Pterodactyls (bats) are nocturnal animals with significant sensory differentiation in different bat species: carnivorous bats rely mainly on echolocation to navigate and prey, and their eyes degenerate, while Old World fruit bats have no echo localization ability, and their eyes are well developed, relying mainly on sight and smell to find food. In the previous study, Zhang Yaping, vice president of the Chinese Academy of Sciences, academician of the Chinese Academy of Sciences, and researcher of the Kunming Institute of Zoology of the Chinese Academy of Sciences, found that the three genes of CRX, RHO and SAG in the visual pathway converged and evolved in the old continent fruit bat and tomb bat (insectivorous bat, vision is not degraded), suggesting that the adaptive evolution of complex traits requires a series of genes.
In order to further systematically reveal the mechanism of dark vision adaptability of Pterodactyl, Zhang Yaping's research group of Kunming Institute of Zoology, Hu Xintian's research group, Xu Fuqiang, researcher of Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, jointly tackled the problem, and under the leadership of associate researcher Shen Yongyi, doctoral students Liu Hequn, Wei Jingkuan and Li Bo first used manganese ion enhanced magnetic resonance imaging (MEMRI) technology to scan the brain structure of bats and compare the structural differences of various bat visual and auditory systems. It was found that the Old World fruit bat had a large upper moth (involved in visual information processing), and its upper and lower hill volumes were about 3:1, and the insectivore bat had a larger lower mound (involved in the processing of auditory information), and its upper and lower hill volume ratio was about 1:7, revealing the brain structure basis of the dark visual differentiation of pterodactyls; subsequently, the visual ability of bats was quantified by flash evoked potential technology, and it was found that their absolute light perception threshold was: Old World fruit bat> tomb bat > mid-valley manta rays (small bat suborder, echo localization), Reflects the differences in visual performance function of these different bat species. Finally, the retinal transcriptomes of 5 bat species were sequenced by transcriptome sequencing (RNA-seq), and adaptive signal detection was carried out from the aspects of sequence variation (positive selection, convergence/parallel evolution) and expression, and the transcriptome horizontal expression pattern of the ocular genes of the tomb bat was found to be more similar to that of the fox bat family. This study systematically expounds the mechanism of dark visual differentiation of the pterodactyl order from multiple angles such as structure, function and molecular mechanism, and provides an example for the study of the adaptive mechanism of complex traits.
The results of the study were recently published online in Scientific Reports.