Learned conspecific mate preference in a species pair of sticklebacks

Sexual isolation between species often depends on preferences for conspecific mates. Recent models suggest that whether conspecific preference is determined genetically or learned will affect the process of speciation: Learned conspecific preferences might make speciation more likely. However, we understand little about how often and for which taxa, conspecific preferences are learned. Some species learn conspecific preference by imprinting on conspecifics; others learn from experience with heterospecifics. Even when one sex learns conspecific preference, the other may not. We tested whether conspecific mate preference is learned through social experience in males and females from 2 three-spined stickleback species that show strong sexual isolation (benthics and limnetics: Gasterosteus spp.). We reared fish with either mostly conspecifics or mostly heterospecifics and measured how this experience affected conspecific preference. In both sexes, experience enhanced conspecific mate preference but the sexes differed in the outcome. Females learned to prefer their own species through experience with conspecifics; males learned to discriminate through experience with heterospecifics. We also found species differences in the effect of social experience related to differences in sociality. Our results suggest that learned conspecific mate preference may have facilitated rapid speciation in the post Pleistocene radiation of sticklebacks.