title: Ploidy-dependent survival of progeny arising from crosses between natural allotriploid Cobitis females and diploid C. taenia males (Pisces, Cobitidae).
abstract: Crosses between 21 triploid hybrid Cobitis females and 19 C. taenia (2n = 48) males led to viable progeny; whereas no embryonic development was observed in crosses with tetraploid males (4n = 98). The ploidy status of 491 progenies randomly selected with flow cytometry (316) or chromosome analysis (175) revealed an average of 55.2 % triploids and 44.8 % tetraploids, but the ratio of 3n versus 4n fish did change during development. In the first 2 days after hatching, approximately 65.1 % of tetraploid larvae were observed. Their number decreased significantly to 30.8 and 6.2 % on average during 2-5 and 10-15 months of life, respectively. The karyotype of tetraploid progeny (4n = 98) included 3n = 74 chromosomes of the parental female and n = 24 of C. taenia male. The number of tetraploid progeny indicated indirectly that about 66 % of eggs from 3n females were fertilized with C. taenia. The rest of the eggs developed clonally via gynogenesis or hemiclonally via hybridogenesis into triploids of the same karyotype structure as parental females. We have documented for the first time that (at least under experimental conditions) tetraploids are commonly formed, but are less viable than triploids, and a ratio similar to what is found under natural conditions is finally attained. The current explanation concerning the ploidy and karyotype structure of the progeny confirms that the eggs of 3n Cobitis females are not only capable of maintaining all chromosomes but are also capable of incorporating the sperm genome, thus creating the potential to produce tetraploids.
authors: Department of Zoology, Faculty of Biology and Biotechnology, University of Warmia and Mazury in Olsztyn, M. Oczapowskiego 5 St., 10-718, Olsztyn, Poland, juchno@uwm.edu.pl.
authors: Dorota
authors: D
authors: Juchno
authors: Olga
authors: O
authors: Jabłońska
authors: Alicja
authors: A
authors: Boroń
authors: Roman
authors: R
authors: Kujawa
authors: Anna
authors: A
authors: Leska
authors: Anna
authors: A
authors: Grabowska
authors: Anna
authors: A
authors: Nynca
authors: Sylwia
authors: S
authors: Swigońska
authors: Magdalena
authors: M
authors: Król
authors: Aneta
authors: A
authors: Spóz
authors: Natalia
authors: N
authors: Laskowska
authors: Miłosz
authors: M
authors: Lao
mesh_terms: D000818:Animals; D002875:Chromosomes / Q000235:genetics; D003433:Crosses, Genetic; D003531:Cypriniformes / Q000235:genetics* / Q000254:growth & development / Q000502:physiology; D005260:Female; D059785:Karyotype; D008297:Male; D011003:Ploidies; D012098:Reproduction