Evolution of the North American Whiptail Lizards (Teiidae: Cnemidophorus) and Re-evaluation of Unisexual Origins: A Multi-genic Approach

[01084884]芦苇鞭尾（鞭尾属）属于蜥科。鞭尾在新大陆分布广泛，从美国向南一直延伸到阿根廷。然而，它们最大的多样性是在美国西南部和墨西哥的干旱和半干旱地区，在那里它们是爬行动物群的一个显著组成部分。鞭尾蜥蜴是生态学上重要的蜥蜴类群，这在许多生态学和生活史研究中得到了反映。鞭尾蜥是被研究得最广泛的一种蜥蜴，仅次于长刺蜥和长爪蜥。除了它们的丰富和与北美生物学家的地理位置接近外，鞭尾被深入研究的另一个原因是单性生殖的全雌性物种（可能是杂交起源）的出现。大约三分之一的物种是单性的，其中大多数都是雌性物种（=单性），分布在美国西南部和墨西哥北部。虽然鞭尾已经被广泛研究，并且对它们的生物学、生态学和自然史有了很多了解，但鞭尾之间的系统发育关系仍然知之甚少。此外，在墨西哥北部，关于三个主要物种复合体的物种限制存在许多混乱。许多种群不能分配给当前的亚种或种。目前尚不清楚这种混淆是由于某些分类群之间的广泛杂交引起的，还是由于存在新的未描述的分类群。最后，虽然生物学家花了一些精力研究这一群体中无性恋者的起源，但许多谱系的母系和父系祖先仍然模糊不清。DNA序列数据可以用来解决这些问题的系统发育，物种限制，和单性起源在北美的鞭尾组。然而，在收集分子数据之前，仍然需要从许多双性恋和单性鞭尾种群和/或物种中获得组织样本。圣地亚哥州立大学的托德·里德博士和他在墨西哥的同事阿德里安·涅托·蒙特斯·德·奥卡博士将在美国西南部和墨西哥进行广泛的实地调查，以获得必要的组织样本。样本将从基本上所有的北美双性恋和单性鞭尾分类群中收集。一旦组织可用，DNA序列数据将从快速进化的线粒体和核基因中收集。除了解决鞭尾的系统发育、物种限制和单性起源等具体问题外，本研究结果具有更广泛的科学意义。鞭尾系统发育可以利用现代比较/系统发育方法重新评估鞭尾的广泛生物学/生态学数据，并为这一多样化群体的进化提供新的见解。其他动物群中也有单性动物；因此，将产生更多关于自然界中无性恋者的起源和持续的背景数据。这将是第一个使用快速进化的核内含子序列来研究杂交和物种形成的研究之一。因此，这项研究将测试这些基因区域的效用，以解决进化生物学家长期感兴趣的这些领域的问题。本科生和研究生将参与该项目的各个方面。学生将获得现代野外和实验室技术的宝贵经验，学习进化和系统生物学的基本概念，并获得展示研究成果的技能（通过口头报告和书面手稿）。

0108484Reeder Whiptails (genus Cnemidophorus) belong to the lizard family Teiidae. Whiptails range widely throughout the New World, extending from the U.S. southward to Argentina. However, their greatest diversity is in the arid and semi-arid regions of the Southwest U.S. and Mexico where they are a conspicuous component of the reptile fauna. Whiptails are an ecologically important lizard group, which is reflected by numerous ecological and life history studies. Whiptails have been one of the most extensively studied group of lizards, third only to Sceloporus (spiny and fence lizards) and Anolis (anoles). Besides their abundance and geographic proximity to North American biologists, another reason whiptails have been intensively studied is the occurrence of parthenogenetic all-female species (of likely hybrid origin). Approximately one third of the species are unisexual, with the majority of these all-female species (=unisexuals) occurring in the southwestern U.S. and northern Mexico. While whiptails have been extensively studied and much is known about their biology, ecology, and natural history, the phylogenetic relationships among whiptails is still poorly understood. Also, in northern Mexico, much confusion exists regarding the species limits within three major species complexes. Many populations cannot be allocated to current subspecies or species. It is unclear whether the confusion arises from extensive hybridization between some taxa or whether new, undescribed taxa exist. And finally, while biologists have spent some effort studying the origins of the unisexuals in this group, the maternal and paternal ancestry of many lineages is still ambiguous. DNA sequence data can be used to address these issues of phylogeny, species limits, and unisexual origins within the North American group of whiptails. However, before molecular data can be collected, tissue samples are still needed from many bisexual and unisexual whiptail populations and/or species. Extensive fieldwork will be conducted in the Southwest U.S. and Mexico by Dr. Tod Reeder of San Diego State University and his colleague Dr. Adrian Nieto Montes de Oca in Mexico, to obtain the necessary tissue samples. Samples will be collected from essentially all North American bisexual and unisexual whiptail taxa. Once tissues are available, DNA sequence data will be gathered from rapidly evolving mitochondrial and nuclear genes. Besides addressing specific issues in whiptail phylogeny, species limits, and unisexual origins, the results of this research have broader scientific significance. The whiptail phylogeny can be used to re-evaluate the extensive biological/ecological data on whiptails using modern comparative/phylogenetic approaches and provide new insights on the evolution of this diverse group. Unisexuals occur in other animal groups; thus, more background data will be generated on the origins and persistence of unisexuals in nature. This will be one of the first studies to use rapidly evolving nuclear intron sequences to study hybridization and speciation. Thus, this study will test the utility of these gene regions for addressing issues in these areas that have been of long interest to evolutionary biologists. Undergraduate and graduate students will be involved in all aspects of this project. Students will gain valuable experience in modern field and laboratory techniques, learn basic concepts in evolutionary and systematic biology, and acquire skills in the presentation of research results (through oral presentation and written manuscripts).