scholarly journals What maintains genetic variation in natural populations? A commentary on ‘The maintenance of genetic variability by mutation in a polygenic character with linked loci’ by Russell Lande

2007 ◽  
Vol 89 (5-6) ◽  
pp. 371-372 ◽  
Author(s):  
PATRICK C. PHILLIPS
Keyword(s):  
Genetic Variation ◽  
Genetic Variability ◽  
Natural Populations

Genetic Variability for Herbicide Reaction in Plant Populations

Weed Science ◽  
1983 ◽  
Vol 31 (5) ◽  
pp. 652-657 ◽  
Author(s):  
Steven C. Price ◽  
James E. Hill ◽  
R. W. Allard
Keyword(s):  
Genetic Variation ◽  
Genetic Variability ◽  
Analysis Of Variance ◽  
Genetic Variance ◽  
Natural Populations ◽  
Herbicide Tolerance ◽  
Avena Fatua ◽  
Wild Oat ◽  
Plant Populations ◽  
Avena Barbata

The level of genetic variation for tolerance to herbicides was quantified in populations of slender wild oat (Avena barbata Brott. # AVEBA), wild oat (Avena fatua L. # AVEFA), and godetia (Clarkia williamsonii Lewis & Lewis) that had not been previously exposed to herbicides. Seedlings of wild oat and godetia were treated with barban (4-chloro-2-butynl-m-chlorocarbanilate) and bromoxynil (3,5-dibromo-4-hydroxybenzonitrile), respectively. The plants were rated for phytotoxic effects following treatment. A one-way analysis of variance on arcsin-transformed phytotoxicity ratings showed significant amounts of inter- and intrapopulation variability for herbicide reaction. Furthermore, the amount of genetic variance for herbicide reaction is higher than expected on the basis of mutation alone, suggesting selection favoring genes conferring herbicide tolerance occurs in natural populations.

scholarly journals Enzymatic analysis in Anopheles nuneztovari Gabaldón (Diptera, Culicidae)

2000 ◽  
Vol 60 (4) ◽  
pp. 539-550 ◽  
Author(s):  
V. M. SCARPASSA ◽  
W. P. TADEI
Keyword(s):  
Genetic Variation ◽  
Genetic Variability ◽  
Genetic Divergence ◽  
Allelic Variation ◽  
Natural Populations ◽  
Brazilian Amazon ◽  
High Variability ◽  
The Other ◽  
Enzymatic Analysis ◽  
Phenotypic Variations

Enzymatic analysis in Anopheles nuneztovari was made using four populations from the Brazilian Amazon and two from Colombia. The enzymes ME and XDH presented a monomorphic locus in all of the studied populations. EST and LAP presented a higher number of loci. In EST, genetic variation was observed in the five loci; LAP presented four loci, with allec variation in two loci. In IDH, three activity regions were stained, with genetic variation for locus Idh-1 in the Brazilian Amazon populations. A locus for MDH was observed, with genetic variation in the six populations. A region was verified for ACON, with four alleles in Sitronela and three in the other populations. PGM constituted one locus, with a high variability in the Brazilian Amazon populations. A locus was observed for 6-PGD with allelic variation in all of the populations with the exception of Tibú. Enzyme PGI presented two loci, both with genetic variability in the Tucuruí population. The enzyme alpha-GPD showed an activity region with polymorphism in the Tucuruí, Tibú and Sitronela populations. The phenotypic variations detected for these enzymes suggest that four (EST, LAP, ACON and PGM) possess monomeric structures and five (IDH, MDH, 6-PGD, PGI and alpha-GPD) dimeric structures in their proteins. These enzymes constitute in important markers to estimate variability and genetic divergence in natural populations of A. nuneztovari.

