HOW TO MEASURE MATURATION: A COMPARISON OF PROBABILISTIC METHODS USED TO TEST FOR GENOTYPIC VARIATION AND PLASTICITY IN THE DECISION TO MATURE
Article first published online: 31 AUG 2012
© 2012 The Author(s). Evolution© 2012 The Society for the Study of Evolution.
Volume 67, Issue 2, pages 525–538, February 2013
How to Cite
Harney, E., Dooren, T. J. M. V., Paterson, S. and Plaistow, S. J. (2013), HOW TO MEASURE MATURATION: A COMPARISON OF PROBABILISTIC METHODS USED TO TEST FOR GENOTYPIC VARIATION AND PLASTICITY IN THE DECISION TO MATURE. Evolution, 67: 525–538. doi: 10.1111/j.1558-5646.2012.01758.x
- Issue published online: 28 JAN 2013
- Article first published online: 31 AUG 2012
- Accepted manuscript online: 1 AUG 2012 01:13PM EST
- Received March 20, 2012 Accepted July 13, 2012 Data Archived: Dryad doi:10.5061/dryad.r13f5
- Age and size at maturity;
- life-history evolution;
- maturation thresholds;
- phenotypic plasticity;
- probabilistic maturation reaction norms
Maturation is a developmental trait that plays a key role in shaping organisms’ life-history. However, progress in understanding how maturation phenotypes evolve has been held back by confusion over how best to model maturation decisions and a lack of studies comparing genotypic variation in maturation. Here, we fitted probabilistic maturation reaction norms (PMRNs) to data collected from five clones of Daphnia magna and five of Daphnia pulex collected from within and between different populations. We directly compared the utility of modeling approaches that assume maturation to be a process with an instantaneous rate with those that do not by fitting maturation rate and logistic regression models, and emphasize similarities and differences between them. Our results demonstrate that in Daphnia, PMRNs using a logistic regression approach were simpler to use and provided a better fit to the data. The decision to mature was plastic across a range of growth trajectories and dependent upon both body size and age. However, the age effect was stronger in D. magna than D. pulex and varied considerably between clones. Our results support the idea that maturation thresholds can evolve but also suggest that the notion of a threshold based on a single fixed state is an oversimplification that underestimates the adaptability of these important traits.