Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 11/17/2001
Publication Date: N/A
Technical Abstract: An expectation of biology is to understand earth's species in the context of their genetic relationships. Realization of this possibility will bring an understanding of evolutionary processes and such practical applications as rapid species identification, prediction of genetic and physiological properties and the potential for estimating species interactions in natural and manmade ecosystems. For yeasts, as well as for many other groups of microorganisms, reliance on phenotypic characters for species identification and prediction of natural relationships has lead to erroneous concepts and disappointments. In contrast, molecular analyses offer a genetic means for comparing species. Whole genome DNA reassociation, the first of the quantitative molecular methods used to compare yeasts, suggested that conspecific strains share 70-80% complementary sequences. Because DNA reassociation has a limited range of resolution, interest has shifted to gene sequencing and a variety of genes have been examined. The application of gene sequence analyses has brought an understanding of genetic relationships among species allowing reconstruction of phylogenetic histories. Analysis of ribosomal RNA gene sequences has shown the ascomycetous fungi to be comprised of three major clades, one of which is exclusive to the budding yeasts. The basidiomycetous fungi, which represent a sister group to the ascomycetes, are comprised of three to four major groups, but the yeast forms are more widely distributed. Despite present advances in understanding yeast relationships from molecular comparisons, much work remains to reliably resolve closely related species and to recognize genera.