We used cranial geometric morphometric methods (GMM) to explore interspecific variation in Perognathus (silky pocket mice). We digitized 67 cranial landmarks on photographs of 305 adult voucher specimens (10 species and 33 subspecies, 121 localities). After summarizing variation patterns, we explored their association with biological, ecological, and climatic factors, and how (and why) shape evolved through time. Phenotypic clusters did not accord with phylogenetic clades, and we found instances of convergence, divergence, and increased rates of shape change. These are discussed in terms of shared selective pressures (e.g. habitat substrate and burrowing plus historic shifts in habitat/climate and desert adaptation). We also used variation patterns and phenetics to address ongoing taxonomic issues. While pocket mice are difficult to distinguish externally, GMM allowed us to precisely characterize interspecific cranial variation. Species significantly differed and could be classified based on their shape. We find P. alticola to be the most cranially distinct species and suggest raising the P. alticola + P. parvus (including P. mollipilosus) cluster/clade to subgenus status (=Cricetodipus). Cranial GMM found differences among taxa that seemed similar (i.e. cryptic) when previously explored using linear measurements (e.g. P. parvus vs. P. mollipilosus).

中文翻译：

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丝质袖珍小鼠（Perognathus：Perognathinae：Rodentia）颅骨的几何形态测量揭示了对其变异、进化和分类学的新见解

我们使用颅骨几何形态测量方法 (GMM) 来探索 Perognathus（丝袋小鼠）的种间变异。我们对 305 个成年凭证标本（10 个物种和 33 个亚种，121 个地点）照片上的 67 个颅骨标志进行了数字化。在总结了变化模式后，我们探讨了它们与生物、生态和气候因素的关联，以及形状如何（以及为何）随着时间演变。表型簇与系统发育分支不一致，我们发现了趋同、趋异和形状变化率增加的情况。这些是根据共同的选择压力（例如栖息地基质和洞穴以及栖息地/气候和沙漠适应的历史变化）进行讨论的。我们还使用变异模式和表型来解决持续存在的分类问题。虽然袖珍小鼠很难从外部区分，但 GMM 使我们能够精确地表征种间颅骨变异。物种差异很大，可以根据形状进行分类。我们发现 P. alticola 是颅骨最独特的物种，并建议将 P. alticola + P. parvus（包括 P. mollipilosus）簇/进化枝提升至亚属状态（= Cricetodipus）。颅脑 GMM 发现了以前使用线性测量（例如 P. parvus 与 P. mollipilosus）探索时看似相似（即神秘）的类群之间的差异。