Impact of selection pressure for social behavior on canid brain evolution

这个项目将研究神经系统组织的特征，这些特征可以与改变的社会行为联系在一起，包括减少或增加攻击性。两种犬科动物，一种是实验驯化的银狐(Vulpe Vulpe)，另一种是家犬(Canis Familiaris)，是人类为了改变社会行为而有选择地培育出来的。这些行为变化与一系列有限的基因变化同时发生，创造了一个无与伦比的机会，将行为特征(表型)的进化与神经表型联系起来。最近的技术进步使得以相对较低的成本进行详细的、非侵入性的大脑解剖研究成为可能。该项目将利用这些创新，使用结构磁共振成像、扩散张量成像和数字化组织学来创建高分辨率三维(3D)脑图。这项研究的预期产品包括：(1)确定与减少或增加社会性或攻击性有关的神经组织特征，预计这些特征可推广到其他物种；(2)制作在线狐狸和狗脑图谱，作为一般科学界的研究工具公开提供；(3)为年轻科学家提供培训机会；以及(4)通过博客和社交媒体帖子向公众宣传。由于狗是不同文化中的“共同点”，这项研究有一个独特的机会来与社会各界的人们产生个人的相关性和吸引力，并提高公众对科学的欣赏。实验驯养的狐狸和家犬都通过改变社交接近-回避行为而与它们的野生祖先区分开来。之前对啮齿动物和灵长类动物的研究，以及研究人员自己的初步数据，允许形成关于神经适应的有根有据的假设，这些假设是由于社交接近-回避行为的选择压力造成的。具体地说，这个项目将研究控制社会行为和反应选择的边缘和额缘系统。为了确定与改变的社会行为相关的神经系统组织的特征，我们将比较(A)不同品种的家犬之间，每种狗的社交回避/攻击行为测试，以及(B)繁殖用于社交回避行为的狐狸和为社交接近行为而培育的狐狸之间的比较，前者对社交接触做出积极反应，后者像狗一样驯服和友好，与野性狐狸进行比较。全脑MRI和DTI图像将使用3.0和9.4特斯拉MRI扫描仪收集。组织学图像将进行数字扫描，并与MRI图像对齐。分析将包括基于体素的形态测量、基于区域的空间统计、概率光谱分析和基于k-均值连通性的分割。这项研究将促进关于进化如何改变大脑组织的知识，以回应对社交方法和回避的选择。

This project will investigate features of neural system organization that can be linked to altered social behavior, including reduced or increased aggression. Two species of canids, experimentally domesticated silver foxes (Vulpes vulpes) and domestic dogs (Canis familiaris), have been selectively bred by humans for altered social behavior. These behavioral changes occurred alongside a restricted set of genetic changes, creating an unparalleled opportunity to link the evolution of behavioral characteristics (phenotypes) to neural phenotypes. Recent technological advancements enable detailed, non-invasive studies of brain anatomy at relatively low cost. This project will take advantage of these innovations to create high-resolution three-dimensional (3D) brain maps using structural magnetic resonance imaging, diffusion tensor imaging, and digitized histology. Expected products of this research include: (1) identification of features of neural organization that are linked to reduced or increased sociality or aggression, expected to be generalizable to other species, (2) the production of online fox and dog brain atlases that will be publicly available as a research tool for the general scientific community, (3) training opportunities for young scientists, and (4) outreach efforts using blog and social media posts for the general public. Because dogs are a "common denominator" across various cultures, this research has a unique opportunity to be personally relevant and compelling to people from all walks of society, and to enhance public appreciation for science.Both experimentally-domesticated foxes and domestic dogs are distinguished from their wild forebears by altered social approach-avoidance behavior. Previous research in rodents and primates, and the researchers' own preliminary data, allow for the formation of well-grounded hypotheses about neural adaptations that result from selection pressure on social approach-avoidance behavior. Specifically, this project will investigate limbic and fronto-limbic systems governing social behavior and response selection. In order to identify features of neural system organization associated with altered social behavior, whole-brain white and gray matter organization will be compared (a) between various breeds of domestic dogs, each tested for social approach-avoidance/aggression behavior, and (b) between strains of foxes bred for social avoidance behavior, which react aggressively to social contact, versus foxes bred for social approach behavior, which are tame and friendly like dogs, versus wild type foxes. Whole-brain MRI and DTI images will be collected using 3.0 and 9.4 Tesla MRI scanners. Histology images will be digitally scanned and aligned to MRI images. Analyses will include voxel-based morphometry, tract-based spatial statistics, probabilistic tractography, and k-means connectivity-based parcellation. The research will advance knowledge about how evolution modified brain organization in response to selection for social approach and avoidance.