Karyological differences between northern Dolly Varden Salvelinus malma malma and white char Salvelinus albus from the Kamchatka River basin

The karyotypes of northern Dolly Varden and white char, sympatrically inhab iting the Kamchatka River basin, were studied. The karyotype of Dolly Varde n was stable: 2n = 78 and NF = 98 + 2, while in white char, polymorphism an d mosaicism for the chromosome number were revealed: 2n = 76-79, NF = 98 2. Using a routine chromosome staining technique, the karyotype of white ch ar (2n = 78) was shown to be identical to that of Dolly Varden. In both kar yotypes, similar sets of marker chromosomes were present: two pairs of subm etacentric (SM), one pair of submeta-subtelocentric (SM-ST), one pair of la rge acrocentric (A), and one pair of large subtelocentric (ST) chromosomes. However, the karyotypes of Dolly Varden and white char differed in the num ber and location of nucleolus organizer regions (NORs). In Dolly Varden, si ngle 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 te lomeric regions of the marker SM-ST chromosomes and on the short and long a rms of large ST chromosomes. The identical marker chromosomes indicate cons iderable phylogenetic relatedness between Dolly Varden and white char from the Kamchatka River basin. Variation in, NORs provides evidence for the rep roductive isolation of these chars and their species status.