Doctoral Dissertation Improvement: Olfactory Communication, Kin Selection, and the MHC in Wild and Captive Sifakas

也许是因为气味在人类中的功能减弱，研究人员很少探索气味在灵长类动物交流中的作用。嗅觉信息有可能传递有关发送者的重要物种和个体特定信息。破译这一信息对于更好地了解哺乳动物的社会互动是至关重要的。博士生T·L·莫雷利将利用国家科学基金会的资金，利用行为、遗传、化学和实验技术，探索气味标记的使用以及主要组织相容性复合体(MHC)在灵长类动物亲属识别中的重要性，重点是濒危的Milne-Edward‘s sifakas(Propithecus Edwardsi)的野生种群。这项研究是一个更广泛的框架的一部分，目的是确定身份(包括亲属关系)如何影响社会互动，并探索嗅觉对灵长类的重要性。本论文项目有四个目标。首先，莫雷利将对野生华氏原猴种群中的主要组织相容性复合体基因进行测序，以确定MHC在狐猴交流和生活史中扮演的角色。在其他分类群中的证据表明，MHC多样性对免疫功能至关重要，并可通过嗅觉特征识别相似种。鉴于气味交流是狐猴生活中不可或缺的一部分，需要更多关于MHC在原猴社会互动中的影响的数据。然后，她将把这些结果与气相色谱-质谱仪产生的嗅觉指纹进行比较，以确定sifakas是否可以利用MHC的气味相关性，通过亲属选择获得包容性的健康益处，并通过优化配偶兼容性来提高后代存活率。此外，她将进行双选择偏好测试，以揭示西法卡是否可以利用气味来区分亲属关系。最后，这项研究中产生的数据将被用来评估野生狐猴种群中MHC的杂合度水平，从而提供一个与进化相关的测量方法来计算濒危物种的健康状况。如果栖息地破坏和种群隔离正在降低MHC的变异性，这可能会通过降低病原体抵抗力和扰乱行为过程(例如基于MHC类型的配偶选择)来影响生存能力。灵长类动物的感觉生态学是一个令人兴奋且不断扩大的研究领域；很少有人进行研究，特别是关于嗅觉的研究。这个项目将通过测试关于社会性和交配系统的假设而具有智力上的价值。无论研究是否显示气味被用作亲属辨别的线索，结果都将揭示有关气味标记实际传达什么的重要信息。此外，这将是第一次深入描述非人类灵长类动物的嗅觉线索，这是基因与生理和行为之间的直接联系。该项目的更广泛影响包括吸引、教授和雇用来自不同背景的人，包括美国本科生、美国和国际志愿者、马达加斯加本科生和毕业生以及马达加斯加当地专家，以及最终获得成功的博士学位。此外，这项研究将对在面临快速栖息地破坏的情况下保护濒危马达加斯加灵长类动物具有重要意义，提供有助于保护濒危灵长类动物种群的数据，并有助于未来对野生和圈养灵长类动物种群的管理。

Perhaps due to its reduced function in humans, researchers have rarely explored the use of scent in primate communication. Olfactory messages have the potential to transmit important species- and individual-specific information about the sender. It is critical to decode this message to better understand mammalian social interactions.Using funding from the National Science Foundation, doctoral student T. L. Morelli will explore the use of scent-marking and the importance of the Major Histocompatibility Complex (MHC) in primate kin recognition using behavioral, genetic, chemical, and experimental techniques, focusing specifically on wild populations of endangered Milne-Edward's sifakas (Propithecus edwardsi). This research is part of a broader framework to determine how identity, including kinship, affects social interactions and to explore the importance of olfaction to primates. This dissertation project has four objectives. First, Morelli will sequence major histocompatibility complex genes in a wild Propithecus edwardsi population to determine what role the MHC plays in lemur communication and life history. Evidence in other taxa indicates that MHC diversity is both critical in immune function and recognizable to conspecifics through olfactory signatures. Given that scent communication is integral to the life of a lemur, more data about the effect of MHC in prosimian social interactions are needed. She will then compare these results to olfactory fingerprints produced from gas chromatography-mass spectrometry to determine whether sifakas could use scent correlates of the MHC to gain inclusive fitness benefits through kin selection and increased offspring survival resulting from optimizing mate compatibility. Furthermore, she will conduct two-choice preference tests to reveal whether sifakas can use scent to discriminate kinship. Finally, data produced in this study will be used to assess heterozygosity levels at the MHC in a wild lemur population, thus providing an evolutionarily relevant measurement to calculate the health of an endangered species. If habitat destruction and population isolation are reducing MHC variability, this could affect viability both through reduced pathogen resistance and through disrupted behavioral processes, such as mate choice based on MHC type. Sensory ecology of primates is an exciting and expanding field of study; little research has been conducted, particularly on olfaction. This project will have intellectual merit by testing hypotheses on sociality and mating systems. Whether or not the study reveals that odor is used as a cue in kin discrimination, results will reveal important information about what the scent mark is actually communicating. Moreover, this would be the first in-depth description of an olfactory cue for kin recognition in a non-human primate, a direct link from genes to physiology and behavior. The broader impacts of this project include engaging, teaching, and employing people from diverse backgrounds, including U.S. undergraduates, U.S. and international volunteers, Malagasy undergraduates and graduates, and local Malagasy experts, as well as culminating in a successful Ph.D. degree. In addition, this research will have important implications for conserving endangered Malagasy primates in the face of rapid habitat destruction, providing data that can be useful to conserving populations of an endangered primate, and aiding future management of both wild and captive primate populations.