Global patterns of body size evolution in squamate reptiles are not driven by climate

Anat Feldman, A Allison, Aaron Bauer, Monika Böhm, L Chirio, Guarino Colli, I Das, T Doan, M LeBreton, M Martins, D Meirte, Z Nagy, C Nogueira, O Pauwels, Daniel Pincheira-Donoso, Uri Roll, P Wagner, Y Wang, Shai Meiri

Research output: Contribution to journalArticlepeer-review

42 Citations (Scopus)


Variation in body size across animal species underlies most ecological and evolutionary processes shaping local‐ and large‐scale patterns of biodiversity. For well over a century, climatic factors have been regarded as primary sources of natural selection on animal body size, and hypotheses such as Bergmann's rule (the increase of body size with decreasing temperature) have dominated discussions. However, evidence for consistent climatic effects, especially among ectotherms, remains equivocal. Here, we test a range of key hypotheses on climate‐driven size evolution in squamate reptiles across several spatial and phylogenetic scales.


Time period

Major taxa studied
Squamates (lizards and snakes).

We quantified the role of temperature, precipitation, seasonality and net primary productivity as drivers of body mass across ca. 95% of extant squamate species (9,733 spp.). We ran spatial autoregressive models of phylogenetically corrected median mass per equal‐area grid cell. We ran models globally, across separate continents and for major squamate clades independently. We also performed species‐level analyses using phylogenetic generalized least square models and linear regressions of independent contrasts of sister species.

Our analyses failed to identify consistent spatial patterns in body size as a function of our climatic predictors. Nearly all continent‐ and family‐level models differed from one another, and species‐level models had low explanatory power.

Main conclusions
The global distribution of body mass among living squamates varies independently from the variation in multiple components of climate. Our study, the largest in spatial and taxonomic scale conducted to date, reveals that there is little support for a universal, consistent mechanism of climate‐driven size evolution within squamates.
Original languageEnglish
Pages (from-to)471-483
JournalGlobal Ecology & Biogeography
Issue number4
Early online date21 Jan 2019
Publication statusPublished - 01 Apr 2019


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