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其严峻，因为我们刚刚开始了解在热带近岸动物群中产生巨大多样性的进化过程。海洋进化中的一个中心悖论是，许多分支中的物种形成率如何高到足以在地理范围内产生大型兄弟物种复合体，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。该项目的目的是探讨海湾-大西洋区域分布的加勒比形态种的遗传分离如何相对于其集体地理范围内其他区域经历的遗传结构的大小。三种不同的系统发育轨迹被假设，这取决于海湾-大西洋对单个研究类群的遗传分离是起源于中新世苏万尼海的历史早期，还是晚于上新世的闭合，以及是否保持了跨越海洋扩散障碍的遗传凝聚力。这些假说将使用三个模范的肉豆蔻类形态种进行检验，这些样例是根据它们适当的地理范围、不同沿海生境的生态丰富度、巴拿马地峡太平洋一侧的参考同系物的可用性以及拥有快速进化的父系遗传的线粒体谱系而选择的。将为跨越佛罗里达东南部基因断裂、通往百慕大的海洋扩散障碍以及加勒比海盆地代表性地点的种群样本生成线粒体和核基因树。对加勒比/东太平洋同类物种的采样将有助于确定过渡性和过渡性参考双生物种，并为种内基因树拓扑结构提供有意义的时间视角。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.