Maternal basking behaviour determines offspring sex in a viviparous reptile

Erik Wapstra*, Mats Olsson, Richard Shine, Ashley Edwards, Roy Swain, Jean M P Joss

*Corresponding author for this work

    Research output: Contribution to journalArticlepeer-review

    75 Citations (Scopus)


    Two primary dichotomies within vertebrate life histories involve reproductive mode (oviparity versus viviparity) and sex determination (genotypic sex determination versus environmental sex determination). Although reptiles show multiple evolutionary transitions in both parameters, the co-occurrence of viviparity and environmental-dependent sex determination have heretofore been regarded as incompatible. Our studies on the viviparous lizard Niveoscincus ocellatus show that the extent of basking by a female influences the sex of her offspring. Critically, our data reveal this effect both in the field (via correlations between date of birth and litter sex ratio) and in a laboratory experiment (females with reduced basking opportunities produced more male offspring). Changes in thermoregulatory behaviour thus allow pregnant female lizards to modify the sex of their offspring.

    Original languageEnglish
    JournalProceedings of the Royal Society B: Biological Sciences
    Issue numberSUPPL. 4
    Publication statusPublished - 7 May 2004


    • Environmental sex determination
    • Sex ratio
    • Squamate
    • Viviparity


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