This model is an a reimplementation of the model described in:
de Aguiar MA, Baranger M, Baptestini EM, Kaufman L, Bar-Yam Y. (2009) Global Patterns of speciation and diverity. Nature. Jul 16;460(7253):334-5
http://www.nature.com/nature/journal/v460/n7253/full/nature08168.html