Results are presented of a comparative study of the spatial and temporal structure of fish species from the standpoint of biochemical population genetics. Local fish stocks within historically established natural boundaries are considered as genetically stable population systems, in contrast to the elementary populations, which are variable structural components of such systems. The general principle in maintaining a rational fish industry is formulated on the basis of an approach to the population system as a whole, to distribute the appropriate efforts among all components of its structure.Key words: biochemical population genetics, stock concept of fish, optimal fishing industry
Two types of molecular genetic markers were used for genetic identification of species and local stocks of palearctic coregonids (Coregonidae, Salmoniformes, Teleostei). Seven nominate species of whitefishes and ciscoes Coregonus spp. of Eurasia Arctic Sea basin and inconnu Stenodus leucichthys nelma represented by specimens from North America were studied. Using restriction analysis of PCR-amplified products of the ND-1 gene of mitochondrial DNA (mtDNA) and allelic composition at several allozyme loci discrimination was successful between C. lavaretus pidschian Siberian whitefish, C. nasus broad whitefish, C. autumnalis Arctic cisco, C. migratorius Baikal omul, C. peled peled, and C. sardinella least cisco. Muksun C. muksun was indistinguishable from Siberian whitefish. Creatine kinase (CK) isozyme patterns and Rsa I restriction patterns of ND-1 were the most effective markers allowing discrimination among species. Intra-specific differentiation in mtDNA was found in all species but was much less pronounced than inter-species variation. In several specimens composite haplotypes typical of another species were found that reflect probable gene introgression by hybridization. A combination of mtDNA and nuclear genetic markers is suggested for reliable identification of both typical species representatives and hybrids. 2000 The Fisheries Society of the British Isles
Swiss stone pine Pinus cembra L. is a species with fragmented range, occurring in the Alpine-East Carpathian mountain system. Seeds of P. cembra are dispersed by nutcrackers, which offers potential possibilities for gene exchange among populations. Using isozyme analysis, we have examined five samples from two parts of the Swiss stone pine range: the Alps (Switzerland and Austria) and the Carpathians (two samples from the northern macroslope of the Gorgany Ridge, Eastern Carpathians, Ivano-Frankivs'ka oblast and one sample from Zakarpats'ka oblast of Ukraine). The allele frequencies of 30 isozyme loci, coding for enzymes ADH, FDH, FEST, GDH, GOT, IDH, LAP, MNR, MDH, PEPCA, 6-PGD, PGI, PGM, SDH, SKDH, SOD, were analyzed using cluster analysis and Principal Component Analysis. Two clusters, corresponding to the isolated Alpine and Carpathian parts of the range, were found. The main contribution to these differences were made by loci Adh-1, . The interpopulation differentiation proved to be somewhat higher than that typical for pines ( F ST = 7.4%), but within the limits characteristic for taxonomically close species. Thus, isolation of the populations did not lead to their marked differentiation, which may be explained by gene flow and balancing selection, which equalizes gene frequencies across the fragmented species area. Interlocus ( F ST heterogeneity (from 0.003 to 0.173) suggests adaptive significance of some of the allozyme polymorphisms or linkage of some loci with adaptive genes. The Carpathian populations were shown to have higher gene diversity than the Alpine ones (expected heterozygosities 0.095-0.114 and 0.060-0.080, respectively). A deficiency of heterozygotes (as compared to the Hardy-Weinberg proportions), observed in the embryo sample, was probably explained by inbreeding. The reduction in the area of Carpathian pine forests in Holocene, caused by the global climatic changes and the anthropogenic impact, is hazardous for the gene pool of the species. The maintenance of genetic uniqueness of both Carpathian populations of P. cembra in general, and individual stands in particular, requires special measures for protection of Swiss stone pine in the Eastern Carpathians.
This paper summarizes world literature and the authors' results on straying intensity and genetic differentiation in salmon populations. The following points are discussed: straying intensity in salmonid species; the concept of effective population size and its estimates for different salmon species; relation between the Nem parameter of population structure and spatial genetic differentiation at allozyme loci; possible genetic consequences of homing distortion. We conclude that homing is a historically established species‐specific trait responsible for the equilibrium between population differentiation and integration processes which regulate the ratio of intra‐ and interpopulation gene diversity levels. The distortion of this ratio results in negative genetic effects for rational fishery and successful management of populations.
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