Disentangling the Causes for Faster-X Evolution in Aphids

Abstract : The faster evolution of X chromosomes has been documented in several species, and results from the increased efficiency of selection on recessive alleles in hemizygous males and/or from increased drift due to the smaller effective population size of X chromosomes. Aphids are excellent models for evaluating the importance of selection in faster-X evolution because their peculiar life cycle and unusual inheritance of sex chromosomes should generally lead to equivalent effective population sizes for X and autosomes. Because we lack a high-density genetic map for the pea aphid, whose complete genome has been sequenced, we first assigned its entire genome to the X or autosomes based on ratios of sequencing depth in males (X0) to females (XX). Then, we computed nonsynonymous to synonymous substitutions ratios (dN/dS) for the pea aphid gene set and found faster evolution of X-linked genes. Our analyses of substitution rates, together with polymorphism and expression data, showed that relaxed selection is likely to be the greatest contributor to faster-X because a large fraction of X-linked genes are expressed at low rates and thus escape selection. Yet, a minor role for positive selection is also suggested by the difference between substitution rates for X and autosomes for male-biased genes (but not for asexual female-biased genes) and by lower Tajima's D for X-linked compared with autosomal genes with highly male-biased expression patterns. This study highlights the relevance of organisms displaying alternative chromosomal inheritance to the understanding of forces shaping genome evolution.
Type de document :
Article dans une revue
Genome Biology and Evolution, Society for Molecular Biology and Evolution, 2018, 10 (2), pp.507-520. 〈10.1093/gbe/evy015〉
Liste complète des métadonnées

Littérature citée [3 références]  Voir  Masquer  Télécharger

Contributeur : Laurent Jonchère <>
Soumis le : jeudi 11 octobre 2018 - 11:33:20
Dernière modification le : jeudi 7 février 2019 - 14:25:34
Document(s) archivé(s) le : samedi 12 janvier 2019 - 13:59:07


Fichiers éditeurs autorisés sur une archive ouverte



Julie Jaquiéry, Jean Peccoud, Tiphaine Ouisse, Fabrice Legeai, Nathalie Prunier-Leterme, et al.. Disentangling the Causes for Faster-X Evolution in Aphids. Genome Biology and Evolution, Society for Molecular Biology and Evolution, 2018, 10 (2), pp.507-520. 〈10.1093/gbe/evy015〉. 〈hal-01701165〉



Consultations de la notice


Téléchargements de fichiers