Update of phylogenetic and genetic diversity of Sporothrix schenckii sensu lato.

Abstract

Sporothrix schenckii sensu lato causes subcutaneous mycosis. In this article we analysed its phylogeny and genetic diversity using calmodulin DNA sequences deposited in GenBank database. Population genetics indices were calculated, plus phylogenetic and haplotype network trees were built. Five clades with high values of posterior probability, 47 haplotypes and high diversity in the complex were found. Analysis of partial calmodulin sequences alignment revealed conserved and polymorphic regions that could be used as reference for taxonomic identification. The use of population genetics analysis allowed understanding the phylogenetic proximity of S. schenckii s. str. and S. brasiliensis; scarce genetic flow among them with low migration index and high ancestry coefficient was found. Similarly, S. globosa, S. mexicana and S. pallida sequences showed highly differentiated species with no genetic exchange. The phylogenetic tree suggests that S. mexicana shared a common ancestor with S. pallida; while S. globosa and S. brasiliensis are more related to S. schenckii s. str. and showed less haplotype diversity and restrictions in geographic distribution. In the haplotype network tree S. schenckii s. str. species displayed worldwide distribution without dispersion centres; while S. brasiliensis and S. globosa, exhibited Brazil and Euro-Asia as dispersion centres, respectively. Our data suggest that S. schenckii complex has been submitted to a divergent evolution process, probably due to the pressure of the environment and of the host. In contrast, S. brasiliensis could have been submitted to purifying selection or expansion process.