Hu Yibo, Wu Qi, Ma Shuai, Ma Tianxiao, Shan Lei, Wang Xiao, Nie Yonggang, Ning Zemin, Yan Li, Xiu Yunfang, Wei Fuwen
Key Laboratory of Animal Ecology and Conservation Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China.
University of Chinese Academy of Sciences, Beijing 100049, China.
Proc Natl Acad Sci U S A. 2017 Jan 31;114(5):1081-1086. doi: 10.1073/pnas.1613870114. Epub 2017 Jan 17.
Phenotypic convergence between distantly related taxa often mirrors adaptation to similar selective pressures and may be driven by genetic convergence. The giant panda (Ailuropoda melanoleuca) and red panda (Ailurus fulgens) belong to different families in the order Carnivora, but both have evolved a specialized bamboo diet and adaptive pseudothumb, representing a classic model of convergent evolution. However, the genetic bases of these morphological and physiological convergences remain unknown. Through de novo sequencing the red panda genome and improving the giant panda genome assembly with added data, we identified genomic signatures of convergent evolution. Limb development genes DYNC2H1 and PCNT have undergone adaptive convergence and may be important candidate genes for pseudothumb development. As evolutionary responses to a bamboo diet, adaptive convergence has occurred in genes involved in the digestion and utilization of bamboo nutrients such as essential amino acids, fatty acids, and vitamins. Similarly, the umami taste receptor gene TAS1R1 has been pseudogenized in both pandas. These findings offer insights into genetic convergence mechanisms underlying phenotypic convergence and adaptation to a specialized bamboo diet.
远缘分类群之间的表型趋同通常反映了对相似选择压力的适应，并且可能由基因趋同驱动。大熊猫（Ailuropoda melanoleuca）和小熊猫（Ailurus fulgens）属于食肉目不同的科，但二者都进化出了专门的竹子饮食和适应性假拇指，代表了趋同进化的经典模型。然而，这些形态和生理趋同的遗传基础仍然未知。通过对小熊猫基因组进行从头测序，并利用新增数据改进大熊猫基因组组装，我们确定了趋同进化的基因组特征。肢体发育基因DYNC2H1和PCNT经历了适应性趋同，可能是假拇指发育的重要候选基因。作为对竹子饮食的进化反应，参与竹子营养物质（如必需氨基酸、脂肪酸和维生素）消化和利用的基因发生了适应性趋同。同样，鲜味味觉受体基因TAS1R1在两种熊猫中都已成为假基因。这些发现为表型趋同以及对专门竹子饮食的适应背后的基因趋同机制提供了见解。
