royalsociety | Studies aimed at explaining the evolution of phenotypic traits have
often solely focused on fitness considerations, ignoring underlying
mechanisms. In recent years, there has been an increasing call for
integrating mechanistic perspectives in evolutionary considerations, but
it is not clear whether and how mechanisms affect the course and
outcome of evolution. To study this, we compare four mechanistic
implementations of two well-studied models for the evolution of
cooperation, the Iterated Prisoner's Dilemma (IPD) game and the Iterated
Snowdrift (ISD) game. Behavioural strategies are either implemented by a
1 : 1 genotype–phenotype mapping or by a simple neural network.
Moreover, we consider two different scenarios for the effect of
mutations. The same set of strategies is feasible in all four
implementations, but the probability that a given strategy arises owing
to mutation is largely dependent on the behavioural and genetic
architecture. Our individual-based simulations show that this has major
implications for the evolutionary outcome. In the ISD, different
evolutionarily stable strategies are predominant in the four
implementations, while in the IPD each implementation creates a
characteristic dynamical pattern. As a consequence, the evolved average
level of cooperation is also strongly dependent on the underlying
mechanism. We argue that our findings are of general relevance for the
evolution of social behaviour, pleading for the integration of a
mechanistic perspective in models of social evolution.
