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The Biotic Crust Project web site and relational database is designed to disseminate results of an NSF-funded (Biotic Systems and Inventories) project to document the diversity of green algae, cyanobacteria, lichens and bryophytes of the desert crust communities of the western United States.
Gray, D.W., Z. G. Cardon, and L.A. Lewis. 2006. Simultaneous collection of chlorophyll fluorescence induction kinetics, fluorescence quenching parameters, and environmental data using an automated PAM-2000 / CR10X data logging system. Photosynthesis Research 87: 295-301.
Lewis, L. A. and P. O. Lewis. 2005. Unearthing the molecular diversity of desert soil green algae (Chlorophyta). Systematic Biology 54: 936-947.
McManus, H. A. and L. A. Lewis. 2005. Molecular phylogenetics, morphological variation and colony-form evolution in the family Hydrodictyaceae (Sphaeropleales, Chlorophyta). Phycologia 44: 582-595.
Adl, S. M., A. G. B. Simpson, M. A. Farmer, R. A. Andersen, R. A. Anderson, J. Barta, S. Bowser, G. Brugerolle, R. Fensome, S. Fredericq, T. Y. James, S. Karpov, P. Kugrens, J. Krug, C. Lane, L. A. Lewis, J. Lodge D. H. Lynn, D. Mann, R. M. McCourt, L. Mendoza, O. Moestrup, S. E. Mozeley-Standridge, T. A. Nerad, C. Shearer, F. Spiegel, and M. F. J. R. Taylor. 2005. A new higher level classification of eukaryotes and taxonomy of protists. Journal of Eukaryotic Microbiology 52(5): 399-432.
Lewis, L. A. and V. R. Flechtner. 2004. Cryptic Species of Scenedesmus (Chlorophyta) from Desert Soil Communities of Western North America. Journal of Phycology 40: 1127-1137. Download PDF file. This is an electronic version of an article published in Journal of Phycology (C)2004, the Phycological Society of America.
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Lewis, L. A. and G. Muller-Parker. 2004. Phylogenetic placement of "Zoochlorellae" (Chlorophyta), algal symbiont of the temperate anemone Anthopleura elegantissima. Biological Bulletin 207: 87-92. |
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Lewis, L. A. and R. M. McCourt. 2004. Green Algae and the Origin of Land Plants. American Journal of Botany 91: 1535-1556. |
Shoup, S. and L. A. Lewis. 2003. Polyphyletic origin of parallel basal bodies in swimming cells of chlorophycean green algae (Chlorophyta). Journal of Phycology 39: 789-796.
Lewis, L. A. and V. R. Flechtner. 2002. Green algae (Chlorophyta) of desert microbiotic crusts: diversity of North American taxa. Taxon 51: 443-451.
Watanabe, S., A. Himizu, L. A. Lewis, G. L. Floyd, and P. A. Fuerst. 2000. Pseudoneochloris marina, a new coccoid Ulvophycean alga, and its phylogenetic position inferred from morphological and molecular data. Journal of Phycology 36: 596-604.
Chapman, R., M. A. Buchheim, C. F. Delwiche, T. Friedl, V. A. R. Huss, K. G. Karol, L. A. Lewis, J. Manhart, R. M. McCourt, J. L. Olsen, and D. A. Waters. 1998. Molecular systematics of the green algae. pp. 508-540 In: D. E. Soltis, P. S. Soltis, and J. J. Doyle (eds.) The Molecular Systematics of Plants II . Chapman and Hall, New York.
Lewis, L. A., B.D. Mishler, and R. Vilgalys. 1997. Phylogenetic relationships of the liverworts (Hepaticae), a basal embryophyte lineage, inferred from nucleotide sequence data of the chloroplast gene, rbc L. Molecular Phylogenetics and Evolution 7: 377-393.
Hershkovitz, M.A. and L. A. Lewis. 1996. Deep-level diagnostic value of the rDNA-ITS region. Molecular Biology and Evolution 13: 1276-1295.
