Ethological, Immunohistochemical And Visual Evoked Potential Study Of Color Vision In Four Different Species Of Bats

Bats (Chiroptera) are the second largest group of mammal, which are the only mammals that achieve true self-powered flight. They live a nocturnal life. This evolutionary advantage makes them can use a new niche compared to another animals. Bats are extremely rich in species diversity and indispensable to ecosystems. Therefore, the protection of and research on bats has very important significance. Because of their unique echolocation ability, previous researches in bats are focused on the auditory area. But there are not so many researches which focused on the vision of the bats, especially color vision.In this study, for the first time, we studied color vision of four different groups of bats through ethological, immunohistochemical and electroneurophysiological experiments. The results showed that the frequency modulation (FM) microbats and the tree habited old world fruit bats had UV band vision. On the contrary, the old world fruit bats which live in the caves and the constant frequency (CF) niicrobats could not detect the UV light. And this further verified early molecular studies' conclusions (Zhao et al,2009). Old world fruit bats originally lived in trees. Small part of their habitats shaded into dark caves during evolution, which lead the visual degradation of the cave-lived magabats. To the CF bats, the basic reason of visual degradation is that they have more developed echolocation capabilities. Developed audition makes the CF bats no longer need developed vision, thereby causes the visual degradation. And this supports the longstanding but weakly supported assumption that tradeoffs are indeed associated with ecological specializations (Speakman,2001).In this study we also found that the action spectrum function of FM microbats, CF microbats and cave-lived old world fruit bats all showed a maxima around 550nm (green). And that of tree-lived old world fruit bats around 550nm was the strongest among the medium/long-wavelength lights. These electrophysiological findings were consistent with the molecular evidence that the medium/long-wavelength opsin (M/LWS) gene was highly conserved in mammals, and most bats M/LWS had peak light absorption at 553nm (Zhao et al.,2009).