LEWIS, LOUISE A. Ecology & Evolutionary Biology, University of Connecticut, Storrs, CT 06269 USA. - Molecular diversity of green algae from biotic crust communities.
Biotic crusts are communities of microorganisms such as algae, fungi,
and bacteria, that together with lichens and bryophytes, aggregate
soil in semi-arid and arid habitats world-wide. A survey of biotic
crust algae from several biotic crust sites in western North America
is currently underway. One aspect of this project is to assess the
diversity of green algae from the soil samples, using both
morphological and molecular data. At present, there are over 200
isolates of green algae in hand. Based on morphological, the isolates
have been provisionally assigned to genera in three green algal
classes: the Charophyceae, Chlorophyceae, and Trebouxiophyceae. A
small proportion of the isolates have been sequenced thus far.
Phylogenetic analyses using the molecular data can be used to
demonstrate that the phylogenetic diversity of the desert green algae
is very high. In addition, a significant proportion of the isolates
are not closely related to published sequences of other green algae.
In each of the Classes, there appear to be distinct clades of desert
algae. Most interesting is the association of clades of desert algae
to aquatic sister taxa. These pairs of taxa offer an interesting
comparison between aquatic and desert taxa with regard to
physiological adaptations to desert-living. A project to explore
possible physiological adaptations is underway.
Key words: 18S rDNA, biotic crusts, Chlorophyta, desert