Structure et variabilité génétique de populations d'épinette noire (Piceamariana (Mill.) B.S.P.) dans la zone hémiarctique du Nouveau-Québec

1987 ◽  
Vol 17 (9) ◽  
pp. 1006-1012 ◽  
Author(s):  
Mireille Desponts ◽  
Jean-Pierre Simon
Keyword(s):  
Gene Flow ◽  
Genetic Structure ◽  
Genetic Variability ◽  
Gel Electrophoresis ◽  
Black Spruce ◽  
Geographic Isolation ◽  
Marginal Populations ◽  
Isolated Populations ◽  
Subarctic Region ◽  
Enzyme Systems

The genetic structure of five populations of black spruce located at l'Eau Claire Lake, in the subarctic region of Nouveau-Québec, were analysed by acrylamide gel electrophoresis of seven enzyme systems. The analysis of 25 loci disclosed an average polymorphism of 0.80 and a level of heterozygosity of 0.351. Results indicate that there is no loss of genetic variability in these marginal populations that could be attributed to genetic drift. Data based on Wright's statistics indicate an excess of heterozygotes for most loci. Populations share the same alleles at most loci and are only slightly differentiated from each other (Fst = 0.06). Results suggest that gene flow between these isolated populations remains sufficiently high to override the effect of geographic isolation.

Intraspecific genetic variability of isozymes in the ectomycorrhizal fungus Suillus tomentosus

1988 ◽  
Vol 66 (3) ◽  
pp. 588-594 ◽  
Author(s):  
Hong Zhu ◽  
Kenneth O. Higginbotham ◽  
Bruce P. Dancik ◽  
Stan Navratil
Keyword(s):  
Genetic Variability ◽  
Host Selection ◽  
Gel Electrophoresis ◽  
Genetic Similarity ◽  
Ectomycorrhizal Fungus ◽  
Habitat Isolation ◽  
Starch Gel Electrophoresis ◽  
Enzyme Systems ◽  
Forest Regions ◽  
Starch Gel

Mycelial extracts of 43 isolates of Suillus tomentosus (Kauffm.) Singer, Snell & Dick collected from four boreal forest regions in Alberta were subjected to starch gel electrophoresis. A total of 21 bands was resolved from eight different enzyme systems presumably representing 13 loci. Six loci were polymorphic among these isolates. Cluster and principal components analyses demonstrated that intraspecific genetic variability of this fungus existed among and within forest regions. Polymorphic loci of acid phosphatase and alkaline phosphatase exhibited the greatest genetic similarity among the isolates within forest regions. Habitat isolation and host selection could be the major sources of genetic variation among forest regions.

Isozyme Variation in Broom Snakeweed (Gutierrezia sarothrae)

Weed Science ◽  
1995 ◽  
Vol 43 (1) ◽  
pp. 156-162 ◽  
Author(s):  
Yanglin Hou ◽  
Tracy M. Sterling
Keyword(s):  
Cluster Analysis ◽  
New Mexico ◽  
Genetic Variability ◽  
Gel Electrophoresis ◽  
Isozyme Analysis ◽  
Starch Gel Electrophoresis ◽  
Enzyme Systems ◽  
Starch Gel ◽  
Morphological Differences ◽  
Gutierrezia Sarothrae

Broom snakeweed, a perennial rangeland shrub, is highly variable morphologically and can grow under a broad range of environmental conditions. In this study, isozyme analysis using starch gel electrophoresis was used to quantify genetic variability within and among New Mexico populations of broom snakeweed. Eight separate populations of broom snakeweed and one population of threadleaf snakeweed as a comparison were investigated. of the 10 enzyme systems examined, 16 loci were identified in eight populations and two species. Eleven loci were monomorphic in eight populations and two species and five loci were polymorphic in at least one population or species. Genetic variability was large in broom and threadleaf snakeweed populations as determined by isozyme analysis. Genetic variability among broom snakeweed populations was greater than that within populations for the five polymorphic loci. Cluster analysis of genetic distance and identity for the eight populations and two species characterized two major groups. Within broom snakeweed, cluster analysis characterized five groups. The two species shared most common alleles. The genetic variation identified in this research may account for the morphological differences and broad geographical distribution of broom snakeweed.

