Rodrigues António M M, Kokko Hanna
Department of Zoology, University of Cambridge, Downing Street, Cambridge CB2 3EJ, UK Wolfson College, Barton Road, Cambridge CB3 9BB, UK
Department of Evolutionary Biology and Environmental Studies, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
Philos Trans R Soc Lond B Biol Sci. 2016 Feb 5;371(1687):20150088. doi: 10.1098/rstb.2015.0088.
Models of social evolution and the evolution of helping have been classified in numerous ways. Two categorical differences have, however, escaped attention in the field. Models tend not to justify why they use a particular assumption structure about who helps whom: a large number of authors model peer-to-peer cooperation of essentially identical individuals, probably for reasons of mathematical convenience; others are inspired by particular cooperatively breeding species, and tend to assume unidirectional help where subordinates help a dominant breed more efficiently. Choices regarding what the help achieves (i.e. which life-history trait of the helped individual is improved) are similarly made without much comment: fecundity benefits are much more commonly modelled than survival enhancements, despite evidence that these may interact when the helped individual can perform life-history reallocations (load-lightening and related phenomena). We review our current theoretical understanding of effects revealed when explicitly asking 'who helps whom to achieve what', from models of mutual aid in partnerships to the very few models that explicitly contrast the strength of selection to help enhance another individual's fecundity or survival. As a result of idiosyncratic modelling choices in contemporary literature, including the varying degree to which demographic consequences are made explicit, there is surprisingly little agreement on what types of help are predicted to evolve most easily. We outline promising future directions to fill this gap.
社会进化模型以及帮助行为的进化模型已经以多种方式进行了分类。然而，该领域有两个分类上的差异却未得到关注。这些模型往往没有说明为何采用关于谁帮助谁的特定假设结构：许多作者构建本质上相同个体之间的对等合作模型，可能是出于数学便利性的原因；其他作者则受到特定合作繁殖物种的启发，倾向于假设单向帮助，即下属更有效地帮助占主导地位的繁殖者。关于帮助行为所达成的结果（即被帮助个体的哪种生活史特征得到改善）的选择同样缺乏深入探讨：尽管有证据表明，当被帮助个体能够进行生活史重新分配（减轻负担及相关现象）时，繁殖力益处和生存能力增强可能会相互作用，但在模型中，繁殖力益处的建模远比生存能力增强更为常见。我们回顾了当前的理论理解，这些理解来自于明确提出“谁帮助谁去实现什么”时所揭示的效应，范围从伙伴关系中的互助模型到极少数明确对比帮助增强另一个体繁殖力或生存能力的选择强度的模型。由于当代文献中存在特殊的建模选择，包括人口统计学后果的明确程度各不相同，对于哪种类型的帮助最容易进化，令人惊讶的是几乎没有达成共识。我们概述了填补这一空白的有前景的未来方向。
