An X-linked sex ratio distorter in Drosophila simulans that kills or incapacitates both noncarrier sperm and sons.
Bottom Line: X-linked son-killers are predicted by theory to be favored by natural selection and evolve when brothers and sisters compete for shared limiting resources and/or when brothers reduce the inclusive fitness of their sisters via sib-mating-a phenomenon called SA-zygotic drive.Autosomal-dominant suppressors of Winters (Nmy) and Durham (Tmy) failed to suppress skew.A Y-linked suppressor of Paris, however, did suppress skew, and a recombination test failed to detect recombinants between these two sex ratio distorters, indicating that they are tightly linked and plausibly identical or allelic.
Affiliation: Department of Ecology, Evolution & Marine Biology, University of California, Santa Barbara, California 93106.Show MeSH
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Mentions: However, the sex ratio distortion was not reversed as was observed by Tao et al. (2007). Because Y chromosomes within D. simulans are known to be highly polymorphic for their influence on the level of sex ratio distortion by the Paris SD driver (including sex ratio reversal, see Montchamp-Moreau et al. 2001), I next crossed the backcrossed YSec males to females from the compound-X stock used to propagate the Paris and SR X chromosomes (X^XsimYsim females; see Figure S1, G0). This cross placed the YSec into compound-X females (X^XsimYsec; see Figure S1, G1), from which it could be introduced to males carrying both XParis and XSR in the same genetic background. Males carrying XParis or XSR from the attached-X stock were next crossed to the compound-X females carrying Ysec (X^XYsec) or females carrying Ysim (X^XYsim; see Figure S1, G2) and the sex ratios produced by sons from these crosses were measured by mating them to females from the EVEN line (see Figure S1, G3). As shown in Figure 5, both XParis and XSR males carrying Ysim produced biased sex ratios, with the Paris driver producing a larger sex ratio bias (offspring from XParisYsim sires: %♀ = 82.1 with a 95% CI of [79.7, 84.4] vs. offspring from XSRYsim sires: %♀ = 72.0 with a 95% CI of [71.0, 75.0]). When paired with the Ysec, however, neither driver produced any substantive sex ratio bias (offspring from XParisYsec sires: %♀ = 51.3 with a 95% CI of [49.9, 52.7] and offspring from XSRYsec sires: %♀ = 51.8 with a 95% CI of [50.3, 53.3]). This assay—that paired both the Paris and SR drivers with the same Y chromosomes (Ysim or YSec) and in the same Y and autosomal backgrounds—demonstrates that the both the Paris and SR drivers are silenced by the same Y chromosome from D. sechellia.
Affiliation: Department of Ecology, Evolution & Marine Biology, University of California, Santa Barbara, California 93106.