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

Details

Serval ID
serval:BIB_38CA0C260197
Type
Article: article from journal or magazin.
Collection
Publications
Institution
Title
The balanced lethal system of crested newts: a ghost of sex chromosomes past?
Journal
American Naturalist
Author(s)
Grossen C., Neuenschwander S., Perrin N.
ISSN
1537-5323 (Electronic)
ISSN-L
0003-0147
Publication state
Published
Issued date
2012
Peer-reviewed
Oui
Volume
180
Number
6
Pages
E174-E183
Language
english
Abstract
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.
Keywords
balanced lethal system, maladaptive trait, sex chromosome turnovers, sex ratio selection
Pubmed
Web of science
Create date
06/08/2012 8:04
Last modification date
20/08/2019 13:28
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