is of major interest to evolutionary ecologists. The theory has proved very successful in explaining social phenomena in some respects, but not in others. Two general reasons for the failures of the theory have been proposed. The first is that social interactions are resolved by as-yet poorly-investigated aspects of the theory, namely, in social conflicts, the relative power held by different sets of individuals, and/or the overall costs to the social group of conflict behaviour. The second explanation is that individuals' social behaviour is driven by direct benefits (gains from personal reproduction), not kin-selected benefits. We propose to test both these ideas using the bumble bee Bombus terrestris as our study organism. In the social Hymenoptera (ants, bees and wasps), kin selection predicts that either queens or workers (which, if reproductive, produce only sons) should monopolise the production of adult male offspring, depending on the relatedness structure of the colony. But the actual level of worker reproduction is often far lower than that predicted. This is the case in B. terrestris. In this species, the theory predicts that workers should produce most of the adult males, but our data show that in fact they produce only c. 5%. We propose to test two hypotheses for the lack of fit between male parentage data and predictions of kin selection theory in B. terrestris. The hypotheses stem, respectively, from the ideas of conflict resolution (through the unequal distribution of power) and direct benefits. They are: (1) most worker-laid eggs are selectively destroyed by the queen or by other workers, with which power over male parentage largely lies; and (2) worker reproduction is not determined by the relatedness of workers to nestmates, as kin selection theory proposes, but is instead a by-product of workers' capacity for intraspecific social parasitism. These hypotheses arise from two sets of observations. The first is that worker-laid eggs in B. terrestris are frequently eaten by the queen or other workers, although the extent of this has never been quantified. The second is our recent discovery that B. terrestris workers enter other colonies of their own species in which they then produce sons as reproductive 'drifters' (intraspecific social parasites). We will test Hypothesis 1 by using observations, experimentation and genetic parentage analyses (based on microsatellite markers) to determine whether the major consumers of worker-laid eggs in B. terrestris are the queen, reproductive workers, or workers as a whole. We will test Hypothesis 2 by using the same techniques to determine whether colonies with the most reproduction by resident workers are those exporting the most reproductive drifter workers, and/or whether reproductive drifters are losers in dominance battles with resident workers. We will also measure the frequency of reproductive drifter workers in field colonies and effects of nest aggregation on drifting behaviour. Our planned work is novel because it addresses new phenomena and unanswered research questions. Its impact will be broad because of the fundamental nature of the research, widespread interest in social evolution, and the possibility that the results will cause a reassessment of long-standing concepts. It should advance considerably our understanding of the evolutionary ecology of social behaviour.