scholarly journals STATISTICAL STUDIES ON PROTEIN POLYMORPHISM IN NATURAL POPULATIONS II. GENE DIFFERENTIATION BETWEEN POPULATIONS

Genetics ◽  
1978 ◽  
Vol 88 (2) ◽  
pp. 367-390
Author(s):  
Ranajit Chakraborty ◽  
Paul A Fuerst ◽  
Masatoshi Nei
Keyword(s):  
Genetic Differentiation ◽  
Natural Populations ◽  
Drift Theory ◽  
Alternative Hypotheses ◽  
Mean And Variance ◽  
Statistical Studies ◽  
Different Populations ◽  
Using Data ◽  
Almost All ◽  
Good Agreement

ABSTRACT With the aim of testing the validity of the mutation-drift hypothesis, we examined the pattern of genetic differentiation between populations by using data from Drosophila, fishes, reptiles, and mammals. The observed relationship between genetic identity and correlation of heterozygosities of different populations or species was generally in good agreement with the theoretical expectations from the mutation-drift theory, when the variation in mutation rate among loci was taken into account. In some species of Drosophila, however, the correlation was unduly high. The relationship between the mean and variance of genetic distance was also in good agreement with the theoretical prediction in almost all organisms. We noted that both the distribution of heterozygosity within species and the pattern of genetic differentiation between species can be explained by the same set of genetic parameters in each group of organisms. Alternative hypotheses for explaining these observations are discussed.

scholarly journals The probability of genetic parallelism and convergence in natural populations

2012 ◽  
Vol 279 (1749) ◽  
pp. 5039-5047 ◽  
Author(s):  
Gina L. Conte ◽  
Matthew E. Arnegard ◽  
Catherine L. Peichel ◽  
Dolph Schluter
Keyword(s):  
Adaptive Evolution ◽  
Natural Populations ◽  
Small Subset ◽  
Phenotypic Traits ◽  
Phenotypic Evolution ◽  
Genomic Studies ◽  
Genetic Level ◽  
Candidate Gene Studies ◽  
Different Populations ◽  
Using Data

Genomic and genetic methods allow investigation of how frequently the same genes are used by different populations during adaptive evolution, yielding insights into the predictability of evolution at the genetic level. We estimated the probability of gene reuse in parallel and convergent phenotypic evolution in nature using data from published studies. The estimates are surprisingly high, with mean probabilities of 0.32 for genetic mapping studies and 0.55 for candidate gene studies. The probability declines with increasing age of the common ancestor of compared taxa, from about 0.8 for young nodes to 0.1–0.4 for the oldest nodes in our study. Probability of gene reuse is higher when populations begin from the same ancestor (genetic parallelism) than when they begin from divergent ancestors (genetic convergence). Our estimates are broadly consistent with genomic estimates of gene reuse during repeated adaptation to similar environments, but most genomic studies lack data on phenotypic traits affected. Frequent reuse of the same genes during repeated phenotypic evolution suggests that strong biases and constraints affect adaptive evolution, resulting in changes at a relatively small subset of available genes. Declines in the probability of gene reuse with increasing age suggest that these biases diverge with time.

scholarly journals STATISTICAL STUDIES ON PROTEIN POLYMORPHISM IN NATURAL POPULATIONS I. DISTRIBUTION OF SINGLE LOCUS HETEROZYGOSITY

Genetics ◽  
1977 ◽  
Vol 86 (2) ◽  
pp. 455-483
Author(s):  
Paul A Fuerst ◽  
Ranajit Chakraborty ◽  
Masatoshi Nei
Keyword(s):  
Goodness Of Fit ◽  
Natural Populations ◽  
Single Locus ◽  
Random Genetic Drift ◽  
Average Heterozygosity ◽  
Significant Discrepancy ◽  
Homologous Locus ◽  
Kolmogorov Smirnov ◽  
Statistical Studies ◽  
Good Agreement

ABSTRACT Surveying the literature, the frequency distribution of single-locus heterozygosity among protein loci was examined in 95 vertebrate and 34 invertebrate species with the aim of testing the validity of the mutation-drift hypothesis. This distribution did not differ significantly from that expected under the mutation-drift hypothesis for any of the species examined when tested by the Kolmogorov-Smirnov goodness-of-fit statistic. The agreement between the observed interlocus variance of heterozygosity and its theoretical expectation was also satisfactory. There was an indication that variation in the mutation rate among loci inflates the interlocus variance of heterozygosity. The variance of heterozygosity for a homologous locus among different species was also studied. This variance generally agreed with the theoretical value very well, though in some groups of Drosophila species there was a significant discrepancy. The observed relationship between average heterozygosity and the proportion of polymorphic loci was in good agreement with the theoretical relationship. It was concluded that, with respect to the pattern of distribution of heterozygosity, the majority of data on protein polymorphisms are consistent with the mutation-drift hypothesis. After examining alternative possible explanations involving selection, it was concluded that the present data cannot be explained adequately without considering a large effect of random genetic drift, whether there is selection or not.

