Gene flow versus selection pressure and ancestral differentiation in the composition of species: Analysis of populational variation ofJuniperus ashei buch. Using terpenoid data

1975 ◽  
Vol 5 (3) ◽  
pp. 177-185 ◽  
Author(s):  
R. P. Adams
Keyword(s):  
Gene Flow ◽  
Selection Pressure ◽  
Species Analysis

Modeling the Influence of Gene Flow and Selection Pressure on the Frequency of a GE Herbicide‐Tolerant Trait in Non‐GE Wheat and Wheat Volunteers

Crop Science ◽  
2006 ◽  
Vol 46 (4) ◽  
pp. 1704-1710 ◽  
Author(s):  
Anita L. Bruˆl'‐Babel ◽  
Christian J. Willenborg ◽  
Lyle F. Friesen ◽  
Rene C. Acker
Keyword(s):  
Gene Flow ◽  
Selection Pressure ◽  
Herbicide Tolerant

scholarly journals Site-Specific Insertion Polymorphism of the MITE Alex-1 in the Genus Coffea Suggests Interspecific Gene Flow

2011 ◽  
Vol 2011 ◽  
pp. 1-9 ◽  
Author(s):  
Christine Dubreuil-Tranchant ◽  
Romain Guyot ◽  
Amira Guellim ◽  
Caroline Duret ◽  
Marion de la Mare ◽  
...  
Keyword(s):  
Gene Flow ◽  
Transposable Elements ◽  
Phylogenetic Relationships ◽  
Insertion Site ◽  
Coffea Canephora ◽  
Insertion Polymorphism ◽  
Interspecific Gene Flow ◽  
Species Analysis ◽  
Eukaryotic Genomes ◽  
Mite Family

Miniature Inverted-repeat Transposable Elements (MITEs) are small nonautonomous class-II transposable elements distributed throughout eukaryotic genomes. We identified a novel family of MITEs (named Alex) in the Coffea canephora genome often associated with expressed sequences. The Alex-1 element is inserted in an intron of a gene at the CcEIN4 locus. Its mobility was demonstrated by sequencing the insertion site in C. canephora accessions and Coffea species. Analysis of the insertion polymorphism of Alex-1 at this locus in Coffea species and in C. canephora showed that there was no relationship between the geographical distribution of the species, their phylogenetic relationships, and insertion polymorphism. The intraspecific distribution of C. canephora revealed an original situation within the E diversity group. These results suggest possibly greater gene flow between species than previously thought. This MITE family will enable the study of the C. canephora genome evolution, phylogenetic relationships, and possible gene flows within the Coffea genus.

scholarly journals Local selection in the presence of high levels of gene flow: Evidence of heterogeneous insecticide selection pressure across Ugandan Culex quinquefasciatus populations

2017 ◽  
Vol 11 (10) ◽  
pp. e0005917 ◽  
Author(s):  
Walter Fabricio Silva Martins ◽  
Craig Stephen Wilding ◽  
Keith Steen ◽  
Henry Mawejje ◽  
Tiago Rodrigues Antão ◽  
...  
Keyword(s):  
Gene Flow ◽  
Culex Quinquefasciatus ◽  
Selection Pressure ◽  
Local Selection

scholarly journals A decade of herbicide-resistant crops in Canada

2006 ◽  
Vol 86 (4) ◽  
pp. 1243-1264 ◽  
Author(s):  
H. J. Beckie ◽  
K. N. Harker ◽  
L. M. Hall ◽  
S. I. Warwick ◽  
A. Légère ◽  
...  
Keyword(s):  
Gene Flow ◽  
Weed Management ◽  
Selection Pressure ◽  
Cropping System ◽  
Fundamental Principle ◽  
Transgenic Crop ◽  
Economic Returns ◽  
Weed Species ◽  
Eastern Canada ◽  
Herbicide Resistant

This review examines some agronomic, economic, and environmental impacts of herbicide-resistant (HR) canola, soybean, corn, and wheat in Canada after 10 yr of growing HR cultivars. The rapid adoption of HR canola and soybean suggests a net economic benefit to farmers. HR crops often have improved weed management, greater yields or economic returns, and similar or reduced environmental impact compared with their non-HR crop counterparts. There are no marked changes in volunteer weed problems associated with these crops, except in zero-tillage systems when glyphosate is used alone to control canola volunteers. Although gene flow from glyphosate-HR canola to wild populations of bird’s rape (Brassica rapa L.) in eastern Canada has been measured, enrichment of hybrid plants in such populations should only occur when and where herbicide selection pressure is applied. Weed shifts as a consequence of HR canola have been documented, but a reduction in weed species diversity has not been demonstrated. However, reliance on HR crops in rotations using the same mode-of-action herbicide and/or multiple in-crop herbicide applications over time can result in intense selection pressure for weed resistance and consequently, greater herbicide use in the future to control HR weed biotypes. History has repeatedly shown that cropping system diversity is the pillar of sustainable agriculture; stewardship of HR crops must adhere to this fundamental principle. Key words: Canola, Brassica napus, corn, Zea mays, soybean, Glycine max, wheat, Triticum aestivum, gene flow, herbicide resistance, transgenic crop, volunteer crop

scholarly journals Evaluating Gene Flow Using Selected Markers: A Case Study

Genetics ◽  
1998 ◽  
Vol 149 (3) ◽  
pp. 1383-1392 ◽  
Author(s):  
Thomas Lenormand ◽  
Thomas Guillemaud ◽  
Denis Bourguet ◽  
Michel Raymond
Keyword(s):  
Gene Flow ◽  
Insecticide Resistance ◽  
Local Adaptation ◽  
Culex Pipiens ◽  
Selection Pressure ◽  
Fitness Costs ◽  
Southern France ◽  
Culex Pipiens Pipiens ◽  
Selection Intensities

