Gene duplication in the family Salmonidae 111. Linkage between two duplicated loci coding for aspartate aminotransferase in the cutthroat trout (\u3ci\u3eSalmo clarki\u3c/i\u3e)

The genetic control of the supernatant form of aspartate aminotransferase (AAT) was studied in the cutthroat trout (Salmo clarki) through a series of experimental matings. 509 individuals of eight families were examined to determine (1) the number of loci, (2) the mode of inheritance (i.e. disomic or tetrasomic), and (3) the linkage relationship of the loci involved. The variation observed is controlled by a duplicated locus resulting from a presumed tetraploid event of an ancestral salmonid. The inheritance experiments revealed .the presence of two disomic loci rather than a single tetrasomic locus. indicating that disomy has been reestablished for the chromosomes carrying the AAT loci. The two families in which linkage between these loci could be tested displayed significant nonrandom segregation between these loci with an estimated frequency of recombination of 30.6x,. These results are discussed in regard to the proposed evolution of tetraploidy in the family Salmonidae

Population Genetics and Pattern of Larval Dispersal of the Endemic Hawaiian Freshwater Amphidromous Gastropod \u3ci\u3eNeritina granosa \u3c/i\u3e (Prosobranchia: Neritidae)

Protein electrophoresis was used to study the population genetics of the endemic Hawaiian freshwater amphidromous gastropod Neritina granosa Sowerby. The genetic information was used to infer the pattern and degree of planktonic larval dispersal. Samples were taken from 12 streams located throughout the Hawaiian Archipelago during July, August, and September 1991. Overall mean heterozygosity was 0.052. Heterozygote deficiency was comparable with that found in other mollusks and marine invertebrates. Gene flow was substantial and was generally sufficient to maintain similar allele frequencies among stream populations. An island model of migration was indicated. However, significant heterogeneity among populations was observed and was due primarily to three geographically disparate streams. Causes of deficiency and heterogeneity remain unknown. Demographic information suggests that, although high from a genetic point of view, the rate of migration calculated from gene flow might be insufficient to affect demographic processes in large populations of N. granosa

Population Genetic Structure in a Social Landscape: Barley in a Traditional Ethiopian Agricultural System

Conservation strategies are increasingly driven by our understanding of the processes and patterns of gene flow across complex landscapes. The expansion of population genetic approaches into traditional agricultural systems requires understanding how social factors contribute to that landscape, and thus to gene flow. This study incorporates extensive farmer interviews and population genetic analysis of barley landraces (Hordeum vulgare) to build a holistic picture of farmer-mediated geneflow in an ancient, traditional agricultural system in the highlands of Ethiopia. We analyze barley samples at 14 microsatellite loci across sites at varying elevations and locations across a contiguous mountain range, and across farmer-identified barley types and management strategies. Genetic structure is analyzed using population-based and individual-based methods, including measures of population differentiation and genetic distance, multivariate Principal Coordinate Analysis, and Bayesian assignment tests. Phenotypic analysis links genetic patterns to traits identified by farmers. We find that differential farmer management strategies lead to markedly different patterns of population structure across elevation classes and barley types. The extent to which farmer seed management appears as a stronger determinant of spatial structure than the physical landscape highlights the need for incorporation of social, landscape, and genetic data for the design of conservation strategies in human-influenced landscapes

Genetic variation in Scandinavian brown trout (\u3ci\u3eSalmo trutta \u3c/i\u3e L.): evidence of distinct sympatric populations

Large differences in certain morphological traits between populations of brown trout (Salmo trutfa L.) in the lakes of northern Sweden led us to initiate an electrophoretic examination in an effort to understand the genetic structure of these populations. A total of 549 brown trout from four lakes were examined at 10 electrophoretically detected loci. Genetic variation was found at only three loci, coding for lactate dehydrogenase (LDH), alpha-glycerophosphate dehydrogenase (AGP), and creatine phosphokinase (CPK). A total absence of heterozygotes at the LDH-I locus in Lake Bunnersjoarna, coupled with significant correlations between LDH-I type and both CPK-I allele frequencies and body size, is interpreted as evidence of two genetically isolated populations of brown trout in this lake. This finding, in addition to large allele frequency difTerences between brown trout from different lakes, is evidence of a large amount of genetic differentiation in these populations within a small geographical area. The implications of these results are discussed from both an evolutionary and a fishery management perspective. Further studies are planned to determine if these two sympatric populations are representatives of two widespread sibling species or are a locally evolved phenomenon. We also intend to detail the biochemical genetic, behavioral, and ecological differences between the two distinct populations in Lake Bunnersjoarna