Mishler, B. D., L. A. Lewis, M.A. Buchheim, K.S. Renzaglia, D.J. Garbary, C.F. Delwiche, F.W. Zechman, T.S. Kantz, and R.L. Chapman. 1994. Phylogenetic relationships of the "green algae" and "bryophytes." Annals of the Missouri Botanical Garden 81: 451-483.
Systematics of green algae in the Chlorophyceae. The green algal class Chlorophyceae contains algae with very different body forms, ranging from simple biflagellate swimming cells and colonies (Chlamydomonas and Volvox) to unflagellated coccoids, to larger, branched, filaments. My research on these algae includes the examination of morphological and molecular evolution within the class, to the description of new species. With collaborators Shin Watanabe (Toyama University) and former student Suzanne Shoup, we have recently compiled a morphological and ultrastructural data set that is being used with molecular data to better resolve the deeper branches of chlorophycean phylogenetic tree of life. With collaborator Valerie Flechtner (John Carroll University), we have uncovered new species of Scenedesmus from desert habitats.
Phylogenetic Diversity Measure. A project with Paul O. Lewis to quatify the amount of evolutionary divergence unique to desert-dwelling green algae. Deserts are not usually considered biodiversity hotspots, but desert microbiotic crust communities exhibit a rich diversity of both eukaryotic and prokaryotic life forms. Like many communities dominated by microscopic organisms, they defy characterization by traditional species-counting approaches to assessing biodiversity. We use exclusive molecular phylodiversity (E) to quantify the amount of evolutionary divergence unique to desert green algae (Chlorophyta) in microbiotic crust communities. We found substantial exclusive molecular phylodiversity based on 18S rDNA data, showing that desert lineages are distantly related to their nearest aquatic relatives. Our results challenge conventional wisdom, which holds that there was a single origin of terrestrial green plants and that green algae are merely incidental visitors rather than indigenous components of desert communities. We furthermore identify examples of lineage diversification within deserts, and many separate transitions from aquatic to terrestrial life apart from the most celebrated transition leading to the embryophyte land plants.
Diversity and photophysiology of green algae from arid habitats. (NASA Exobiology Program, in collaboration with EEB faculty member Zoe Cardon and postdoctoral associate Dennis Gray). This project continues the work started during the NSF Biotic Surveys project (see Biotic Crust Project, above). We are characterizing the phylogenetic diversity of numerous lineages of green algae that were previously isolated from geographically distinct habitats in western North America. These taxa are now known to form more than 30 desert lineages. A second component of this work is to compare the photophysiology of each of seven distinct lineages of desert algae with phylogenetically related aquatic taxa.
Evolutionary relationships of symbiotic green algae ("zoochlorellae"). Sea anemones and other cnidarians can form symbiotic relationships with dinoflagellates and green algae. With collaborator Gisele Muller-Parker (Western Washington University), we are investigating the relationship of the symbiotic green algae engaged in symbioses with different species of Anthopleura. We have determined that the tiny green "zoochlorellae" living within A. elegantissima is unrelated to the genus Chlorella. Instead, it is related (although not closely) to lichen algae such as Coccomyxa, and the unusual endophytic algae of Ginkgo. Ph.D. student Molly Letsch is expanding this survey to include another species of cnidarian, Anthopleura xanthogrammica, and is examining the distribution of algae genotypes across the geographical ranges of the green forms of both anemone species.
Systematics of the Hydrodictyaceae. Hilary McManus, Ph.D. student, is working to resolve the phylogenetic relationships among the members of the freshwater family Hydrodictyaceae using molecular markers. She has obtained rbcL, 26S and ITS rDNA data from a large number of culture collection and wild isolates. She also has started to investigate phenotypic plasticity in wall ultrastructure and overall colony morphology of these algae. Together, this information is being used to study both the evolution of three dimensional colonies in the family, and species boundaries within Pediastrum. This work is supported by a NSF Doctoral Dissertation Improvement Grant (DDIG).
