Meeting Abstract
A major goal of evolutionary biology is to understand the events that lead to rapid diversification of form in the living world. Major shifts in sensory function are likely to play an important role in the diversification of signals. We studied whether major transitions in color sensitivity underlie the rapid diversification of male courtship coloration in the Salticidae, or jumping spiders. In many species of jumping spiders, males perform elaborate courtship dances. Courting males often showcase colored body parts during these dances. In the majority of jumping spiders, these male visual signals are limited to a restricted color gamut, typically blues, greens, and browns. However, several jumping spider taxa depart from this trend by employing yellows, oranges, and reds. These jumping spiders present a conundrum, because data collected from closely related taxa suggest that their visual systems should have limited color discrimination abilities based on a system of UV-green dichromacy, and should therefore lack the ability to discriminate long wavelength colors such as yellows or reds. Here, we present evidence for two independent, functionally distinct evolutionary origins of color vision in the Salticidae: filter-based trichromacy in the colorful Habronattus jumping spiders of North and Central America, and non-filter-based tetrachromacy in the Australian “peacock” spiders of the genus Maratus. Using microspectrophotometry, histology, and visual system modeling, we characterize the sensitivities of these novel color vision systems and describe how they might have enabled the evolution of a wider gamut of male courtship coloration in these two spider groups.
