EVOLUTIONARILY SINGULAR STRATEGIES AND THE ADAPTIVE GROWTH AND BRANCHING OF THE EVOLUTIONARY TREE

We present a general framework for modelling adaptive trait dynamics i n which we integrate various concepts and techniques from modern ESS-t heory. The concept of evolutionarily singular strategies is introduced as a generalization of the ESS-concept. We give a full classification of the singular strategies in terms of ESS-stability, convergence sta bility, the ability of the singular strategy to invade other populatio ns if initially rare itself, and the possibility of protected dimorphi sms occurring within the singular strategy's neighbourhood. Of particu lar interest is a type of singular strategy that is an evolutionary at tractor from a great distance, but once in its neighbourhood a populat ion becomes dimorphic and undergoes disruptive selection leading to ev olutionary branching. Modelling the adaptive growth and branching of t he evolutionary tree can thus be considered as a major application of the framework. A haploid version of Levene's `soft selection' model is developed as a specific example to demonstrate evolutionary dynamics and branching in monomorphic and polymorphic populations.