Department of Ecology & Evolutionary Biology, University of California, Los Angeles, Los Angeles, California, USA.
J Evol Biol. 2023 Oct;36(10):1365-1374. doi: 10.1111/jeb.14215. Epub 2023 Sep 5.
Eusocial Hymenoptera are often characterized by having facultatively or obligately sterile worker castes. However, findings across an increasing number of species are that some workers are non-natal-they have 'drifted' away from where they were born and raised. Moreover, drifters are often indistinguishable from natal workers in the work and benefits provided to joined groups. This seems an evolutionary paradox of providing benefits to potentially unrelated individuals over close kin. Rather than being mistakes, drifting is proposed to be adaptive if joiners either gain inclusive fitness by preferentially moving to other kin groups or through generalized reciprocity in which exchanging workers across groups raises group-level genetic diversity and creates social heterosis. It is unclear, however, if reciprocity is unlikely because of a susceptibility to cheating. In resolving this question, a series of evolutionary simulations show: (1) Reciprocity can persist under a range of genetic assumptions and scenarios of cheating, (2) cheating almost always evolves, but can be expressed in a variety of ways that are not always predictable, (3) the inclusive fitness hypothesis is equally or more susceptible to cheating. Moreover, existing data in Hymenoptera (although not extensive) are more consistent with generalized reciprocity. This supports a hypothesis that drifting, as a phenomenon, may more often reflect maximization of group and parental fitness rather than fitness gains for the individual drifters.
社会性膜翅目昆虫通常具有可育或必需的不育工蜂等级。然而，越来越多的物种发现，一些工蜂是非原生的——它们已经“漂移”远离了出生和成长的地方。此外，漂移工蜂在为加入的群体提供的工作和福利方面通常与原生工蜂无法区分。这似乎是一种进化悖论，即为潜在的非亲缘个体提供利益，而不是近亲。如果加入者通过优先转移到其他亲缘群体或通过广义互惠（通过在群体之间交换工人来提高群体水平的遗传多样性并产生社会杂种优势）获得包容性适合度，那么漂移被认为是适应性的，而不是错误的。然而，如果由于容易受骗而不太可能互惠，那么情况就不清楚了。在解决这个问题时，一系列进化模拟表明：（1）在一系列遗传假设和欺骗场景下，互惠可以持续存在；（2）欺骗几乎总是会进化，但可以以各种不可预测的方式表达；（3）包容性适合度假说同样或更容易受到欺骗。此外，膜翅目（尽管不广泛）中的现有数据更符合广义互惠。这支持了一个假设，即漂移作为一种现象，可能更经常反映出最大化群体和父母的适应性，而不是个体漂移者的适应性收益。
