Summary of the thesis by Claus Rüffler
Universiteit Leiden
Thursday 27 April 2006
Traits traded-off
The course of evolution is restricted by constraints. A special type of constraint is a trade-off where different traits are negatively correlated. In this situation a mutant type that shows an improvement in one trait suffers from a decreased performance through another trait. In a fixed fitness landscape evolution is expected to come up with a compromise of the competing fitness components that is optimal in the sense that no other realized compromise can be more successful. However, in most ecological settings the resident community will form a vital part of the selective environment experienced by a mutant. In this case each component in a fitness trade-off can be affected by the phenotype of the conspecifics, which causes the fitness landscape to change as evolution proceeds. We refer to selection in a changing fitness landscape as frequency dependent. With frequency dependence the concept of optimality cannot be applied anymore. This thesis explores, by means of mathematical models, how frequency dependence can be detected and how it alters the evolutionary dynamics of traits that are coupled by a trade-off. Special attention is paid to the phenomenon of evolutionary branching where directional selection drives a population's trait distribution into a region of the trait space where selection turns disruptive.
For full text: see here
For the thesis, email: rueffler@zoo.utoronto.ca