Range shifts and non-monotonic clines in studies of Bergmann’s rule as applied to climate change

Abstract

Abstract Bergmann’s rule states that organisms should be smaller in warmer climates. This traditionally implied warmer latitudes, but also applies to warmer eras, as forming due to climate change. Integrating spatial and temporal ecology (chronoecogeography) can help us understand and predict how different species respond to environmental changes over time. However, study results can be misinterpreted if researchers do not take steps in the data collection or analysis stages to account for range shifting or non-monotonic patterns. Multiple variables can cause an organism’s geographic and recent temporal size clines to differ significantly, as seen in a review in this article, and these cannot easily be modeled. Range shifting can affect Bergmann’s rule modeling, especially regarding effects from climate change, and this article suggests methods to account for this when incorporating the dimension of time into climate change-focused ecogeographic research.