University of Alaska Museum, 1962 Yukon Drive, Fairbanks, AK, 99775, USA.
Department of Geosciences, University of Alaska, Fairbanks, AK, 99775, USA.
Nat Commun. 2024 Apr 5;15(1):2864. doi: 10.1038/s41467-024-46843-2.
Global climate patterns fundamentally shape the distribution of species and ecosystems. For example, Bergmann's rule predicts that homeothermic animals, including birds and mammals, inhabiting cooler climates are generally larger than close relatives from warmer climates. The modern world, however, lacks the comparative data needed to evaluate such macroecological rules rigorously. Here, we test for Bergmann's rule in Mesozoic dinosaurs and mammaliaforms that radiated within relatively temperate global climate regimes. We develop a phylogenetic model that accounts for biases in the fossil record and allows for variable evolutionary dispersal rates. Our analysis also includes new fossil data from the extreme high-latitude Late Cretaceous Arctic Prince Creek Formation. We find no evidence for Bergmann's rule in Mesozoic dinosaurs or mammaliaforms, the ancestors of extant homeothermic birds and mammals. When our model is applied to thousands of extant dinosaur (bird) and mammal species, we find that body size evolution remains independent of latitude. A modest temperature effect is found in extant, but not in Mesozoic, birds, suggesting that body size evolution in modern birds was influenced by Bergmann's rule during Cenozoic climatic change. Our study provides a general approach for studying macroecological rules, highlighting the fossil record's power to address longstanding ecological principles.
全球气候模式从根本上决定了物种和生态系统的分布。例如，伯格曼法则预测，生活在较冷气候中的恒温动物，包括鸟类和哺乳动物，通常比来自温暖气候的近亲更大。然而，现代世界缺乏严格评估此类宏观生态规律所需的比较数据。在这里，我们在中生代恐龙和哺乳动物中测试伯格曼法则，这些恐龙和哺乳动物在相对温和的全球气候条件下辐射。我们开发了一种系统发育模型，该模型考虑了化石记录中的偏差，并允许可变的进化扩散率。我们的分析还包括来自极端高纬度晚白垩世北极王子溪组的新化石数据。我们没有发现中生代恐龙或哺乳动物（现生恒温鸟类和哺乳动物的祖先）存在伯格曼法则的证据。当我们的模型应用于数千种现生恐龙（鸟类）和哺乳动物物种时，我们发现体型进化与纬度无关。在现生鸟类中发现了适度的温度效应，但在中生代鸟类中没有发现，这表明现代鸟类的体型进化受到中生代气候变化期间伯格曼法则的影响。我们的研究为研究宏观生态规律提供了一种通用方法，强调了化石记录在解决长期生态原则方面的强大功能。
