Functions and mechanism of recognition systems in social birds

从基因和细胞到个人和物种，识别和区分系统在生物组织的各个层面上的相互作用中发挥着关键作用。例如，免疫系统必须能够可靠地识别自我和非我，而雌性在决定与谁交配时可能不得不歧视相关的雄性或不同物种的雄性。同样，希望投资于子女的父母可能需要在一些潜在的接受者中进行歧视，偏袒自己的子女。对识别系统的研究很重要，因为在这些不同背景下演变的决策和歧视取决于识别的有效性。如果犯错误的代价非常高，我们预计会有强有力的选择来进行准确的识别和歧视，但如果这种识别错误的成本很低，那么歧视和识别的精确度就会低得多，因为没有通过识别测试的个人会受到较弱的选择。因此，我们希望看到识别系统的性质和有效性根据这一过程发生的背景而有所不同。社会有机体提供了一个明显的例子，在这种情况下，识别个人、亲属和其他类别的同类特征是一个关键要求。事实上，有大量证据表明，在各种各样的背景下存在歧视行为，往往会产生明显的健康后果。然而，我们对识别系统以及社会动物区分不同类别个体的能力的理解很差，尽管这种机制对于定义对适应性社会行为的限制很重要。该项目的目的是研究识别系统在一系列空间尺度和不同社会背景下的功能和机制，利用群居编织者Philetairus Socius独特的群体繁殖系统。这种善于交际的编织者建造了一个非凡的公共鸟巢，可以容纳数百只鸟，这些鸟要么成对繁殖，要么在合作的家庭小组中繁殖，由帮手帮助他们的亲戚抚养后代。蜂群之间的传播是有限的，帮助者通常与他们帮助的繁殖者密切相关。然而，近亲关系密切也可能产生近亲交配的重大风险。在更广泛的空间尺度上，蜂群或多或少是离散的社会群体，表现出高于家庭的另一种社会组织水平。社会性编织者社会系统的这些特征使它们非常适合在社会和空间尺度上调查识别和歧视。具体目标是检验关于亲属辨别能力、避免近亲交配以及帮助者在育儿方面的合作投资的假设。在每种情况下，我们将测试个体是否能够主动区分亲属和非亲属，或者区分是否基于亲属关系的空间线索。我们还将通过观察和实验，通过对社会网络的分析，测试对家庭层面以上的社会群体的歧视。最后，我们将进行实地观察和实验，以确定假定识别线索(联系电话)的发展，并确定这些识别信号的遗传和环境成分。通过这些研究，我们的目标是对识别系统在任何社会脊椎动物中的功能和机制提供最全面的理解。

Systems for recognition and discrimination play a critical role in interactions at every level of biological organisation from genes and cells through to individuals and species. For example, immune systems must be able to reliably recognise self from non-self, and females may have to discriminate against related males or males of different species when making decisions about whom to mate with. Similarly, a parent who wishes to invest in their offspring may need to discriminate in favour of their own offspring from among a number of potential recipients. The study of recognition systems is important because the decision-making and discrimination that evolves in these various contexts depends on the effectiveness of recognition. If the costs of making a mistake are very high, we would expect strong selection for accurate recognition and discrimination, but if the costs of such recognition errors are low, then discrimination and recognition would be expected to be much less accurate because of the weak selection imposed on individuals who fail tests of recognition. Therefore, we expect to see variation in the nature and effectiveness of recognition systems according to the context in which that process occurs. Social organisms provide an obvious case in which the recognition of individuals, kin and other categories of conspecifics is a critical requirement. Indeed, there is abundant evidence for discriminatory behaviour in a wide variety of contexts, often with demonstrable fitness consequences. However, our understanding of recognition systems and hence the ability of social animals to discriminate among different classes of individuals is poor, despite the importance of such mechanisms for defining the constraints on adaptive social behaviour. The aim of this project is to investigate the function and mechanisms of recognition systems at a range of spatial scales and in diverse social contexts using the unique colonial breeding system of the sociable weaver Philetairus socius. The sociable weaver builds an extraordinary communal nest that may house hundreds of birds, that breed either in pairs or in cooperative family groups with helpers assisting their relatives in raising offspring. Dispersal between colonies is limited, and helpers are typically closely related to the breeders that they help. However, the close proximity of kin is also likely to generate a significant risk of inbreeding. At a broader spatial scale, colonies are more or less discrete social groups that exhibit another level of social organisation above that of the family.These features of the sociable weaver social system make them ideally suited for investigation of recognition and discrimination at a range of social and spatial scales. Specific objectives are to test hypotheses concerning kin discrimination ability in the avoidance of inbreeding and in cooperative investment in brood care by helpers. In each case, we will test whether individuals are able to actively discriminate kin from non-kin, or whether discrimination is based on spatial cues to kinship. We will also use observations and experiments to test discrimination of social groups above the level of family using analysis of social networks. Finally, we will conduct field observations and experiments to determine the development of putative recognition cues (contact calls), and determine the genetic and environmental components of these recognition signals. Through these studies we aim to provide the most comprehensive understanding of the function and mechanism of recognition systems in any social vertebrate.