PUBLIC GOODS AND SOCIALLY RESPONSIVE FEMALES

动物之间为什么以及如何相互合作仍然是一个令人着迷的挑战。我们知道，家庭内部或经常相互互动的个人更有可能从彼此的合作中获得互惠利益。然而，在整个动物界，有许多例子不符合这些条件，在没有预测到的情况下观察到合作。我们最近在对果蝇社会反应的研究中发现了这样一个例子。他们不生活在家庭或社会群体中，这意味着他们不太可能表现出社会合作行为。然而，我们发现，女性对其社会环境的反应非常微妙。例如，当它们探测到其他雌性的存在时，它们会非常迅速地提高产卵率，并改变它们的性接受能力。雌鸟在食物基质上产卵，雌鸟与其他雌鸟在一起产卵。出乎意料的是，这些卵似乎受益于其他雌鸟卵的合作保护。分批次产卵似乎是有好处的，因为产卵时有抗菌和抗衰老“涂层”：这会扩散和防止产卵底物的腐烂，并防止卵被任何存在的幼虫吃掉。防御性涂层保护食物块上的一批批卵(以及由此产生的幼虫)。然而，这些抗微生物和抗杀菌化学品的生产成本高昂，并有可能被其他人利用。这是因为，如果一些个体在那些有着强大的抗菌外套或具有有效的反食人防御系统的鸡蛋旁边产下没有防御能力的鸡蛋，他们可以在不支付成本的情况下受益，因此可以搭乘这个系统的便车。是什么阻止了大多数人像这样作弊，其原因在于一套关于“公共产品”的强大理论。解释的关键是，生产公共产品(即抗微生物和反食人的防御措施)的好处是否是“非线性的”，例如，如果每个人都能受益的唯一方式是一定数量的合作个人参与进来。我们项目的目的是衡量在我们的测试系统中如何以及为什么在公共产品上进行合作，从而测试这一重要理论的预测。利用果蝇系统的力量，我们可以通过实验操纵整个系统，从感官输入，到公共产品本身的生产，再到女性个体生殖输出的结果。我们将调查：(1)通过生产公共产品，如抗菌剂和反食人化学品，女性从对社会环境的反应中受益的性质。(2)公共产品的生产与健康之间关系的形成。(3)生产具有社会响应性的公共产品的基因调控机制。这项计划的结果将为我们理解社会生物学的基本组成部分向前迈出重要的一步。这些原则将对整个类群产生广泛的影响，并将有助于向我们展示我们如何以及为什么要这样做。

Why and how animals cooperate with each other remains a fascinating challenge to explain. We know that individuals within families or that regularly interact with each other are far more likely to gain reciprocal benefits from cooperating with each other. However, there are many examples across the animal kingdom where these conditions don't hold and where cooperation is observed in situations in which it isn't predicted. We have recently uncovered such an example in our studies of the social responses of fruitflies. They don't live in familial or social groups, which predicts that they should be very unlikely to express socially cooperative behaviour. Nevertheless, we have found that females have remarkably fine-tuned responses to their social environments. For example, when they detect the presence of other females they very rapidly increase their rate of egg laying and alter their sexual receptivity. Eggs laid by groups of females that meet on food substrates females are laid together in clumps together with those of other females and, unexpectedly, these eggs seem to benefit from the cooperative protection offered by the eggs of other females.Laying eggs in communal batches seems to be beneficial because eggs are laid with an antimicrobial and anticannibalism 'coating': this diffuses and prevents spoilage of the substrate on which the eggs are laid, and prevents eggs from being eaten by any larvae that are present. The defensive coating protects batches of eggs (and resulting larvae) on a food patch. However, the production of these antimicrobial and anticannibalistic chemicals is energetically costly and potentially open to exploitation by others. This is because, if some individuals lay 'defenceless' eggs next to those with a strong antimicrobial coat or with effective anti-cannibalism defences, they can benefit without paying costs and hence can 'free-ride' the system. The explanation for what prevents most individuals from cheating like this resides in a powerful body of theory concerning 'public goods'. Key to the explanation is whether the benefits of producing public goods (i.e. the antimicrobial and anti-cannibalism defences) are 'non linear', for example if the only way everyone can benefit is if a threshold number of cooperating individuals pitch in. The aim of our project is to measure how and why cooperation over public goods occurs in our test system, and hence test the predictions of this important theory. Using the power of the fruitfly system, we can do this by experimentally manipulating the whole system, from the sensory inputs, to the production of public goods themselves, to the outcome in terms of the reproductive output of individual females.We will investigate:(1) The nature of benefits to females from responding to social environments through the production of public goods such as antimicrobial and anti-cannibalistic chemicals. (2) The shape of the relationship between the production of public goods and fitness.(3) The gene regulatory mechanisms underlying the production of socially responsive public goods.The results of this programme will provide a significant step forward in our understanding of fundamental components of social biology. These principles will have broad impact across taxa and will help to show us how and why we behave as we do.