We investigate an individual-based model of adaptive radiation based on
the biogeographical changes of the Great African Lakes where cichlid
fishes radiated. In our model, the landscape consists of a mosaic of three
habitat types which may or may not be separated by geographic barriers. We
study the effect of the alternation between allopatry and sympatry called
landscape dynamics. We show that landscape dynamics can generate a
significantly higher diversity than allopatric or sympatric speciation
alone. Diversification is mainly due to the joint action of allopatric,
ecological divergence, and of disruptive selection increasing assortative
mating and allowing for the coexistence in sympatry of species following
reinforcement or character displacement. Landscape dynamics possibly
increase diversity at each landscape change. The characteristics of the
radiation depend on the speed of landscape dynamics and of the number of
geographically isolated regions at steady state. Under fast dynamics of a
landscape with many fragments, the model predicts a high diversity,
possibly subject to the temporary collapse of all species into a hybrid
swarm. When fast landscape dynamics induce the recurrent fusion of several
sites, diversity is moderate but very stable over time. Under slow
landscape dynamics, diversification proceeds similarly, although at a
slower pace. revised_simul_DLCode for simulation and diversity estimation. NOTE: Please use revised_simul_DL.zip and not simul_DL.zip. Version 1 was uploaded by mistake, and this is not the simulation code corresponding to the published paper. Version 2 is the correct simulation code.