Marine Biotech Fellowship: Genetic Population Structure and Gene Flow in Deep-Sea Invertebrates

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9212994 France The deep sea is the largest environment of Earth and is known to be highly diverse in its invertebrate fauna. Although considerable effort has been devoted to measuring the patterns of species diversity, the evolutionary forces which have generated the deep- sea fauna remain poorly studied. In order to estimate gene flow and the potential for population differentiation and speciation, studies of the genetic patterns of geographic variation are required. Yet only a handful of such studies have been done in the deep sea. One of the major obstacles to quantifying genetic population structure in deep-sea species has been the difficulty of obtaining sufficient quantities of appropriately preserved tissue for genetic studies. Most of the deep-sea benthos is comprised of small, sparsely distributed organisms which are recovered dead or moribund during typical sampling; these specimens have been inadequate for the standard techniques of allozyme electrophoresis. However, with the advent of new molecular biological techniques which make possible the characterization of DNA sequences from ancient, dried, and alcohol-preserved tissues, studies of the population genetics of deep-sea species are now feasible. In particular, the extensive collections of specimens from dozens of deep-sea sampling efforts provide a wealth of potential information ready to be analyzed. This project will apply the techniques of the polymerase chain reaction (PCR) to characterize genetic variation from alcohol-preserved specimens of deep-sea amphipods, with the goal of estimating genetic population structure and gene flow at intra-ocean and inter-ocean geographic scales. To accomplish this goal, this project will, 1.) with PCR, amplify rapidly evolving portions of the mitochondrial DNA (mtDNA) from 15-25 individuals in each population with universal primers constructed from mtDNA sequences of Drosophila; 2.) inspect amplified segments for hypervariable regions; 3.) identify 15-20 base pair regions where most variation is confined to 1 or 2 polymorphic nucleotides and design allele-specific oligonucleotide (ASO) probes for each allele; 4. hybridize ASO probes to amplified hypervariable regions from 100-200 individuals per population; 5) calculate allele and genotype frequencies in each population and evaluate population structure. The results of this project should provide the first detailed examination of genetic population structure across deep ocean basins and between world oceans. In addition, this project has the potential to demonstrate the applicability of molecular biological techniques to problems in deep-sea ecology and to promote further use of available resources in addressing important evolutionary issues in the oceans. ***