Grebelnyi S.D. 2006. [How many clonal species are there in the world. Part 2. Cloning in nature and its role in formation of biodiversity] // Invertebrate Zoology. Vol.3. No.1: 77–109 [in Russian, with English summary].

Zoological Institute, Universitetskaya naberezhnaya, 1, Saint-Petersburg 199034, Russia. E-mail:

KEY WORDS: clonal competition, all-female races, unisexual species, stoppage of recombination, parthenogenesis, gynogenesis, hybridogenesis, apomixis, geographic distribution of polyploids, “biological species”, climatic changes.

ABSTRACT: In the regions where fauna and flora have been exposed to recent consi-derable climatic shifts, there is a pretty good number of clonal forms in many plant and animalian taxa. Within the groups, which are capable of non-recombinating reproduction, the rapid increase in number of «species» happens through formation of new usually highly heterozygous clones, which are able to disperse to unoccupied lands (e.g. free geographical localities or ecological niches). The main source of new clonal forms (apart from some contribution produced by mutations) is extant populations of bisexual species, which, owing to recombination, can quickly generate a rich spectrum of variability by means of new allelic combinations. Possessing a rich genotypic diversity species are able to wide scale of environmental conditions and they can survive in spite of considerable climatic changes. However, due to the genetic polymorphism of the species, the proportion of individuals well adapted to given conditions is rather low. As to the clones, they are of a very low evolutionary potency compared to ancestral bisexual populations. At the same time, the successful clones are entirely composed of elite individuals that are most adapted to the current environment. Only those clonal animals and plants do well within most of a species range whereas bisexual populations are forced to settle in refuges of rather restricted space and unstable environmental conditions, where they succeed to survive due to their much higher evolutionary potency, caused by genetic polymorphism.

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