Originally published as Genetics Published Articles Ahead of Print on June 18, 2008.

Genetics, Vol. 179, 1497-1502, July 2008, Copyright © 2008
doi:10.1534/genetics.107.082479

Both Costs and Benefits of Sex Correlate With Relative Frequency of Asexual Reproduction in Cyclically Parthenogenic Daphnia pulicaria Populations

Desiree E. Allen*,{dagger},1 and Michael Lynch*

* Department of Ecology and Evolution, Indiana University, Bloomington, Indiana 47405 and {dagger} Institute of Evolutionary Biology, University of Edinburgh, Edinburgh EH9 3JT, United Kingdom

1 Corresponding author: Institute of Evolutionary Biology, University of Edinburgh, W. Mains Rd., Edinburgh EH9 3JT, United Kingdom.
E-mail: desiree.allen{at}ed.ac.uk

Sexual reproduction is generally believed to yield beneficial effects via the expansion of expressed genetic variation, which increases the efficiency of selection and the adaptive potential of a population. However, when nonadditive gene action is involved, sex can actually impede the adaptive progress of a population. If selection promotes coupling disequilibria between genes of similar effect, recombination and segregation can result in a decrease in expressed genetic variance in the offspring population. In addition, when nonadditive gene action underlies a quantitative trait, sex can produce a change in trait means in a direction opposite to that favored by selection. In this study we measured the change in genotypic trait means and genetic variances across a sexual generation in four populations of the cyclical parthenogen Daphnia pulicaria, which vary predictably in their incidence of sexual reproduction. We show that both the costs and benefits of sex, as measured by changes in means and variances in life-history traits, increase substantially with decreasing frequency of sex.


Related articles in Genetics:

ISSUE HIGHLIGHTS

Genetics 2008 179: NP. [Full Text]