Genetic evidence for co-occurrence of chromosomal and thermal sex-determining systems in a lizard

Rajkumar S. Radder, Alexander E. Quinn, Arthur Georges, Stephen D. Sarre, Richard Shine*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

105 Citations (Scopus)

Abstract

An individual's sex depends upon its genes (genotypic sex determination or GSD) in birds and mammals, but reptiles are more complex: some species have GSD whereas in others, nest temperatures determine offspring sex (temperature-dependent sex determination). Previous studies suggested that montane scincid lizards (Bassiana duperreyi, Scincidae) possess both of these systems simultaneously: offspring sex is determined by heteromorphic sex chromosomes (XX-XY system) in most natural nests, but sex ratio shifts suggest that temperatures override chromosomal sex in cool nests to generate phenotypically male offspring even from XX eggs. We now provide direct evidence that incubation temperatures can sex-reverse genotypically female offspring, using a DNA sex marker. Application of exogenous hormone to eggs also can sex-reverse offspring (oestradiol application produces XY as well as XX females). In conjunction with recent work on a distantly related lizard taxon, our study challenges the notion of a fundamental dichotomy between genetic and thermally determined sex determination, and hence the validity of current classification schemes for sex-determining systems in reptiles.

Original languageEnglish
Pages (from-to)176-178
Number of pages3
JournalBiology Letters
Volume4
Issue number2
DOIs
Publication statusPublished - 23 Apr 2008
Externally publishedYes

Keywords

  • discordant sex
  • reptile
  • sex chromosomes
  • temperature-dependent sex determination

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