Meeting Abstract
Mate recognition can be important for maintaining reproductive isolation between closely-related species. Although much is known about animal mate recognition from studying male signaling traits and female preferences, it is more challenging to study the neurobiological basis of how females evaluate male signals. Enallagma damselflies provide a powerful model to understand the mechanistic basis of female mate selection. Females control whether mating occurs and it has been suggested that females evaluate tactile signals from the male grasping organs using sensory bristles (sensilla) on the thorax. These sensilla provide an external, quantifiable phenotype that can be used to test hypotheses about female mating decisions. E. anna and E. carunculatum hybridize in nature and hybrid males suffer reduced reproductive success. Because the species occur in both sympatry and allopatry, we can test the hypothesis that thoracic sensilla play a major role in species recognition and the evolution of reproductive isolation. We predicted that sympatric females would have denser thoracic sensilla and/or a different spatial pattern of sensilla than allopatric females. We measured sensilla number, density, and pattern of female E. anna and E. carunculatum from 19 populations. We found that although individual sensilla traits vary widely within a population, intraspecific population means are not significantly different in sympatry vs allopatry. Our results suggest that species-specific spatial locations of sensilla may be sufficient for detecting large differences in male morphologies (species recognition), whereas sensilla number may be more important for fine discrimination among conspecific males (sexual selection).