Assessment of temporal genetic variability of two epibenthic amphipod species in an eastern Australian estuarine environment and their suitability as biological monitors

2014 ◽  
Vol 62 (3) ◽  
pp. 206
Author(s):  
Pann Pann Chung ◽  
Ida Chu ◽  
J. William O. Ballard
Keyword(s):  
Genetic Variation ◽  
Genetic Variability ◽  
Environmental Monitoring ◽  
Organic Contaminants ◽  
Population Studies ◽  
Temporal Trends ◽  
Natural Populations ◽  
Cytochromec Oxidase ◽  
Basic Research ◽  
Amphipod Species

Population studies often assume temporally stable and consistent patterns of genetic variability. Violations of this assumption can lead to misrepresentation of the amount and patterns of genetic variability in natural populations, which can be problematic in basic research and environmental monitoring studies that are designed to detect environmental perturbation. We collected two endemic species of amphipods, Melita plumulosa and Melita matilda, in a major eastern Australian waterway between November 2009 and October 2011, and assessed genetic variation at the mitochondrial cytochromec oxidase subunitI locus. Overall, M. plumulosa was found to be more genetically variable than M. matilda. No distinct temporal trends in levels and patterns of genetic variation were identified in either species. These findings, combined with the published results demonstrating that M. plumulosa has greater sensitivity to a range of sediment-bound metals and organic contaminants, suggests it to be an informative species for environmental monitoring purposes.

scholarly journals Genetic variability of three natural populations of Maytenus aquifolium (Celesteraceae) from Telêmaco Borba, Paraná, Brazil

2010 ◽  
Vol 53 (5) ◽  
pp. 1037-1042 ◽  
Author(s):  
Sandra Aparecida Sahyun ◽  
Eduardo Augusto Ruas ◽  
Claudete de Fátima Ruas ◽  
Cristiano Medri ◽  
José Roberto Pinto de Souza ◽  
...  
Keyword(s):  
Genetic Variation ◽  
Genetic Variability ◽  
Bayesian Analysis ◽  
Rapd Markers ◽  
Gene Diversity ◽  
Natural Populations ◽  
Soil Types ◽  
Number Of Clusters ◽  
Analysis Of Molecular Variance ◽  
Molecular Variance

Three populations of Maytenus aquifolium from Monte Alegre farm, Telemaco Borba county, Paraná, Brazil were analyzed by RAPD markers. A total of 13 primers were applied wich yielded 283 well amplified markers in all the studied populations (Mortandade, Vila Preta and Trinita), producing different values of gene diversity and polymorphic loci. The analysis of molecular variance (AMOVA) indicated that 21.77% of the genetic variation was among the population. Pairwise F ST analysis showed that the most divergent populations were closer geographically, demonstrating that other factors such as different soil types could explain this variation. Bayesian analysis for K number of clusters and the Principal Coordinate indicated that these three populations were highly structured, corroborating the high values found for the F ST and indicating that for conservation purposes all populations should be maintained.

scholarly journals POPULATION GENETICS OF ALLOZYME VARIATION IN NEUROSPORA INTERMEDIA

Genetics ◽  
1975 ◽  
Vol 80 (4) ◽  
pp. 785-805
Author(s):  
P T Spieth
Keyword(s):  
Genetic Variation ◽  
Vegetative Reproduction ◽  
Vascular Plant ◽  
Natural Populations ◽  
Allozyme Variation ◽  
Regular Feature ◽  
Local Populations ◽  
Neurospora Intermedia ◽  
Pattern Of Variation ◽  
High Level

ABSTRACT Electrophoretically detectable variation in the fungus Neurospora intermedia has been surveyed among isolates from natural populations in Malaya, Papua, Australia and Florida. The principal result is a pattern of genetic variation within and between populations that is qualitatively no different than the well documented patterns for Drosophila and humans. In particular, there is a high level of genetic variation, the majority of which occurs at the level of local populations. Evidence is presented which argues that N. intermedia has a population structure analogous to that of an annual vascular plant with a high level of vegetative reproduction. Sexual reproduction appears to be a regular feature in the biology of the species. Substantial heterokaryon function seems unlikely in natural populations of N. intermedia. Theoretical considerations concerning the mechanisms underlying the observed pattern of variation most likely should be consistent with haploid selection theory. The implications of this constraint upon the theory are discussed in detail, leading to the presentation of a model based upon the concept of environmental heterogeneity. The essence of the model, which is equally applicable to haploid and diploid situations, is a shifting distribution of multiple adaptive niches among local populations such that a given population has a small net selective pressure in favor of one allele or another, depending upon its particular distribution of niches. Gene flow among neighboring populations with differing net selective pressures is postulated as the principal factor underlying intrapopulational allozyme variation.

