The decision to cooperate: kin recognition mechanisms in female house mice

这个项目涉及亲属识别的机制，以及亲属关系在雌性之间合作繁殖中的重要性。当动物帮助抚养不是自己的后代时，就会发生合作繁殖。例如，雌性家鼠经常与另一只繁殖雌性共同抚养它们的后代，为公共巢穴中的所有幼崽提供乳汁。这一决定是任意的-他们可以选择是否与某一特定伙伴合作。然而，社会伙伴选择的基础因素，以及这种选择如何影响个体女性对自己和其他幼崽的投资，知之甚少。一般认为，亲属关系通过增加共享基因的亲属的成功来驱动这种合作行为。不言而喻，这需要在相关和不相关个体混合的物种中可靠地识别近亲，尽管我们对动物识别亲属的能力以及可能导致这种情况的机制的理解令人惊讶地贫乏。最近，我们发现了一个高度多态性的遗传身份信号，用于避免近亲近亲交配的家鼠。这为遗传识别机制提供了明确的证据，该机制用于识别共享相同高度多态性遗传标记的近亲。我们将使用这种已被证实的遗传标记来测试雌性家鼠是否喜欢已知的亲属作为合作伙伴。我们还将使用一种新的非侵入性方法来标记单个母亲的乳汁，并首次测量公共巢穴中每只幼崽的投资。这将使我们能够解决那些与已知亲属合作的人是否比与其他女性合作的人对自己和其他后代表现出更多的平等主义投资。然而，这种简单的遗传亲缘关系识别机制是有限的，因为它只能识别一小部分近亲。通过建模，我们已经产生了可测试的预测，将被确认使用替代遗传亲属识别机制的同胞和无关动物的比例。从理论上讲，行为印迹母亲的等位基因检测通过母亲的表型在饲养过程中可以允许可靠的识别一个非常高的比例近亲。然而，使用这一机制确认亲属关系的关键要求还有待检验。在这个项目中，我们将确定是否正常，遗传变异家鼠可以识别母系亲属通过行为印记的母系等位基因。我们将确定它们是否特异性地印在三个高度多态的基因簇上，这些基因簇编码小鼠气味中已建立的遗传身份信号，或者印在其他遗传位点上。我们还将测试是否有一个共同的母体环境，这影响了近交遗传纯合实验室小鼠的气味，有助于任何母亲的同胞和半同胞的识别。我们的研究结果对于理解动物在广泛的社会背景下能够识别近亲的程度具有普遍意义。亲属关系不太可能是唯一的因素影响的决定，合作之间的繁殖女性。小鼠通过犁鼻嗅觉子系统检测尿蛋白和代谢产物（类固醇硫酸盐），可以获得有关雌性生理状态的大量信息。我们将测试是否个别合作伙伴的喜好，不确定的亲属关系与这些生理变量的气味成分的表达。我们还将测试女性是否避免近亲交配的合作伙伴（从同胞交配），将有显着较差的成功，提高后代断奶。

This project addresses mechanisms underlying kin recognition, and the importance of kinship in cooperative breeding between females. Cooperative breeding occurs when animals assist in rearing offspring that are not their own. For example, female house mice frequently rear their offspring communally with another breeding female, providing milk to all pups in the communal nest. This decision is facultative - they can choose to cooperate with a particular partner or not. However, the factors that underlie social partner choice, and how this choice influences an individual female's investment in own and other pups, are poorly understood. It is generally assumed that kinship drives such cooperative behaviour by increasing the success of relatives that share genes. Implicitly, this requires reliable recognition of close kin in species where related and unrelated individuals mix, although we have surprisingly poor understanding of the abilities of animals to recognize kin and the mechanisms that might underlie this. Recently, we discovered a highly polymorphic genetic identity signal that is used to avoid inbreeding with close kin by house mice. This has provided clear evidence of a genetic recognition mechanism that is used to identify close kin sharing the same highly polymorphic genetic marker. We will use this proven genetic marker to test whether female house mice prefer known kin as cooperative partners. We will also use a novel non-invasive approach to label the milk of individual mothers and measure investment in each pup in communal nests for the first time. This will allow us to address whether those cooperating with known kin show more egalitarian investment in their own and other offspring than those cooperating with other females. This type of simple genetic kin recognition mechanism is limited, though, because it identifies only a small proportion of close kin. Through modeling, we have generated testable predictions concerning the proportion of sibs and unrelated animals that would be recognized using alternative genetic kin recognition mechanisms. Theoretically, behavioural imprinting on maternal alleles detected through a mother's phenotype during rearing could allow reliable recognition of a very high proportion of close kin. However, the key requirements for recognition of kin using this mechanism have yet to be tested. In this project, we will establish whether normal, genetically variable house mice can recognize maternal kin through behavioural imprinting on maternal alleles. We will determine whether they imprint specifically on three highly polymorphic gene clusters that encode established genetic identity signals in mouse scents, or on other genetic loci. We will also test whether a common maternal environment, which influences the scents of inbred genetically homozygous laboratory mice, contributes to any recognition of maternal sibs and half-sibs. Our findings will have general relevance for understanding the extent to which animals are able to recognize close kin in a broad range of social contexts. Kinship is unlikely to be the only factor influencing the decision to cooperate among breeding females. Mice can gain considerable information about female physiological status through urinary proteins and metabolites (steroid sulphates) detected through the vomeronasal olfactory subsystem. We will test whether individual partner preferences that are not determined by kinship correlate with expression of these physiologically-variable scent components. We will also test whether females avoid inbred partners (from sib matings) that would have significantly poorer success in raising offspring to weaning.