Phylogeny of Physid Snails (Basommatophora: Physidae) and Evolution of Reproductive Isolation

蜗牛科是一种淡水蜗牛，原产于北美洲、中美洲、南美洲和欧亚大陆，但其多样性在北美洲达到最大。在许多湖泊、池塘和溪流栖息地中，该科构成了淡水软体动物动物群的主要组成部分。尽管物理学家在行为学、生理学和生态学的研究中占有突出地位，但人们对这些分类群之间的系统发育关系知之甚少。此外，许多问题仍然存在，如许多目前公认的物种、亚种和“变种”是否构成有效的进化实体。尽管有近200年的分类学和系统学研究，但没有采用现代方法和分析进行严谨的研究。这项由美国国家科学基金会资助的研究的目的是收集蜗牛标本，代表已知的物种、亚种和“变种”，利用线粒体和核基因DNA序列、壳和解剖数据来估计进化“树”。此外，主要研究人员将研究蜗牛科是否构成蜗牛的自然组合，它们彼此之间的关系比与任何其他蜗牛群的关系更密切。尽管对具有重要生态学意义的物理科的系统发育进行估计本身就很重要，但由此得出的进化“树”将与现代的、基于分析的物种观点结合使用，以检验目前公认的群体是否构成有效的物种。在进行物种调查以发现热点和优先采取各种保护措施的地区时，必须使已确认的物种与系统发育物种相对应。此外，研究人员将通过在实验室进行一系列对照实验，研究选定的物理物种之间生殖隔离的进化。这项研究将为蜗牛科提供一个健全的进化“树”和现代分类。此外，对物理学中物种问题的实证研究将为估计该科中实际存在的物种数量提供重要数据。这些数据将对保护和进化生物学家以及联邦和州野生动物机构的工作人员有相当大的用处。

The Physidae (Gastropoda: Basommatophora) is a group of freshwater snails with a native distribution in North, Middle, and South America, and Eurasia, but reach their greatest diversity in North America. The family constitutes a major component of the freshwater molluscan fauna in many lake, pond, and stream habitats. Despite the prominence of physids in behavioral, physiological and ecological studies, little is know of the phylogenetic relationships among the taxa. Furthermore, many questions remain as to whether many of the currently recognized species, subspecies, and "morphs" constitute valid evolutionary entities. Despite nearly 200 years of taxonomic and systematics studies, no rigorous study has been done employing modern methods and analyses. The purpose of the NSF-sponsored research is to collect physid snail specimens representing recognized species, subspecies, and "morphs" to estimate an evolutionary "tree" using on mitochondrial and nuclear gene DNA sequences and shell and anatomical data. In addition, the principal investigators will examine whether the family Physidae constitutes a natural assemblage of snails, being more closely related to each other than to any other group of snails. Although estimating a phylogeny for the ecologically important Physidae is important for its own sake, the resultant evolutionary "tree" will be used in conjunction with a modern, analytically based view of species to test whether currently recognized groups constitute valid species. At a time when species inventories are being made to discover hotspots and prioritize areas for various protection measures, it is imperative that recognized species correspond with phylogenetic species. Furthermore, the researchers will examine the evolution of reproductive isolation among selected physid species by conducting a series of controlled experiments in the laboratory.This research will provide a robust evolutionary "tree" and modern classification of the snail family Physidae. In addition, an empirical examination of species issues in physids will provide important data for estimating how many species actually exist within the family. These data will be of considerable use to conservation and evolutionary biologists as well to federal and state wildlife agency personnel.