Is nest-drifting behaviour an insurance policy for maximising indirect fitness in primitively eusocial paper wasps?

达尔文的自然选择理论预测，生物体应该自私地行动，以便尽可能多地将他们的基因传递给下一代。社会行为的演变是一个悖论，因为它要求一些人放弃生育，以帮助养育另一些人的后代。自达尔文以来，解释动物社会中帮助行为的进化一直是进化生物学家的主要关注点。一种主要的解释是，帮助者从抚养亲戚的后代中获得净收益。这个项目将研究最近发现的一种帮助社会昆虫的策略，并询问是否可以从保险单的角度解释它。群居昆虫(蜜蜂、黄蜂、蚂蚁和白蚁)通常以亲戚群体的形式生活，帮助者从饲养相关后代中受益。因此，生物学家感到困惑的是，偶尔会发现帮手漂流到自己的巢外的其他地方。人们一直在争论漂流的发生是否有原因：有时漂流似乎是偶然的，但在其他情况下，漂流的人会在他们访问的巢中产卵。最近，在一种社会纸蜂身上发现了一种关于漂移的新解释：在一个种群中，超过一半的黄蜂访问了几个相关的巢，从一个巢到另一个巢，运送饲料和喂养幼蜂。这种行为对帮助的演变有着重要的影响，但到目前为止，这种行为一直被忽视。这个项目探讨了这个问题。首先，该项目将决定流浪者是否会根据每个鸟巢的收益在不同的鸟巢之间分配帮助，就像你可能会切换到一份工作，在相同的工作量下提供更多的工资。漂泊者也许能够对帮助的回报变化做出反应，从而最大化他们的基因适应性。然而，如果通过更换巢穴，流浪者失去了他们已经投入的努力，那么流浪者从这一策略中获益甚微。如果你曾经试图抵消你的碳足迹，你会熟悉这个论点。如果你每坐一次飞机都种一棵树，你想要得到的保证是，在抵消你的碳排放之前，你的树不会被砍伐。基于保障的优势可能会以类似的方式解释帮助行为：只有当帮助者死亡或不在时，那些部分抚养的幼崽将由仍在筑巢的伴侣抚养到成年时，她才应该投资帮助。这个项目将决定流浪者在几个不同的巢中投入的帮助努力是否得到保证，即使他们减少(或撤回)对某个特定巢的帮助。漂泊行为实际上可能是一种确保投资的机制。为了弥补一名帮工的损失，可能会从一群流浪汉中招募新的帮工。如果没有新的招募人员，部分养育的幼崽可能会死亡，帮助者的投资可能会损失。召唤一批现成的新人，更像是一个商人去就业中心填补一个紧急职位空缺。这种形式的招聘(对黄蜂和商人来说)比找到一个新手并从头开始培训要快得多，成本也低得多。这个项目将确定漂流是否是一种确保帮助者投资的机制。最后，实施任何战略都需要考虑利弊。例如，在全球经济陷入动荡之际，你可能会考虑是否值得投资于股票和股票。以类似的方式，群居动物可能会权衡帮助的成本和好处。例如，如果漂流会导致很高的死亡率，那么成本往往会超过能够根据收益在不同巢之间切换投资的好处。基于对漂流在这个项目中获得的成本和收益的估计，最终目标将是确定漂流行为如何改变我们目前对帮助行为的理解，以及在理论背景下社会性的演变。

Darwin's theory of natural selection predicts that organisms should act selfishly in order to pass on as many of their genes to the next generation as possible. The evolution of social behaviour is a paradox because it requires that some individuals forgo reproduction in order to help raise the offspring of others. Explaining the evolution of helping behaviour in animal societies has been a major focus for evolutionary biologists ever since Darwin. A leading explanation is that helpers gain a net benefit from raising the offspring of relatives. This project will examine a recently discovered strategy for helping in a social insect, and ask whether it can be explained in terms of an insurance policy. Social insect (bees, wasps, ants and termites) usually live as groups of relatives, where helpers benefit from raising related offspring. Biologists were perplexed, therefore, to find that helpers are occasionally found drifting to nests other than their own. It has been debated whether drifting happens for a reason: sometimes nest-drifting appears to be accidental, but on other occasions drifters lay eggs in the nest they visit. Recently, a new explanation for drifting was discovered in a social paper wasp: over half of the wasps in a population visited several related nests, drifting from nest to nest, delivering forage and feeding the brood. This behaviour has important implications on the evolution of helping, but until now has been neglected. This project explores this question. To begin with, the project will determine whether drifters divide their help amongst different nests in relation to each nest's payoff, in the same way that you might switch to a job that offers more money for the same amount of work. Drifters may be able to respond to changes in the payoffs of helping and so maximise their genetic fitness. If, however, by switching nests drifters forfeit the effort they have already invested, then drifters benefit little from this strategy. You will be familiar with this argument if you have ever tried to offset your carbon footprint. If you plant a tree for every flight you take, you want to be assured that your trees will not be cut down before they have offset your carbon emissions. Assurance-based advantages may explain helping behaviour in a similar way: a helper should only invest help if, in the event of her death or absence, those part-raised brood will be reared to adulthood by remaining nestmates. This project will determine whether the helping effort invested by drifters in several different nests is assured, even if they reduce (or withdraw) their help from a particular nest. Drifting behaviour may actually be a mechanism for assuring investment. To compensate for the loss of a helper, new helpers may be recruited from a pool of drifters. Without new recruits, the part-raised brood may die and the helper's investment lost. Calling on a supply of ready recruits is rather like a businessman going to the job centre to fill an urgent vacancy. This form of recruitment (both for the wasps and the businessman) is much quicker and less costly than finding a novice and training them up from scratch. This project will ascertain whether drifting is a mechanism for assuring investment for helpers. Finally, undertaking any strategy demands a consideration of the pros and cons. For example, you might deliberate whether it is worth investing in stock and shares at a time when the global economy is in turmoil. In a similar way, social animals may weigh up the costs and benefits of helping. For example, if drifting incurs high mortality, then the costs may often outweigh the benefits of being able to switch investment between nests according to payoffs. Based on estimates of the costs and benefits of drifting obtained during this project, the final aim will be to determine how drifting behaviour changes our current understanding of helping behaviour and the evolution of sociality in a theoretical context.