Expanding our horizons in understanding brain and dietary evolution in Primates and their kin

拓展我们的视野，了解灵长类动物及其亲属的大脑和饮食进化

• 批准号: RGPIN-2022-03073
• 负责人: Silcox, Mary
• 金额: $ 2.4万
• 依托单位: University of Toronto
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2022
• 资助国家: 加拿大
• 起止时间: 2022-01-01 至 2023-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=743617
• 关键词: Expanding; our; horizons; understanding; brain

The evolution of the diet is central to the process of primate origins. All of the competing scenarios for primate origins have a dietary component: visual predation focusing on adaptations for insectivory; terminal branch feeding involving an expansion of the arboreal dietary niche to include more fruit; and the grasp-leaping hypothesis, which incorporates a shift to greater herbivory in early primate evolution. Diet is of particular importance in understanding the evolution of the enlarged and complex primate brain. Building such a brain requires access to high energy food, while retrieving such broadly dispersed and irregularly available foodstuffs (e.g., fruit) requires greater degrees of processing power. Although analyses of modern primates have supported the important role of diet in brain evolution, they necessarily simplify the origin of primates down to a single node. The fossil record demonstrates that there were many lineages of stem primates, making it clear that the story is much more complex than the idealized version implied by such studies. Although there have been strides in recent years, there are still several lineages of early primates for which no quantitative work has been done to estimate aspects of diet. A critical component of this shortfall is that early primates have patterns of adaptations not found among living primates, meaning that living members of the order are insufficient models for reconstructing diet in those groups. The current study will seek to fill some of these gaps by considering a much broader range of model taxa and by using cutting edge dental topographic methods to allow for precise quantification of dental form. This study will also seek to expand the types of information that can be collected and compared with respect to the early evolution of the brain in primates. The strong evidence for rampant parallelism in primate brain size evolution implies that studies that are limited to living taxa will be constrained in reconstructing the size and shape of the brain in the common ancestor of all primates. This underscores the importance of fossils to an understanding of the early stages of primate brain evolution. Since the brain does not fossilize, the data available from even the best-preserved fossils is limited to the imprint of the brain preserved on the internal surface of the cranium (i.e., the endocast). The current study will seek to use geometric morphometric and DiceCT methods to expand the information about changing shape and function that can be extracted from such endocasts. Ultimately, the goal of this study will be to amass a dataset that will allow for a synthetic consideration of how shifting diets are aligned (or not) with changes in brain size and shape, using a phylogenetic framework that incorporates both fossil and extant members of Primates, and of closely related groups.

饮食的进化对于灵长类动物的起源过程至关重要。灵长类起源的所有竞争场景都具有饮食成分：视觉捕食侧重于对昆虫的适应；末端树枝取食涉及扩大树栖饮食生态位以包括更多水果；以及跳跃式假说，该假说包含了早期灵长类动物进化中向更大的草食性的转变。饮食对于理解灵长类动物大脑的扩大和复杂的进化特别重要。构建这样的大脑需要获取高能量食物，而检索这种广泛分散且不定期获取的食物（例如水果）则需要更高程度的处理能力。尽管对现代灵长类动物的分析支持了饮食在大脑进化中的重要作用，但它们必然将灵长类动物的起源简化为单个节点。化石记录表明，干灵长类动物有许多谱系，这清楚地表明这个故事比此类研究所暗示的理想化版本要复杂得多。尽管近年来取得了长足的进步，但仍有几个早期灵长类动物谱系尚未进行定量工作来估计饮食的各个方面。这一缺陷的一个关键组成部分是早期灵长类动物具有现存灵长类动物中没有的适应模式，这意味着该目中的现存成员不足以成为重建这些群体饮食的模型。目前的研究将通过考虑更广泛的模型分类单元并使用最先进的牙齿地形方法来精确量化牙齿形态，从而寻求填补其中的一些空白。这项研究还将寻求扩大可以收集和比较灵长类动物大脑早期进化的信息类型。灵长类动物大脑尺寸进化中普遍存在平行性的有力证据表明，仅限于活体类群的研究将在重建所有灵长类动物共同祖先的大脑尺寸和形状方面受到限制。这强调了化石对于了解灵长类大脑进化早期阶段的重要性。由于大脑不会形成化石，因此即使是保存最完好的化石，所获得的数据也仅限于保留在颅骨内表面（即内铸件）上的大脑印记。当前的研究将寻求使用几何形态测量和 DiceCT 方法来扩展可从此类内铸件中提取的有关形状和功能变化的信息。 最终，这项研究的目标是收集一个数据集，利用包含灵长类化石和现存成员以及密切相关群体的系统发育框架，综合考虑饮食变化如何与大脑大小和形状的变化保持一致（或不一致）。