Borrowed Chloroplasts: Secondary Endosymbiosis and the Chromalveolates
Phillips, Naomi , sam, calhoun , Moustafa, Ahmed , Bhattacharya, Debashish , braun, edward .
Genomic insights into evolutionary relationships among Heterokont lineages.
Brown algae are one of the largest, most taxonomically diverse and ecologically critical groups of heterokont lineages in marine environments. Despite their importance, a consensus in terms of brown algal evolution or overall taxonomic relationships is missing. Our long-term research goal is to produce a well-resolved taxon rich multi-gene phylogeny across the group to assess evolutionary patterns and taxonomic relationships among the group. However, only a few loci exist for systematic studies within brown algae. The first step is to generate expressed sequence tags (ESTs) from five heterokont lineages representing the closest sister group to browns and four major lineages within the group. These EST data will be combined with all published data providing numerous candidate genes for all levels of phylogenetic inference. The next step is to use EST data to time divergence rates and major shifts within the group. To date, we have cDNA libraries constructed from Choristocarpus tenellus and Schizocladia ischiensis with ~ 1600 EST reads per genome. Annotation results show a gene discovery rate from 63% to 85% for each library with ~1000 unique genes determined per genome. We have manually selected several potential genes for phylogenetics testing and will in the future complete a thorough automated phylogenomic analysis of these and other heterokont genome data to identify many candidate genes for phylogenetic inference within this group. Molecular clock analyses are also underway and are expected to provide divergence dates for the split of the major heterokont lineages, such as the diatoms. Here we will report on current progress on EST genomics in brown heterokont algae and the utility of these data to resolving the phylogeny of this group.
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1 - Arcadia University, 450 S. Easton RD, Glenside, pA, 19038, united States
2 - Arcadia University, Biology Department, 450 S. Easton RD, Glenside, PA, 19038, united States
3 - University of Iowa, Genetics, 456 Biology Building, Iowa City, Iowa, 52242, USA
4 - University of Iowa, Department of Biological Sciences and Roy J. Carver Center for Comparative Genomics, 446 Biology Building, Iowa City, Iowa, 52242, USA
5 - University of Florida, Zoology, Bartrum Hall, Gainesville, FL, United States
Presentation Type: Symposium or Colloquium Presentation
Location: Waldorf Room/Hilton
Date: Wednesday, July 11th, 2007
Time: 10:30 AM