Natural polyploidy in amphibians
This article examines polyploidy in amphibians. 53 polyploid species from 15 genera and 10 families (only anurans) are currently recognized. They can be arranged in 4 groups with different ploidy levels: I (triploids), 4 species of the toad genus Bufotes, II (tetraploids), 33 species from 14 genera and 10 families, III (octoploids), 12 species from 3 genera and 3 families, and IV (dodeсaploids), 4 species of the genus Xenopus. Only one taxon above the species level totally consisting of polyploid (4n to 12n) species is known (the subgenus Xenopus). At least 10 diploid-polyploid species complexes were revealed among amphibians. In nature, triploid individuals can originate in the hybridization zone between di- and tetraploid species. Occasionally, some triploids occur within populations of diploid species. Also polyploids (3n to 5n) are common among diploid-polyploid hybridogenetic forms, which breed clonally (Ambystoma and Pelophylax). The concept of reticulate (hybridogenous) speciation involved the hybridization between species, clonal inheritance and polyploidy is supported by current data. Polyploid amphibian species are mainly distributed in southern regions (Africa, South America, and Australia). In fact, the Oriental realm lacks polyploid amphibians. Refs 39. Figs 1. Tables 2.
amphibians, hybridization, polyploidy, reticulate speciation
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