A Model of Behavioral Evolution from Genotype to Phenotype

行为的进化依赖于基因组水平的变化，但很少有脊椎动物的行为可以直接追溯到特定的基因序列。在这个项目中，研究团队将使用自然产生的动物模型--白喉麻雀，以具体的方式将行为与基因序列联系起来。在这个物种中，50%的鸟类有一种不寻常的染色体，这使得它们更具攻击性。因此，染色体是一个很好的工具，可以用来理解基因表达的个体差异如何导致行为的差异。该团队最近发现，具有不寻常染色体的动物在大脑的某些区域有一种类固醇受体的高表达。在这里，研究小组在分子水平上确定了导致某些鸟类比其他鸟类表达更多这些受体的遗传机制。在这样做的过程中，该团队展示了对类固醇激素的反应是如何在基因组中编码的。这项工作很适合教育和推广，因为它说明了一种常见的后院鸟的基本生物学概念。因此，它以一种学生可以理解的方式整合了典型生物课程的多个单元。高中教师被招募参与研究，并制定关于遗传学、荷尔蒙、大脑解剖和社会行为的教案。PI还在实验室指导高中生、本科生和研究生。在埃默里，超过75%的少年派学员是代表不足的少数族裔或女性。行为的进化依赖于基因组水平的变化，但很少有脊椎动物的行为可以直接追溯到遗传序列。在白喉麻雀中，染色体倒位与攻击性行为表型分离，提供了以具体方式将基因和行为联系起来的难得机会。反转捕获了编码雌激素受体α(ERpha)的基因ESR1。研究小组最近发现，ERpha在大脑中的局部表达取决于倒位的存在或不存在，ERpha表达的变化预测了基因对领土攻击性的影响。该研究小组使用体外报告分析、亚硫酸氢盐测序和等位基因特异性定量聚合酶链式反应来确定导致ERα表达变化的遗传和表观遗传机制。选择性ERpha配体对每种基因的动物攻击行为的影响被用来确定ERpha表达和功能的变化是否导致领土攻击的差异。由于该团队使用的是具有行为特征的自由生活动物的组织，分子和行为水平在相同的动物身上整合在一起，从而实现了新的联系。这些结果为基因变化如何导致表型变化提供了一个跨学科的综合模型。这项工作很适合教育和推广，因为它说明了一种常见的后院鸟的基本生物学概念。

The evolution of behavior relies on changes at the level of the genome, yet few vertebrate behaviors can be traced directly to specific gene sequences. In this project, the research team will use a naturally-occurring animal model, the white-throated sparrow, to connect behavior with gene sequence in a concrete way. In this species, 50% of the birds have an unusual chromosome that makes them more aggressive. The chromosome is therefore an excellent tool for understanding how individual variation in gene expression contributes to variation in behavior. The team recently showed that animals with the unusual chromosome have higher expression of a type of steroid receptor in some areas of the brain. Here, the research group determines the genetic mechanisms, at the molecular level, that cause some birds to express more of these receptors than others. In so doing, the team demonstrates how responsiveness to steroid hormones is encoded in the genome. The work lends itself well to education and outreach because it illustrates basic biological concepts in a common backyard bird. Thus, it serves to integrate multiple units of a typical biology course in a way that is accessible to students. High school teachers are recruited to participate in the research and to develop lesson plans about genetics, hormones, brain anatomy, and social behavior. The PI also mentors high school students, undergraduates, and graduate students in the lab. More than 75% of the PI's mentees at Emory have been underrepresented minorities or women. The evolution of behavior relies on changes at the level of the genome, yet few vertebrate behaviors can be traced directly to genetic sequences. In the white-throated sparrow (Zonotrichia albicollis), a chromosomal inversion segregates with an aggressive behavioral phenotype, offering a rare opportunity to connect genes and behavior in a concrete way. The inversion has captured the gene ESR1, which encodes estrogen receptor alpha (ERalpha). The research team recently showed that the local expression of ERalpha in the brain depends on the presence or absence of the inversion and that variation in ERalpha expression predicts the effect of genotype on territorial aggression. The research group uses in vitro reporter assays, bisulfite sequencing, and allele-specific quantitative PCR to identify the genetic and epigenetic mechanisms that contribute to variation in expression of ERalpha. The effects of selective ERalpha ligands on aggressive behavior in animals of each genotype is used to determine whether variation in ERalpha expression and function is causal for variation in territorial aggression. Because the team uses tissue from behaviorally characterized, free-living animals, the molecular and behavioral levels are integrated in the same animals to allow novel connections. The results provide an interdisciplinary, integrated model of how genetic change leads to phenotypic change. The work lends itself well to education and outreach because it illustrates basic biological concepts in a common backyard bird.