Placing the Floridian Genetic Break for Nearshore Taxa into a Regional Phylogenetic Perspective Using Three Lineages of Marine Mussels

了解生物多样性的时空模式是生态学家和系统学家面临的主要挑战之一。这一挑战在海洋环境中尤为严峻，因为我们现在才刚刚开始理解产生热带近岸动物群中明显的巨大多样性的进化过程。海洋进化中的一个中心悖论是，许多分支的物种形成率如何高到足以在地理尺度上产生大型的兄弟物种复合体，而这些复合体与其浮游幼虫阶段的扩散潜力相比相形见绌。 该项目的目的是解决海湾-大西洋区域分布的加勒比形态种的遗传分离尺度相对于其集体地理范围的其余部分经历的遗传结构。三个不同的系统发育轨迹的假设，铰链是否海湾-大西洋遗传分离的个别研究类群起源于早在中新世的Suwannee海道的历史，或追溯它的上新世关闭，以及是否遗传凝聚力一直保持跨海洋屏障扩散。这些假设将使用三个示范mytilid形态种进行测试，这些种是根据其适当的地理范围、不同沿海栖息地的生态丰度、巴拿马地峡太平洋一侧参考同源物的可用性以及拥有快速进化的父系传播线粒体谱系而选择的。线粒体和核基因树将产生跨越东南部佛罗里达遗传断裂，百慕大的海洋扩散障碍，在加勒比海盆地的代表性地点的人口样本。加勒比/东太平洋同源物的采样将允许transisthmian参考双生种的识别，并提供一个有意义的时间内的种内基因树拓扑结构的角度来看。该项目有望对该区域动物群和更广泛的海洋环境中生物多样性的性质和起源产生重要的新见解。

Understanding spatio-temporal patterns of biotic diversity represents one of the central challenges facing ecologists and systernatists. This challenge is particularly acute in the marine environment where we are only just now beginning to comprehend the evolutionary processes which have produced the epic diversity evident in tropical nearshore faunas. A central paradox in marine evolution is how speciation rates in many clades are sufficiently high to produce large sibling species complexes on geographic scales that are dwarfed by the dispersal potential of their planktonic larval stages. The aim of this project is to address how the Gulf-Atlantic genetic disjunction for regionally distributed Caribbean morphospecies scales relative to the genetic structuring experienced over the rest of their collective geographic ranges. Three distinct phylogenetic trajectories are hypothesized that hinge on whether the Gulf--Atlantic genetic disjunction for individual study taxa originated early in the history of the Miocene Suwannee Seaway, or postdated it's Pliocene closure, and whether or not genetic cohesiveness has been maintained across oceanic barriers to dispersal. These hypotheses will be tested using three exemplar mytilid morphospecies chosen on the basis of their appropriate geographic ranges, ecological abundance in distinct coastal habitats, availability of reference congeners on the Pacific side of the isthmus of Panama, and possession of rapidly evolving paternally -transmitted mitochondrial lineages. Mitochondrial and nuclear gene trees will be generated for population samples spanning the southeastern Florida genetic break, the oceanic dispersal barrier to Bermuda, and representative locations in the Caribbean Basin. Sampling of Caribbean/eastern Pacific congeners will allow the identification of transisthmian reference geminate species and provide a meaningful temporal perspective for the intraspecific gene tree topologies. The project promises to yield important new insights into the nature and origin of biotic diversity in both this regional fauna and in the broader marine environment.