Fungi: individuals, populations, and speciation
Department of Mycology and Algology, Lomonosov Moscow State University Leninskie Gory, 119992 Moscow e-mail: diakov@herba.msu.ru
Under considerations are specific features of the fungal individuals associated with their mycelial life mode and affecting their population structure and speciation. Special attention is paid to the sympatric speciation which can be caused by trophic niche segregation, by use of different host plants, by invasion to the plants at different stage of their ontogeny, and by differences in the weather requirements. Decrease of genetic interchanges in subdivided populations promoting speciation without spatial isolation is achieved by homotallism and pseudohomotallism, by a cassette mechanism of switching among various breeding systems, and by complete lost of sexual process. Recombination reduction in agamic fungi is achieved by means of vegetative incompatibility. As the latter is similar functionally to the immune system (recognition of an alien culture and death of conjugated cells), it is possible that the fungi were the first to have developed mechanisms of sympatric speciation on the basis of the simpliest immune system.
