title: Ecological differentiation of cryptic species within an asexual protist morphospecies: a case study of filamentous green alga Klebsormidium (Streptophyta).
abstract: Taxa of microbial eukaryotes defined on morphological basis display a large degree of genetic diversity, implying the existence of numerous cryptic species. However, it has been postulated that genetic diversity merely mirrors accumulation of neutral mutations. As a case taxon to study cryptic diversity in protists, we used a widely distributed filamentous genus, Klebsormidium, specifically the lineage E (K. flaccidum/K. nitens complex) containing a number of morphologically similar strains. Fourteen clades were recognized in the phylogenetic analysis based on a concatenated ITS rDNA + rbcL data set of more than 70 strains. The results of inferred character evolution indicated the existence of phylogenetic signal in at least two phenotypic characters (production of hydro-repellent filaments and morphology of zoosporangia). Moreover, the lineages recovered exhibited strong ecological preferences to one of the three habitat types: natural subaerial substrata, artificial subaerial substrata, and aquatic habitats. We interpret these results as evidence of existence of a high number of cryptic species within the single morphospecies. We consider that the permanent existence of genetically and ecologically well-defined cryptic species is enabled by the mechanism of selective sweep.
authors: Department of Botany, Faculty of Science, Charles University in Prague, Benátská 2, Praha CZ 128 01, Czech Republic. skaloud@natur.cuni.cz
authors: Pavel
authors: P
authors: Škaloud
authors: Fabio
authors: F
authors: Rindi
mesh_terms: D004275:DNA, Ribosomal / Q000235:genetics; D004463:Ecology; D014644:Genetic Variation / Q000235:genetics; D010802:Phylogeny; D057949:Streptophyta / Q000145:classification / Q000235:genetics*
chemical_list: D004275:DNA, Ribosomal
keywords: Algae; cryptic diversity; ecotype; speciation; species concept