Learned mate recognition and reproductive isolation in guppies

Research on learned species discrimination has focused on the consequences of early experience. However, in species where parental care is limited or absent, including most fish, juveniles have fewer opportunities to learn from adult conspecifics. We examined male mate recognition in Trinidadian guppies, Poecilia reticulata, and in their sister species, the swamp guppy, P. picta. Choice tests revealed that males from localities where their species is the only poeciliid present initially mated with conspecific and heterospecific females at random. In contrast, P. reticulata and P. picta found in sympatry preferred their own females. We then investigated the acquisition of mating discrimination by wild P. reticulata males from two allopatric populations. Males that were allowed to interact with females of both species learned within 4 days to distinguish conspecific partners, and within a week their species discrimination matched that of sympatric populations. This study confirms that learning is important in the acquisition of adult mating preferences and shows why learned mate preferences can be important in the last stages of speciation.