PDF(Pubmed)
Abstract：
Understanding how cooperation evolved and is maintained remains an important and often controversial topic because cheaters that reap the benefits of cooperation without paying the costs can threaten the evolutionary stability of cooperative traits. Cooperation-and especially reproductive altruism-is particularly relevant to the evolution of multicellularity, as somatic cells give up their reproductive potential in order to contribute to the fitness of the newly emerged multicellular individual. Here, we investigated cheating in a simple multicellular species-the green alga Volvox carteri, in the context of the mechanisms that can stabilize reproductive altruism during the early evolution of clonal multicellularity. We found that the benefits cheater mutants can gain in terms of their own reproduction are pre-empted by a cost in survival due to increased sensitivity to stress. This personal cost of cheating reflects the antagonistic pleiotropic effects that the gene coding for reproductive altruism-regA-has at the cell level. Specifically, the expression of regA in somatic cells results in the suppression of their reproduction potential but also confers them with increased resistance to stress. Since regA evolved from a life-history trade-off gene, we suggest that co-opting trade-off genes into cooperative traits can provide a built-in safety system against cheaters in other clonal multicellular lineages.
摘要：
了解合作如何演变和维持仍然是一个重要且经常引起争议的话题，因为骗子在不支付成本的情况下获得合作的好处可能会威胁到合作特征的进化稳定性。合作-尤其是生殖利他主义-与多细胞的进化特别相关，体细胞放弃其生殖潜力，以促进新出现的多细胞个体的适应性。这里,我们调查了一个简单的多细胞物种——绿藻VolvoxCarteri的作弊行为，在克隆多细胞早期进化过程中可以稳定生殖利他主义的机制。我们发现，由于对压力的敏感性增加，骗子突变体在自身繁殖方面可以获得的好处被生存成本所取代。作弊的个人成本反映了编码生殖利他主义的基因regA在细胞水平上具有的拮抗多效性作用。具体来说,体细胞中regA的表达导致其繁殖潜力的抑制，但也赋予其增加的抗应激能力。由于regA是从生活史权衡基因进化而来的，我们建议,在其他克隆多细胞谱系中,将权衡基因选择为合作性状可以提供一个内置的安全系统,防止作弊者.
