Chars of the genus Salvelinus , inhabiting lakes and lake-river systems, comprise morphological and ecological forms whose taxonomic status is under dispute. In the present work, we have examined genetic variation and divergence in various chars from the Kronotsky lake basin: the lacustrine chars (white, nose, and longhead) and riverine Dolly Varden Salvelinus malma. The study was conducted using analysis of allozyme and microsatellite loci, myogens, RAPD, and restriction analysis of two mtDNA segments. The estimates of heterozygosity at allozyme and microsatellite loci were similar to the corresponding parameters in populations of northern Dolly Varden and Arctic char. Heterozygote deficit was recorded in both samples of separate forms, and in the total sample of all chars from Kronotsky Lake. For allozyme and microsatellite loci, appreciable genetic differentiation among the samples of different char forms was found, which was comparable to that among the spatially isolated populations of northern Dolly Varden. This result indicates reproductive isolation among the char forms examined. However, this isolation is not complete, because no fixed differences between the forms by any of the genetic systems analyzed were found. The genetic differentiation among different forms of lacustrine chars, which corresponds to the interpopulation rather than interspecific level, is thought to be explained by their comparatively recent divergence. PLANT GENETICS

Genetic differences and relationships within charrs Salvelinus alpinus, northern and southern S. malma, S. taranetzi, S. levanidovi and S. leucomaenis, were studied by examination of 31-35 allozyme loci and PCR-RFLP analysis of mtDNA segment (about 2600 bp) including the cytochrome b gene and D-loop. Data for mtDNA were also obtained for samples of S. drjagini, S. albus and for European samples of S. alpinus. Generally allozyme and mtDNA segment analyses produced similar pictures of genetic divergence and relationships. The southern S. malma exhibited the greatest genetic variability (allozyme heterozygosity and mtDNA haplotype diversity). S. alpinus, S. malma, S. levanidovi and S. leucomaenis had fixed differences from one another at various allozyme loci, and differed in fixed (but polymorphic in S. malma) individual mtDNA haplotypes produced with MspI restrictase. Such genetic individuality is typical of distinct taxa. S. taranetzi is closest genetically to allopatric S. alpinus, but exhibited fixed differences from the northern S. malma in sympatry. In all samples of S. alpinus the only mtDNA haplotype was shared with S. drjagini. S. albus shared its single haplotype with the northern S. malma from the same locality. S. leucomaenis is differentiated from the other species to the greatest extent, possibly reflecting an early evolutionary divergence. Some evolutionary and taxonomic implications of the genetic relationships of charrs studied are discussed. 2000 The Fisheries Society of the British Isles

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