Strassmann Joan E, Queller David C
Department of Ecology and Evolutionary Biology, Rice University, Houston, TX 77005, USA.
Proc Natl Acad Sci U S A. 2007 May 15;104 Suppl 1(Suppl 1):8619-26. doi: 10.1073/pnas.0701285104. Epub 2007 May 9.
Individual organisms are complex in a special way. The organization and function of their parts seem directed toward a purpose: the survival and reproduction of that individual. Groups of organisms are different. They may also be complex, but that is usually because their parts, the individual organisms, are working at cross-purposes. The most obvious exception to this rule is the social insects. Here, the individuals cooperate in complex ways toward the common goal of the success of the colony, even if it means that most of them do not reproduce. Kin selection theory explains how this can evolve. Nonreproductive individuals help in the reproduction of their kin, who share and transmit their genes. Such help is most favored when individuals can give more to their kin than they give up by not reproducing directly. For example, they can remain at their natal site and help defend a valuable resource ("fortress defenders"), or they can ensure that at least one adult survives to care for helpless young ("life insurers"). Although kin selection explains the extensive cooperation and common purpose of social insect colonies, it also predicts a certain amount of cross-purpose and conflict behavior. Kin selection has predicted how workers and queens disagree over sex ratios, how potential queens struggle to be the colony's head, how workers try to produce sons, and how other workers often prevent them. Kin selection analysis of cooperation and conflict in social insects is one of the outstanding achievements of evolutionary theory.
个体生物体以一种特殊的方式呈现出复杂性。其各个部分的组织和功能似乎都朝着一个目的：该个体的生存与繁殖。生物体群体则有所不同。它们或许也很复杂，但这通常是因为其组成部分，即个体生物体，在朝着相互矛盾的目标运作。这条规则最明显的例外就是群居昆虫。在这里，个体以复杂的方式进行协作，朝着群体成功这个共同目标努力，即便这意味着它们中的大多数不会繁殖。亲缘选择理论解释了这种情况是如何进化而来的。不繁殖的个体帮助其亲属繁殖，亲属会共享并传递它们的基因。当个体给予亲属的帮助多于因不直接繁殖而放弃的利益时，这种帮助就最受青睐。例如，它们可以留在出生地，帮助守护宝贵的资源（“堡垒守护者”），或者确保至少有一只成年个体存活下来照顾无助的幼崽（“生命保障者”）。尽管亲缘选择解释了群居昆虫群体中广泛的合作与共同目标，但它也预测了一定程度的目标冲突行为。亲缘选择预测了工蚁和蚁后在性别比例上如何产生分歧，潜在的蚁后如何争夺群体的领导权，工蚁如何试图生育雄性后代，以及其他工蚁又常常如何阻止它们。对群居昆虫合作与冲突的亲缘选择分析是进化理论的杰出成就之一。
