Sex determination: Viviparous lizard selects sex of embryos

  title={Sex determination: Viviparous lizard selects sex of embryos},
  author={Kylie A. Robert and Michael B. Thompson},
No one suspected that temperature-dependent sex determination (TSD), whereby the sex of embryos depends on the temperature at which they develop, might occur in viviparous (live-bearing) reptiles, because thermoregulation in the mother results in relatively stable, raised gestation temperatures. But here we show that developing embryos of the actively thermoregulating viviparous skink Eulamprus tympanum are subject to TSD, offering the mother the chance to select the sex of her offspring and a… 

Do operational sex ratios influence sex allocation in viviparous lizards with temperature‐dependent sex determination?

Although maternal body temperature during pregnancy was influenced by OSR, the variation in temperature was not great enough to affect litter sex ratios or any other phenotypic traits of the offspring.

Viviparity and Temperature-Dependent Sex Determination

Fast maturing squamate reptiles provide an excellent, but as yet underutilized, model system for studying the adaptive significance of TSD, and the occurrence of T SD in viviparous species requires substantially more work on a phylogenetically diverse range of species.

Facultative sex allocation in the viviparous lizard Eulamprus tympanum, a species with temperature-dependent sex determination

Maternal manipulation of the sex ratio of the offspring in E. tympanum illustrates a selective advantage of temperature-dependent sex determination in a viviparous species.

Windows of embryonic sexual lability in two lizard species with environmental sex determination.

The hypothesis that TSD evolves because it enables offspring sex to be matched to conditions that are unpredictable at the time of laying is less likely to apply to squamates than to turtles, sphenodontians, and (especially) crocodiles, in which the period of sexual lability is delayed until long after oviposition.

Yolk steroid hormones and sex determination in reptiles with TSD.

  • P. Elf
  • Biology
    General and comparative endocrinology
  • 2003


Temperature-dependent sex determination (TSD) has evolved independently in at least two lineages of viviparous Australian scincid lizards, but its adaptive significance remains unclear; a montane lizard species (Eulamprus heatwolei) is studied with TSD, suggesting that mothers can modify the body sizes of their offspring by selecting specific thermal regimes during pregnancy, but cannot influence sons versus daughters differentially.

A study of thermally-induced sex reversal in casque-headed lizards

It is shown that XY chromosomes are dominant, however, the hypothesis of a conserved transcriptional response to incubation temperatures across non-avian reptiles that could be the reminiscence of an ancestral sex determination system is supported.



Sex Determination in Reptiles

  • J. Bull
  • Biology
    The Quarterly Review of Biology
  • 1980
Temperature-dependent sex determination (TSD) is common in turtles and has been reported in two lizards and alligators; however, data on TSD are available for few non-turtle species and an attempt is made to deduce their ancestries.

Environmental Sex Determination in Reptiles: Ecology, Evolution, and Experimental Design

Physiological investigations of TSD have clarified the roles of steroid hormones, various enzymes, and H-Y antigen in sexual differentiation, whereas molecular studies have identified several plausible candidates for sex-determining genes in species with TSD.

Facultative sex allocation in snow skink lizards (Niveoscincus microlepidotus)

Field studies on viviparous alpine skinks document a case, whereby among‐ and within‐year shifts in OSR were followed by shifts in sex allocation, and females that were courted and mated by many males produced mainly daughters.

Characteristics of gonads and oviducts in hatchlings and young of Chelydra serpentina resulting from three incubation temperatures

Eggs of Chelydra serpentina were incubated at 30°C and 26°C during the temperature‐sensitive period for sex determination and the average gonadal length was less in the males.

Climate change and temperature-dependent sex determination in reptiles.

  • F. Janzen
  • Environmental Science
    Proceedings of the National Academy of Sciences of the United States of America
  • 1994
Monitoring of nests of a population of painted turtles with temperature-dependent sex determination found annual offspring sex ratio was highly correlated with mean July air temperature, validating concerns about the effect of climate change on population demography.

Reptiles and Amphibians of Australia

Reptiles and Amphibians of Australia is a complete guide to Australia’s rich and varied herpetofauna, including frogs, crocodiles, turtles, tortoises, lizards and snakes. For each of the 1218 species

Developing scenarios of climate change for Southeastern Australia: an example using regional climate model output

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