Understanding the evolutionary forces that influence baculum divergence across three timescales

进化生物学的一个基本目标是了解物种内部和物种之间的多样性是如何产生的。在有性繁殖物种中，许多特征进化出了惊人的多样性，尽管驱动这种模式的过程仍然鲜为人知。金字塔符合这种随时间快速分化的经典模式。在某些情况下，杆状突起的形状与繁殖成功相关，这意味着随着时间的推移，这种变化是选择性的，而不是随机的。不幸的是，由于缺乏适当的方法来量化复杂的形态，以及缺乏综合的方法来评估不同的进化假说，严格的进化假说测试一直受到阻碍。因此，关于形态多样性是如何产生的许多基本问题仍然没有答案。形态分化是由某种形式的选择加速的吗？的不同部分是否经历了不同的选择强度？不同物种积累的杆状分化是否不同，这是否与它们交配系统的进化有关？对交配历史等环境条件有反应吗？这些问题跨越多个时间尺度，从理解跨物种和物种内种群的进化过程，到个体一生中骨骼的发育。该项目将支持对博士后研究人员的培训、公民科学倡议，以及参与一个大型科学外展节，以吸引更广泛的社区。为了回答这些问题，研究人员提出了三个具体目标，将现代形态计量学与比较系统学方法以及实验室操作相结合。首先，依靠博物馆收藏，他们将使用最先进的方法量化来自三大哺乳动物群体(灵长类、食肉动物和Permyscus啮齿动物)的杆状结构的大小和形状差异，以测试随着时间的推移，选择是否以及如何形成形态差异，以及这种差异如何与交配系统的变化相关。在第二个目标中，他们将他们的方法扩展到定义明确的浣熊种群和亚种，同时从这些相同的标本中生成低覆盖率的序列数据，以严格测试形态差异如何随着遗传差异的扩大而扩大。最后，在一系列实验室操作中，他们测试了不同交配史或饮食的小鼠之间杆状组织形态的差异。最终，这项工作将导致更好地理解产生多样性的力量。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

A fundamental goal of evolutionary biology is to understand how diversity arises within and among species. Among sexually reproducing species, many traits have evolved astonishing diversity, although the processes that drive this pattern remain poorly understood. The baculum fits this classic pattern of rapid divergence over time. In some cases, baculum shape correlates with reproductive success, implying that this change over time is shaped by selective, rather than random, processes. Unfortunately, rigorous testing of evolutionary hypotheses has been hampered by the lack of appropriate methods to quantify complex morphology, and the absence of integrated methods to evaluate different evolutionary hypotheses. Thus, many basic questions about how morphological diversity arises remain unanswered. Is morphological divergence accelerated by some form of selection? Do different parts of the baculum experience different strengths of selection? Do different species accumulate baculum divergence differently, and might this be related to the evolution of their mating systems? Does the baculum respond to environmental conditions such as mating history? These questions span multiple time scales, from understanding evolutionary processes acting across species and populations within a species, to the development of the bone over an individual’s lifetime. This project will support the training of a postdoctoral researcher, a citizen science initiative, and participation in a large science outreach festival to engage the broader community. To answer these questions, the researchers have proposed three specific aims that combine modern morphometrics with comparative phylogenetic methodology, as well as laboratory manipulation. First, relying on museum collections, they will quantify baculum size and shape variation across species from three large mammal groups (primates, carnivores, and Peromyscus rodents) using state-of-the-art methods to test if and how selection shapes morphological divergence over time, and how that divergence correlates with variation in mating systems. In the second aim, they extend their approach to well-defined populations and subspecies of raccoons, while generating low coverage sequence data from these same specimens to rigorously test how morphological divergence scales with genetic divergence. Lastly, in a series of laboratory manipulations, they test how baculum morphology varies across mice with different mating histories or diet. Ultimately, this work will lead to a better understanding of the forces that generate diversity.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.