scholarly journals Crustal Thickness of Antarctica estimated using data from gravimetric satellites

2017 ◽  
Author(s):  
Muriel Llubes ◽  
Lucia Seoane ◽  
Sean Bruinsma ◽  
Frédérique Rémy
Keyword(s):  
Spatial Resolution ◽  
Crustal Thickness ◽  
Density Contrast ◽  
Moho Depth ◽  
West Antarctica ◽  
Gravity Field Model ◽  
Gravimetric Data ◽  
Using Data ◽  
Almost All ◽  
Good Agreement

Abstract. Computing a better crustal thickness model is still a necessary improvement in Antarctica. In this far continent where almost all the rocky surface is covered by the ice sheet, seismic investigations do not reach a sufficient spatial resolution for geological and geophysical purposes. Here, we computed a global map of Antarctic crustal thicknesses based on space gravity observations. The DIR5 gravity field model, built from GOCE and also GRACE gravimetric data, is inverted with the Parker–Oldenburg's iterative algorithm. The BEDMAP products are used to estimate the gravity effect of the ice and the rocky surface. Our result is compared to crustal thickness provided by seismological studies, CRUST1.0 and AN1 models. Although CRUST1.0 shows a very good agreement with our model, the spatial resolution is smaller with gravimetric data. Finally, we adjust the crust/mantle density contrast considering the Moho depth from CRUST1.0 model. In East Antarctica, the density contrast clearly shows higher values than in West Antarctica.

Genetic variation within and between populations of two endangered endemic species of the laurel forest from the Canary Islands, Myrica rivas-martinezii (Myricaceae) and Sideritis discolor (Lamiaceae)

2004 ◽  
Vol 52 (4) ◽  
pp. 471 ◽  
Author(s):  
F. Batista ◽  
N. Bouza ◽  
M. A. González-Pérez ◽  
J. Caujapé-Castells ◽  
P. A. Sosa
Keyword(s):  
Genetic Differentiation ◽  
Canary Islands ◽  
Endemic Species ◽  
Rapd Markers ◽  
Natural Populations ◽  
Laurel Forest ◽  
La Palma ◽  
Donor Population ◽  
Different Populations ◽  
Very High

Myrica rivas-martinezii A.Santos and Sideritis discolor Bolle, two endangered endemic species of the laurel forest from the Canary Islands, were studied by using RAPD markers with the goal of assessing their within- and among-population apportionment of genetic variability. Ten- and 11-oligonucleotide primers assayed in three populations of each of M. rivas-martinezii and S. discolor resulted in 32 molecular markers in the former species and 49 in the latter (90.6% and 100% polymorphic, respectively). The value of the coefficient of genetic differentiation among populations was very high for M. rivas-martinezii (FST = 0.487) but only moderate for S.�discolor (FST = 0.149). These results suggest that gene flow among populations is extremely low in M.�rivas-martinezii and quite substantial in S. discolor. The UPGMA cluster obtained from Dice's coefficient mixed individuals from different populations in S. discolor but not in M. rivas-martinezii, where they were grouped by their island of occurrence. On the basis of these results and the vulnerability of these two species, we suggest protection of all natural populations. However, if habitat conservation is not possible, our results suggest that for S.�discolor, the La Virgen population would make a good donor population because of geographical and genetic factors. The high genetic differentiation detected among populations of M. rivas-martinezii suggests that each island should be considered as a distinct management unit. However, considering the situation of this species on La Palma Island with only two isolated individuals, reintroductions of germoplasma from El Hierro may be a viable way to guarantee the existence of M. rivas-martinezii in that island.

scholarly journals GENETIC DIFFERENTIATION BETWEEN GEOGRAPHICALLY DISTANT POPULATIONS OF DROSOPHILA MELANOGASTER

Genetics ◽  
1982 ◽  
Vol 101 (2) ◽  
pp. 235-256
Author(s):  
Rama S Singh ◽  
Donal A Hickey ◽  
Jean David
Keyword(s):  
Drosophila Melanogaster ◽  
Genetic Differentiation ◽  
Gene Frequency ◽  
Natural Populations ◽  
Allozyme Variation ◽  
Clinal Variation ◽  
Significant Genetic Differentiation ◽  
African Populations ◽  
Latitudinal Clines ◽  
North And South

ABSTRACT We have studied allozyme variation at 26 gene loci in nine populations of Drosophila melanogaster originating on five different continents. The distant populations show significant genetic differentiation. However, only half of the loci studied have contributed to this differentiation; the other half show identical patterns in all populations. The genetic differentiation in North American, European and African populations is correlated with the major climatic differences between north and south. These differences arise mainly from seven loci that show gene-frequency patterns suggestive of latitudinal clines in allele frequencies. The clinal variation is such that subtropical populations are more heterozygous than temperate populations. These results are discussed in relation to the selectionist and neutralist hypotheses of genetic variation in natural populations.

scholarly journals Spontaneous Gac Mutants of Pseudomonas Biological Control Strains: Cheaters or Mutualists?

