Sibling species and cryptic speciation in the Brachionus plicatilis species complex (Rotifera)

An attempt is made to identify sibling species within the Brachionus plicatilis complex (Rotifera). Allozyme and morphological data for nine strains from all over the world are provided. Although the analysis of morphological data classified individuals from nine strains into two groups, cluster analysis using genetic distance data obtained from allozyme data revealed at least three groups. A male choice design is described for the first time in rotifers and was used to test for male mating preferences among sympatric strains belonging to three distinct species. The results suggest that the B. plicatilis complex is actually composed of more than three sibling species.