Doctoral Dissertation Improvement: Social and Hormonal Mechanisms of Male Reproductive Skew in Black Howler Monkeys (Alouatta pigra)

这项为期12个月的研究将调查社会和激素机制的分配之间的男性在两个部队的黑色吼猴（Alouatta pigra）在帕伦克国家公园，墨西哥。具体来说，PI将使用所有成年部队成员的系统焦点样本来检查男性社会互动与粪便睾酮和皮质醇水平之间的关系，以评估男性生殖策略是否与他们的睾酮和皮质醇水平相关。 了解这些关系将为深入了解灵长类动物社会和性行为的生物学基础提供有价值的见解。在多雄性群体中，灵长类雄性动物的生殖分布可以从高度偏斜（当一个雄性动物在其居住期间垄断所有生殖机会时）到较少偏斜（当生殖在一个群体中的雄性动物之间分布更均匀时）。 群体中有一个以上的生殖活跃的男性可能会导致（1）的主导男性无法排除其他男性生殖（拔河模型），或（2）的主导男性的让步生殖机会从属男性作为一个留下来的激励，与主导男性受益于从属男性的存在，通过增加生殖成功（让步模型）。 虽然对几种野生灵长类动物的亲子关系研究已经证实了雄性优势等级和生殖成功之间的正相关关系，但影响生殖偏斜的近似机制尚未被理解。 的挑战假说，假定在循环睾酮浓度的时间变化有关的模式，男性的侵略在生殖环境中，结合社会等级和模式之间的关系，通过皮质醇水平测量的个人压力反应，提供了一个新的框架调查的关键组成部分的机制，男性生殖偏斜。PI还将收集关于回吼雄性之间的相关性的数据，以进一步了解亲属关系对雄性之间的合作和竞争互动水平及其生殖策略的影响。 女性的择偶应该通过其对占主导地位的男性垄断受精能力的影响来影响男性的生殖偏斜。 PI将使用粪便孕酮和雌二醇曲线来确定其卵巢周期的时间，然后将男性和女性的性引诱和拒绝映射到这些周期上，以评估女性是否选择只与占主导地位的男性交配，在整个生育期与多个男性交配，或者除了排卵期之外与多个男性交配，这项研究将建立在灵长类动物社会性进化的既定理论基础上，该理论认为雄性的社会互动是合作与竞争之间的平衡。研究和分析将由一名研究生进行博士论文研究，从而推进NSF的教育和培训使命。 这种濒危灵长类动物种群的保护计划也将受益，因为这项研究将允许在连续与分散的栖息地中比较社会和激素变量。 这项研究将通过墨西哥大学生的参与加强地方能力建设。

This 12-month study will investigate the social and hormonal mechanisms underlying the partitioning of reproduction among males in two troops of black howler monkeys (Alouatta pigra) at Palenque National Park, Mexico. Specifically, the PIs will examine the relationships between male social interactions and fecal testosterone and cortisol levels using systematic focal samples on all adult troop members to assess whether male reproductive strategies correlate with their testosterone and cortisol levels. Understanding these relationships will provide valuable insights into the biology underlying primate social and sexual behavior. The distribution of reproduction among primate males in multimale groups can range from highly skewed, when one male monopolizes all reproductive opportunities during his residence, to less skewed when reproduction is more evenly distributed among males in a group. Groups with more than one reproductively active male could result from either (1) the inability of the dominant male to exclude other males from reproducing (tug-of-war model), or (2) the dominant male's concession of reproductive opportunities to subordinate males as a staying incentive, with the dominant male benefiting from the presence of subordinate males through increased reproductive success (concession model). While paternity studies in several wild primates have confirmed a positive relationship between male dominance rank and reproductive success, the proximate mechanisms that affect reproductive skew are not yet understood. The challenge hypothesis, which posits that temporal variation in circulating testosterone concentrations is related to patterns of male aggression in reproductive contexts, combined with the relationship between social rank and patterns of individual stress response measured via cortisol levels, provides a new framework for investigating key components of the mechanisms of male reproductive skew. The PIs will also gather data on relatedness among back howler males to gain further insights into the influence of kinship on levels of cooperative and competitive interactions among males and their reproductive strategies. Female mate choice should influence male reproductive skew through its effects on the dominant male's ability to monopolize fertilizations. The PIs will use fecal progesterone and estradiol profiles to determine the timing of their ovarian cycles, and then map male and female sexual solicitations and rejections onto these cycles to evaluate whether females choose to mate exclusively with dominant males, with multiple males throughout their fertile periods, or with multiple males except during their periovulatory periods, when conceptions are more likely to occur.The study will build on established theories of the evolution of primate sociality positing that male social interactions are a balance between cooperation and competition. The research and analyses will be conducted by a graduate student for her doctoral dissertation research, thereby advancing the educational and training mission of the NSF. Conservation programs for populations of this endangered primate will also benefit because the study will permit a comparison between social and hormonal variables in continuous versus fragmented habitats. The study will enhance local capacity building through the participation of Mexican university students.