2011 ◽  
Vol 77 (20) ◽  
pp. 7227-7235 ◽  
Author(s):  
William W. Driscoll ◽  
John W. Pepper ◽  
Leland S. Pierson ◽  
Elizabeth A. Pierson
Keyword(s):  
Alternative Hypothesis ◽  
Natural Populations ◽  
Regulatory System ◽  
Wild Type ◽  
Content Type ◽  
The Public ◽  
Extracellular Metabolites ◽  
Mutualistic Interaction ◽  
Alternative Hypotheses

ABSTRACTBacteria rely on a range of extracellular metabolites to suppress competitors, gain access to resources, and exploit plant or animal hosts. The GacS/GacA two-component regulatory system positively controls the expression of many of these beneficial external products in pseudomonad bacteria. Natural populations often contain variants with defective Gac systems that do not produce most external products. These mutants benefit from a decreased metabolic load but do not appear to displace the wild type in nature. How could natural selection maintain the wild type in the presence of a mutant with enhanced growth? One hypothesis is that Gac mutants are “cheaters” that do not contribute to the public good, favored within groups but selected against between groups, as groups containing more mutants lose access to ecologically important external products. An alternative hypothesis is that Gac mutants have a mutualistic interaction with the wild type, so that each variant benefits by the presence of the other. In the biocontrol bacteriumPseudomonas chlororaphisstrain 30-84, Gac mutants do not produce phenazines, which suppress competitor growth and are critical for biofilm formation. Here, we test the predictions of these alternative hypotheses by quantifying interactions between the wild type and the phenazine- and biofilm-deficient Gac mutant within growing biofilms. We find evidence that the wild type and Gac mutants interact mutualistically in the biofilm context, whereas a phenazine-defective structural mutant does not. Our results suggest that the persistence of alternative Gac phenotypes may be due to the stabilizing role of local mutualistic interactions.

Spatial genetic substructure within natural populations of jack pine (Pinus banksiana)

1991 ◽  
Vol 69 (3) ◽  
pp. 547-551 ◽  
Author(s):  
Chang Yi Xie ◽  
Peggy Knowles
Keyword(s):  
Spatial Autocorrelation ◽  
Pinus Banksiana ◽  
Pollen Dispersal ◽  
Natural Populations ◽  
Jack Pine ◽  
Spatial Autocorrelation Analysis ◽  
Autocorrelation Analysis ◽  
Long Distance ◽  
Genetic Substructure ◽  
Good Agreement

Spatial autocorrelation analysis was used to investigate the geographic distribution of allozyme genotypes within three natural populations of jack pine (Pinus banksiana Lamb.). Results indicate that genetic substructuring within these populations is very weak and the extent differs among populations. These results are in good agreement with those inferred from mating-system studies. Factors such as the species' predominantly outbreeding system, high mortality of selfs and inbreds prior to reproduction, long-distance pollen dispersal, and the absence of strong microhabitat selection may be responsible for the observed weak genetic substructuring. Key words: jack pine, Pinus banksiana, genetic substructure, allozyme, spatial autocorrelation analysis.

Risk Analysis for Knowledge Sharing in Tax Payment

2016 ◽  
Vol 6 (1) ◽  
pp. 20-37
Author(s):  
Zahra Kazemi ◽  
Ahmad Jafari Samimi ◽  
Hamed Fazlollahtabar
Keyword(s):  
Knowledge Sharing ◽  
Tax Evasion ◽  
Developed Countries ◽  
Government Expenditures ◽  
Positive Effects ◽  
The People ◽  
Using Data ◽  
Tax Payments ◽  
Almost All ◽  
Tax Payers

