The evolution of harm: effect of sexual conflicts and population size

Gay, Laurene, Hosken, David J., Eady, Paul , Vasudev, Ram and Tregenza, Tom (2010) The evolution of harm: effect of sexual conflicts and population size. Evolution: International Journal of Organic Evolution, 65 (3). pp. 725-737. ISSN 0014-3820

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Conflicts of interest between mates can lead to the evolution of male traits reducing female fitness and to coevolution between the sexes. The rate of adaptation and counter-adaptation is constrained by the intensity of selection and its efficiency, which depends on drift and genetic variability. This leads to the largely untested prediction that coevolutionary adaptations such as those driven by sexual conflict should evolve faster in large populations where the response to selection is stronger and sexual selection is more intense. We test this using the bruchid beetle Callosobruchus maculatus, a species with well documented male harm. Whilst most experimental evolution studies remove sexual conflicts, we reintroduce sexual conflict in populations where it has been experimentally removed. Both population size and standing genetic variability were manipulated in a factorial experimental design. After 90 generations of relaxed conflict (monogamy), the reintroduction of sexual conflicts for 30 generations favoured males that harmed females and females more resistant to the genital damage inflicted by males. Large population size rather than high initial genetic variation allowed males to evolve faster and become more harmful. Sexual selection thus creates conditions where males benefit from harming females and this selection is more effective in larger populations.

Keywords:Experimental evolution, sexual selection, Callosobruchus maculatus, genital damage, population size
Subjects:C Biological Sciences > C120 Behavioural Biology
C Biological Sciences > C170 Population Biology
C Biological Sciences > C142 Reproductive Biology
C Biological Sciences > C182 Evolution
Divisions:College of Science > School of Life Sciences
ID Code:2644
Deposited On:09 Jun 2010 14:29

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