IPC/PSA 2013 (Orlando)
Talk presented by postdoctoral associate Karolina Fučíková as part of the Tree of Life Symposium at the 9th International Phycological Congress in Orlando, August 4-19, 2013.
PSA 2012 (Charleston)
Poster presented by PI Ken Karol at the Phycological Society of America meeting in Charleston, June 20-23, 2012.
GRATOL: ASSEMBLING THE GREEN ALGAL TREE OF LIFE. John D. Hall, Kenneth G. Karol, Louise A. Lewis, Paul O. Lewis, Karolina Fucikova, ZiMin Hu, Brian Wysor, Juan M. Lopez-Bautista, Charles F. Delwiche, & Richard M. McCourt.
Green algae and land plants comprise one of the most structurally and taxonomically diverse groups of eukaryotes. There are more than 14,000 species of green algae and a few hundred thousand species of land plants. Green plants are important primary producers in terrestrial and aquatic ecosystems. They are also important sources of food and fuel throughout the world. Although green algae have been the subject of numerous morphological and molecular phylogenetic studies, many of the important relationships remain controversial: the sister taxon to land plants; placement of early-branching lineages; and relationships among three large green algal clades, Chlorophyceae, Trebouxiophyceae and Ulvophyceae. Assembling a robust phylogeny for the green plants is critically important to our understanding of algal evolution and the origin of land plants.
The Green Algal Tree of Life (GrAToL) project is a collaborative research effort involving six PIs at five different institutions. More than 25 postdocs, collaborators and students have contributed time and expertise to the GrAToL project. The overall goal of the project is to provide a molecular phylogenetic framework for the study of systematics and evolution in the green algae. Our sequencing efforts involve traditional targeted gene sequencing, as well as next generation sequencing of organellar genomes and transcriptomes of selected taxa. A public website has been developed (www.gratol.org) that provides information about the project, green algae and outreach efforts at schools and science festivals. We will present an update on the project’s progress, the methods being used and some challenges facing us as we continue to assemble the Green Algal Tree of Life.
IBC 2011 (Melbourne)
PSA 2011 (Seattle)
GRATOL – ASSEMBLING THE GREEN ALGAL TREE OF LIFE. L. A. Lewis, University of Connecticut, Storrs, Connecticut, USA; K. Karol, New York Botanical Garden, Bronx, New York, USA; J. Lopez-Bautista, University of Alabama, Tuscaloosa, Alabama, USA; R. McCourt, Academy of Natural Sciences, Philadelphia, Pennsylvania, USA; J. Hall, Academy of Natural Sciences, Philadelphia, Pennsylvania, USA; C. Delwiche, University of Maryland, College Park, Maryland, USA; P. O. Lewis, University of Connecticut, Storrs, Connecticut, USA.
Green algae are an understudied, yet diverse group of eukaryotes with critical ecological roles in terrestrial and aquatic habitats, with diverse life styles ranging from autotrophic to symbiotic (including parasitic), and of particular prominence because embryophytes inherited their basic genetic toolkit from green algal ancestors. The overall goal of GrAToL is a new classification for all major branches of green algae. The project includes over 25 scientists and trainees contributing taxonomic expertise and extensive knowledge of data collection and analysis. We are using a hybrid approach of PCR-based multi-gene sequencing, morphology and next-generation sequencing methods. The team will collect data from 10 genes for 425 taxa, sampled from the nucleus, mitochondria, and plastid genomes for phylogenetic analysis. Next-generation sequencing of 16 taxa will generate data to study deep phylogenetic relationships in the green algae, identify new target genes for detailed analysis of particular groups, and examine organellar genome evolution. A public web site includes a library of images, phylogenetic trees, and other resources. We will disseminate new phylogenetic analysis methods through free, open-source software.
NEAS 2011 (Woods Hole)
EVALUATION OF CHLOROPLAST GENES FOR RESOLVING ORDINAL PHYLOGENETIC RELATIONSHIPS IN CHLOROPHYCEAE. Nicholas P. Tippery, Louise A. Lewis & Paul O. Lewis. Department of Ecology and Evolutionary Biology, University of Connecticut, Storrs, CT 06269-3043, U.S.A.Relationships among chlorophycean algae are being resolved with ever increasing frequency due to an abundance of molecular data and phylogenetic methods. Despite the current bulk of data, however, many crucial phylogenetic relationships remain insufficiently resolved. In addition, analyses using different sources of molecular data often obtain incongruent results. Following an initial reliance on relatively few genes (e.g., 18S, rbcL), current studies employ data from several loci simultaneously. With whole chloroplast genome sequences available for a sparse sample of all major Chlorophyceae lineages, we are poised to evaluate the relative utility of various chloroplast genes for resolving phylogenetic relationships, and thus to make informed decisions about the most useful genes to pursue in future phylogenetic studies. To this end, we investigated (1) the ability of nine chloroplast genes (atpA, atpB, psaA, psaB, psbA, psbB, psbC, psbD, rbcL) to resolve ordinal relationships in Chlorophyceae, (2) the effect of increased taxon sampling on the topology and support values for four of these gene regions (psaA, psaB, psbC, rbcL), and (3) the topology achieved by analyzing multiple gene regions simultaneously. Several relationships were recovered in a majority of single-gene analyses (e.g., the monophyly of Chaetopeltidales + Chaetophorales + Oedogoniales and Sphaeropleales + Volvocales), occasionally with high statistical support. Inclusion of additional taxa in single-gene analyses did not appreciably alter branch support for ordinal relationships. Analyses of combined data from multiple genes, however, achieved the highest overall branch support and congruence with expected relationships. Preliminary results support psaA, psaB, and psbC as candidate regions for resolving ordinal relationships in Chlorophyceae, whereas rbcL data produced trees that were less well resolved at deeper nodes and less consistent with the current understanding of chlorophycean phylogenetic relationships.