Genetic structure of the arboreal squirrels (Glaucomys sabrinus and Tamiasciurus hudsonicus) in the North American Black Hills

2012 ◽  
Vol 90 (9) ◽  
pp. 1191-1200 ◽  
Author(s):  
A.M. Kiesow ◽  
E.M. Monroe ◽  
H.B. Britten
Keyword(s):  
Gene Flow ◽  
Genetic Structure ◽  
Management Practices ◽  
Allelic Diversity ◽  
Black Hills ◽  
Tamiasciurus Hudsonicus ◽  
Glaucomys Sabrinus ◽  
Red Squirrel ◽  
Isolated Populations ◽  
Red Squirrels

We selected two isolated mammalian populations, the Black Hills northern flying squirrel ( Glaucomys sabrinus (Shaw, 1801)) and red squirrel ( Tamiasciurus hudsonicus (Erxleben, 1777)), to elucidate their genetic structure. We trapped both squirrels from 2005 to 2007, in three regions of the Black Hills, differing in geology and vegetation, to collect ear samples for genetic analyses. Microsatellite loci (northern flying (9) and red squirrel (13)) were used to examine genetic structure. Data analyses estimated genetic variability, substructure, and gene flow. Northern flying and red squirrel populations have allelic diversity and observed heterozygosity similar to other isolated populations. Each species shows weak substructure from STRUCTURE and GENELAND analyses, suggesting squirrel movements may be inhibited by topography or unsuitable habitat. Recent gene flow estimates from BAYESASS indicate that both species experience some within population gene flow and red squirrels may be more structured than northern flying squirrels because of lower migration rates. Concordant patterns of genetic structure in northern flying and red squirrels indicate that other species’ movements in the Black Hills may be affected by topography and habitat. Because their habitat is isolated in the Black Hills, management practices and conservation measures are recommended to promote viability and survival of each species.

Genetic structure of marginal populations of white spruce (Piceaglauca) at its northern limit of distribution in Nouveau-Québec

1989 ◽  
Vol 19 (11) ◽  
pp. 1371-1379 ◽  
Author(s):  
Monique Tremblay ◽  
Jean-Pierre Simon
Keyword(s):  
Genetic Structure ◽  
Genetic Differentiation ◽  
Geographic Distance ◽  
White Spruce ◽  
Gene Exchange ◽  
Northern Limit ◽  
Marginal Populations ◽  
Subarctic Region ◽  
Hardy Weinberg Equilibrium ◽  
Or Gene

The genetic structure of six marginal populations of white spruce (Piceaglauca (Moench) Voss) located at Richmond Gulf in the subarctic region of Nouveau-Québec, and one southern population located at Kuujjuaraapik (Poste-de-la-Baleine) were analyzed by acrylamide gel electrophoresis for seven enzyme systems. The analysis of 27 loci disclosed an average polymorphism of 76.2% and a level of heterozygosity of 0.319. Data based on Wright's; statistics: indicated a deficiency of heterozygotes for 60% of the loci, as calculated from the Hardy–Weinberg equilibrium. These results, coupled with the very low percentage of filled seeds in cones of all populations, suggest that a certain level of inbreeding or gene exchange among near-neighbour relatives influences the genetic structure of these populations. The genetic differentiation among populations is relatively high for a conifer [Formula: see text] and is not correlated with geographic distance. The age of trees, covering a period of 400 years affected by climatic changes, does not contribute to the genetic differentiation of the populations.

scholarly journals Does selection occur at the intermediate zone of two insufficiently isolated populations? A whole-genome analysis along an altitudinal gradient

2021 ◽  
Author(s):  
Naofumi Yoshida ◽  
Shin-Ichi Morinaga ◽  
Takeshi Wakamiya ◽  
Yuu Ishii ◽  
Shosei Kubota ◽  
...  
Keyword(s):  
Gene Flow ◽  
Genetic Structure ◽  
Altitudinal Gradient ◽  
Intermediate Zone ◽  
Adaptive Divergence ◽  
Population Divergence ◽  
Whole Genome ◽  
Isolated Populations ◽  
Whole Genome Analysis ◽  
Single Nucleotide

Abstract Adaptive divergence would occur even between the insufficiently isolated populations when there is a great difference in the environments of their habitats. The individuals present in the intermediate zone of the two divergent populations are expected to have an admixed genetic structure due to gene flow. A selective pressure that acts on the genetically admixed individuals may limit the gene flow and promote the adaptive divergence. Here, we addressed a question whether the selection occurs in the genetically admixed individuals between the divergent populations and assessed its effects on the population divergence. We obtained the whole-genome sequences of a perennial montane plant, Arabidopsis halleri, which has clear phenotypic dimorphisms between altitudes, along an altitudinal gradient of 359–1,317 m with a high spatial resolution (mean altitudinal interval of 20 m). We found the zone where the highland and lowland genes were mixing. Using the FST approach, we found that 35 and 13 genes in the admixed zone had a high frequency of alleles that are accumulated in highland and lowland subpopulations, respectively, suggesting that these genes have been selected in the admixed zone. This selection might limit the gene flow and contribute to the adaptive divergence along the altitudes. In the single-nucleotide polymorphism (SNP)-based analysis, 3,000 out of 27,792 Altitude-Dependent SNPs had extremely high homozygosity in the admixed zone. In 84.7% of these SNPs, the frequency of homozygotes of highland alleles was comparable to that of lowland alleles, suggesting that these alleles are neutral but the heterozygotes were selectively eliminated. The distribution of highland and lowland alleles of these SNPs was not clearly separated between altitudes, implying that such selection did not impede the gene flow. We conclude that the selection occurring at the intermediate altitude affects the genetic structure in the admixed zone and adaptive divergence along the altitudes.

