LaPoint Scott, Keicher Lara, Wikelski Martin, Zub Karol, Dechmann Dina K N
Department of Migration and Immuno-Ecology , Max Planck Institute for Ornithology , Am Obstberg 1, Radolfzell 78315 , Germany.
Department of Biology , University of Konstanz , Universitätsstrasse 10, Konstanz 78457 , Germany.
R Soc Open Sci. 2017 Jan 25;4(1):160947. doi: 10.1098/rsos.160947. eCollection 2017 Jan.
Ontogenetic changes in mammalian skulls are complex. For a very few species (i.e. some shrews), these also include seasonally driven, bidirectional size changes within individuals, presumably to reduce energy requirements during low resource availabilities. These patterns are poorly understood, but are likely most pronounced in high-metabolic species with limited means for energy conservation. We used generalized additive models to quantify the effect of location, Julian day, age and sex on the length and depth of 512 and 847 skulls of stoat () and weasel () specimens collected throughout the northern hemisphere. Skull length of both species varies between sexes and geographically, with stoat skull length positively correlated with latitude. Both species demonstrate seasonal and ontogenetic patterns, including a rare, absolute growth overshoot in juvenile braincase depth. Standardized braincase depths of both species peak in their first summer, then decrease in their first winter, followed by a remarkable regrowth that peaks again during their second summer. This seasonal pattern varies in magnitude and timing between geographical regions and the sexes, matching predictions of Dehnel's phenomenon. This suggests implications for the evolution of over-wintering strategies in mammals, justifying further research on their mechanisms and value, with implications for applied osteology research.
哺乳动物头骨的个体发育变化很复杂。对于极少数物种（如一些鼩鼱），这些变化还包括个体内部受季节驱动的双向大小变化，推测这是为了在资源匮乏时降低能量需求。人们对这些模式了解甚少，但它们可能在能量保存方式有限的高代谢物种中最为明显。我们使用广义相加模型来量化位置、儒略日、年龄和性别对在北半球收集的512个白鼬（Mustela erminea）和847个伶鼬（Mustela nivalis）标本的头骨长度和深度的影响。两种物种的头骨长度在性别和地理上都有所不同，白鼬的头骨长度与纬度呈正相关。两种物种都表现出季节性和个体发育模式，包括幼年脑壳深度罕见的绝对生长过度。两种物种的标准化脑壳深度在它们的第一个夏季达到峰值，然后在第一个冬季下降，随后显著再生长，并在第二个夏季再次达到峰值。这种季节性模式在地理区域和性别之间的幅度和时间上有所不同，符合德内尔现象的预测。这表明其对哺乳动物越冬策略进化的影响，为进一步研究其机制和价值提供了依据，对应用骨科学研究也有启示。
