Sharp gene pool transition in a population affected by phenotype-based   selective hunting
  We use a microscopic model of population dynamics, a modified version of the well known Penna model, to study some aspects of microevolution. This research is motivated by recent reports on the effect of selective hunting on the gene pool of bighorn sheep living in the Ram Mountain region, in Canada. Our model finds a sharp transition in the structure of the gene pool as some threshold for the number of animals hunted is reached. 
E. Brigatti, J.S. Sa' Martins and I. Roditi