Pheromones exert top-down effects on visual recognition in the jumping spiderLyssomanes viridis

Abstract

In diverse and productive habitats, predaceous arthropods are expected to frequently encounter dangerous conspecifics and heterospecifics. This should make quick and accurate discriminations between species and sexes adaptive. By simultaneously sampling both visual cues and pheromones, and by utilizing stringent species- and sex-specific visual recognition templates, an individual should be able to increase both its speed and accuracy in making such discriminations. We tested for the use and stringency of visual recognition templates in the jumping spider Lyssomanes viridis by presenting males with animated images of conspecifics, heterospecifics and composite images that combined the facial coloration and morphology of one sex or species with the leg coloration of another. Males' courtship versus threat displays indicated whether a stimulus was perceived as a potential mate or a threat. By comparing males' visual inspection times of, and display types towards, the various images in the presence versus absence of female pheromones, we were able to deduce whether males tend to inspect a subset of the color pattern and morphological features that make up their conspecific recognition templates (i.e. those on just the face or just the legs), or all features, and whether this changes in the presence of pheromones. We found that the male recognition template for conspecific female was surprisingly coarse, whereas the recognition template for conspecific male, and especially the male face, was more specific. Pheromones hastened the recognition of images with coloration and morphology closely matching those of conspecifics, presumably by activating conspecific visual recognition templates. When males were presented with an image that was, overall, a poor match to a conspecific female, but that contained a subset of female or female-like features, female pheromones usually did not hasten recognition, but did increase the likelihood that the image would be identified as a female. Taken together, our data suggest that males examined features on both the face and the legs in both the presence and absence of pheromones, and that female pheromones tipped the balance in favor of a female identification when a male was unsure how to categorize an incongruous set of visual features.