Dissertation Research: Dispersal, Evolution, and Phylogeny of Membranipora (Bryozoa: Cheilostomata)

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9423868 Harvell Dispersal of organisms and gene flow among populations are poorly understood in open systems like the ocean where the life history of many marine groups includes long distance dispersing stages. This is in contrast to terrestrial and fresh water organisms with their often obvious physical discontinuities in habitat to explain genetic structure of populations and, with a more long-term view, allopatric speciation or the origin of new species from geographically isolated populations. This project will focus on the marine bryozoan genus Membranipora (Bryozoa: Cheilostomata) and the species M. membranacea to investigate whether ocean currents are a major factor in structuring gene flow. Molecular genetic methods (primarily mitochondrial DNA sequencing with a small component of protein electrophoresis) will be used to investigate patterns and rates of gene flow among populations. In addition, a phylogeny or diagram of relationships among species in the genus Membranipora will be constructed using mtDNA sequence data and interpreted in a geographic context to address hypotheses about the causes of speciation in the genus Membranipora. %%% This study will contribute to our knowledge of marine biodiversity by studying a genus in the group of organisms known as Bryozoa. These are most commonly seen in their plant-like branching colonies but the small larval dispersing phase is very important to gene flow among populations. The project will investigate current gene flow patterns within one species and begin to address geologically historical gene flow by determining relationships among species in the genus and examining their geographic distributions.