Sympatric Speciation in a Simple Food Web
  Observations of the evolution of species groups in nature, such as well recognized Galapagos finches, have motivated much theoretical research aimed at understanding the processes associated with such radiations. The Penna model is one such model and has been widely used to study aging. In this paper we use the basic Penna model to investigate the process of sympatric speciation in a simple food web model. Initially our web consists of a primary food source and a single herbivore species that feeds on this resource. Subsequently we introduce a predator that feeds on the herbivore. In both instances we directly manipulate the food source, that is, its size distribution, and monitore the changes in the populations structures. Sympatric speciation is obtained for the consumer species in both webs, and our results confirm that the speciation velocity depends on how far up,in the food chain, the focus population is feeding. Simulations are done with three different sexual imprinting-like mechanisms, in order to discuss adaptation by natural selection. 
K. Luz-Burgoa, Tony Dell and Toshinori Okuyama