DISSERTATION RESEARCH: Species limits, hybrid zones, and systematics of the North American turtle genus Sternotherus

生物多样性通常是通过计算一个地区的物种数量来衡量的，物种的保护状况是通过定期清查来评估的，以衡量随着时间的推移物种的增加或减少。然而，现代科学已经发现了神秘物种的普遍存在。这些物种很少或没有明显的形态特征，传统上定义物种，但不会杂交，因此是单独的生物物种。 新的遗传技术可以识别神秘物种，并为更准确地衡量生物多样性提供重要工具。美国东南部，特别是亚拉巴马，是水生生物多样性的热点，特别是海龟。 由于物种之间和物种内部的形态保守性，北美海龟属Sternotherus的多样性在分类学上相对于其他海龟谱系被低估了。这些数据可用于制定基于证据的保护规划决策，从而优化资金的使用，以保护和保护生物多样性。在完成项目目标的同时，本科生将接受各种生物子学科的指导，包括野外生态学，分子生物学和生物信息学。将努力包括在STEM领域代表性不足的学生以及亚拉巴马本地人。该研究项目将测试物种的限制，并推断一个解决不好和危险的海龟属内的关系：Sternotherus。Sternotherus目前由四个物种组成，过去的研究提出了相互矛盾的关系。这就对某些物种的分类学有效性提出了质疑，并表明其他种群是神秘的类群。 研究人员将从美国东南部整个海龟分布区收集样本。这些海龟将被测量许多形态特征，包括形状和大小。研究人员将使用mtDNA和海龟DNA的RAD标签测序进行遗传分析。 本研究采取综合的方法，考虑基因的历史和杂交，以确定物种和种内的关系Sternotherus。这些数据将用于测试1）属宽物种限制; 2）物种间杂交的作用;以及，3）这组海龟内的物种水平关系。这种综合分析方法将解决分类关系，以及确定不完整的谱系排序，快速辐射，和低水平的基因流，混淆了遗传信号在以前的工作

Biodiversity is typically measured by counting the number of species in an area and the conservation status of species is assessed through periodic inventories to measure gain or loss of species over time. However modern science has discovered the prevalence of cryptic species. These are species that have few or no obvious morphological distinguishing features, which traditionally define species, but do not interbreed and therefore are separate biological species. New genetic technologies can identify cryptic species and provide important tools to more accurately measure biodiversity. The southeastern United States, especially Alabama, is a hotspot of aquatic biodiversity, especially for turtles. The North American turtle genus, Sternotherus, diversity has been under-described taxonomically relative to other turtle lineages due to morphological conservatism between and within species This project will investigate the morphology and genetics of Sternotherus to identify cryptic diversity and the evolutionary relationships among taxa. These data can be used to make evidence based conservation planning decisions which can optimize the use of funding to protect and conserve biodiversity. While accomplishing the project goals, undergraduate students will be mentored in a variety of biological sub-disciplines including field ecology, molecular biology, and bioinformatics. Effort will be made to include students underrepresented in STEM fields as well as Alabama natives.The research project will test species limits and infer relationships within a poorly resolved and imperiled turtle genus: Sternotherus. Sternotherus currently consists of four species for which past studies have presented conflicting relationships. This calls into question the taxonomic validity of some species and suggests that other populations are cryptic taxa. The researchers will collect samples from turtles across their entire distribution in the southeastern United States. These turtles will be measured for many morphological characters including shape and size. The researchers will perform genetic analyses using mtDNA and RAD-tag sequencing on the turtle DNA. This research takes an integrative approach considering gene history and hybridization for identifying species and species relationships within Sternotherus. These data will be used to test 1) genus wide species limits; 2) the role of hybridization between species; and, 3) species-level relationships within this group of turtles. This integrative analytical approach will resolve taxonomic relationships as well as identify incomplete lineage sorting, rapid radiations, and low level gene flow which confounded genetic signal in previous work