A global analysis of viviparity in squamates highlights its prevalence in cold climates

Anna Zimin, Sean V. Zimin, Richard Shine, Luciano Avila, Aaron Bauer, Monika Böhm, Rafe Brown, Goni Barki, Gabriel Henrique de Oliveira Caetano, Fernando Castro Herrera, David G. Chapple, Laurent Chirio, Guarino R. Colli, Tiffany M. Doan, Frank Glaw, L. Lee Grismer, Yuval Itescu, Fred Kraus, Matthew LeBreton, Marcio MartinsMariana Morando, Gopal Murali, Zoltán T. Nagy, Maria Novosolov, Paul Oliver, Paulo Passos, Olivier S.G. Pauwels, Daniel Pincheira-Donoso, Marco Antonio Ribeiro-Junior, Glenn Shea, Reid Tingley, Omar Torres-Carvajal, Jean François Trape, Peter Uetz, Philipp Wagner, Uri Roll, Shai Meiri

Research output: Contribution to journalArticlepeer-review


Aim: Viviparity has evolved more times in squamates than in any other vertebrate group; therefore, squamates offer an excellent model system in which to study the patterns, drivers and implications of reproductive mode evolution. Based on current species distributions, we examined three selective forces hypothesized to drive the evolution of squamate viviparity (cold climate, variable climate and hypoxic conditions) and tested whether viviparity is associated with larger body size. Location: Global. Time period: Present day. Taxon: Squamata. Methods: We compiled a dataset of 9061 squamate species, including their distributions, elevation, climate, body mass and reproductive modes. We applied species-level and assemblage-level approaches for predicting reproductive mode, both globally and within biogeographical realms. We tested the relationships of temperature, interannual and intra-annual climatic variation, elevation (as a proxy for hypoxic conditions) and body mass with reproductive mode, using path analyses to account for correlations among the environmental predictors. Results: Viviparity was strongly associated with cold climates at both species and assemblage levels, despite the prevalence of viviparity in some warm climates. Viviparity was not clearly correlated with climatic variability or elevation. The probability of being viviparous exhibited a weak positive correlation with body size. Conclusions: Although phylogenetic history is important, potentially explaining the occurrence of viviparous species in regions that are warm at present, current global squamate distribution is characterized by a higher relative abundance of viviparity in cold environments, supporting the prediction of the “cold-climate” hypothesis. The roles of climatic variation and hypoxia are less important and not straightforward. Elevation probably exerts various selective pressures and influences the prevalence of viviparity primarily through its effect on temperature rather than on oxygen concentration.

Original languageEnglish
Pages (from-to)2437-2452
Number of pages16
JournalGlobal Ecology and Biogeography
Issue number12
StatePublished - Dec 2022
Externally publishedYes

Bibliographical note

Publisher Copyright:
© 2022 The Authors. Global Ecology and Biogeography published by John Wiley & Sons Ltd.


  • biogeography
  • body size
  • climatic variability
  • cold climate
  • elevation
  • global analysis
  • reproduction
  • squamates
  • structural equation modelling
  • viviparity

ASJC Scopus subject areas

  • Global and Planetary Change
  • Ecology, Evolution, Behavior and Systematics
  • Ecology


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