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

[9213281]奇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植物和动物分类群，包括海洋和陆地。这些“反热带”分类群的多样性包括许多被认为是鲸鱼、海豚和鼠海豚的种群或物种对。该项目将研究在北温带和南温带海洋中发现的Lagenorhynchus属海豚物种之间的关系和差异，并将测试更新世冰川或中新世中期变暖的替代假设，以解释目前观察到的反热带物种分布。海豚线粒体DNA的部分序列分析，加上核DNA标记的补充使用，将用于建立属内的关系，并与海豚科内相关的外群属进行比较。为了更好地了解Lagenorhynchus物种间的遗传差异，有必要对Lagenorhynchus物种内的种群标本进行测序，以提供解释种间差异的尺度。该项目还将调查连续分布在北太平洋的白边海豚（L. obliquidens）的种群结构，以及来自南部海洋的广泛分散的黑边海豚（L. obscurus）种群。这将是第一次尝试建立遗传标准，以区分这些物种的种群，或识别来自不同地区的潜在的特殊地位。这些资料可能有助于确定某些区域的特定鱼类是否受到捕鱼活动的威胁。为了评估Lagenorhynchus物种之间分化的大致时间，遗传距离将通过种群结构分析、与已发表的外群序列的比较以及与已知在中新世和更新世分化的其他分类群的遗传距离进行解释。由于两种选择的时间尺度差异很大，因此即使没有速率校准，也可以确定Lagenorhynchus发散时间与其中一种的一致性。＊＊＊

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. ***