Abstract

Sexual reproduction and meiotic recombination generate new genetic combinations and may thereby help an individual infected by a parasite to protect its offspring from being infected. While this idea is often used to understand the evolutionary forces underlying the maintenance of sex and recombination, it also suggests that infected individuals should increase plastically their rate of recombination. We tested the latter idea with the mosquito Aedes aegypti and asked whether females infected by the microsporidian Vavraia culicis were more likely to have recombinant offspring than uninfected females. To measure the rate of recombination over a chromosome we analysed combinations of microsatellites on chromosome 3 in infected and uninfected females, in the (uninfected) males they copulated with and in their offspring. As predicted, the infected females were more likely to have recombinant offspring than the uninfected ones. These results show the ability of a female to diversify her offspring in response to parasitic infection by plastically increasing her recombination rate.

Highlights

  • Genetic recombination shuffles the genes of adults and generate novel genotypes

  • The recombination rates between pairs of microsatellites ranged from 0% to 50%

  • Infected mothers had higher recombination rates than uninfected ones in 10 out of the 13 pairs of microsatellites in which recombination was detected in both treatments (Fig 1)

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Summary

Introduction

Genetic recombination shuffles the genes of adults and generate novel genotypes. This has the disadvantage of breaking up genetic associations built by selection and combinations of genes that were beneficial to the adults, replacing them with new ones [1,2,3]. The modification of genotypes at each generation through recombination may help the host to respond and adapt to a changing environment [4, 5], in accordance with the abandon-ship hypothesis predicting that, under stressful and poor conditions, sex should be favoured [6,7,8,9] Part of this environmental variation is represented by the biotic pressure imposed by harmful and virulent parasite (i.e. parasites reducing host’s fitness) [10]. Interactions between hosts and parasites are at the basis of several ideas about the maintenance of sexual reproduction [11,12,13] It is, for example, often the case that hosts and parasites are genetically variable in their resistance and infectivity [14, 15].

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