Molecular evolution of Dmrt1 accompanies change of sex-determining mechanisms in reptilia

Daniel E Janes; Christopher L Organ; Rami Stiglec; Denis O'Meally; Stephen D Sarre; Arthur Georges; Jennifer A M Graves; Nicole Valenzuela; Robert A Literman; Kim Rutherford; Neil Gemmell; John B Iverson; Jeffrey W Tamplin; Scott V Edwards; Tariq Ezaz

doi:10.1098/rsbl.2014.0809

Molecular evolution of Dmrt1 accompanies change of sex-determining mechanisms in reptilia

Biol Lett. 2014 Dec;10(12):20140809. doi: 10.1098/rsbl.2014.0809.

Authors

Affiliations

¹ Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA 02138, USA Department of Ecology, Evolution, and Organismal Biology, Iowa State University, Ames, IA 50011, USA [email protected].
² Department of Microbiology and Immunology, Montana State University, Bozeman, MT 59717, USA.
³ Institute for Applied Ecology, University of Canberra, Canberra, Australian Capital Territory 2601, Australia.
⁴ Department of Ecology, Evolution, and Organismal Biology, Iowa State University, Ames, IA 50011, USA.
⁵ Allen Wilson Centre, Department of Anatomy, University of Otago, Dunedin 9054, New Zealand.
⁶ Department of Biology, Earlham College, Richmond, IN 47374, USA.
⁷ Department of Biology, University of Northern Iowa, Cedar Falls, IA 50614, USA.
⁸ Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA 02138, USA.

Abstract

In reptiles, sex-determining mechanisms have evolved repeatedly and reversibly between genotypic and temperature-dependent sex determination. The gene Dmrt1 directs male determination in chicken (and presumably other birds), and regulates sex differentiation in animals as distantly related as fruit flies, nematodes and humans. Here, we show a consistent molecular difference in Dmrt1 between reptiles with genotypic and temperature-dependent sex determination. Among 34 non-avian reptiles, a convergently evolved pair of amino acids encoded by sequence within exon 2 near the DM-binding domain of Dmrt1 distinguishes species with either type of sex determination. We suggest that this amino acid shift accompanied the evolution of genotypic sex determination from an ancestral condition of temperature-dependent sex determination at least three times among reptiles, as evident in turtles, birds and squamates. This novel hypothesis describes the evolution of sex-determining mechanisms as turnover events accompanied by one or two small mutations.

Keywords: ancestral reconstruction; archosaur; convergence; sex determination; squamate.

Publication types

Research Support, Non-U.S. Gov't
Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

Animals
Evolution, Molecular*
Female
Male
Reptiles / physiology*
Sex Determination Processes*
Transcription Factors / genetics*

Substances

DMRT1 protein
Transcription Factors