Temperature sex reversal implies sex gene dosage in a reptile.
Sex in reptiles is determined by genes on sex chromosomes or by incubation temperature. Previously these two modes were thought to be distinct, yet we show that high incubation temperatures reverse genotypic males (ZZ) to phenotypic females in a lizard with ZZ and ZW sex chromosomes. Thus, the W chromosome is not necessary for female differentiation. Sex determination is probably via a dosage-sensitive male-determining gene on the Z chromosome that is inactivated by extreme temperatures. Our data invite a novel hypothesis for the evolution of temperature-dependent sex determination (TSD) and suggest that sex chromosomes may exist in many TSD reptiles.
Quinn
Alexander E
AE
Institute for Applied Ecology, University of Canberra, ACT 2601, Australia. quinn@aerg.canberra.edu.au
Georges
Arthur
A
Sarre
Stephen D
SD
Guarino
Fiorenzo
F
Ezaz
Tariq
T
Graves
Jennifer A Marshall
JA
D000818:Animals; D012734:Disorders of Sex Development; D005260:Female; D018628:Gene Dosage; D005838:Genotype; D008116:Lizards / Q000196:embryology / Q000235:genetics* / Q000502:physiology*; D008297:Male; D010641:Phenotype; D016133:Polymerase Chain Reaction; D012730:Sex Chromosomes / Q000235:genetics; D019849:Sex Determination Processes; D012744:Sex Ratio; D013696:Temperature