Influence of ambient water coloration on habitat and conspecific choice in the female Lake Malawi cichlid, .

Female cichlid fish living in African great lakes are known to have sensory systems that are adapted to ambient light environments. These sensory system adaptations are hypothesized to have influenced the evolution of the diverse male nuptial coloration. In rock-dwelling Lake Malawi cichlids, however, the extent to which ambient light environments influence female sensory systems and potentially associated male nuptial coloration remains unknown. Yet, the ubiquitous blue flank coloration and UV reflection of male cichlids suggest the potential impacts of the blue-shifted ambient light environment on these cichlid's visual perception and male nuptial coloration in the shallow water depth in Lake Malawi. In the present study, we explored whether and how the sensory bias of females influences intersexual communication in the cichlid, . A series of choice experiments in various light environments showed that females 1) have a preference for the blue-shifted light environment, 2) prefer to interact with males in blue-shifted light environments, 3) do not show a preference between dominant and subordinate males in full-spectrum, long-wavelength filtered, and short-wavelength filtered light environments, and 4) show a "reversed" preference for subordinate males in the UV-filtered light environment. These results suggest that the visual perception of females may be biased to the ambient light spectra in their natural habitat by local adaptation and that this sensory bias may influence the evolution of blue and UV reflective patterns in male nuptial coloration.