Shabanov (2007) On Clonal Evolution of Genomes

Shabanov D.A. Hybrid frogs Rana esculenta that produce gametes of both parental forms: a result of independent clonal evolution of genomes? // Proceedings of the conference “Modern Problems of Biological Evolution. To the 100th Anniversary of the State Darwin Museum.” Moscow: SDM Publishing House, 2007. P. 199-201. In the copy of the 2007 publication posted here, some changes were made (and highlighted by color) to reflect current terminology usage. In addition, please note that at present we assign green frogs to the genus Pelophylax. Hybrid frogs (Rana esculenta) producing gametes of both parental species: a result of independent clonal evolution of genomes? Shabanov D.A. Department of Zoology and Animal Ecology, Kharkiv National University, Kharkiv 61077, Ukraine e-mail: d_sh@i.ua d.a.shabanov@gmail.com Maintenance of complex population systems of green frogs (Rana esculenta complex) is possible due to merogemiclonaI inheritance characteristic of hybrid individuals (traditionally designated as Rana esculenta). As established by numerous studies (see review: Plötner, 2005), Rana esculenta produce gametes containing parental genomes in a clonal way; depending on the population system type, one parental genome may be excluded while the other is transmitted. The existence of individuals producing gametes of both parental forms appears paradoxical. One possible explanation is independent clonal evolution of parental genomes in different hybrid lineages, followed by their meeting in one population system. If lineages clonally transmitting Rana lessonae genomes (specialized in eliminating Rana ridibunda genomes during gametogenesis) encounter lineages clonally transmitting Rana ridibunda genomes (capable of suppressing Rana lessonae genomes), then offspring may arise with paradoxical gametogenesis. If the competitive abilities of clonal genomes are approximately equal, gametes of such frogs should carry them in roughly equal proportions; superiority of one genome should increase the proportion of gametes carrying it. This assumption corresponds to observed data: some frogs produce approximately equal numbers of the two gamete types, while in others the equilibrium is shifted toward one or the other parental genome. To test the proposed hypothesis, it is necessary to trace transmission of individual genomes across generations and to investigate meiosis and gamete formation in hybrid frogs with paradoxical gametogenesis.