DISSERTATION RESEARCH: The effects of sexual dimorphism on morphological diversification of Musteloidea

物种数量和解剖变异的不均匀多样性代表了生命之树中更令人困惑的进化模式之一。虽然越来越多的研究人员已经开始了解是什么导致了物种之间的不均匀多样性，但很少有研究人员研究过单一物种内的差异如何影响这些大规模的进化模式。差异的一个来源在于两性之间的差异。这项研究的主要目标是通过研究性别差异如何对物种和表型多样性做出贡献来建立进化理论。这项研究填补了我们对物种内变异如何驱动更大的物种多样性模式的理解的一个关键空白。通过这项研究计划，科学家们将有助于通过他们的高中生导师培养下一代学生通过加州大学圣克鲁斯科学实习计划（SIP），在森林中的小哺乳动物本科生研究（SMURF）计划的本科生培训，通过圣克鲁斯公共图书馆公开讲座，并在比较脊椎动物解剖学本科教学。鼬科动物（獾，水獭，浣熊，臭鼬和黄鼠狼）的头骨将被用作一个模型，以检查在宏观进化尺度上的表型差异的性别二型性的影响。鼬科动物是一个分类学上丰富且表型不同的进化枝，其谱系表现出不均匀的多样性模式。研究人员将使用3D几何形态测量学并开发新的比较方法来测试假设[H1 a]，即纳入性别的影响将揭示颅骨差异的增加。预计每个物种中的雄性和雌性将占据颅骨形态空间的大部分非重叠部分;此外，纳入两性将填充以前在分析集中于单一性别时未被占据的形态空间。然后，研究人员将分别量化男性和女性随时间推移的颅骨差异率，并汇总在一起（物种平均值）来检验假设[H1b]，即性别的结合增强了适应性辐射的模式（即进化速率在生态机会附近迅速增加，然后是速率放缓）。使用汇总的男性和女性数据集时，预计发生在中中新世气候转变开始后不久的颅骨进化率的变化。最后，研究人员将通过测试假设[H2]来研究两性异形的生态基础，即食肉的程度与整个鼬总科的头骨形状和大小的两性异形的进化相对应。因此，超肉食性鼬类被预测表现出最高程度的颅性别二型性。我们怀疑这种差异在超级食肉动物中存在，以减轻性别之间的竞争。

Uneven diversity in both numbers of species and anatomical variability represents one of the more perplexing evolutionary patterns across the Tree of Life. Although an increasing number of researchers have begun to understand what drives uneven diversity between species, few researchers have examined how differences within single species can affect these broad scale evolutionary patterns. One source of variation lies in the difference between the sexes. The primary goal of this research is to build upon evolutionary theory by examining how sex differences contribute to species and phenotypic diversity. This research fills a critical gap in our understanding of how variation within species may drive larger patterns of species diversity. Through this research program, scientists will contribute to training the next generation of students through their mentorship of high school students through the UC Santa Cruz Science Internship Program (SIP), undergraduate student training in the Small Mammal Undergraduate Research in the Forest (SMURF) program, public talks through the Santa Cruz Public Library, and undergraduate teaching in Comparative Vertebrate Anatomy. The skulls of musteloids (badgers, otters, raccoons, skunks, and weasels) will be used as a model to examine the effects of sexual dimorphism on phenotypic disparity at the macroevolutionary scale. Musteloids are a taxonomically rich and phenotypically disparate clade whose lineages exhibit uneven patterns of diversity. The researchers will use 3D geometric morphometrics and develop new comparative methods to test the hypothesis [H1a] that incorporating the effects of sex will reveal increased cranial disparity. Males and females in each species are predicted to occupy mostly non-overlapping parts of cranial morphospace; furthermore, the inclusion of both sexes will fill morphospace that was previously unoccupied when the analysis focused on a single sex. The researchers will then quantify the rates of cranial disparity through time in males and females separately and pooled together (species means) to test the hypothesis [H1b] that incorporating sex enhances the pattern of adaptive radiation (i.e. rapid increases in evolutionary rates near ecological opportunity followed by a slowdown in rates). A rate shift in cranial evolution is predicted to occur just after the onset of the Mid-Miocene Climate Transition when using the pooled male and female dataset. Lastly, the researchers will examine an ecological basis for sexual dimorphism by testing the hypothesis [H2] that the degree of carnivory corresponds with the evolution of sexual dimorphism in cranial shape and size across Musteloidea. Therefore, hypercarnivorous musteloids are predicted to exhibit the highest degree of cranial sexual dimorphism. We suspect that this disparity in hypercarnivores is present to mitigate competition between the sexes.