A multivariate analysis of soil yeasts isolated from a latitudinal gradient.

Yeast isolates from soil samples collected from a latitudinal gradient (>77 degrees S to >64 degrees N) were subjected to multivariate analysis to produce a statistical foundation for observed relationships between habitat characteristics and the distribution of yeast taxa (at various systematic levels) in soil microbial communities. Combinations of temperature, rainfall (highly correlated with net primary productivity), and electrical conductivity (EC) could explain up to ca. 44% of the distribution of the predominant yeast species, rainfall and pH could explain ca. 32% of the distribution of clades in the most common orders (Filobasidiales and Tremellales), whereas vegetation type (trees, forbs, and grass) played the same role for orders. Cryptococcus species with appropriate maximum temperatures for growth predominated in most soils. Cryptococcus species in the Albidus clade of the Filobasidiales predominated in desert soils; Cryptococcus species of other clades in the Filobasidiales and Tremellales predominated in wetter and more-vegetated soils, with Tremellalean species favored in soils of lower pH or higher EC. The predominance of Cryptococcus species in soils has been attributed to their polysaccharide capsules, particularly important when competing with bacteria in arid soils.