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Asexual evolution: do intragenomic parasites maintain sex?
Bernard Crespi1, Tanja Schwander
1Department of Biological Sciences, Simon Fraser University, Burnaby, BC, Canada.
Molecular Ecology
|July 28, 2012
Summary
Asexual organisms may carry more harmful genetic elements than sexual ones, but this depends on the type of element. This study used genomic data to explore the costs of sex and asexual reproduction.
Area of Science:
- Evolutionary biology
- Genomics
- Molecular evolution
Background:
- The paradox of sex explains the evolutionary disadvantage of sexual reproduction due to its twofold cost of gene transmission.
- Asexual lineages may accumulate more deleterious genetic elements because they lack mechanisms for purging them, which are present in sexual reproduction.
Purpose of the Study:
- To conduct the first genome-scale comparative study of related sexual and asexual animal lineages.
- To test the hypothesis that asexual lineages accumulate heavier loads of deleterious transposable elements compared to sexual lineages.
Main Methods:
- Genome-scale comparative analysis of related sexual and asexual animal lineages.
- Identification and quantification of transposable element loads in both sexual and asexual genomes.
Main Results:
- Asexual lineages showed a higher density of certain transposable elements, supporting the hypothesis.
- The accumulation of transposable elements varied depending on the specific family of transposon considered, indicating a nuanced answer.
- The study opens avenues for molecular evolutionary analyses of intragenomic conflicts and the costs of sex.
Conclusions:
- The genomic load of transposable elements in asexuals is not uniform and depends on the transposon family.
- Intragenomic parasites and their interactions with host genomes play a role in mediating the costs of sex.
- This research provides a foundation for further molecular evolutionary investigations into the maintenance of sex.
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