Climate effects on offspring sex ratio in a viviparous lizard

Erik Wapstra*, Tobias Uller, David L. Sinn, Mats Olsson, Katrina Mazurek, Jean Joss, Richard Shine

*Corresponding author for this work

Research output: Contribution to journalArticle

77 Citations (Scopus)


1. Understanding individual and population responses to climate change is emerging as an important challenge. Because many phenotypic traits are sensitive to environmental conditions, directional climate change could significantly alter trait distribution within populations and may generate an evolutionary response. 2. In species with environment-dependent sex determination, climate change may lead to skewed sex ratios at hatching or birth. However, there are virtually no empirical data on the putative link between climatic parameters and sex ratios from natural populations. 3. We monitored a natural population of viviparous lizards with temperature-dependent sex determination (Niveoscincus ocellatus) over seven field seasons. Sex ratios at birth fluctuated significantly among years and closely tracked thermal conditions in the field, with the proportion of male offspring increasing in colder years. 4. This is the first study to demonstrate the effect of local climatic conditions (e.g. temperature) on offspring sex ratio fluctuations in a free-living population of a viviparous ectotherm. A succession of warmer-than-usual years (as predicted under many climate-change scenarios) likely would generate female-biased sex ratios at birth, while an increase in interannual variation (as also predicted under climate change scenarios) could lead to significant fluctuations in cohort sex ratios. If cohort sex ratio bias at birth leads to adult sex ratio bias, long-term directional changes in thermal conditions may have important effects on population dynamics in this species.

Original languageEnglish
Pages (from-to)84-90
Number of pages7
JournalJournal of Animal Ecology
Issue number1
Publication statusPublished - Jan 2009


  • Climate change
  • Climate variability
  • Environmental sex determination
  • Reptile
  • Squamate

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