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，通过定期清点来评估物种的保护状况，以衡量物种在一段时间内的得失。然而，现代科学已经发现了神秘物种的盛行。这些物种很少或没有明显的形态特征，这些特征传统上是物种的定义，但不进行杂交，因此是独立的生物物种。新的基因技术可以识别神秘的物种，并为更准确地衡量生物多样性提供重要工具。美国东南部，特别是阿拉巴马州，是水生生物多样性的热点地区，特别是对海龟来说。由于物种之间和物种内的形态保守性，北美海龟属Sternotherus的多样性相对于其他海龟谱系一直没有得到足够的分类描述。本项目将研究Sternotherus的形态和遗传学，以确定隐藏的多样性和类群之间的进化关系。这些数据可用于做出基于证据的保护规划决策，从而优化资金的使用，以保护和养护生物多样性。在完成项目目标的同时，本科生将接受包括田野生态学、分子生物学和生物信息学在内的各种生物子学科的指导。研究项目将努力纳入STEM领域代表性不足的学生以及阿拉巴马州的原住民。研究项目将测试物种限制，并推断一种解析不佳且濒临灭绝的海龟属--海龟属--海龟的关系。Sternotherus目前由四个物种组成，过去的研究表明这些物种之间存在相互冲突的关系。这使一些物种的分类学有效性受到质疑，并表明其他种群是神秘的类群。研究人员将从美国东南部所有分布的海龟身上收集样本。这些海龟将被测量许多形态特征，包括形状和大小。研究人员将使用线粒体DNA和RAD标签对海龟DNA进行遗传分析。本研究采取综合考虑基因历史和杂交的方法来确定物种和物种间的关系。这些数据将被用来测试1)广泛的物种限制；2)物种间杂交的作用；以及3)这组海龟之间的物种水平关系。这种综合分析方法将解决分类关系，并识别不完整的谱系分类、快速辐射和先前工作中混淆遗传信号的低水平基因流动

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