Closely related species that occur across steep environmental gradients often display clear body size differences, and examining this pattern is crucial to understanding how environmental variation shapes diversity. Australian endemic rodents in the Pseudomys Division (Muridae: Murinae) have repeatedly colonized the arid, monsoon, and mesic biomes over the last 5 million years. Using occurrence records, body mass data, and Bayesian phylogenetic models, we test whether body mass of 31 species in the Pseudomys Division can be predicted by their biome association. We also model the effect of eight environmental variables on body mass. Despite high phylogenetic signal in body mass evolution across the phylogeny, we find that mass predictably increases in the mesic biome and decreases in arid and monsoon biomes. As per Bergmann's rule, temperature is strongly correlated with body mass, as well as several other variables. Our results highlight two important findings. First, body size in Australian rodents has tracked with climate through the Pleistocene, likely due to several environmental variables rather than a single factor. Second, support for both Brownian motion and predictable change at different taxonomic levels in the Pseudomys Division phylogeny demonstrates how the level at which we test hypotheses can alter interpretation of evolutionary processes.

中文翻译：

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环境预测澳大利亚哺乳动物最近的辐射会反复改变体型

在陡峭的环境梯度中出现的密切相关的物种通常显示出明显的体型差异，检查这种模式对于了解环境变化如何塑造多样性至关重要。在过去的 500 万年里，澳大利亚地方性啮齿动物 Pseudomys Division（鼠科：鼠科）多次在干旱、季风和中湿生物群落中定居。使用发生记录、体重数据和贝叶斯系统发育模型，我们测试是否可以通过它们的生物群系关联来预测 Pseudomys Division 中 31 个物种的体重。我们还模拟了八个环境变量对体重的影响。尽管在整个系统发育过程中体重进化中存在高系统发育信号，但我们发现质量在中生生物群落中可预测地增加，而在干旱和季风生物群落中则减少。根据伯格曼法则，温度与体重以及其他几个变量密切相关。我们的结果突出了两个重要的发现。首先，澳大利亚啮齿动物的体型在整个更新世都与气候有关，这可能是由于几个环境变量而不是单个因素。其次，在 Pseudomys Division 系统发育中，对布朗运动和可预测变化的不同分类学水平的支持证明了我们测试假设的水平如何改变对进化过程的解释。