Suzuki Satoshi, Abe Mikiko, Motokawa Masaharu
Department of Zoology, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan.
Zoolog Sci. 2011 Sep;28(9):676-88. doi: 10.2108/zsj.28.676.
We conducted an interspecific comparison of skulls from two closely related but differently sized mustelid species, Mustela itatsi and M. sibirica (Mammalia, Carnivora, Mustelidae); a sexual comparison within the latter species showed remarkable size dimorphism. We clarified several differences in skull proportion related to size using allometric analyses and qualitative comparisons. Allometric analysis revealed that the skulls of male M. itatsi (the smaller species) have a relatively long palate; a slender viscerocranium and postorbital constriction; a broad, short, and low neurocranium; small carnassials; and a short mandible with a thin body and small ramus compared to the skulls of male M. sibirica (the larger species). Similar results were obtained when male M. itatsi were compared to female M. sibirica, although the male M. itatsi had a broader viscerocranium than female M. sibirica. A sexual comparison in M. sibirica revealed a larger skull size among the males with a relatively wide viscerocranium; wide postorbital constriction; a slender, long, and high neurocranium; short and wide auditory bullae; short carnassials; and a long and high mandible compared to females. Qualitative comparisons revealed changes in a few characters depending on skull size or with respect to some cranial components in each species. The interspecific differences observed were clearly larger than the intraspecific differences for three qualitative characters. The allometric and qualitative differences detected between these species suggest that each species is not simply the dwarf and/or giant morph of the other, and complicated differences were clarified.
我们对两种亲缘关系密切但体型不同的鼬科动物——黄喉貂（Mustela itatsi）和西伯利亚鼬（M. sibirica）（哺乳纲，食肉目，鼬科）的头骨进行了种间比较；对后者的性别比较显示出显著的体型二态性。我们通过异速生长分析和定性比较，阐明了与体型相关的头骨比例的几个差异。异速生长分析表明，雄性黄喉貂（体型较小的物种）的头骨有相对较长的腭；细长的面颅和眶后缩窄；宽阔、短小且低矮的脑颅；较小的裂齿；与雄性西伯利亚鼬（体型较大的物种）的头骨相比，下颌短，体薄且下颌支小。当将雄性黄喉貂与雌性西伯利亚鼬进行比较时，也得到了类似的结果，尽管雄性黄喉貂的面颅比雌性西伯利亚鼬宽。对西伯利亚鼬的性别比较显示，雄性的头骨尺寸更大，面颅相对较宽；眶后缩窄宽；脑颅细长、长且高；听泡短而宽；裂齿短；与雌性相比，下颌长且高。定性比较揭示了一些特征根据头骨大小或每个物种的一些颅骨成分而发生的变化。观察到的种间差异在三个定性特征上明显大于种内差异。这些物种之间检测到的异速生长和定性差异表明，每个物种并非简单地是另一个物种的侏儒和/或巨型形态，并且阐明了复杂的差异。
