Evolution of the closely related, sex-related genes DM-W and DMRT1 in African clawed frogs (Xenopus).
DM-W is a dominant, female-specific, regulator of sex determination in the African clawed frog Xenopus laevis. This gene is derived from partial duplication of DMRT1, a male-related autosomal gene. We set out to better understand sex determination in Xenopus by studying this pair of genes. We found that DM-W evolved in Xenopus after divergence from the sister genus Silurana but before divergence of X. laevis and X. clivii, and that DM-W arose from partial duplication of DMRT1β, which is one of the two DMRT1 paralogs in the tetraploid ancestor of Xenopus. Using the rate ratio of nonsynonymous to synonymous substitutions per site and multilocus polymorphism data, we show that DM-W evolved non-neutrally. By cloning paralogs and using a pyrosequencing assay, we also demonstrate that DMRT1 underwent phylogenetically biased pseudogenization after polyploidization, and that expression of this gene is regulated by mechanisms that vary through development. One explanation for these observations is that the expression domain of DMRT1β was marginalized, which would explain why this paralog is dispensable in Xenopus polyploids and why DM-W has a narrow expression domain. These findings illustrate how evolution of the genetic control of stable phenotypes is facilitated by redundancy, degeneration, and compartmentalized regulation.
Department of Biology, Life Sciences Building Room 328 McMaster University, 1280 Main Street West Hamilton, ON, L8S 4K1, Canada.
Adam J
AJ
Bewick
Dave W
DW
Anderson
Ben J
BJ
Evans
D000818:Animals; D004268:DNA-Binding Proteins / Q000235:genetics*; D019143:Evolution, Molecular; D010802:Phylogeny; D012641:Selection, Genetic; D019849:Sex Determination Processes; D014157:Transcription Factors / Q000235:genetics*; D014981:Xenopus / Q000145:classification* / Q000235:genetics*; D029867:Xenopus Proteins / Q000235:genetics*; D014982:Xenopus laevis / Q000235:genetics
C551581:DM-W protein, Xenopus; C110547:DMRT1 protein; D004268:DNA-Binding Proteins; D014157:Transcription Factors; D029867:Xenopus Proteins