SPECIATION AS PATTERN-FORMATION BY COMPETITION IN A SMOOTH FITNESS LANDSCAPE

We investigate the problem of speciation and coexistence in simple eco systems when the competition among individuals is included in the Eige n model for quasispecies. By suggesting an analogy between the competi tion among strains and the diffusion of a chemical inhibitor in a reac tion-diffusion system, the speciation phenomenon is considered the ana logous of chemical pattern formation in genetic space. In the limit of vanishing mutation rate we obtain analytically the conditions for spe ciation. Using different forms of the competition interaction we show that the speciation is absent for the genetic equivalent of a normal d iffusing inhibitor, and is present for shorter-range interactions.