Meeting Abstract
In many animals, vision plays a central role in navigation, foraging, and communication. The diversification of visual systems is thus important for exploitation of new visual niches. Jumping spiders are visually guided predators with principal eyes that provide high spatial acuity and colour vision. They also exhibit major differences in colour signalling across species, particularly in the use of long-wavelength colours. Given that most jumping spiders are thought to have UV-green dichromatic vision, we hypothesized that jumping spider groups that use of long-wavelength colours in communication may have evolved improved colour vision. Within a comparative framework, we investigated the number and peak sensitivities of photoreceptor types in the principal eyes of jumping spiders using microspectrophotometry. We identify one origin of trichromacy, in the Harmochirines and Pellenines. We also report two independent origins of tetrachromacy, one in the Euophryini and a second in the Aelurillina. Trichromacy is achieved using spectral tuning via an intraretinal long-pass filter, whereas both instances of tetrachromacy are achieved by the addition of photoreceptors with different spectral sensitivities. Jumping spiders thus represent a promising group for the study of repeated evolution of transitions of colour vision from dichromacy to tri- and tetrachromacy in terrestrial habitats. We discuss the potential role of predatory behaviour, sexual selection, light conditions and background complexity in the context of evolution of colour vision in this group of spiders.
