Speciation in monogonont rotifers

Monogonont rotifers are cyclical parthenogens living in limnic habitats with considerable seasonal variation and often with island-like features. The occurrence of bisexual reproduction in these organisms makes it feasible to define 'fields for gene recombination', i.e. biological species. In this paper, we analyze the structure of the diversity in monogonont rotifers using several data sets: taxonomic and intraspecific diversity as reported in identification keys, morphological variation reported in ecological studies, and allozyme and mating behavior patterns. Our analysis suggests that sibling species may be frequent in rotifers. Monogonont rotifers seem to meet conditions for an active speciation, which might be particularly promoted by seasonal specialization and timing of bisexual reproduction.