Cognitive systems of obligate brood parasites

动物的思维方式（认知）或行为会影响其生存和繁殖（适应性）。然而，直到最近才发现非模式生物的行为、认知和大脑之间存在明显的联系。空间记忆是证明这些联系的最强的认知系统之一，因为（i）空间记忆在动物运动中与资源有关的作用以及（ii）海马体在空间记忆中的作用，最终，健身。 专性育雏寄生虫，完全依赖于其他物种来抚养他们的年轻人的物种，是研究大脑和认知专业化的理想系统，因为女性比男性有更复杂的空间使用，这与其他系统形成对比，我们看到性别差异有利于男性（例如一夫多妻制哺乳动物）。在一些育雏寄生虫中，如褐头燕八哥（Molothrus ater），每个季节只有雌性寻找并寄生多达50个宿主巢。我发现，雌性燕八哥在空间记忆任务中的表现优于雄性燕八哥，这种任务类似于野外的宿主巢穴访问。此外，行为和认知的差异与大脑的差异有关;雌性燕八哥比雄性具有更高水平的海马神经发生（海马中招募的新神经元），在非寄生性亲属中没有性别差异。对性别在野生动物空间记忆中的作用进行强有力的测试，需要一个对空间记忆有明确的性别特异性需求和这些需求的性别角色逆转（以避免许多混淆性别特异性因素）的系统，而专性育雏寄生就是这样一个系统。 在这里，我建议研究认知和神经专业化的几种育雏寄生虫使用系统发育，发育，机械和功能的方法。我的目的是确定是否（一）女性偏见的性别差异在海马神经发生持续在整个类群的育雏寄生虫，除了潜在的发展专业化，（二）海马属性，如神经发生影响生态相关的空间记忆，和（iii）海马神经发生影响健身。我假设，育雏寄生虫已经进化出适应海马属性，最大限度地提高他们的能力，记住主机巢的位置，以增加其一生的繁殖成功。为了验证这一假设，我将结合联合收割机认知测试在实验室，现场工作，并使用免疫组织化学和细胞室的时间活动荧光原位杂交（catFISH）的精细尺度海马测量。 检查育雏寄生虫提供了一个独特的机会，在认知神经科学领域内研究一个系统，其中女性，而不是男性，有更复杂的空间使用，从而使我们能够显示是否空间需求，而不是性别本身，可以塑造这些参数。使用这个系统，我将提供一个整体的角度在野生动物的空间记忆的形式和功能之间的联系。

The way an animal thinks (cognition) or behaves can influence its survival and reproduction (fitness). However, only recently have clear links been shown between behaviour, cognition and the brain in non-model organisms. Spatial memory is one of the strongest cognitive systems to demonstrate these links because of the clear role of (i) spatial memory in animal movement in relation to resources and (ii) the hippocampus in spatial memory, and ultimately, fitness. Obligate brood parasites, species that rely solely on other species to raise their young, are an ideal system to study specializations in the brain and cognition because females have more complex space use than males, which contrasts with other systems in which we see a sex difference favouring males (e.g. polygynous mammals). In some brood parasites, like brown-headed cowbirds (Molothrus ater), only females search for and parasitize up to 50 host nests per season. I showed that female cowbirds outperformed males on a spatial memory task that resembled host nest visits in the wild. In addition, differences in behaviour and cognition were linked to differences in the brain; female cowbirds had higher levels of hippocampal neurogenesis (new neurons recruited into the hippocampus) than males, with no sex difference in a non-parasitic relative. Strong tests of the role of sex in spatial memory in wild animals requires a system with both clear sex-specific demands on spatial memory and sex role reversal of those demands (to avoid the many confounding sex-specific factors), and obligate brood parasitism is one such system. Here, I propose to examine cognitive and neural specializations in several species of brood parasites using phylogenetic, developmental, mechanistic, and functional approaches. I aim to determine whether (i) female-biased sex differences in hippocampal neurogenesis persist in brood parasites across taxa, in addition to potential developmental specializations, (ii) hippocampal attributes such as neurogenesis affect ecologically-relevant spatial memory, and (iii) hippocampal neurogenesis affects fitness. I hypothesize that brood parasites have evolved adaptations in hippocampal attributes that maximize their ability to remember the location of host nests to increase their lifetime reproductive success. To test this hypothesis, I will combine cognitive testing in the lab, field work, and fine-scale measures of the hippocampus using immuhistochemistry and cellular compartment analysis of temporal activity by fluorescence in situ hybridization (catFISH). Examining brood parasites offers a unique opportunity within the field of cognitive neuroscience to study a system in which females, instead of males, have more complex space use, thus enabling us to show whether spatial demands, rather than sex itself, can shape these parameters. Using this system, I will provide a holistic perspective on the link between form and function in spatial memory in wild animals.