Cranial endocasts can be used as a reliable proxy for brain size, reflecting the evolutionary and environmental selection pressure of species. Although studies on endocasts in amphibians have increased in recent years, those performed on endocasts of Anura are comparatively rare, especially at the intraspecific level. Here, using a high-altitude endemic toad—Scutiger boulengeri—as a model, through the application of integrative methods (morphology, anatomy, phylogeny, and ecology), we studied intraspecific variations in endocast morphology and explored its driving forces. Three-dimensional reconstruction and the brain-to-endocranial cavity (BEC) index suggested that the endocast of S. boulengeri can reflect brain morphology to a large extent. Elliptic Fourier analysis and principal component analysis revealed great variability in the cranial endocast morphology among individuals, as well as the variation concentrated in the regions of telencephalon and optic tectum. In the species, individuals with large bodies are accompanied by a larger endocast size; the relative endocast sizes have significant clade differences but no sexual dimorphism. Additionally, the relative endocast sizes of S. boulengeri were not associated with phylogenetic history and aquatic preference but were positively correlated with altitude and negatively correlated with oxygen content, temperature, and precipitation factors (annual mean temperature, temperature seasonality, annual precipitation, and precipitation seasonality). These findings suggested that high-altitude and extreme environmental conditions acted as important selective forces in morphological variation of the cranial endocast of S. boulengeri.

Yinmeng HOU;Xiaoxiao SHU;Shengchao SHI;Xiuqin LIN;Luyao XIAO;Jianping JIANG;Jianghong RAN;Feng XIE

CAS Key Laboratory of Mountain Ecological Restoration and Bioresource Utilization,Ecological Restoration and Biodiversity Conservation Key Laboratory of Sichuan Province,Chengdu Institute of Biology,Chinese Academy of Sciences,Chengdu 610041,Sichuan,China;College of Life Sciences,Sichuan University,Chengdu 610065,Sichuan,China;University of the Chinese Academy of Sciences,Beijing 100049,China;Mangkang Biodiversity and Ecological Station,Tibet Ecological Safety Monitor Network,Changdu 854500,Tibet,China

亚洲两栖爬行动物研究（英文版）

[1]Yinmeng HOU;Xiaoxiao SHU;Shengchao SHI;Xiuqin LIN;Luyao XIAO;Jianping JIANG;Jianghong RAN;Feng XIE-.Endocast Morphological Variation and Its Driving Forces in Scutiger boulengeri)[J].亚洲两栖爬行动物研究（英文版）,2022(04):269-283,中插14-中插19

Endocast,endocasts,endocast,endocranial,tectum

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