COMPLEXITY, PLEIOTROPY, AND THE FITNESS EFFECT OF MUTATIONS
Article first published online: 3 MAR 2011
© 2011 The Author(s). Evolution© 2011 The Society for the Study of Evolution.
Volume 65, Issue 6, pages 1559–1571, June 2011
How to Cite
Lourenço, J., Galtier, N. and Glémin, S. (2011), COMPLEXITY, PLEIOTROPY, AND THE FITNESS EFFECT OF MUTATIONS. Evolution, 65: 1559–1571. doi: 10.1111/j.1558-5646.2011.01237.x
- Issue published online: 3 JUN 2011
- Article first published online: 3 MAR 2011
- Accepted manuscript online: 1 FEB 2011 07:47AM EST
- Received September 22, 2009, Accepted January 5, 2011
- Drift load;
- genetic drift;
- molecular evolution;
- natural selection
One of the assumptions underlying many theoretical predictions in evolutionary biology concerns the distribution of the fitness effect of mutations. Approximations to this distribution have been derived using various theoretical approaches, of which Fisher's geometrical model is among the most popular ones. Two key concepts in this model are complexity and pleiotropy. Recent studies have proposed different methods for estimating how complexity varies across species, but their results have been contradictory. Here, we show that contradictory results are to be expected when the assumption of universal pleiotropy is violated. We develop a model in which the two key parameters are the total number of traits and the mean number of traits affected by a single mutation. We derive approximations for the distribution of the fitness effect of mutations when populations are either well-adapted or away from the optimum. We also consider drift load in a well-adapted population and show that it is independent of the distribution of the fitness effect of mutations. We show that mutation accumulation experiments can only measure the effect of the mean number of traits affected by mutations, whereas drift load only provides information about the total number of traits. We discuss the plausibility of the model.