"Public Goods and the evolution of strategic altruism"Labourel, FlorianOrganisms often make costly self-sacrifice to produce public goods that provide benefits to all members of their group. Given that some individuals could potentially reap the rewards from public goods without contributing to their production, why does such apparently selfless behaviour persist? The simple answer to that paradox is kin selection, where a gene contributes to public goods because most of the benefits go to copies of itself. However, while kin selection theory provides generic conditions favouring altruism, existing models provide limited insights into the evolution of group-beneficial traits themselves. To fill this critical gap in our understanding, I will introduce an analytical framework of public goods altruism that combines group-structured interactions derived from classical population genetics models with a fitness function that includes a trade-off. This framework then allows us to consider how selection should shape levels of altruistic investment. No less importantly, it reveals many conditions susceptible to promote polymorphism, either between cheaters and altruists or between different types of altruists. Noticeably, I will explain how our model can help understand the well-documented persistence of polymorphism in greenbeard genes, which enable individuals to recognise and preferentially cooperate with other bearers of the same allele (the greenbeard ‘colour’). Hitherto, such strategic altruism (and hence, greenbeard genes) has been considered unstable because once an allele (and its ‘colour’) becomes common in the population, its bearers more often benefit from cooperation: this should therefore drive out other colours from the population and remove the information necessary to maintain the behaviour itself. I will show here that this process, known as Crozier’s paradox, essentially vanishes when cooperation occurs in groups, and opens up the possibility for greenbeard hyper-polymorphism under certain conditions. |
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