Joshi Jaideep, Couzin Iain D, Levin Simon A, Guttal Vishwesha
Centre for Ecological Sciences, Indian Institute of Science, Bengaluru, India.
Department of Collective Behaviour, Max Planck Institute for Ornithology, Konstanz, Germany.
PLoS Comput Biol. 2017 Sep 8;13(9):e1005732. doi: 10.1371/journal.pcbi.1005732. eCollection 2017 Sep.
The evolution of costly cooperation, where cooperators pay a personal cost to benefit others, requires that cooperators interact more frequently with other cooperators. This condition, called positive assortment, is known to occur in spatially-structured viscous populations, where individuals typically have low mobility and limited dispersal. However many social organisms across taxa, from cells and bacteria, to birds, fish and ungulates, are mobile, and live in populations with considerable inter-group mixing. In the absence of information regarding others' traits or conditional strategies, such mixing may inhibit assortment and limit the potential for cooperation to evolve. Here we employ spatially-explicit individual-based evolutionary simulations to incorporate costs and benefits of two coevolving costly traits: cooperative and local cohesive tendencies. We demonstrate that, despite possessing no information about others' traits or payoffs, mobility (via self-propulsion or environmental forcing) facilitates assortment of cooperators via a dynamically evolving difference in the cohesive tendencies of cooperators and defectors. We show analytically that this assortment can also be viewed in a multilevel selection framework, where selection for cooperation among emergent groups can overcome selection against cooperators within the groups. As a result of these dynamics, we find an oscillatory pattern of cooperation and defection that maintains cooperation even in the absence of well known mechanisms such as kin interactions, reciprocity, local dispersal or conditional strategies that require information on others' strategies or payoffs. Our results offer insights into differential adhesion based mechanisms for positive assortment and reveal the possibility of cooperative aggregations in dynamic fission-fusion populations.
代价高昂的合作行为的演变，即合作者为使他人受益而付出个人代价，要求合作者与其他合作者更频繁地互动。这种被称为正向分类的条件，已知会出现在空间结构的粘性种群中，在这种种群中，个体通常移动性低且扩散有限。然而，从细胞、细菌到鸟类、鱼类和有蹄类动物等跨分类群的许多社会生物都是可移动的，并且生活在群体间有大量混合的种群中。在缺乏关于他人特征或条件策略的信息的情况下，这种混合可能会抑制分类并限制合作进化的潜力。在这里，我们采用基于个体的空间明确的进化模拟，纳入两个共同进化的代价高昂的特征的成本和收益：合作倾向和局部凝聚倾向。我们证明，尽管没有关于他人特征或收益的信息，但移动性（通过自我推进或环境强迫）通过合作者和背叛者凝聚倾向的动态演变差异促进了合作者的分类。我们通过分析表明，这种分类也可以在多层次选择框架中看待，其中对新兴群体之间合作的选择可以克服对群体内合作者的选择。由于这些动态变化，我们发现了一种合作与背叛的振荡模式，即使在没有诸如亲属互动、互惠、局部扩散或需要关于他人策略或收益信息的条件策略等众所周知的机制的情况下，也能维持合作。我们的结果为基于差异粘附的正向分类机制提供了见解，并揭示了动态裂变 - 融合种群中合作聚集的可能性。
