Phase transition in a mean-field model for sympatric speciation
  We introduce an analytical model for population dynamics with intra-specific competition, mutation and assortative mating as basic ingredients. The set of equations that describes the time evolution of population size in a mean-field approximation may be decoupled. We find a phase transition leading to sympatric speciation as a parameter that quantifies competition strength is varied. This transition, previously found in a computational model, occurs to be of first order. 
V. Schw\"ammle, K. Luz-Burgoa, J. S. S\'a Martins and S. Moss de   Oliveira