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The clonal progeny of sturgeon hybrids as an experimental reproduction of the first stages of the reticular speciationтезисы доклада
- Авторы: Vasil’ev V.P., Medvedev D.A., Rachek E.I., Amvrosov D.Yu, Vasil’eva Е.D.
- Сборник: Генетика популяций: прогресс и перспективы. Материалы Международной научной конференции, посвященной 80-летию со дня рождения академика Ю.П. Алтухова (1936-2006) и 45-летию основания лаборатории плопуляционной генетики им. Ю.П. Алтухова ИОГен РАН
- Тезисы
- Год издания: 2017
- Место издания: Ваш Формат Москва
- Первая страница: 52
- Аннотация: Three related events, namely hybridization, unisexual reproduction and polyploidy, underlie reticular speciation in vertebrates. The complete cycle of reticular speciation involves several stages: 1) interspecific hybridization between diploid bisexual species and the origin of new clonal (gynogenetic in fish) or semiclonal (hybridogenetic) species; 2) back-cross hybridization between clonal or semiclonal species and one of its parental or the third diploid bisexual species resulting in the origin of triploid clonal species; 3) hybridization between triploid clonal species and one of parental bisexual species resulting in the origin of tetraploid clonal species or, more important, tetraploid bisexual species by the restoration of bisexuality. A large enough number of bisexual species from polyploid origin are found among fishes. Three levels of ploidy are revealed in recent sturgeons (Acipenseridae): species with a chromosome number of about 120 (functional diploids, but evolutionary tetraploids); species with about 250-270 chromosomes (functional tetraploids, evolutionary octoploids) and the only species Acipenser brevirostrum Lesueur, 1818 with about 372 chromosomes (functional hexaploid, evolutionary didekaploid). By now, it is generally accepted that the polyploid species of sturgeon have allopolyploid origin: they originated by the hybridization of species with lower levels of ploidy. Indeed, many species of sturgeon have extremely high ability to form a viable and more or less fertile hybrids when artificial crossings. However, it is known that normal fertile hybrids (that can successfully reproduce) arise from the parental species with the same ploidy level, whereas among hybrids of species with different ploidy levels both sexes and females are sterile. In some cases, the hybrid females in fishes are fertile not only if their parental species have similar karyotypes, but even these karyotypes are significantly different. The fecundity of these females is caused the fact that they produce unreduced eggs, owing to premeiotic endoreduplication of chromosomes, and then in the first division of meiosis the conjugation occurs between not homologous but newly appeared sister chromosomes. As a result, such females, provided blocking of true fertilization, produce the offspring genetically identical to the mother, i.e. a clone. The experimental crossbreeding to produce clonal offspring in sturgeons was carried out in Luchegorsk station of Pacific Fisheries Research Center. Females of previously obtained hybrid between kaluga sturgeon A. dauricus Georgi, 1775 (2n = 250) and sterlet A. ruthenus Linnaeus, 1758 (2n = 120) were used as well as intact and inactivated sterlet sperm and inactivated sperm of Amur sturgeon, A. schrenckii Brandt, 1869. The karyological analysis of back-cross hybrid fingerlings (kaluga sturgeon x sterlet) x sterlet and (sterlet x kaluga) x sterlet showed that they are triploids (have about 250 chromosomes), it means that hybrid females produce unreduced eggs (about 190 chromosomes). The success of the inactivation of the sperm in the other two crossings is confirmed by microsatellite analysis and karyological data; microsatellite analysis shows complete identity of the hybrid female and its progeny. Thus, we succeeded in producing of clonal progeny of sturgeon the first time. Artificial obtaining of clonal lines of hybrids and triploid hybrids of sturgeons can be considered as an experimental reproduction of the first stages of reticular speciation.
- Добавил в систему: Васильева Екатерина Денисовна