DISSERTATION RESEARCH: Genetic signatures of mate choice: Influences of MHC genes on behavior and fitness-associated traits in European starlings

主要组织相容性复合体（MHC）基因编码向免疫系统呈递病原体的蛋白质，因此对个体在疾病中存活的程度有直接影响。令人惊讶的是，这些基因也影响许多脊椎动物的择偶。在哺乳动物和鱼类中，MHC改变了身体的气味，从而使个体能够选择配偶，并通过嗅觉识别亲属。个体可以通过以下方式优化后代的MHC基因：1)MHC杂合度高或多样性高；2)特定的适应性良好的MHC等位基因；3)互补自身的MHC基因。拥有“良好”MHC基因的人对某些疾病更有抵抗力，但也可能更有吸引力。这是因为MHC基因不仅可以影响体味，还可以影响身体特征，比如鹿的鹿角，当一个人健康、身体状况良好时，这些特征会得到最大程度的表达。这些“条件依赖特征”在择偶决策中经常被展示和检查（想象一下孔雀的尾巴）。结合田野调查和分子方法，研究MHC基因如何影响欧洲椋鸟（Sturnus vulgaris）的条件依赖性状和交配模式，并采取真正综合的方法来理解鸟类配偶选择的行为、生理和遗传成分。这项研究的结果有望对与行为和分子生态学有关的广泛工作产生影响。更广泛的影响：欧洲椋鸟在150年前从欧洲被引入北美，在此期间，它们的数量急剧增加。研究这些鸟类如何选择配偶，以及它们的免疫系统如何成功地适应新的病原体，将有助于更深入地了解它们的生物学，从而应用于控制它们扩张的方法。分析MHC杂合性和特定等位基因在疾病易感性和耐药性中的非排他性作用，将有助于深入了解鸟类种群和脊椎动物如何应对随着人类在全球范围内的影响增加而不断增加的传入病原体。由于这项研究在行为生态学和分子生态学中都有应用，这个项目引起了广泛的学生的兴趣。已经有两名本科生参与了这个项目的实地调研，并且还会有更多的本科生参与这个实地调研季。对遗传学技术感兴趣的学生也将有机会在这个项目的分子方面密切合作。因为这项研究是在奶牛场进行的，在那里椋鸟是农业和经济害虫，在偏远的农田周围放置巢箱已经产生了惊人的效果，减少了在谷仓内和周围繁殖的椋鸟数量，并在研究人员和当地农民之间建立了积极的工作关系。

Major histocompatibility complex (MHC) genes code for proteins that present pathogens to the immune system and therefore have a direct effect on how well an individual survives disease. Amazingly, these genes also influence mate choice in many vertebrates. In mammals and fish, the MHC alters body odor thereby allowing individuals to choose mates and recognize kin through the sense of smell. Individuals can optimize MHC genes in their offspring by choosing mates with 1) high MHC heterozygosity or diversity, 2) specific well-adapted MHC alleles, or 3) MHC genes that complement their own. Individuals with "good" MHC genes are more resistant to some diseases, but also may be more attractive. This is because MHC genes can influence, not only body odor, but also physical traits, such as antlers in deer, that are expressed to their fullest extent when an individual is healthy and in good body condition. These "condition-dependent traits" are often displayed and examined during mate choice decisions (imagine the peacock's tail). Combining fieldwork with molecular approaches, the proposed research investigates how MHC genes may influence condition-dependent traits and mating patterns in European starlings (Sturnus vulgaris) and takes a truly integrative approach to understanding behavioral, physiological, and genetic components of mate choice in birds. Results from this research are expected to have impact on a broad range of work relating to behavioral and molecular ecology.Broader Impacts: European starlings were introduced to North America from Europe 150 years ago, and during this time, their numbers have dramatically increased. Studying how these birds choose mates and how their immune systems successfully adapt to new pathogens will lead to a deeper understanding of their biology that can be applied to methods for controlling their expansion. Parsing out the non-exclusive roles of MHC heterozygosity and specific alleles in disease susceptibility and resistance will provide insight into how avian populations, and vertebrates in general, deal with an increasing barrage of introduced pathogens as human impact increases across the globe. Because this research has applications to both behavioral and molecular ecology, this project piques the interest of a broad range of students. Two undergraduates have participated in field research for this project, and more will participate this field season. Students interested in genetics techniques will also have the opportunity to work closely on molecular aspects of this project. Because this research is conducted on dairy farms, where starlings are agricultural and economic pests, placing nest boxes around the outlying agricultural fields has had the surprising effect of reducing the numbers of starlings breeding in and around barns and has created a positive working relationship between the researchers and local farmers.