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Sexually antagonistic "zygotic drive" of the sex chromosomes.

Rice WR, Gavrilets S, Friberg U - PLoS Genet. (2008)

Bottom Line: The phenomenon occurs because there is selection in the heterogametic sex for sex-linked mutations that harm the sex of offspring that does not carry them, whenever there is competition among siblings.This harmful phenotype can be expressed as an antagonistic green-beard effect that is mediated by epigenetic parental effects, parental investment, and/or interactions among siblings.A combination of mathematical modeling and a survey of empirical studies is used to show that sexually antagonistic zygotic drive is feasible, likely to be widespread in nature, and that it can promote a genetic "arms race" between the homo- and heteromorphic sex chromosomes.

View Article: PubMed Central - PubMed

Affiliation: Department of Ecology, Evolution, and Marine Biology, University of California Santa Barbara, Santa Barbara, CA, USA. rice@lifesci.ucsb.edu

ABSTRACT
Genomic conflict is perplexing because it causes the fitness of a species to decline rather than improve. Many diverse forms of genomic conflict have been identified, but this extant tally may be incomplete. Here, we show that the unusual characteristics of the sex chromosomes can, in principle, lead to a previously unappreciated form of sexual genomic conflict. The phenomenon occurs because there is selection in the heterogametic sex for sex-linked mutations that harm the sex of offspring that does not carry them, whenever there is competition among siblings. This harmful phenotype can be expressed as an antagonistic green-beard effect that is mediated by epigenetic parental effects, parental investment, and/or interactions among siblings. We call this form of genomic conflict sexually antagonistic "zygotic drive", because it is functionally equivalent to meiotic drive, except that it operates during the zygotic and postzygotic stages of the life cycle rather than the meiotic and gametic stages. A combination of mathematical modeling and a survey of empirical studies is used to show that sexually antagonistic zygotic drive is feasible, likely to be widespread in nature, and that it can promote a genetic "arms race" between the homo- and heteromorphic sex chromosomes. This new category of genomic conflict has the potential to strongly influence other fundamental evolutionary processes, such as speciation and the degeneration of the Y and W sex chromosomes. It also fosters a new genetic hypothesis for the evolution of enigmatic fitness-reducing traits like the high frequency of spontaneous abortion, sterility, and homosexuality observed in humans.

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Related in: MedlinePlus

Fitness function for α = 0.4 (stronger selection, steeper blue curve), α = 0.1 (moderate selection, green curve), and α = 0.025 (weaker selection, red curve).
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pgen-1000313-g007: Fitness function for α = 0.4 (stronger selection, steeper blue curve), α = 0.1 (moderate selection, green curve), and α = 0.025 (weaker selection, red curve).

Mentions: where α>0 is a parameter measuring the strength of selection (larger values of α imply stronger selection; see Figure 7). We assumed that initially there was no genetic variation and the x and y effects of all individuals were set to zero. We varied the mutation rate μ and the strength of selection α while the number of individuals of each sex was always set at N = 1000. For each parameter combination, we did 20 runs each for 10000 generations. Overall, the dynamics are expected to be very similar to those observed in models of sexual conflict over mating rate [69]–[71].


Sexually antagonistic "zygotic drive" of the sex chromosomes.

Rice WR, Gavrilets S, Friberg U - PLoS Genet. (2008)

Fitness function for α = 0.4 (stronger selection, steeper blue curve), α = 0.1 (moderate selection, green curve), and α = 0.025 (weaker selection, red curve).
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2596966&req=5

pgen-1000313-g007: Fitness function for α = 0.4 (stronger selection, steeper blue curve), α = 0.1 (moderate selection, green curve), and α = 0.025 (weaker selection, red curve).
Mentions: where α>0 is a parameter measuring the strength of selection (larger values of α imply stronger selection; see Figure 7). We assumed that initially there was no genetic variation and the x and y effects of all individuals were set to zero. We varied the mutation rate μ and the strength of selection α while the number of individuals of each sex was always set at N = 1000. For each parameter combination, we did 20 runs each for 10000 generations. Overall, the dynamics are expected to be very similar to those observed in models of sexual conflict over mating rate [69]–[71].

Bottom Line: The phenomenon occurs because there is selection in the heterogametic sex for sex-linked mutations that harm the sex of offspring that does not carry them, whenever there is competition among siblings.This harmful phenotype can be expressed as an antagonistic green-beard effect that is mediated by epigenetic parental effects, parental investment, and/or interactions among siblings.A combination of mathematical modeling and a survey of empirical studies is used to show that sexually antagonistic zygotic drive is feasible, likely to be widespread in nature, and that it can promote a genetic "arms race" between the homo- and heteromorphic sex chromosomes.

View Article: PubMed Central - PubMed

Affiliation: Department of Ecology, Evolution, and Marine Biology, University of California Santa Barbara, Santa Barbara, CA, USA. rice@lifesci.ucsb.edu

ABSTRACT
Genomic conflict is perplexing because it causes the fitness of a species to decline rather than improve. Many diverse forms of genomic conflict have been identified, but this extant tally may be incomplete. Here, we show that the unusual characteristics of the sex chromosomes can, in principle, lead to a previously unappreciated form of sexual genomic conflict. The phenomenon occurs because there is selection in the heterogametic sex for sex-linked mutations that harm the sex of offspring that does not carry them, whenever there is competition among siblings. This harmful phenotype can be expressed as an antagonistic green-beard effect that is mediated by epigenetic parental effects, parental investment, and/or interactions among siblings. We call this form of genomic conflict sexually antagonistic "zygotic drive", because it is functionally equivalent to meiotic drive, except that it operates during the zygotic and postzygotic stages of the life cycle rather than the meiotic and gametic stages. A combination of mathematical modeling and a survey of empirical studies is used to show that sexually antagonistic zygotic drive is feasible, likely to be widespread in nature, and that it can promote a genetic "arms race" between the homo- and heteromorphic sex chromosomes. This new category of genomic conflict has the potential to strongly influence other fundamental evolutionary processes, such as speciation and the degeneration of the Y and W sex chromosomes. It also fosters a new genetic hypothesis for the evolution of enigmatic fitness-reducing traits like the high frequency of spontaneous abortion, sterility, and homosexuality observed in humans.

Show MeSH
Related in: MedlinePlus