Evolution of beak morphology in the Ground Tit revealed by comparative transcriptomics

Frontiers in Zoology

Xin Lu¹  Fumin Lei²  Naijian Han²  Gang Song²  Yong E. Zhang²  Yalin Cheng²  Yanhua Qu²  Shimiao Shao²  Xiaojia Zhu²  Bin Gao²  Shaoyuan Wu³  Haitao Wang⁴ 

[1] Department of Ecology, College of Life Sciences, Institute for Advanced Studies, Wuhan University;Key Laboratory of Zoological Systematics and Evolution, Institute of Zoology, Chinese Academy of Sciences;School of Life Sciences, Jiangsu Normal University;School of Life Sciences, Northeast Normal University;

关键词: Parus humilis;    Beak;    Morphology;    Transcriptomics;    Osteoblasts;    Osteoclasts;   

DOI  :  10.1186/s12983-017-0245-6

来源: DOAJ

【 摘 要 】

Abstract Background Beak morphology exhibits considerable adaptive plasticity in birds, which results in highly varied or specialized forms in response to variations in ecology and life history. As the only parid species endemic to the Qinghai-Tibet Plateau, the Ground Tit (Parus humilis) has evolved a distinctly long and curved beak from other parids. An integration of morphometrics, phylogenetics, transcriptomics and embryology allows us to address the evolutionary and developmental mechanisms of the adaptive beak structure observed in the Ground Tit. Results A morphometric approach quantified that the Ground Tit has a comparatively longer and more decurved upper beaks than other parids. We estimated that the ancestor of the Ground Tit likely had a short straight upper beak similar to most current recognized parid species using an ancestral state reconstruction. This morphological specialization is considered an adaptation to its ground-oriented behavior on the high plateau. To identify genetic mechanisms behind this adaptive change, a comparative transcriptomic analysis was applied between the Ground Tit and its closely related species, the Great Tit (Parus major). We detected that 623 genes were significantly differentially expressed in embryonic upper beaks between the two species, 17 of which were functionally annotated to correlate with bone development and morphogenesis, although genes related to bone development were not found to undergo accelerated evolution in the Ground Tit. RT-qPCR validation confirmed differential expression of five out of eight genes that were selected from the 17 genes. Subsequent functional assays in chicken embryos demonstrated that two of these genes, FGF13 and ITGB3, may affect beak morphology by modulating levels of osteoblasts and osteoclasts. Conclusions Our results provide preliminary evidence that development of the long decurved beak of the Ground Tit is likely regulated by transcriptional activities of multiple genes coordinating osteoblasts and osteoclasts. The integration of multiple approaches employed here sheds light on ecological and genetic mechanisms in the evolution of avian morphology.

【 授权许可】

Unknown