Systematics, introgression, and adaptation in Western Rattlesnakes: a model system for studying gene flow, selection, and speciation

西部响尾蛇的系统学、基因渗入和适应：研究基因流、选择和物种形成的模型系统

基本信息

批准号：
1655571
负责人：
Todd Castoe
金额：
$ 86.74万
依托单位：
University of Texas at Arlington
依托单位国家：
美国
项目类别：
Standard Grant
财政年份：
2017
资助国家：
美国
起止时间：
2017-06-01 至 2023-03-31
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=1655571&HistoricalAwards=false
关键词：
Systematics introgression adaptation Western Rattlesnakes

项目摘要

Despite substantial research, the roles of natural selection in the formation of species and in preventing hybridization between species remain poorly understood. In a rapidly changing world, there is an urgent need to understand the importance of these processes in species formation and the impact of these processes on how scientists identify and name species. This research program will study genetic, venom protein, and anatomical data to test how natural selection shapes and maintains species, and it will use these results to test several approaches for appropriately identifying species in nature. The researchers will focus on a widespread and medically important group of rattlesnake species (Western Rattlesnakes and their close relatives) as a model system to study species formation. Many previous studies have disagreed about how many species should be recognized within this group of snakes, and different populations can produce diverse symptoms from snake bite due to differences in venom biochemistry. This study will resolve these issues by developing a new system for naming species, provide new insight into the process of species formation, develop new methods for identifying species, and refine the appropriate medical treatment of snakebite in North America. The proposed research includes methodological and theoretical scientific innovation, undergraduate and graduate student training, establishment of collaborative networks, and public outreach. Public outreach will be conducted at the Dallas and Denver Zoos, thereby reaching millions of public visitors per year.The overarching goals of this research program are to understand the interaction of admixture and selection in speciation, and to leverage an empirical system to test how these processes may influence coalescent-based species delimitation methods. This research program will focus on the Western Rattlesnake species group (Crotalus viridis species complex and its sister taxon, C. scutulatus; collectively Cvos hereafter) as a study system. This recently diverged species complex has offered major challenges for systematics, yet provides an ideal model system for studying speciation and species delimitation. This integrated study will combine genomic and phenotypic data to delimit species, inform species delimitation approaches, and provide new genome-scale insight into the process of speciation. This research program will also test hypotheses about the repeatability of patterns selection in the processes of speciation and resistance to gene flow and hybridization. The specific aims of this proposal are to: (1) integrate genome-wide sampling and ecological niche modeling to infer population structure and test hypotheses of gene flow among lineages of Cvos; (2) analyze selection in contact zones between putative taxa by integrating niche modeling, genotypic, and phenotypic data to test hypotheses regarding divergence and selection in the speciation process; and (3) develop and test new approaches for delimiting species that more appropriately handle admixture and selection, and apply these methods to test taxonomic hypotheses for the Cvos complex. Successful completion of the project will provide important data to understanding the role of admixture and selection in speciation and vastly improve our analytical methods for delimiting species in the presence of interbreeding across organismal groups. Additionally, an added benefit of the project is the information that will be obtained regarding venom complexity and evolution, which could contribute to better treatment of envenomation from snake bites.

尽管进行了大量研究，但自然选择在物种形成和防止物种之间的杂交方面的作用仍然很少。在一个快速变化的世界中，迫切需要了解这些过程在物种形成中的重要性以及这些过程对科学家如何识别和命名物种的影响。该研究计划将研究遗传，毒液蛋白和解剖学数据，以测试自然选择的形状和维护物种，并将使用这些结果来测试几种方法，以适当地识别自然界中的物种。研究人员将专注于广泛且具有医学上重要的响尾蛇物种（西方响尾蛇及其近亲）作为研究物种形成的模型系统。以前的许多研究都不同意这群蛇中应识别多少物种，并且由于毒液生物化学的差异，不同的种群可以从蛇咬伤中产生各种症状。这项研究将通过为命名物种开发新的系统，对物种形成过程，开发识别物种的新方法，并完善北美蛇咬的适当医疗治疗方法来解决这些问题。拟议的研究包括方法论和理论科学创新，本科和研究生培训，协作网络的建立以及公共宣传。公众推广将在达拉斯和丹佛动物园进行，从而每年吸引数百万个公共访客。该研究计划的总体目标是了解混合物和选择在物种物种中的相互作用，并利用经验系统来测试这些过程如何影响基于煤层的物种划界方法。该研究计划将重点介绍西方响尾蛇种群（Crotalus viridis物种综合体及其姊妹分类群C. scutulatus；此后统称CVOS）作为研究系统。这个最近分歧的物种综合体为系统学提供了主要挑战，但为研究物种和物种划界提供了理想的模型系统。这项综合研究将将基因组和表型数据结合在一起，以划定物种，为物种划界方法提供信息，并为物种过程提供新的基因组规模。该研究计划还将测试有关模式选择在物种形成和对基因流和杂交的抗性过程中选择性的可重复性的假设。该提案的具体目的是：（1）整合全基因组抽样和生态位模型，以推断CVO谱系中基因流量的种群结构和检验基因流的假设；（2）通过整合利基建模，基因型和表型数据来测试有关物种形成过程中有关差异和选择的假设，分析推定分类单元之间的接触区选择；（3）开发和测试新方法，以划定更适当处理混合和选择的物种，并将这些方法应用于CVOS复合体的分类假设。该项目的成功完成将提供重要的数据，以了解混合和选择在物种形成中的作用，并大大改善我们在存在跨有机群体杂交的情况下划界物种的分析方法。此外，该项目的额外好处是将获得有关毒液复杂性和进化的信息，这可能有助于更好地治疗蛇咬伤。

项目成果

期刊论文数量（39）

专著数量（0）

科研奖励数量（0）

会议论文数量（0）

专利数量（0）

Vertebrate Lineages Exhibit Diverse Patterns of Transposable Element Regulation and Expression across Tissues

DOI：
10.1093/gbe/evaa068
发表时间：
2020-04
期刊：
Genome Biology and Evolution
影响因子：
3.3
作者：
G. M. Pasquesi;B. W. Perry;Michael W. Vandewege;Robert Ruggiero;Drew R. Schield;T. Castoe
通讯作者：
G. M. Pasquesi;B. W. Perry;Michael W. Vandewege;Robert Ruggiero;Drew R. Schield;T. Castoe

Allopatric divergence and secondary contact with gene flow: a recurring theme in rattlesnake speciation

DOI：
10.1093/biolinnean/blz077
发表时间：
2019-06
期刊：
Biological Journal of the Linnean Society
影响因子：
1.9
作者：
Drew R. Schield;B. W. Perry;Richard H. Adams;D. Card;Tereza Jezkova;G. M. Pasquesi;Zachary L. Nikolakis;Kristopher W. Row;J. Meik;Cara F. Smith;S. Mackessy;T. Castoe
通讯作者：
Drew R. Schield;B. W. Perry;Richard H. Adams;D. Card;Tereza Jezkova;G. M. Pasquesi;Zachary L. Nikolakis;Kristopher W. Row;J. Meik;Cara F. Smith;S. Mackessy;T. Castoe

Assessing the Impacts of Positive Selection on Coalescent-Based Species Tree Estimation and Species Delimitation