Sex determination systems in reptiles are related to ambient temperature but not to the level of climatic fluctuation

Paola Cornejo-Páramo, Andrés Lira-Noriega, Ciro Ramírez-Suástegui, Fausto R. Méndez-De-La-Cruz, Tamás Székely, Araxi O. Urrutia, Diego Cortez

Research output: Contribution to journalArticlepeer-review

11 Citations (SciVal)


Background: Vertebrates exhibit diverse sex determination systems and reptiles stand out by having highly variable sex determinations that include temperature-dependent and genotypic sex determination (TSD and GSD, respectively). Theory predicts that populations living in either highly variable or cold climatic conditions should evolve genotypic sex determination to buffer the populations from extreme sex ratios, yet these fundamental predictions have not been tested across a wide range of taxa. Results: Here, we use phylogenetic analyses of 213 reptile species representing 38 families (TSD = 101 species, GSD = 112 species) and climatic data to compare breeding environments between reptiles with GSD versus TSD. We show that GSD and TSD are confronted with the same level of climatic fluctuation during breeding seasons. However, TSD reptiles are significantly associated with warmer climates. We found a strong selection on the breeding season length that minimises exposure to cold and fluctuating climate. Phylogenetic path analyses comparing competing evolutionary hypotheses support that transitions in sex determination systems influenced the ambient temperature at which the species reproduces and nests. In turn, this interaction affects other variables such as the duration of the breeding season and life-history traits. Conclusions: Taken together, our results challenge long-standing hypotheses about the association between sex determination and climate variability. We also show that ambient temperature is important during breeding seasons and it helps explain the effects of sex determination systems on the geographic distribution of extant reptile species.

Original languageEnglish
Article number103
JournalBMC Evolutionary Biology
Issue number1
Publication statusPublished - 17 Aug 2020


  • Ambient temperature
  • Breeding seasons
  • Climate fluctuation
  • Genotypic sex determination
  • Geographic ranges
  • Reptiles
  • Sex determination systems
  • Temperature-dependent sex determination

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics


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