Systematics and Biogeography of Lampreys ("Agnatha":Petromyzontiformes) and the Evolution of Parasitic and Non-Parasitic Life Cycles

七鳃鳗（“无颌”：Petromyzontiformes）的系统学和生物地理学以及寄生和非寄生生命周期的进化

• 批准号: 0089507
• 负责人: Richard Mayden
• 金额: $ 20万
• 依托单位: University of Alabama Tuscaloosa
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2001
• 资助国家: 美国
• 起止时间: 2001-06-01 至 2002-02-28
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0089507&HistoricalAwards=false
• 关键词: Systematics; Biogeography; Lampreys; Agnatha; Petromyzontiformes

0089507Mayden and Roe Based on the fossil record, the greatest diversity of jawless vertebrates (agnathans) occurred during the upper Silurian and Early and Middle Devonian geological periods, approximately 420 to 380 million years ago. The majority of agnathans became extinct by the end of the Devonian (360 million years ago) with one or more lineages surviving to give rise to modern jawless vertebrates. Lampreys represent one of the two surviving groups of agnathans (hagfishes are the other group). Living lampreys are classified in the order Petromyzontiformes, which includes 40 extant species. The geographic distribution of lampreys is notable in that they are found in both Northern and Southern hemispheres, but are almost entirely absent from tropical regions. It has been hypothesized that this distribution of lampreys is the result of the breakup of the supercontinent Pangea and the post-Pangean continents of Laurasia and Gondwana. In addition to their interesting geographic distribution lampreys are also remarkable for several reasons: 1) they represent a transitional stage between invertebrate chordates and vertebrates that possess jaws, and as such allow the testing of hypotheses concerning the evolution of characters considered to be unique to vertebrates; 2) they possess a complex life history that involves metamorphosis from a sedentary, filter feeding larval form termed an ammocete, to a sexually reproducing adult; and 3) they can be divided into two groups based on whether the species are parasitic or non-parasitic. Parasitic lampreys include both anadromous species and those restricted to streams and rivers. Species with non-parasitic life-cycles are similar to those with a parasitic life-cycle except that the adults do not feed. Historically, morphological similarities between parasitic and non-parasitic species have been interpreted as evidence that extant non-parasitic species evolved independently on several occasions from different parasitic species. These hypothesized sibling species have been termed "paired species" or "satellite species." Despite agreement among lamprey researchers as to the validity of the satellite species hypothesis, no explicit phylogenetic analysis has been conducted to support such relationships. Drs. Richard Mayden and Kevin Roe at the University of Alabama are seeking to test these hypothesized relationships, and thereby test one of the most remarkable cases of multiple convergence ever suspected in vertebrates. The study will produce phylogenetic hypotheses for all lamprey species using both morphological and molecular (DNA sequences) data sets. Specific objectives are to test hypotheses concerning (1) the evolutionary origins of the parasitic and non-parasitic life histories, (2) the relationships between the various species and genera and families within Petromyzontiformes, (3) the biogeographic history of Petromyzontiformes with reference to the history of the earth and other taxa having similar distributions, and (4) the proposed relationship between lampreys and jawed vertebrates. The project is international in scope, and includes the collection of specimens on several continents (North America, South America, Europe and Australia), and involves collaboration with three acknowledged experts in lamprey biology and systematics: Drs. I. Potter and H. Gill of Murdoch University, Perth, Australia and Dr. C. Renaud from the Canadian Museum of Nature, Ottawa, Ontario, who have primary responsibility for the collection of additional specimens (important for morphological characters and molecular analyses) and the development of morphological data sets. These data will be combined with the molecular data sets based upon the complete DNA sequences of several mitochondrial genes.

0089507Mayden和Roe根据化石记录，最大的无脊椎动物（Agnathans）的多样性发生在上志留纪和早期和中部的泥盆纪地质时期，大约为420至3.8亿年前。 到泥盆纪（3.6亿年前）结束时，大多数阿格纳人都灭绝了，其中一个或多个血统生存下来，产生了现代无知的脊椎动物。 七lamp亵代表了两个幸存的agnathans群体之一（hag鱼是另一组）。 Living Lampreys分类为petromyzontiformes，其中包括40种现存的物种。 七lamp的地理分布值得注意，因为它们在北半球和南半球都发现，但在热带地区几乎完全不存在。 据推测，这种七lamp鼠的分布是超大陆pangea和劳拉西亚和冈德瓦纳后庞吉后大陆的破裂的结果。 除了它们有趣的地理分布式lamp子外，由于几个原因也很引人注目：1）它们代表了具有下颌的无脊椎动物和脊椎动物之间的过渡阶段，因此允许测试有关字符被认为是脊椎动物独有的假设演变的测试； 2）它们具有复杂的生活史，涉及从久坐的，过滤的幼虫形式的变形，称为肢体，到性繁殖的成年人； 3）可以根据物种是寄生虫还是非寄生虫分为两组。 寄生的七lamp虫既包括动物的物种，也包括限制在溪流和河流中的物种。 非寄生生命周期的物种与具有寄生生命周期的生命周期相似，但成年人不喂食。 从历史上看，寄生虫和非寄生虫物种之间的形态相似性被解释为证据表明，现有的非寄生虫物种在不同寄生虫物种的几次中独立演变。 这些假设的同胞物种被称为“配对物种”或“卫星物种”。 尽管七lamp虫研究人员就卫星物种假设的有效性一致，但仍未进行明确的系统发育分析来支持这种关系。 博士。阿拉巴马大学的理查德·梅登（Richard Mayden）和凯文·罗（Kevin Roe）正在寻求测试这些假设的关系，从而测试了脊椎动物中怀疑有史以来最引人注目的多种融合案例之一。 这项研究将使用形态学和分子（DNA序列）数据集为所有lamp带，为所有lamp带。 具体目的是检验有关（1）寄生和非寄生生命历史的进化起源，（2）彼得罗宗身份中的各种物种与属以及家庭之间的关系，（3）petromyzontiformes的生物地理史，参考地球和其他分布和其他分布和J之间的分布和J. 4）和J. 4）和（4）的关系。该项目的范围是国际性的，包括在多个大洲（北美，南美，欧洲和澳大利亚）上收集标本，并涉及与三位公认的lamprey生物学和系统学专家合作：DRS。 I. Potter and H. Gill，珀斯，澳大利亚，澳大利亚默多克大学和安大略省渥太华的加拿大自然博物馆的C. Renaud博士，他们对收集其他标本（对于形态学特征和分子分析很重要）和形态数据集的发展负有主要责任。 这些数据将基于几个线粒体基因的完整DNA序列与分子数据集结合使用。