Data from: Ecogeographical patterns of morphological variation in pygmy shrews Sorex minutus (Soricomorpha: Soricinae) within a phylogeographic and continental-and-island framework

Ecogeographical patterns of morphological variation were studied in the Eurasian pygmy shrew Sorex minutus aiming to understand the species’ morphological diversity in a continental and island setting, and within the context of previous detailed phylogeographical studies. In total, 568 mandibles and 377 skulls of S. minutus from continental and island populations from Europe and Atlantic islands were examined using a geometric morphometrics approach, and the general relationships of mandible and skull size and shape with geographical and environmental variables were studied. Samples were then pooled into predefined geographical groups to evaluate the morphological differences among them using analyses of variance, aiming to contrast the morphological and genetic relationships based on morphological and genetic distances and ancestral state reconstructions, as well as assess the correlations of morphological, genetic, and geographical distances with Mantel tests. We found significant relationships of mandible size with geographical and environmental variables, fitting the converse Bergmann's rule; however, for skull size, this was less evident. Continental groups of S. minutus could not readily be differentiated from each other by shape. Most island groups of S. minutus were easily discriminated from the continental groups by being larger, indicative of an island effect. Moreover, morphological and genetic distances differed substantially and, again, island groups were distinctive morphologically. Morphological and geographical distances were significantly correlated, although this was not the case for morphological and genetic distances, indicating that morphological variation does not reflect genetic subdivision in S. minutus. Our analyses showed that environmental variables and insularity had important effects on the morphological differentiation of S. minutus.

本研究以欧亚 pygmy 鼩鼱（Eurasian pygmy shrew，Sorex minutus）为研究对象，旨在明确该物种在大陆与岛屿生境中的形态多样性，并结合既往详尽的系统地理学（phylogeographical）研究背景，分析其形态变异的生态地理格局。研究共采集并分析了采自欧洲大陆及大西洋岛屿的大陆种群与岛屿种群的568件下颌骨与377件头骨标本，采用几何形态测量学（geometric morphometrics）方法，探究了下颌骨与头骨的大小、形态与地理及环境变量之间的普遍关联。随后，研究人员将标本按预先划定的地理群组进行合并，通过方差分析评估各组间的形态差异；旨在基于形态与遗传距离及祖先状态重建结果，对比形态与遗传之间的关联，并通过曼特尔检验（Mantel test）分析形态距离、遗传距离与地理距离三者间的相关性。研究发现，下颌骨大小与地理及环境变量存在显著关联，符合反伯格曼法则；但头骨大小的相关规律则并不显著。该物种的大陆种群群组无法通过形态特征进行有效区分；而多数岛屿种群群组因体型更大，可与大陆种群群组清晰区分，这一结果印证了岛屿效应（island effect）。此外，形态距离与遗传距离存在显著差异，且岛屿种群群组在形态上同样具有独特性。形态距离与地理距离呈显著相关，但形态距离与遗传距离则无此关联，这表明该物种的形态变异无法反映其遗传分化格局。本研究结果表明，环境变量与岛屿性均对Sorex minutus的形态分化具有重要影响。