Neogene Caribbean Biotic Turnover and Evolution of Geminate Mollusc Species Separated by the Isthmus of Panama

巴拿马地峡分隔的新近纪加勒比海生物周转和双生软体动物物种的进化

• 批准号: 0344419
• 负责人: Peter Marko
• 金额: $ 29.51万
• 依托单位: University of North Carolina at Chapel Hill
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2004
• 资助国家: 美国
• 起止时间: 2004-01-15 至 2006-02-28
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0344419&HistoricalAwards=false
• 关键词: Neogene; Caribbean; Biotic; Turnover; Evolution

The rise of the Central American Isthmus (CAI) and the gradual closure of the seaway connecting the tropical Eastern Pacific (EP) and Western Atlantic (WA) oceans has long served as a model for understanding the formation of new species in the sea. Given geological information that dates the final stage of seaway closure at 3.1-3.5 million years ago, researchers have hypothesized that hundreds of morphologically similar pairs of species found today on either side of the isthmus (called "geminate" or twin species) are believed to represent the descendants of single ancestral species broadly distributed throughout the tropical EP and WA oceans prior to the isthmus formation. Recent evidence, however, raises questions about how closure of the CAI actually affected patterns of species diversity in tropical America. Given that extinction rates may have been as high as 70% for some groups following isthmus formation, researchers think that sister-taxa that survived in both oceans should be rare. How can the apparent survival of so many living geminate species in both the EP and WA be reconciled with the developing paleontological picture of massive Caribbean biotic turnover? To answer this question, Dr. Peter Marko of the University of North Carolina will conduct a combined molecular and paleontological analysis of speciation and extinction among geminate species complexes in the bivalve mollusk family Arcidae. Living species will be discriminated with a combination of phylogeographic surveys of nuclear and mitochondrial gene variation along with discriminant analysis of morphological traits. Species discrimination in the fossil record will then be accomplished by extending statistical tests of morphological differences among genetically distinct species in the living fauna to specimens from the fossil record. The research will provide financial support and training in field collections, morphometrics, and molecular phylogenetics for two graduate students plus funds to send students to a national meeting to gain experience presenting research results. Funds will also offer opportunities for undergraduate education and training in molecular research and the PI will actively recruit individuals from traditionally underrepresented groups. Although not directly funded by this proposal, the molecular phylogenetic work will also be integrated with a phylogenetic effort conducted by a morphological systematist in the UK.

中美洲地峡的兴起和连接热带东太平洋和西大西洋的海道的逐渐关闭，长期以来一直是理解海洋中新物种形成的模式。根据310万-350万年前海道关闭最后阶段的地质资料，研究人员推测，今天在地峡两侧发现的数百对形态相似的物种(称为“双生”物种或双胞胎物种)被认为是在地峡形成之前广泛分布在热带EP和Wa海洋的单一祖先物种的后代。然而，最近的证据提出了一些问题，即关闭计算机辅助教学实际上是如何影响热带美洲物种多样性的模式的。鉴于地峡形成后某些种群的灭绝率可能高达70%，研究人员认为，在两个大洋中幸存下来的姐妹类群应该是罕见的。这么多活着的双生物种在EP和WA的表面生存如何与加勒比海生物大规模周转的不断发展的古生物学图景相一致？为了回答这个问题，北卡罗来纳大学的彼得·马尔科博士将对双壳软体动物科双壳类物种复合体的物种形成和灭绝进行分子和古生物学联合分析。将结合核和线粒体基因变异的系统地理调查以及形态特征的判别分析来区分活的物种。然后，化石记录中的物种鉴别将通过将对现存动物群中遗传上不同物种之间的形态差异的统计测试扩展到化石记录中的标本来实现。这项研究将为两名研究生提供野外采集、形态计量学和分子系统发育方面的资金支持和培训，并资助学生参加全国会议，以获得展示研究成果的经验。基金还将提供分子研究方面的本科生教育和培训机会，国际和平协会将积极从传统上代表性不足的群体中招募个人。尽管这项提议没有直接资助分子系统学工作，但分子系统学工作也将与英国一位形态系统学家进行的系统学工作相结合。