Dissertation Research: A Multidimensional Analysis of Geographic Variation in the Plain Titmouse (Parus inornatus)

北美西部的平原山雀(Parus Inornatus)在整个范围内的整体大小、喙大小和颜色都不同。目前根据形态和颜色识别出十种地理类型(美国鸟类学家联盟，1957年，北美鸟类名录)。在内华达州喀斯喀特山脉以西，该物种通常出现在山脚下的橡树林地。西南部和山间地区的密度较低，在松柏或刺柏栖息地发现种群零星分布。该项目的目标是整合形态、分子和行为数据，以阐明种群之间的分化模式和过程。种群结构的差异将使测试基因流动的替代模型成为可能。关于适应和更新世隔离的作用的假设也将被评估。各种现代系统技术将被用来检查种群内和种群之间的形态和遗传变异模式。到目前为止的结果表明，太平洋坡地和山间种群之间存在着强烈的遗传分化，其程度与密切相关的鸟类物种之间的遗传分化程度相当。形态(特别是喙的大小和形状)和颜色的变化模式支持遗传数据。对基因流动的定量估计将有助于揭示种群之间遗传和形态分化的过程。由于许多鸟类物种在太平洋斜坡和山间地区表现出相似的分化模式，这项研究将有助于了解北美西部鸟类物种形成的新图景。这项研究的结果可能会导致美国鸟类学家联盟分类和命名委员会正式的分类学变化。确定遗传和/或形态上不同的种群将为美国西部松柏或橡树林地的保护和管理管理人员提供重要信息。加州橡树林地的未来越来越令人担忧，因为喀斯喀特-塞拉山脉、内华达山脉和海岸山脉山脚下的开发压力越来越大。

The Plain Titmouse (Parus inornatus) varies in overall size, bill size, and color throughout its range in western North America. Ten geographic forms are currently recognized (American Ornithologists' Union, 1957, Check-list of North American Birds) on the basis of morphology and color. West of the Cascade-Sierra Nevada Mountains, the species occurs commonly in foothill oak woodland. Density is lower in the Southwest and Intermountain Regions, where populations are found patchily in pinyon-juniper or juniper habitat. The goal of this project is to integrate morphologic, molecular, and behavioral data on Parus inornatus in order to elucidate patterns and processes of divergence among populations. Differences in population structure will enable testing of alternative models of gene flow. Hypotheses concerning the role of adaptation and Pleistocene isolation also will be evaluated. A variety of modern systematic techniques will be used to examine patterns of morphologic and genetic variation within and among populations of Parus inornatus. Results to date indicate strong genetic differentiation between Pacific slope and Intermountain populations, on the order of that found between closely related species of birds. Patterns of variation in morphology (especially bill size and shape) and color support the genetic data. A quantitative estimate of gene flow will shed light on the process of genetic and morphologic divergence among populations. Because numerous bird species show similar patterns of divergence between the Pacific slope and Intermountain Regions, this study will contribute to an emerging picture of avian speciation in western North America. The results of this study will likely lead to formal taxonomic changes by the American Ornithologists' Union Committee on Classification and Nomenclature. The identification of genetically and/or morphologically distinct populations will provide critical information for managers concerned with the protection and management of pinyon-juniper or oak woodlands in the western United States. The future of oak woodlands in California is of growing concern because of increasing pressures for development in the foothills of the Cascade-Sierra, Nevada and Coast Ranges.