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Scott Hodges >
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Genetic Structure, Conservation Biology and Biotechnology
Faculty Research: Genetic Structure, Conservation Biology and Biotechnology
During the past several years I have begun to focus a facet of my research program on the genetic structure of organisms on and around the California Channel Islands. This geographic area has an exceptionally rich level of biodiversity and a number of organisms are of strong conservation concern. Below I briefly describe three individual projects on different taxa and the specific reasons we have chosen to study them. While these studies may seem only distantly connected, one of my long-term goals is to investigate a number of species in this area to determine if there are general patterns to their genetic structure. General patterns of genetic structure could occur due to common historical processes. Identification of such patterns would provide a framework for conservation efforts on a host of species and could influence the design of reserves and management plans across the entire region.
The Island Ironwoods grow only on four of the California Channel Islands. Previously we have shown that the large groves on Santa Cruz Island are generally single genetic clones and that the number of genetic individuals is closer to 1,125 individuals than the 32,000 individuals based on counting individual tree trunks (Bushakra et al. 1999). Thus, this tree is one of the rarest species growing in California. I have now expanded this study, in collaboration with Dr. Deborah Kaska and Anne Mecham (undergraduate student), to study the degree of clonality for a distinct subspecies on Santa Catalina Island as well as groves on San Clemente and Santa Rosa Islands. In addition we are assessing the genetic diversity of this species within and among the islands and estimating the phylogenetic position of this enigmatic member of the Rose family. We have also investigated the mycorrhizal associates of this species.
Surfgrass (Phyllospadix torreyi). Along our coast grows a very unusual flowering plant, the marine angiosperm, Phyllospadix torreyi commonly known as surfgrass. This species is ecologically very important in that it stabilizes the substrate and provides the basis for large communities. Given its central role in community structure, there have been large efforts to understand its basic biology and to devise methods for its restoration. We have been conducting the first molecular genetic analyses of surfgrass in order to determine the degree of population differentiation, the degree of clonality, and its mating system. We have found that this species is not highly clonal as is commonly assumed and that high outcrossing occurs even when males are scarce in this dioecious plant (separate male and female plants). In addition, we have found that populations separated by as little as 50 km are genetically differentiated suggesting that populations may adapt to local conditions. This finding suggests that a great deal of care should be exercised when source material is collected for restoration efforts. We have now been funded to expand these studies to determine on what spatial scale population differentiation occurs. In addition we have developed genetic markers to identify the separate sexes even when they are not flowering. These studies will be important not only in establishing ecological differences between the sexes but also for establishing restored populations with natural sex ratios. This research is being conducted in collaboration with Dr. Douglas Bush, Dr. Sally Hollbrook, and Dr. Daniel Reed. It is funded by the Minerals Management Service.
Bryozoa (Bugula neritina) and Biotechnology. We have begun a project (in collaboration with RJ Schmitt, JE Dugan, S Gaines, RS Jacobs, HM Page and L Wilson) to study the potential of using oil platforms as a source for organisms with potential for biotechnological uses. There is a great deal of interest in exploring whether marine organisms produce compounds with pharmacological properties. Unfortunately, when they do, harvesting these organisms can have huge consequences to natural ecosystems. For instance, the bryozoan, Bugula neritina produces bryostatin-1, a potential anti-cancer drug. This drug cannot be synthesized and in order to isolate milligram quantities of bryostatin, tons of Bugula neritina must be harvested. This harvesting can decimate natural reefs and therefore there is interest in using populations that have colonized oil platforms as a source until the drug can be synthesized. As it turns out, Bugula nertina is actually two cryptic species only one of which produces bryostatin-1. Using DNA sequencing of mitochondrial DNA (mtDNA) we are determining the distribution of the two cryptic species as well as whether populations on oil platforms have a similar genetic structure as those populations on natural reefs. These studies will be important because they will address central questions about the communities inhabiting oil platforms. For instance we will determine if colonization is a rare event with resulting low genetic diversity. We also hope to determine whether colonization occurs from specific natural source populations. This project is funded by the Minerals Management Service. |
| Department of Ecology, Evolution and Marine Biology • University of California, Santa Barbara |