One way to finance government expenditures is to collect taxes. Regarding to this financial source compared with other sources positive tax knowledge sharing amongst people or tax payers lead to effective investment. Unlike developing countries in developed countries - that taxes have little effects - almost all government expenditures is financed by taxes. One of the main challenges in the tax system is how to collect taxes due to tax evasion. The main reason is the uncertainty surrounding how government uses the taxes paid by the people. A major factor in the outbreak of the sense of failure to pay taxes, is the discussion and sharing the viewpoint of each other. If there is any positive tax effect prevalence of speech among people motivate them to pay more and if not, paying taxes is impaired. Therefore in order to avoid disorderliness in paying taxes that lead to a reduction in the development growth rate of investing taxes in industry and services sectors procedures should be designed so that taxes spread in speech with more quality. In this article five categories that people share their knowledge about them with each other, have been proposed. Defining risk structure and using data from surveying form the risk values of tax payment the results indicate that sharing tax knowledge amongst people have positive effects on tax payments.

scholarly journals Population Genetics and Evolution Analysis Reveal Diversity and Origin of Ammopiptanthus in China.

2021 ◽  
Author(s):  
Guai-qiang Chai ◽  
Yizhong Duan ◽  
Peipei Jiao ◽  
Zhongyu Du ◽  
Furen Kang
Keyword(s):  
Genetic Diversity ◽  
Genetic Structure ◽  
Genetic Differentiation ◽  
Association Studies ◽  
Natural Populations ◽  
Principal Component ◽  
Nucleotide Polymorphisms ◽  
Future Design ◽  
Ammopiptanthus Nanus ◽  
Genome Wide

Abstract Background：Elucidating and revealing the population genetic structure, genetic diversity and recombination is essential for understanding the evolution and adaptation of species. Ammopiptanthus, which is an endangered survivor from the Tethys in the Tertiary Period, is the only evergreen broadleaf shrub grown in Northwest of China. However, little is known about its genetic diversity and underlying adaptation mechanisms. Results：Here, 111 Ammopiptanthus individuals collected from fifteen natural populations in estern China were analyzed by means of the specific locus amplified fragment sequencing (SLAF-seq). Based on the single nucleotide polymorphisms (SNPs) and insertions and deletions (InDels) detected by SLAF-seq, genetic diversity and markers associated with climate and geographical distribution variables were identified. The results of genetic diversity and genetic differentiation revealed that all fifteen populations showed medium genetic diversity, with PIC values ranging from 0.1648 to 0.3081. AMOVA and Fst indicated that a low genetic differentiation existed among populations. Phylogenetic analysis showed that NX-BG and NMG-DQH of fifteen populations have the highest homology，while the genetic structure analysis revealed that these Ammopiptanthus germplasm accessions were structured primarily along the basis of their geographic collection, and that an extensive admixture occurred in each group. In addition, the genome-wide linkage disequilibrium (LD) and principal component analysis showed that Ammopiptanthus nanus had a more diverse genomic background, and all genetic populations were clearly distinguished, although different degrees of introgression were detected in these groups. Conclusion：Our study could provide guidance to the future design of association studies and the systematic utilization and protection of the genetic variation characterizing the Ammopiptanthus.

scholarly journals Inversion polymorphism in some natural populations of Drosophila pseudoobscura from central Mexico

Genetika ◽  
2007 ◽  
Vol 39 (3) ◽  
pp. 343-354 ◽  
Author(s):  
Víctor Salceda ◽  
Judith Guzmán ◽  
Olga Olvera
Keyword(s):  
Relative Frequency ◽  
Polytene Chromosomes ◽  
Natural Populations ◽  
Chromosomal Polymorphism ◽  
Drosophila Pseudoobscura ◽  
Central Mexico ◽  
The Third ◽  
Grand Total ◽  
Different Populations ◽  
Single Larva

Samples of D. pseudoobscura were taken in seventeen localities in Central Mexico inside the parallels 18o - 20o N, with the purpose of determine the chromosomal polymorphism in the third of the different populations of this species. From each captured female a single larva of its offspring was taken, its salivary glands extracted and stained with a solution of aceto orcein to observe the polytene chromosomes. From these smears the corresponding karyotype of each larva was determined, keeping a record of them. With the information gathered the relative frequency of each one of the fourteen different inversions found was calculated. A grand total of 1894 third chromosomes were analyzed. The fourteen different inversions found are equivalent to a 34.1 % of the total chromosomal variation of the species. The most abundant inversions found were: TL 50.6 %, CU 27.2 5, SC 9.1 % and EP 5.5 %; the remaining ten inversions detected are in general grounds rare ones with variable relative frequencies depending on the locality. Analysis of the predominant inversions for each population was done. The presence of West-East gradients is reported, even if in cases not so well defined, since as one moves in a particular direction the ups and downs in relative frequency for the alternating pairs TL-CU; TL-SC in the western populations and TL-CU in the eastern ones were observed. The assignment of each population to a particular race was also done, and such a way we were able to recognize three different races coexisting in the area of study.

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