Marine Biotech Fellowship: A Test of Alternative Speciation Hypotheses Using Molecular Systematic Analysis of Lagenorhynchus Dolphins.

9213281西普里亚诺在一个明显的热带屏障的北部和南部发现了各种相关的海洋和陆地动植物分类群。这些“反热带”分类群的多样性包括许多所谓的鲸鱼、海豚和江豚的种群或物种对。该项目将研究在北温带和南温带海洋中发现的海豚属海豚之间的关系和分歧，并将检验更新世冰川或中中新世变暖的替代假说，以解释目前观察到的反热带物种分布。部分海豚线粒体DNA的序列分析，辅以核DNA标记，将被用来建立海豚属内的关系，并与也属于Delphinidae科的相关的外群属进行比较。为了正确认识紫背紫薇种群间的遗传差异，有必要对紫尾紫薇种群内的标本进行测序，为解释种间差异提供标准。该项目还将调查在北太平洋发现的连续分布的白边海豚(L.obliquidens)的种群结构，以及南太平洋广泛分布的暗色海豚(L.Darcurus)的种群结构。这将是首次尝试建立区分这些物种种群的遗传标准，或识别来自不同地区的暗纹夜蛾的潜在特定地位。这一信息可能有助于确定某些区域的捕捞活动是否对特定种群构成风险。为了评估不同物种间分化的大致时间，将利用种群结构分析提供的视角，与已公布的外群序列进行比较，并与中新世和更新世已知的其他分类群的遗传距离进行比较，来解释遗传距离。由于两个备选方案的时间尺度相差很大，因此即使没有速率校准，也应该能够识别拉格诺亨丘发散定时与一个备选方案的一致性。***

9213281 Cipriano A variety of related plant and animal taxa, both marine and terrestrial, are found to the north and south of an apparent tropical barrier. The variety of these "antitropical" taxa includes many supposed populations or species pairs of whales, dolphins and porpoises. This project will study the relationships and divergence between dolphin species of the genus Lagenorhynchus found in northern and southern temperate oceans and will test alternative hypotheses of Pleistocene glaciation or mid-Miocene warming as explanations for the currently observed anti-tropical species distributions. Sequence analysis of portions of dolphin mitochondrial DNA, with supplemental use of nuclear DNA markers, will be used to establish relationships within the genus, and for comparison to related outgroup genera also within the the Family Delphinidae. In order to place amounts of genetic divergence found between Lagenorhynchus species into perspective, it will be necessary to sequence specimens from populations within Lagenorhynchus species to provide a yardstick for interpreting interspecific divergence. This project will also investigate the population structure of white- sided dolphins (L. obliquidens) found continuously distributed in the North Pacific, and of widely separated populations of dusky dolphins (L. obscurus) from the southern oceans. This would be the first attempt to establish genetic criteria for distinction of stocks of these species, or to recognize potential specific status of L. obscurus from different areas. This information may be useful to determine whether particular stocks are at risk form fishing activities in certain regions. In order to assess the approximate timing of the divergence between Lagenorhynchus species, genetic distances will be interpreted using the perspective provided by population structure analysis, comparison to published sequences for outgroups, and comparison to genetic distances of other taxa known to have div erged in Miocene and Pleistocene times. Because of the large difference between the time scale of the two alternatives, identification of the congruence of Lagenorhynchus divergence timing with one should thus be possible even without a rate calibration. ***