scholarly journals DRIFT OR SELECTION: A STATISTICAL TEST OF GENE FREQUENCY VARIATION OVER GENERATIONS

Genetics ◽  
1977 ◽  
Vol 87 (2) ◽  
pp. 371-379
Author(s):  
Henry E Schaffer ◽  
Darrell Yardley ◽  
Wyatt W Anderson
Keyword(s):  
Zea Mays ◽  
Allele Frequency ◽  
Natural Population ◽  
Gene Frequency ◽  
Statistical Tests ◽  
Statistical Test ◽  
Directional Selection ◽  
Drosophila Pseudoobscura ◽  
Frequency Variation ◽  
Experimental Procedure

ABSTRACT The method used by Fisher and Ford (1947) to study the spread of a gene in a natural population has been modified to analyze the variation in allele frequencies from generation to generation in a common experimental procedure. A further analysis has been developed that is more sensitive to directional trends in the allele frequency over generations, and its use in detecting the action of directional selection on gene frequency at a locus is discussed. The power of each of these statistical tests is calculated for a number of cases, and the tests are applied to sets of isozyme data from Drosophila pseudoobscura and Zea mays.

Effects of selection and migration on geotactic and phototactic behaviour of Drosophila . II

1969 ◽  
Vol 173 (1031) ◽  
pp. 191-207 ◽  
Keyword(s):  
Genetic Effects ◽  
Directional Selection ◽  
Drosophila Pseudoobscura ◽  
Negative Phototaxis ◽  
Experimental Procedure ◽  
And Migration ◽  
Phototactic Behaviour

Genetic effects of selection and migration have been studied in populations of Drosophila pseudoobscura kept for twenty generations in plastic population cages. The experimental procedure can be seen in figure 1. Four donor populations are selected for positive or for negative phototaxis or geotaxis. The donor populations yield also migrants, which are selected for phenotypes opposite in sign to the selection in the donor populations themselves. The recipient populations are perpetuated by selecting parents with phenotypes close to the average in the respective populations, and adding to them the migrants from the donor populations. The migration is, thus, unidirectional—from the donors to the recipient populations. The donor populations have, as expected, responded to the directional selection by becoming photo- or geopositive or negative. The recipient populations showed little change for several generations, but eventually changed in the same directions as did the donors. This result seems at first sight paradoxical, because the migrants were selected for phenotypes opposite in sign to the selection in the donor populations. It is shown, however, that the result is explicable when the characteristics concerned have very low heritabilities. The migrants came from genetically improving populations, meaning by ‘improvement’ simply that these populations were changing in the direction for which they were being selected. Such migrants may transfer genetic improvements even if their own phenotypes do not manifest them.

scholarly journals GENE FREQUENCY CHANGES AT THE α-AMYLASE LOCUS IN EXPERIMENTAL POPULATIONS OF DROSOPHILA PSEUDOOBSCURA

Genetics ◽  
1977 ◽  
Vol 87 (2) ◽  
pp. 357-369
Author(s):  
Darrell G Yardley ◽  
Wyatt W Anderson ◽  
Henry E Schaffer
Keyword(s):  
Genetic Drift ◽  
Gene Frequency ◽  
Sampling Error ◽  
Directional Selection ◽  
Drosophila Pseudoobscura ◽  
Weak Selection ◽  
Selective Neutrality ◽  
Experimental Populations ◽  
Frequency Changes

ABSTRACT The frequencies of alleles at the α-Amylase locus of D. pseudoobscura were followed in both large and small experimental populations. No evidence for balancing or directional selection was found, although our ability to detect weak selection is limited. The gene frequency changes in our experimental populations were consistent with the hypothesis of selective neutrality and genetic drift due to sampling error.

scholarly journals NATURAL SELECTION VS. RANDOM DRIFT: EVIDENCE FROM TEMPORAL VARIATION IN ALLELE FREQUENCIES IN NATURE

Genetics ◽  
1985 ◽  
Vol 111 (3) ◽  
pp. 517-554
Author(s):  
Laurence D Mueller ◽  
Lorraine G Barr ◽  
Francisco J Ayala
Keyword(s):  
Natural Selection ◽  
Strong Evidence ◽  
Allele Frequencies ◽  
Drosophila Pseudoobscura ◽  
Frequency Variation ◽  
Random Drift ◽  
Napa County ◽  
Environmental Variations ◽  
Monthly Sample ◽  
Drosophila Persimilis

