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A Concoction Pipeline for Generating Molecular Operational Taxonomic Units (MOTUs) Among Riparian and Aquatic Beetles

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Published on: July 11, 2025

Is Bergmann's rule valid for terrestrial vertebrates?

Oleksandra Oskyrko^1,2,3, Jiajia Liu¹, Weiguo Du¹

¹State Key Laboratory of Wetland Conservation and Restoration, National Observations and Research Station for Wetland Ecosystems of the Yangtze Estuary, Ministry of Education Key Laboratory for Biodiversity Science and Ecological Engineering, and Institute of Eco-Chongming, School of Life Sciences, Fudan University, Shanghai, China.

|February 19, 2026

Summary

Bergmann's rule, which links larger body size to colder climates, applies to endotherms (birds, mammals) but not ectotherms (amphibians, reptiles). This pattern is context-dependent, influenced by thermoregulation and species traits.

Keywords:

Bergmann's rule interspecific intraspecific latitude temperature vertebrates

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Area of Science:

Ecology
Zoology
Evolutionary Biology

Background:

Bergmann's rule predicts larger body size in colder climates.
Its applicability across vertebrate taxa and thermoregulatory strategies is debated.
Previous studies show inconsistent support, particularly between endotherms and ectotherms.

Purpose of the Study:

To test the consistency and strength of Bergmann's rule across major terrestrial vertebrate taxa.
To investigate the influence of thermoregulatory strategy (endothermy vs. ectothermy) on Bergmann's rule.
To assess Bergmann's rule at species and population levels.

Main Methods:

Analysis of species- and population-level body size data for amphibians, reptiles, birds, and mammals.
Correlation analysis between body size and latitude across taxa.
Comparison of rule support between endotherms and ectotherms, and across different taxonomic levels (order/family, species, population).

Main Results:

Bergmann's rule was supported in endotherms (birds, mammals) but not ectotherms (amphibians, reptiles).
Support for the rule was stronger in endotherms (34%) than ectotherms (18%) at the order/family level.
Body size correlated negatively with temperature in endotherms along latitudinal gradients, but not ectotherms.

Conclusions:

Bergmann's rule is not a universal principle but a context-dependent pattern.
Thermoregulatory strategy significantly moderates the rule's applicability.
Ecological traits and phylogenetic history influence Bergmann's rule, highlighting differential sensitivity to environmental changes.