The balanced lethal system of crested newts: a ghost of sex chromosomes past?

Détails

ID Serval
serval:BIB_38CA0C260197
Type
Article: article d'un périodique ou d'un magazine.
Collection
Publications
Titre
The balanced lethal system of crested newts: a ghost of sex chromosomes past?
Périodique
American Naturalist
Auteur(s)
Grossen C., Neuenschwander S., Perrin N.
ISSN
1537-5323 (Electronic)
ISSN-L
0003-0147
Statut éditorial
Publié
Date de publication
2012
Peer-reviewed
Oui
Volume
180
Numéro
6
Pages
E174-E183
Langue
anglais
Résumé
Balanced lethal systems are more than biological curiosities: as theory predicts, they should quickly be eliminated through the joint forces of recombination and selection. That such systems might become fixed in natural populations poses a challenge to evolutionary theory. Here we address the case of a balanced lethal system fixed in crested newts and related species, which makes 50% of offspring die early in development. All adults are heteromorphic for chromosome pair 1. The two homologues (1A and 1B) have different recessive deleterious alleles fixed on a nonrecombining segment, so that heterozygotes are viable, while homozygotes are lethal. Given such a strong segregation load, how could autosomes stop recombining? We propose a role for a sex-chromosome turnover from pair 1 (putative ancestral sex chromosome) to pair 4 (currently active sex chromosome). Accordingly, 1A and 1B represent two variants (Y(A) and Y(B)) of the Y chromosome from an ancestral male-heterogametic system. We formalize a scenario in which turnovers are driven by sex ratio selection stemming from gene-environment interactions on sex determination. Individual-based simulations show that a balanced lethal system can be fixed with significant likelihood, provided the masculinizing allele on chromosome 4 appears after the elimination of the feminizing allele on chromosome 1. Our study illustrates how strikingly maladaptive traits might evolve through natural selection.
Mots-clé
balanced lethal system, maladaptive trait, sex chromosome turnovers, sex ratio selection
Pubmed
Web of science
Création de la notice
06/08/2012 9:04
Dernière modification de la notice
03/03/2018 16:11
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