Genetic distinctiveness of evolutionary units regardless of reproductive modality in sexual and asexual rotifers

Species as evolutionary units form discrete clusters instead of a continuum in genotypic and phenotypic space. Does species discreteness come from adaptation to fill discrete niches, or as a by-product of reproductive isolation generating clusters separated by gaps? The relative importance of reproductive isolation can be inferred by comparing sexual and asexual taxa. I will deal with the pattern of genetic discreteness between asexual bdelloid and sexual monogonont rotifers using several measures of intra- and interspecific variation to explore the problem. The results suggest that sex and reproductive isolation do not fully explain the existence of discrete species.