Research Associated University of Toronto Scarborough Scarborough, Ontario, Canada
Sexual signals may vary among individuals within a species and also among congeners, providing information used for mate choice and species discrimination. Understanding patterns of receiver responses to signal diversity can give insight into how sexual signals are related to processes initiating, mediating, or following from species diversification. Here I study the stages of courtship and outcomes of mating interactions between species representing the two different clades in the genus Latrodectus, using four species (mactans clade: L. mirabilis [South America], L. hesperus [North America], L. hasselti [Australia]; geometricus clade: L. geometricus [North America]) from different biogeographical regions. Male Latrodectus are in control of whether or not they court a particular female, but females are much larger than males and likely to have control over copulation. I paired males and females in all possible crosses of the four species and compared courtship and copulation frequency of heterospecifics relative to conspecifics. Although copulation was less common with heterospecifics overall, there was variation in discrimination as a function of species and sex. In some cases males courted females of all heterspecifics, but copulation success was lower than courtship rates with some species, suggesting female control over discrimination. In other species, male courtship was significantly reduced relative to conspecific pairings, showing male discrimination. Overall, evidence for species discrimination within the species of the mactans clade increased with genetic distance. However, for L. geometricus (geometricus clade) discrimination decreased with genetic distance. I speculate about the cause of these different patterns.