Cyanobacteria of the thermal spring at Pancharevo, Sofia, Bulgaria

Cyanobacteria of the thermal spring at Pancharevo, Sofia, BulgariaEight taxa of cyanobacteria were identified in the thermal spring at Pancharevo (in the Sofia basin, Bulgaria). As well as the widespreadLyngbya thermalis, Phormidesmis molle(syn.Phormidium molle), Phormidium papyraceum, Phormidium coriumandMastigocladus laminosus, four species were identified for the first time in Bulgaria:Calothrix thermalis, Gloeocapsa gelatinosa, Leibleinia epiphyticaandSymploca thermalis.

Ecological Specialization in a Spatially Structured Population of the Thermophilic Cyanobacterium Mastigocladus laminosus

ABSTRACT Laboratory evolution experiments suggest the potential for microbial populations to contribute significant ecological variation to ecosystems, yet the functional importance of genetic diversity within natural populations of microorganisms is largely unknown. Here, we investigated the distribution of genetic and phenotypic variation for a population of the cyanobacterium Mastigocladus laminosus distributed along the temperature gradient of White Creek, Yellowstone NP. A total of 153 laboratory strains were directly isolated from five sites with mean annual temperatures ranging between 39 and 54�C. Genetic characterization at four nitrogen metabolism genes identified 15 closely related lineages in the population sample. These lineages were distributed nonrandomly along White Creek, but the observed geographic structure could not be explained by limited dispersal capabilities. Temperature performance experiments with six M. laminosus lineages that maximized their respective relative abundances at different positions along the gradient provided evidence for niche differentiation within the population. Niche differentiation included a tradeoff in performance at high and low temperatures, respectively. The physiological variation of these lineages in laboratory culture was generally well matched to the prevailing temperature conditions experienced by these organisms in situ. These results suggest that sympatric diversification along an ecological selection gradient can be a potent source of evolutionary innovation in microbial populations.