ABSTRACT We have obtained monthly samples of two species, Drosophila pseudoobscura and Drosophila persimilis, in a natural population from Napa County, California. In each species, about 300 genes have been assayed by electrophoresis for each of seven enzyme loci in each monthly sample from March 1972 to June 1975. Using statistical methods developed for the purpose, we have examined whether the allele frequencies at different loci vary in a correlated fashion. The methods used do not detect natural selection when it is deterministic (e.g., overdominance or directional selection), but only when alleles at different loci vary simultaneously in response to the same environmental variations. Moreover, only relatively large fitness differences (of the order of 15%) are detectable. We have found strong evidence of correlated allele frequency variation in 13-20% of the cases examined. We interpret this as evidence that natural selection plays a major role in the evolution of protein polymorphisms in nature.

scholarly journals ANALISIS TINGKAT KESESUAIAN DARI KLASIFIKASI KEPADATAN LALU LINTAS DAN WAKTU TEMPUH GOOGLE MAPS

2019 ◽  
Vol 2 (2) ◽  
Author(s):  
Laksita Amelia Paramesti ◽  
Dedi Atunggal
Keyword(s):  
Travel Time ◽  
Statistical Tests ◽  
Statistical Test ◽  
Traffic Information ◽  
Actual Condition ◽  
Traffic Density ◽  
Traffic Classification ◽  
Google Maps ◽  
Traffic Condition ◽  
Significant Difference

 Traffic congestion is one of problem that occur in big cities, therefore people need traffic information to determine traffic condition. One of many applications that provides traffic information is Google Maps. From the information generated, there are insuitability between google maps’s traffic update and travel time with the actual condition. So the aim of this study is to analyze the suitability level of traffic density classification and google maps travel time. Based on the speed range by Google, the level of suitability can be determined, while the google maps travel time is done by statistical tests. The statistical test used is a statistical test of two parameters using table t with 95% confidence level. The results of this study indicate that the level of suitability of the traffic classification only reaches 35%. The low level of suitability is caused by network latency. While information on google maps travel time does not have a significant difference in actual time.

scholarly journals Geographic patterns of human allele frequency variation: a variant-centric perspective

2020 ◽  
Author(s):  
Arjun Biddanda ◽  
Daniel P. Rice ◽  
John Novembre
Keyword(s):  
Genetic Variation ◽  
Gene Flow ◽  
Genetic Structure ◽  
Allele Frequency ◽  
Human Genetics ◽  
Geographic Region ◽  
Frequency Variation ◽  
Human Genetic Variation ◽  
Alternative Representation ◽  
Geographic Patterns

AbstractA key challenge in human genetics is to describe and understand the distribution of human genetic variation. Often genetic variation is described by showing relationships among populations or individuals, in each case drawing inferences over a large number of variants. Here, we present an alternative representation of human genetic variation that reveals the relative abundance of different allele frequency patterns across populations. This approach allows viewers to easily see several features of human genetic structure: (1) most variants are rare and geographically localized, (2) variants that are common in a single geographic region are more likely to be shared across the globe than to be private to that region, and (3) where two individuals differ, it is most often due to variants that are common globally, regardless of whether the individuals are from the same region or different regions. To guide interpretation of the results, we also apply the visualization to contrasting theoretical scenarios with varying levels of divergence and gene flow. Our variant-centric visualization clarifies the major geographic patterns of human variation and can be used to help correct potential misconceptions about the extent and nature of genetic differentiation among populations.

Valuing DNA marker tested bulls for commercial beef production

2004 ◽  
Vol 55 (8) ◽  
pp. 825 ◽  
Author(s):  
B. J. Wood ◽  
J. H. J. van der Werf ◽  
P. F. Parnell
Keyword(s):  
Gene Flow ◽  
Allele Frequency ◽  
Gene Frequency ◽  
Dna Marker ◽  
Recessive Gene ◽  
Single Recessive Gene ◽  
Beef Herd ◽  
Thyroglobulin Gene ◽  
Commercial Breeder ◽  
Over Time

This paper quantifies the benefits of using a sire genotyped for a single recessive gene in a commercial beef herd. A modified gene-flow method was used to account for changing allele frequency over time. The benefits to a commercial breeder of using a genotyped sire were highest when initial allele frequency was moderate and when the sire was used in a self-replacing herd that had increased allele frequency over time. An example of the thyroglobulin gene affecting marbling in beef cattle was used. The value to a self-replacing herd of a sire homozygous for the favourable allele of the thyroglobulin gene was shown to be up to $338 more than of an ungenotyped sire, in a population where the initial gene frequency was 0.3 and the genotype accounted for 0.5 standard deviations of phenotypic variation.

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