REU: Phylogenetic Relationships, Population Structure, and Hybrid Zone Dynamics Among Central Mexico Chromosome Races of the Sceloporus grammicus Complex (Iguanidae)

这项研究是由杨百翰大学的Sites博士和伊拉 德克萨斯农工大学的格林鲍姆和斯科特戴维斯有三个 与人类进化史有关的主要目标 墨西哥中部的牧豆树蜥蜴，Sceloporus grammicus。 第一、 一些分子技术（蛋白质和重组DNA）将 被用来测试一个基于染色体的假设， 七个已知染色体种族的进化关系 （形态相似的蜥蜴种群， 染色体数目）来自墨西哥中部。 重构 这些种族的染色体进化模式取决于 从数据集中了解它们的关系， 染色体--这就是分子标记的原因。 一 与此密切相关的第二个目标是评估 基因流在两个种族中，再次使用分子 标记，以确定新染色体 突变可能会持续下去，并最终扩散到整个 染色体种族的范围。 这项工作的第三个方面将 是对两个物种之间基因流动模式的详细研究， 染色体小种相遇并在有限的部分杂交， 他们的范围。 第二个目标还将提供一个内部 “控制”这个混合区的研究。 通过比较染色体 杂交动物的性细胞中的行为与 纯“亲本”染色体种族以外的区域 通过杂交，我们可以确定染色体 造成杂种部分不育的差异， 从而有助于减少基因流动。 如果这 发生时，染色体的变化可能会促进遗传分化， 染色体种族成为不同物种的观点。

This study, by Dr. Sites at Brigham Young University and Ira Greenbaum and Scott Davis at Texas A&M University, has three major objectives relating to the evolutionary history of the mesquite lizard, Sceloporus grammicus, in central Mexico. First, several molecular techniques (protein and recombinant DNA) will be used to test a chromosomally-based hypothesis of the evolutionary relationships of seven known chromosome races (populations of morphologically similar lizards with different chromosome numbers) from central Mexico. Reconstructing the patterns of chromosomal evolution in these races depends upon knowing their relationships from data sets independent of the chromosomes--hence the reason for the molecular markers. A closely related second objective will be to assess the amount of gene flow within two of these races, again using the molecular markers, to determine the likelihood with which a new chromosomal mutation may persist and eventually be spread throughout the range of the chromosome race. The third aspect of this work will be the detailed study of patterns of gene flow between two chromosome races that meet and hybridize in a limited part of their range. The second objective will also provide an internal "control" for this hybrid zone study. By comparing chromosome behavior in the sex cells of hybrid animals relative to that in pure "parental" chromosome races outside of the zone of hybridization, we can determine the role played by chromosomal differences in causing partial sterility in the hybrids and thereby contributing to a reduction of gene flow. If this occurs, the chromosomal changes may foster genetic divergence to the point that the chromosome races become distinct species.