Wright, Margaret E. Evolutionary Genetics of Balanomorpha Barnacles Faculty Mentor: Keith A. Crandall, Integrative Biology Barnacles are one of the most commonly encountered marine organisms. They live along the intertidal shores and can easily be seen attached to rocks or pilings. Barnacles have a rich history of study. Many scientists have been interested in these curious organisms. One such scientist was the great naturalist Charles Darwin. The research he begun on barnacles has been continued for over two centuries, yet, after all that time we still know very little about their phylogenic relationships (family tree). The origins and diversity of this unique invertebrate are not understood as well as they should be, given so many studies available. There have been previous attempts to study barnacle evolution but they have been limited by using characteristics on the outside (Newman and Ross 1976) without taking into account the great things we can learn from analyzing the heredity in the DNA. This would be analogous to trying to build a family tree while only using pictures of your ancestors, no dates. By analyzing the DNA of different species of barnacles we can get a relative date for each species compared to the others and build a phylogenic tree. Analyzing the differences among certain slow mutating genes will show evolution between species. Another limiting factor of previous studies is the lack of a wide variety of samples. It would be impossible to build an accurate tree if one of the links was missing. When the molecular data of slowly evolving genes is added to the previous morphological data the gaps will be filled in. My research project is aimed as collecting and analyzing barnacle samples within the suborder Balanomorpha in order to set up a framework for their classification using molecular phylogenic relationships. This research is part of an internationally collaborative project funded by NSF or National Sciene Foundation. We are cooperating with scientist in Australia and Denmark. One of the main goals of this project is to assess the phylogenetic relationship for the entire known classification of barnacles and my contribution is to analyze the suborder Balanomorpha. Samples have been collected from around the world and are continuing to come in. There are twelve families in Balanomorpha. Samples from most of these families have been obtained. One of the greatest frustrations of this project has been a delay in receiving the samples from sources that originally had promised to send them. We hope to have representatives of most of the remaining families by the end of 2003. Nevertheless, this project is designed such that work and early analysis can begin before all the samples have been received. Samples were kept in 100% ethanol before extraction of DNA. DNA extraction was performed using the Crandall and Fitzpatrick (1996) protocol for each sample. A Polymerase Chain Reaction (PCR)was carried out on a Perkin Elmer 9600 PCR thermocycler to amplify the target gene regions from three mitochondrial genes: CO1, 12S, 16S and three nuclear genes: 18S, 28S, and H3. Sequences of other samples were also obtained using Genbank. These genes have been shown to provide phylogenic data by Harris et al. (2000) and Perez-Losada et al. (2002). PCR products were visualized using 1.5% agarose gel. Once DNA was confirmed the genes were then cleaned and sequenced using the ABI Big-dye Ready-Reaction kit and run by the 3730 Automated sequencer at Brigham Young University. Once the sequences were compiled they were aligned using Clustal X, given a model of evolution using Model Test and maximum likelihood trees were estimated using PAUP. This preliminary tree is estimated with the genes 18S and 12S. Further research is needed to complete the tree for the remaining families within Balanomorpha. Many of the species that are missing are available to us through the contact in Australia. Once we have obtained these the process will be completed and these new sequences will be added to form a more complete tree. We expect to see results that are consistent with this preliminary tree. Balanomorpha has previously been proved to be a monophyletic group by Newman and Ross (2001). Our results are consistent. We have found that Chthamaloidea is a sister group to the remaining Blanomorphs and the addition of the missing families will prove if there are other sister groups as well. The longer we work at collecting new samples from each known family the more complete this tree will become. Crandall, K. A. and J. F. Fitzpatrick, Jr. 1996. Crayfish molecular systematics: Using a combination of procedures to estimate phylogeny. Syst. Biol, 45:1-26. Harris, D.J., L.S. Maxson, L.F. Braithwaite, and K.A. Crandall.2000 Phylogeny of the thoracican barnacles based on 18s rDNA sequences. J. Crust Biol, 20: 393-398. Newman, W.A. and A. Ross. 1976. Revision of the blanomorph barnacles; including a catalog of the species. Mem, San Diego Soc. Nat. Hist. 9:1-108. Newman, W.A. and A. Ross. 2001. Prospectus on larval cirriped setatino formulae, revisted. J. Crust. Biol. 21:56-77. Perez-Losada, M.,J.T. Hoeg, G.A. Kaolbasov and K.A. Crandall. 2002. Reanalysis of the relationships among the Cirrripedia, Ascothoracida, and Facetotecta (Maxillopoda: Thecostraca) using 18s rDNA sequences. J. Crust. Biol. 22:661-669. Perez-Losada, M.,J.T. Hoeg, and K.A. Crandall. 2002. Unrevealing the evolutionary radiation of the thoracican barnacles suing molecular and morphological evidence. Syst. Biol.
Pages to are hidden for
"Wright, Margaret E"Please download to view full document