甘肃鼢鼠头骨几何形态地理分异及其影响因素分析

Geographical differentiation of geometric morphology in Gansu zokor and influencing factors

摘要:

【目的】 从形态学角度揭示地下啮齿动物甘肃鼢鼠（Eospalax cansus）的适应性进化过程。【方法】 选取高低海拔分布的4 个甘肃鼢鼠种群，使用几何形态学分析其头骨形态的种内变异，并选取海拔、年均温、年降水量及植被归一化指数作为生态因子，利用偏最小二乘（Two ‐block partial leastsquares，Two‐block PLS）研究头骨形变与环境之间的联系。【结果】 不同海拔分布下的甘肃鼢鼠种群间头骨大小无显著差异，但头骨形状间差异显著，基于头骨形状数据可以将4 个地理种群准确判别；鼻骨、顶嵴、枕骨、听泡、臼齿及颌颌缝等具有重要生态功能的结构形状随海拔、年降水量及植被归一化指数变化的趋势明显，反映了环境在甘肃鼢鼠种群间头骨形状差异形成中的作用。此外，甘肃鼢鼠的头骨形状进化符合“距离隔离”模型。【结论】 甘肃鼢鼠种群间头骨形状差异显著；在海拔、降水及植被等生态因子的影响下，头骨背面结构鼻骨、顶嵴及枕骨等和头骨腹面结构听泡、臼齿及颌颌缝等具有明显的形变趋势，反映了不同环境下甘肃鼢鼠头骨的适应性进化。

Abstract:

【Objective】 This study aimed to reveal the adaptive evolution process of a typical subterranean rodent，Gansuzokor（Eospalax cansus），from the morphological perspective.【Method】 Four populations of Gansu zokor from different altitudes were selected to analyze intraspecific variation in skull morphology using geometric morphometrics.Elevation，annual mean temperature，annual precipitation，and Normalized Difference Vegetation Index（NVDI） were selected as ecological factors to explore the association between skull morphology variations and environmentusing two-blockpartialleast squares analysis.【Result】 While there was no significant difference in skullsize，asignificant difference in skull shape was observed among the populations of Gansu zokor at different altitudes，and the four populations can be accurately distinguished based on skull shape data. The shape of structures with essentialecological functions，such as nasal bone，temporal ridge，occipital bone，tympanic bulla，molar，and premaxillarymaxillarysuture，exhibited distincttrendsof variation in response toelevation，annual precipitation，and NVDI，reflectingthe role of environment factors in the formation of skull shape morphology of Gansu zokor. In addition，the skullshape evolution of the Gansu zokor was consistent with the“ isolation by distance” model.【Conclusion】Significantdifference in skull shape were found among the populations of Gansu zokor； under the influence of ecological factorssuch as altitude，precipitation，and vegetation，notable deformation rends were observed indorsal skull （nasal bone，temporal ridge，occipital bone） and the ventral skull （tympanic bulla，molar，premaxillary-maxillary suture），reflectingthe adaptive evolution of the skull of Gansu zokor under different environments.