scholarly journals Female Genotypes Affect Sperm Displacement in Drosophila

Genetics ◽  
1998 ◽  
Vol 149 (3) ◽  
pp. 1487-1493 ◽  
Author(s):  
Andrew G Clark ◽  
David J Begun
Keyword(s):  
Drosophila Melanogaster ◽  
Genetic Variation ◽  
Natural Populations ◽  
Isogenic Line ◽  
Female Fitness ◽  
Sperm Displacement ◽  
Extensive Variation ◽  
Polymorphic Genes ◽  
Displacement Parameter ◽  
Competitive Success

Abstract Differential success of sperm is likely to be an important component of fitness. Extensive variation among male genotypes in competitive success of sperm in multiply mated females has been documented for Drosophila melanogaster. However, virtually all previous studies considered the female to be a passive vessel. Nevertheless, under certain conditions female fitness could be determined by her role in mediating use of sperm from multiple males. Here we ask whether females differ among genotypes in their tendency to exhibit last-male precedence. Competition of sperm from two tester male genotypes (bwD and B3-09, a third-chromosome isogenic line from Beltsville, MD) was quantified by doubly mating female lines that had been rendered homozygous for X, second, or third chromosomes isolated from natural populations. The composite sperm displacement parameter, P2′, was highly heterogeneous among lines, whether or not viability effects were compensated, implying the presence of polymorphic genes affecting access of sperm to eggs. Genetic variation of this type is completely neutral in the absence of pleiotropy or interaction between variation in the two sexes.

scholarly journals Differentiation and genetic variability in natural populations of Anopheles (N.) triannulatus (Neiva& Pinto, 1922) of Brazilian Amazonia

2004 ◽  
Vol 64 (2) ◽  
pp. 327-336 ◽  
Author(s):  
J. M. M. Santos ◽  
J. F. Maia ◽  
W. P. Tadei
Keyword(s):  
Genetic Variability ◽  
Natural Populations ◽  
Isozyme Analysis ◽  
Brazilian Amazonia ◽  
F Statistics

Populations of Anopheles triannulatus from Macapá (AP), Aripuanã (MT), Ji-Paraná (RO), and Manaus-Janauari Lake (AM) were studied using 16 enzymatic loci. The results of the isozyme analysis showed that the population of Macapá presented higher polymorphism (56.3%). The lowest variability was observed in the population of Manaus (p = 25.0; Ho = 0.077 ± 0.046). The results of Wright's F statistics showed unbalance due to excess of homozygotes (Fis > Fst), denoting a certain intrapopulational differentiation. Although the populations are genetically very close (D = 0.003 - 0.052), the dendrogram separates the populations in two groups: Macapá separated from that of Manaus, Ji-Paraná, and Aripuanã. This result may suggest a reduction in the genic flow, which possibly had some influence in the substructuration of the populations.

scholarly journals Genetic variation in the dietary sucrose modulation of enzyme activities in Drosophila melanogaster

1984 ◽  
Vol 43 (3) ◽  
pp. 307-321 ◽  
Author(s):  
Billy W. Geer ◽  
Cathy C. Laurie-Ahlberg
Keyword(s):  
Drosophila Melanogaster ◽  
Genetic Variation ◽  
Enzyme Activities ◽  
Glycogen Synthesis ◽  
Krebs Cycle ◽  
Natural Populations ◽  
Substitution Lines ◽  
Chromosome Substitution Lines ◽  
High Sucrose Diet ◽  
Selection Of

SUMMARYGenetic variation in the modulating effect of dietary sucrose was assessed in Drosophila melanogaster by examining 27 chromosome substitution lines coisogenic for the X and second chromosomes and possessing different third isogenic chromosomes derived from natural populations. An increase in the concentration of sucrose from 0·1% to 5% in modified Sang's medium C significantly altered the activities of 11 of 15 enzyme activities in third instar larvae, indicating that dietary sucrose modulates many, but not all, of the enzymes of D. melanogaster. A high sucrose diet promoted high activities of enzymes associated with lipid and glycogen synthesis and low activities of enzymes of the glycolytic and Krebs cycle pathways, reflecting the physiological requirements of the animal. Analyses of variance revealed significant genetic variation in the degrees to which sucrose modulated several enzyme activities. Analysis of correlations revealed some relationships between enzymes in the genetic effects on the modulation process. These observations suggest that adaptive evolutionary change may depend in part on the selection of enzyme activity modifiers that are distributed throughout the genome.

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