scholarly journals Isozyme and RAPD studies in Prosopis glandulosa and P. Velutina (Leguminosae, Mimosoideae)

2000 ◽  
Vol 23 (3) ◽  
pp. 639-648 ◽  
Author(s):  
Cecilia Bessega ◽  
Beatriz O. Saidman ◽  
Juan C. Vilardi
Keyword(s):  
Gene Flow ◽  
Genetic Structure ◽  
Genetic Variability ◽  
Genetic Differentiation ◽  
Rapd Markers ◽  
Random Amplified Polymorphic Dna ◽  
Mantel Test ◽  
Prosopis Glandulosa ◽  
Geographical Distance ◽  
Taxonomic Studies

Allozyme and random amplified polymorphic DNA (RAPD) techniques have been compared for their usefulness for genetic and taxonomic studies in Prosopis glandulosa and P. velutina populations. Isozymes and RAPDs yielded similarly high estimates of genetic variability. Genetic structure and differentiation were analyzed through non-hierarchical Wright's F DT. For all populations considered, both markers produced low gene flow (Nm < 1) estimates. When only P. glandulosa populations were analyzed, isozyme data yielded higher gene flow estimates (Nm > 1), in agreement with that expected for conspecific populations. However, in RAPD data the expected reduction in F DT and the increase in Nm were not observed. Correlation between F DT and geographical distance matrices (Mantel test) for all populations was significant (P = 0.02) when based on isozymes, but not so (P = 0.33) when based on RAPDs. No significant associations among genetic and geographical or climatic variables were observed. Two isoenzyme systems (GOT and PRX) enabled us to distinguish between P. glandulosa and P. velutina, but no diagnostic band for recognition of populations or species studied here were detected by RAPD. However, RAPD markers showed higher values for genetic differentiation among conspecific populations of P. glandulosa and a lower coefficient of variation than those obtained from isozymes.

scholarly journals GENE FLOW AND THE GEOGRAPHICAL DISTRIBUTION OF A MOLECULAR POLYMORPHISM IN DROSOPHILA PSEUDOOBSCURA

Genetics ◽  
1981 ◽  
Vol 98 (1) ◽  
pp. 157-178
Author(s):  
J S Jones ◽  
S H Bryant ◽  
R C Lewontin ◽  
J A Moore ◽  
T Prout
Keyword(s):  
Gene Flow ◽  
Genetic Structure ◽  
Geographical Distribution ◽  
Enzyme Polymorphism ◽  
Seasonal Abundance ◽  
Drosophila Pseudoobscura ◽  
Isolated Population ◽  
Molecular Polymorphism ◽  
Isolated Populations ◽  
High Level

ABSTRACT This paper discusses the relation between the geographical distribution of an enzyme polymorphism and population structure in Drosophila pseudoobscura. California populations of this species living in very different montane and lowland habitats separated by several kilometers are similar to each other in the frequency of an esterase allele. Previous estimates suggest that gene flow is too limited to account for this homogeneity of genetic structure, so that it must reflect some balancing force of natural selection. We show, however, that dispersal over unfavorable habitats is much greater than earlier supposed. Isolated populations of D. pseudoobscura separated by 15 km from other populations are subject to large amounts of immigration. This is shown by changes in the seasonal abundance of this species and in the annual pattern of lethal alleles in such populations. The genetic structure of an experimentally perturbed isolated population in an oasis returned to normal within a single year, suggesting that such populations are ephemeral and that the oasis is subject to annual recolonization by distant migrants. Direct assessment of marked flies shows that they can move at least 10 km in 24 hours over a desert. Such extensive gene flow may help explain the distribution of the esterase allele, and is relevant to the high level of molecular polymorphism and its general lack of geographic differentiation throughout the range of D. pseudoobscura.

scholarly journals Microsatellite variation and population genetic structure of a neotropical endangered Bryconinae species Brycon insignis Steindachner, 1877: implications for its conservation and sustainable management

