Aging and species abundance in the Tangled Nature model of biological   evolution
  We present an individual based model of evolutionary ecology.   The reproduction rate of individuals characterized by their genome depends on the composition of the population in genotype space. Ecological features such as the taxonomy and the macro-evolutionary mode of the dynamics are emergent properties.   The macro-dynamics exhibit intermittent two mode switching with a gradually decreasing extinction rate. The generated ecologies become gradually better adapted as well as more complex in a collective sense.   The form of the species abundance curve compares well with observed functional forms. The models error threshold can be understood in terms of the characteristics of the two dynamical modes of the system. 
Matt Hall, Kim Christensen, Simone A. di Collobiano and Henrik   Jeldtoft Jensen