Breeding biology of Coprinus species in the section Lanatuli

Abstract

Breeding studies on Coprinus species suggest that sympatric speciation may be common in basidiomycetes. It appears that species evolve and remain distinct at the cytoplasmic level. Loss of hyphal recognition and fusion occurs after the species have evolved and does not cause their evolution. The widespread occurrence of suitable habitats for dung species suggests that it is unlikely that allopatric speciation needs to be at all common. Basidiomycetes therefore offer particularly suitable material for the study of internal speciation in contrast to the external speciation which occurs in many angiosperms and in animals. By testing for crossability between strains, and for the homing and lethal reactions which occur between oidia and hyphae of related species, it is possible to define the species in breeding terms, in addition to the morphological characters normally used. The reactions of hyphae to oidia provide a breeding test which may indicate the relationship between taxa above the level of the species. Once the different species have been detected on a breeding basis it is then possible to correlate morphological characters with them and to decide which characters are valid. The angiosperm flower is the site of plasmogamy, kary-ogamy and meiosis which together are the key events of sexual reproduction. The delimitation of species on the basis of floral structure owes much of its success to this. A similar system of sexual classification in basidiomycetes must necessarily involve hyphal fusion as well as the structure of the fruit body. The fruit body is the site of karyogamy and meiosis but not plasmogamy so the integration of breeding and classical studies might help to give a truly Linnaean system of classification.