2009 ◽  
Vol 7 (3) ◽  
pp. 395-402 ◽  
Author(s):  
Cristianne Kayoko Matsumoto ◽  
Alexandre Wagner Silva Hilsdorf
Keyword(s):  
Genetic Structure ◽  
Genetic Variability ◽  
Population Genetic Structure ◽  
Population Genetic ◽  
Food Resource ◽  
Southeastern Brazil ◽  
Captive Population ◽  
Wild Populations ◽  
Isolated Populations ◽  
Microsatellite Variation

Piabanha (Brycon insignis) is a freshwater fish species from the drainages in Southeastern Brazil. During the 1950s, it was an important economic and food resource for local populations, but dramatic and continuous environmental degradation seriously jeopardized the B. insignis populations in the region. Microsatellite markers were used to assess the genetic structure of wild populations of B. insignis and compare the genetic variability and integrity of the wild populations with a captive population. Samples of DNA from 208 specimens from geographically isolated populations were analyzed. Population genetic structure was investigated using F ST, R ST estimates as well as AMOVA. All five loci used in this study were polymorphic with observed heterozygosity ranging from 0.77 (± 0.15) to 0.88 (± 0.07) in the wild population and 0.90 (± 0.09) in the captive population and the allelic richness average were 7.56 (± 0.27) and 5.80 (± 1.02), respectively. Overall genetic differences were significantly partitioned among populations (F ST = 0.072, p = 0.034). Evidence of a genetic bottleneck was found in some of the wild populations, but especially in the captive population. The results showed that genetic variability still can be found in B. insignis populations which are currently structured possibly due to anthropic actions. The implications of these findings for the management and conservation of B. insignis populations are discussed.

scholarly journals Genetic variability of pheasant (Phasianus spp) in breeding station Ristovaca

2004 ◽  
pp. 5-11
Author(s):  
Ljiljana Vapa ◽  
Mihajla Djan ◽  
Dragana Obreht ◽  
Biljana Tosovic-Maric ◽  
Milan Vapa ◽  
...  
Keyword(s):  
Molecular Markers ◽  
Genetic Structure ◽  
Genetic Variability ◽  
Inbreeding Depression ◽  
Gel Electrophoresis ◽  
Polyacrylamide Gel Electrophoresis ◽  
Population Number ◽  
Putative Gene ◽  
Breeding Station ◽  
Fixation Indices

One of the possible reasons for pheasant population number decline in past several years might be loss of adaptability in populations originated from breeding stations caused by inbreeding depression. Due to fact that adaptability is a consequence of genetic structure of the populations, the aim of this paper was the analysis of genetic variability in pheasant population from breeding station Ristovaca using molecular markers. Allozyme variability of 20 putative gene loci was detected by polyacrylamide gel electrophoresis. Polymorphism was revealed in 5 loci: Est-1, Pgd, Sod, Gpi-2 and Odh. The values of genetic variability measures - heterozigosity polymorphism, fixation indices and H/P ratio indicate low level of genetic variability and possible presence of inbreeding depression within pheasant population.

scholarly journals A preliminary study of the allozyme variation in the grey hamster, Cricetulus migratorius (Mammalia: Rodentia), from the Asian part of Turkey

2011 ◽  
Vol 63 (2) ◽  
pp. 381-391 ◽  
Author(s):  
Osman İbiş ◽  
Coşkun Tez ◽  
Servet Özcan ◽  
Metin Kiliç ◽  
Murat Telcioğlu
Keyword(s):  
Genetic Variation ◽  
Gene Flow ◽  
Gel Electrophoresis ◽  
Allozyme Variation ◽  
Genetic Distances ◽  
Average Value ◽  
Enzyme Systems ◽  
The Mean ◽  
Preliminary Study ◽  
Allozyme Loci

The aim of the present study was to evaluate the degree of genetic variation and divergence by cellulose acetate gel electrophoresis between samples of Cricetulus migratorius, a cricetine rodent distributed in the Asian part (Anatolia) of Turkey. Out of twenty allozyme loci scored for fifteen enzyme systems, eleven loci were detected to be polymorphic in at least one locality of the Turkish C. migratorius. Indices of genetic variability (the percentage of polymorphic loci, mean number of alleles per locus, and mean observed and expected heterozygosities) were found to be P(95%) = 28, A = 1.3, Ho = 0.226 and He = 0.218, respectively. Nei?s unbiased genetic distances ranged from 0.000 to 0.153, with an average value of 0.069. The mean gene flow was calculated to be Nm = 0.7484. This is a preliminary study describing the allozymic variations of C. migratorius from Turkey. As there are no extensive data on the allozymic variations of C. migratorius from other regions, our results could not be compared, in detail with those of other populations of the species C. migratorius.

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