Abstract The extent to which an organism is locally adapted in an environmental pocket depends on the selection intensities inside and outside the pocket, on migration, and on the size of the pocket. When two or more loci are involved in this local adaptation, measuring their frequency gradients and their linkage disequilbria allows one to disentangle the forces—migration and selection—acting on the system. We apply this method to the case of a local adaptation to organophosphate insecticides in the mosquito Culex pipiens pipiens in southern France. The study of two different resistance loci allowed us to estimate with support limits gene flow as well as selection pressure on insecticide resistance and the fitness costs associated with each locus. These estimates permit us to pinpoint the conditions for the maintenance of this pocket of adaptation as well as the effect of the interaction between the two resistance loci.

scholarly journals (290) Analysis of Genetic Diversity in Selected Cornus Species Using SSR Markers

HortScience ◽  
2006 ◽  
Vol 41 (4) ◽  
pp. 1077E-1078 ◽  
Author(s):  
Xinwang Wang ◽  
Robert N. Trigiano ◽  
Mark T. Windham ◽  
Renae DeVries ◽  
Timothy A. Rinehart ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Gene Flow ◽  
Ssr Markers ◽  
Selection Pressure ◽  
Size Range ◽  
Linkage Maps ◽  
Ssr Loci ◽  
Species Groups ◽  
High Level ◽  
Ornamental Species

The genus Cornus consists of many species, of which C. florida, C. kousa, C. mas, and C. stolonifera are four main ornamental species in North America, Asia, and Europe. For example, over 200 cultivars of C. florida alone have been developed for the nursery industry. Microsatellite loci, or SSR, are useful markers for studying genetic diversity and for creating linkage maps of the various species. The objective of this study was to investigate the genetic diversity between these four Cornus species and eight hybrids. Evaulation of the diversity will be useful in assessing the selection pressure of breeders and/or genetic drift of these dogwood cultivars/lines. Fifteen SSR primer pairs were selected to examine 56 Cornus cultivars and/or lines of the four species and hybrids. The study included 28 C. florida cultivars and lines, 15 C. kousa cultivars and lines, four C. stolonifera cultivars, one cultivar of C. mass and eight hybrids between various Cornus species. An exceptionally high level of diversity was detected among the 56 entries in both the number and size range of SSR alleles. A total of 95 alleles with an average of 7.8 alleles per loci were detected among these 56 genotypes. These selected Cornus cultivars and/or lines could be clustered into four to six subgroups. Some Cornus species were integrated into other species groups, suggesting gene flow between species via the breeding or evolution. SSR markers can contribute to the exploitation of genetic diversity for existing Cornus germplasm. For further study, examination of more SSR loci could explain more completely the diversity among these Cornus cultivars and lines.

scholarly journals Genetic differentiation between conspecific populations of Merodon avidus A (Diptera, Syrphidae)

2004 ◽  
pp. 33-44 ◽  
Author(s):  
Vesna Milankov ◽  
Jasmina Ludoski ◽  
Ante Vujic
Keyword(s):  
Gene Flow ◽  
Genetic Differentiation ◽  
Genetic Distance ◽  
Selection Pressure ◽  
Geographic Distance ◽  
Inverse Function ◽  
Lower Degree ◽  
Allozyme Variability ◽  
Population Pair ◽  
Biogeographical Regions

Allozyme variability of populations of Merodon avidus A (M i l a n - k o v et al., 2001) from Dubasnica Mountain (Serbia), Morinj Bay (Montenegro) and Pindos Mountain (Greece) was analysed. The influence of gene flow on genetic differentiation among populations from the three biogeographical regions was also investigated. Genetic differentiaiton quantified by the Fst value, which is an inverse function of gene flow between populations, seemed to be correlated to both geographic and genetic distance (D, N e i, 1978), Namely in the population pairs Morinj - Dubasnica (253 km air distance), Morinj - Pindos (390km air distance) genetic differentiation and genetic distance increased with the geographic distance (Fst = 0.133, D = 0.022 and Fst = 0.309, D = 0.052, respectively). The exception was the population pair Dubasnica - Pindos (500 km air distance), where a lower degree of genetic differentiation was observed (Fst = 0.266; D = 0.047) than was expected based solely on the geographic distance. Results of this study suggest that that genetic differentiation among conspecific populations depends not only on the number of migrants (i. e. gene flow), but also on different selection pressure in different habits.

Great Wall blocks gene flow

Nature ◽  
2003 ◽  
Author(s):  
HelenR. Pilcher
Keyword(s):  
Gene Flow ◽  
Great Wall
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