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 to understand the species’ morphological diversity in a continental and island setting, and within the context of previous detailed phylogeographic 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 was studied. Samples were then pooled into predefined geographical groups to evaluate the morphological differences among them using analyses of variance, to contrast the morphological and genetic relationships based on morphological and genetic distances and ancestral state reconstructions, and to assess the correlations of morphological, genetic and geographic distances with Mantel tests. We found significant relationships of mandible size with geographic 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, but not so the 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.

本研究以欧亚小鼩鼱（Sorex minutus）为研究对象，结合既往详尽的系统地理学（phylogeographic）研究背景，探究其在大陆与岛屿生境中的形态多样性，同时分析该物种种群形态变异的生态地理格局。本研究共检视了采自欧洲大陆及大西洋岛屿种群的568件小鼩鼱下颌骨与377件颅骨标本，采用几何形态测量学（geometric morphometrics）方法，分析下颌骨与颅骨的大小、形态与地理及环境变量间的普遍关联。随后，我们将样本按预设地理分组，通过方差分析（analyses of variance）评估组间形态差异；基于形态距离、遗传距离及祖先状态重建（ancestral state reconstructions）结果，对比形态与遗传的关联模式；并借助曼特尔检验（Mantel tests），探究形态、遗传与地理距离三者间的相关性。研究结果显示，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（converse Bergmann’s rule）；但颅骨大小的相关趋势则相对不明显。欧亚小鼩鼱的大陆种群间难以通过形态特征进行有效区分；而多数岛屿种群因体型更大，可与大陆种群清晰区分，这一结果印证了岛屿效应。此外，形态距离与遗传距离存在显著差异，岛屿种群在形态上同样表现出独特性。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明显关联，表明欧亚小鼩鼱的形态变异并未反映其遗传分化。本研究分析表明，环境变量与岛屿性（insularity）对欧亚小鼩鼱的形态分化具有重要影响。