Article Dans Une Revue Evolutionary Biology Année : 2011

Polymorphism at a Sex-Linked Transcription Cofactor in European Tree Frogs (Hyla arborea): Sex-Antagonistic Selection or Neutral Processes ?

Résumé

Nascent sex chromosomes offer a unique opportunity to investigate the evolutionary fate of genes recently trapped in non-recombining segments. A house-keeping gene (MED15) was recently shown to lie on the nascent sex-chromosomes of the European tree frog (Hyla arborea), with different alleles fixed on the X and the Y chromosomes. Here we document a polymorphism (glutamine deletion) in the X copy of the gene, and use population surveys and experimental crosses to test whether this polymorphism is neutral or maintained by sex-antagonistic selection. Tadpoles from parents of known genotypes revealed significant discrepancies from Mendelian inheritance, suggesting possible sex-antagonistic effects under laboratory conditions. Quantitatively, however, these effects did not meet the conditions for polymorphism maintenance. Furthermore, field estimates of female genotypic frequencies did not differ from Hardy-Weinberg equilibrium and allelic frequencies on the X chromosome did not differ between sexes. In conclusion, although sex-antagonistic effects cannot be excluded given the laboratory conditions, the X-linked polymorphism under study appears neutral in the wild. Alternatively, sex-antagonistic selection might still account for the fixation of a male-specific allele on the Y chromosome.

Dates et versions

halsde-00591791 , version 1 (10-05-2011)

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Christophe Dufresnes, Émilien Luquet, Sandrine Plénet, Matthias Stöck, Nicolas Perrin. Polymorphism at a Sex-Linked Transcription Cofactor in European Tree Frogs (Hyla arborea): Sex-Antagonistic Selection or Neutral Processes ?. Evolutionary Biology, 2011, 38 (2), pp.208-213. ⟨10.1007/s11692-011-9114-y⟩. ⟨halsde-00591791⟩
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