Karyological Differences between Northern Dolly Varden Salvelinus malma malma and White Char Salvelinus albusfrom the Kamchatka River Basin

The karyotypes of northern Dolly Varden and white char, sympatrically inhabiting the Kamchatka River basin, were studied. The karyotype of Dolly Varden was stable: 2n= 78 andNF= 98 + 2, while in white char, polymorphism and mosaicism for the chromosome number were revealed: 2n= 76–79, NF= 98 + 2. Using a routine chromosome staining technique, the karyotype of white char (2n= 78) was shown to be identical to that of Dolly Varden. In both karyotypes, similar sets of marker chromosomes were present: two pairs of submetacentric (SM), one pair of submeta-subtelocentric (SM-ST), one pair of large acrocentric (A), and one pair of large subtelocentric (ST) chromosomes. However, the karyotypes of Dolly Varden and white char differed in the number and location of nucleolus organizer regions (NORs). In Dolly Varden, single NORs located in the telomeric regions of the marker SM-ST chromosomes were observed. In white char, NORs were multiple and located both in the telomeric regions of the marker SM-ST chromosomes and on the short and long arms of large ST chromosomes. The identical marker chromosomes indicate considerable phylogenetic relatedness between Dolly Varden and white char from the Kamchatka River basin. Variation in NORs provides evidence for the reproductive isolation of these chars and their species status.