EVOLUTION OF A PLASTIC QUANTITATIVE TRAIT IN AN AGE-STRUCTURED POPULATION IN A FLUCTUATING ENVIRONMENT
Article first published online: 1 JUN 2011
© 2011 The Author(s). Evolution© 2011 The Society for the Study of Evolution.
Volume 65, Issue 10, pages 2893–2906, October 2011
How to Cite
Engen, S., Lande, R. and Sæther, B.-E. (2011), EVOLUTION OF A PLASTIC QUANTITATIVE TRAIT IN AN AGE-STRUCTURED POPULATION IN A FLUCTUATING ENVIRONMENT. Evolution, 65: 2893–2906. doi: 10.1111/j.1558-5646.2011.01342.x
- Issue published online: 3 OCT 2011
- Article first published online: 1 JUN 2011
- Accepted manuscript online: 12 MAY 2011 04:20PM EST
- Received February 14, 2011, Accepted April 29, 2011
- Age structure;
- evolutionary dynamics;
- fluctuating selection;
- life history;
- reproductive value
We analyze weak fluctuating selection on a quantitative character in an age-structured population not subject to density regulation. We assume that early in the first year of life before selection, during a critical state of development, environments exert a plastic effect on the phenotype, which remains constant throughout the life of an individual. Age-specific selection on the character affects survival and fecundity, which have intermediate optima subject to temporal environmental fluctuations with directional selection in some age classes as special cases. Weighting individuals by their reproductive value, as suggested by Fisher, we show that the expected response per year in the weighted mean character has the same form as for models with no age structure. Environmental stochasticity generates stochastic fluctuations in the weighted mean character following a first-order autoregressive model with a temporally autocorrelated noise term and stationary variance depending on the amount of phenotypic plasticity. The parameters of the process are simple weighted averages of parameters used to describe age-specific survival and fecundity. The “age-specific selective weights” are related to the stable distribution of reproductive values among age classes. This allows partitioning of the change in the weighted mean character into age-specific components.