Reduced fertilization constitutes an important prezygotic reproductive barrier between two sibling species of the hybridizing Brachionus calyciflorus species complex

Abstract Brachionus calyciflorus is a species complex consisting of four recently described species. Although several lines evidence support their status, hybridization between two the sibling B. s.s. and elevatus has been inferred from both field laboratory studies. In this study, we tested for existence prezygotic barriers these by performing types cross-fertilization experiments. ‘mate competition’ experiment exposed mictic females to equal numbers conspecific allospecific males demonstrate that intraspecific fertilizations occur at much higher frequencies than interspecific fertilizations, providing strong reproductive barrier. This result was consistent across numerous combinations parental genotypes. addition, creating in ‘no choice’ experiment, found fertilization success independent direction while it does seem depend on maternal genotype. Our results barrier may play an important role maintenance boundaries. Yet, observation hybrids also shows potential gene flow through hybridization.