Evolutionary Dynamics of the Gametologous CTNNB1 Gene on the Z and W Chromosomes of Snakes

Snakes exhibit genotypic sex determination with female heterogamety (ZZ males and ZW females), and the state of sex chromosome differentiation also varies among lineages. To investigate the evolutionary history of homologous genes located in the nonrecombining region of differentiated sex chromosome...

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Bibliographic Details
Published in:The Journal of heredity 2017-03, Vol.108 (2), p.142-151
Main Authors: Laopichienpong, Nararat, Muangmai, Narongrit, Chanhome, Lawan, Suntrarachun, Sunutcha, Twilprawat, Panupon, Peyachoknagul, Surin, Srikulnath, Kornsorn
Format: Article
Language:English
Subjects:
Animals
beta Catenin - genetics
Evolution, Molecular
Exons
Female
Introns
Male
Phylogeny
Sequence Analysis, DNA
Sex Chromosomes - genetics
Snakes - classification
Snakes - genetics
Thailand
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Summary:Snakes exhibit genotypic sex determination with female heterogamety (ZZ males and ZW females), and the state of sex chromosome differentiation also varies among lineages. To investigate the evolutionary history of homologous genes located in the nonrecombining region of differentiated sex chromosomes in snakes, partial sequences of the gametologous CTNNB1 gene were analyzed for 12 species belonging to henophid (Cylindrophiidae, Xenopeltidae, and Pythonidae) and caenophid snakes (Viperidae, Elapidae, and Colubridae). Nonsynonymous/synonymous substitution ratios (Ka/Ks) in coding sequences were low (Ka/Ks < 1) between CTNNB1Z and CTNNB1W, suggesting that these 2 genes may have similar functional properties. However, frequencies of intron sequence substitutions and insertion–deletions were higher in CTNNB1Z than CTNNB1W, suggesting that Z-linked sequences evolved faster than W-linked sequences. Molecular phylogeny based on both intron and exon sequences showed the presence of 2 major clades: 1) Z-linked sequences of Caenophidia and 2) W-linked sequences of Caenophidia clustered with Z-linked sequences of Henophidia, which suggests that the sequence divergence between CTNNB1Z and CTNNB1W in Caenophidia may have occurred by the cessation of recombination after the split from Henophidia.
ISSN:0022-1503
1465-7333
DOI:10.1093/jhered/esw074