A major focus of our research is understanding the evolutionary and genetic mechanisms regulating aflatoxigenicity. Aflatoxin is one of the most carcinogenic compounds known and is responsible for major yield losses in oil seed crops worldwide. We examine the genetic and genomic mechanisms that generate aflatoxin diversity in populations of Aspergillus flavus and A. parasiticus obtained from experimental crosses in the laboratory and from population sampling on a global scale. We are interested in the genetic basis of fertility in these fungi, genotype-toxin associations and in characterizing the genetic and genomic plasticity observed in experimentally evolved populations and in natural populations. Our goal is to apply our knowledge of the evolutionary and genetic processes that influence aflatoxigenicity in these species to the development of novel biocontrol measures.