Recognizing and discriminating between fungal populations and the genetical processes that accompany them, including speciation is now a rapidly developing field that is heavily dependent upon the use of molecular markers. There was no basic text on this subject, John Burnett has provided suchan account. The text describes the methodologies employed and, for the benefit of those without a background in mycology, a brief introduction to basic fungal biology. Recent findings relating to processes in fungal populations - mutation, migration, recombination, heterokaryosis, hybridization,polyploidy, and the operation of selective forces are combined with traditional fungal biology. Finally the taxonomic problems raised by fungal species are discussed, together with the processes of speciation.