THE Y CHROMOSOMES OF DROSOPHILA SIMULANS ARE HIGHLY POLYMORPHIC FOR THEIR ABILITY TO SUPPRESS SEX-RATIO DRIVE

• Published in: Evolution Vol. 55; no. 4; pp. 728 - 737
• Main Authors: Montchamp-Moreau, Catherine, Ginhoux, Valérie, Atlan, Anne
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Publishing Ltd 01.04.2001
• Subjects: Drosophila simulans; meiotic drive; sex ratio; Y chromosome
• ISSN: 0014-3820; 1558-5646
• DOI: 10.1111/j.0014-3820.2001.tb00809.x

The sex‐ratio trait, known in several species of Drosophila including D. simulans, results from meiotic drive of the X chromosome against the Y. Males that carry a sex‐ratio X chromosome produce strongly female‐biased progeny. In D. simulans, drive suppressors have evolved on the Y chromosome and on the autosomes. Both the frequency of sex‐ratio X and the strength of the total drive suppression (Y‐linked and autosomal) vary widely among geographic populations of this worldwide species. We have investigated the pattern of Y‐linked drive suppression in six natural populations representative of this variability. Y‐linked suppressors were found to be a regular component of the suppression, with large differences between populations in the mean level of suppression. These variations did not correspond to differences in frequency of discrete types of Y chromosomes, but to a more or less wide continuum of phenotypes, from nonsuppressor to partial or total suppressor. We concluded that a large diversity of Y‐linked suppressor alleles exists in D. simulans and that some populations are highly polymorphic. Our results support the hypothesis that a Y‐chromosome polymorphism can be easily maintained by a balance between meiotic drive and the cost of drive suppression.