scholarly journals Vertebrate herbivory weakens directional selection for earlier emergence in competition

2021 ◽  
Author(s):  
Joseph Waterton ◽  
Elsa E. Cleland
Keyword(s):  
Directional Selection ◽  
Selection For ◽  
Vertebrate Herbivory

scholarly journals Selection for recombination in a polygenic model – the mechanism

1988 ◽  
Vol 51 (1) ◽  
pp. 59-63 ◽  
Author(s):  
J. Maynard Smith
Keyword(s):  
Linkage Disequilibrium ◽  
Recombination Rate ◽  
Phenotypic Variability ◽  
Directional Selection ◽  
Polygenic Model ◽  
Infinite Population ◽  
Selection For ◽  
Repulsion Linkage

SummaryA polygenic model has been simulated in order to reveal the process whereby selection in an infinite population can lead to an increase in the frequency of alleles causing higher rates of recombination (CH alleles). Directional selection generates repulsion linkage disequilibrium (+ − + −), which is less strong in CH gametes (gametes carrying CH alleles). In consequence, CH gametes contribute greater phenotypic variability, and therefore respond more to directional selection: that is, they accumulate more selectively favoured alleles. CH alleles then increase in frequency by hitch-hiking. In contrast, normalizing selection, or frequent changes in the direction of selection, favour alleles for a low recombination rate.

scholarly journals Increased recombination frequencies resulting from directional selection for geotaxis in Drosophila

Heredity ◽  
1994 ◽  
Vol 72 (1) ◽  
pp. 64-68 ◽  
Author(s):  
Abraham B Korol ◽  
Konstantin G Iliadi
Keyword(s):  
Directional Selection ◽  
Selection For

scholarly journals Understanding specialism when the jack of all trades can be the master of all

2012 ◽  
Vol 279 (1749) ◽  
pp. 4861-4869 ◽  
Author(s):  
Susanna Remold
Keyword(s):  
Habitat Use ◽  
Recent Work ◽  
Habitat Change ◽  
Directional Selection ◽  
Antagonistic Pleiotropy ◽  
Disease Emergence ◽  
Evolutionary Genetic ◽  
The Face ◽  
Genetic Mechanisms ◽  
Selection For

Specialism is widespread in nature, generating and maintaining diversity, but recent work has demonstrated that generalists can be equally fit as specialists in some shared environments. This no-cost generalism challenges the maxim that ‘the jack of all trades is the master of none’, and requires evolutionary genetic mechanisms explaining the existence of specialism and no-cost generalism, and the persistence of specialism in the face of selection for generalism. Examining three well-described mechanisms with respect to epistasis and pleiotropy indicates that sign (or antagonistic) pleiotropy without epistasis cannot explain no-cost generalism and that magnitude pleiotropy without epistasis (including directional selection and mutation accumulation) cannot explain the persistence of specialism. However, pleiotropy with epistasis can explain all. Furthermore, epistatic pleiotropy may allow past habitat use to influence future use of novel environments, thereby affecting disease emergence and populations' responses to habitat change.

scholarly journals INTERACTION BETWEEN NATURAL SELECTION FOR HETEROZYGOTES AND DIRECTIONAL SELECTION

Genetics ◽  
1974 ◽  
Vol 76 (1) ◽  
pp. 163-168
Author(s):  
Margrith Wehrli Verghese
Keyword(s):  
Natural Selection ◽  
First Generation ◽  
Genetic Variance ◽  
Selection Response ◽  
Directional Selection ◽  
Simple Function ◽  
Small Populations ◽  
Gene Frequencies ◽  
Selection For

ABSTRACT When directional selection for an additively inherited trait is opposed by natural selection favoring heterozygous genotypes a selection plateau may be reached where genetic variance is present. The amount of response when this plateau is reached is a simple function of the selection response in the first generation and the intensity of natural selection. When selection is practiced in small populations, the sizes of the initial equilibrium gene frequencies are at least as important as the intensity of natural selection in determining the probability of fixing desirable alleles.

scholarly journals Artificial selection with differing population structures

1980 ◽  
Vol 36 (2) ◽  
pp. 117-131 ◽  
Author(s):  
K. A. Rathie ◽  
F. W. Nicholas
Keyword(s):  
Close Agreement ◽  
Large Population ◽  
Additive Model ◽  
Directional Selection ◽  
Base Population ◽  
Average Response ◽  
Response To Selection ◽  
Bristle Number ◽  
Population Structures ◽  
Selection For

SUMMARYThe effect of subdivision of a population on response to artificial directional selection for abdominal bristle number in Drosophila melanogaster was compared using large, replicated lines. Three different population structures were compared: (i) selection in an Undivided, large population with 50 pairs of parents (treatment U); (ii) selection in each of 10 sublines which were reconstituted every 6th generation by Crossing after Culling the 5 lowest sublines (treatment CC); and (iii) selection in each of 10 sublines which were reconstituted every 6th generation by Crossing after Retaining all 10 sublines (treatment CR). At the end of three cycles of selection and crossing, neither CR nor CC was superior to U; sublining did not increase response to selection. These results agree with the predictions arising from an entirely additive model and provide no evidence for the presence of epistasis.A comparison of 50-pair lines (U) with several 5-pair lines was made over 31 generations. For the 50-pair lines, there was close agreement between response predicted from the base population (using ih2σp) and observed response throughout all 31 generations of selection. Although the best of the 5-pair lines exceeded the 50-pair lines in the early generations, average response to directional selection in the 5-pair lines soon fell behind that predicted from ih2σp, and soon reached a plateau.

scholarly journals Directional selection for flowering time leads to adaptive evolution inRaphanus raphanistrum(Wild radish)

2016 ◽  
Vol 9 (4) ◽  
pp. 619-629 ◽  
Author(s):  
Michael B. Ashworth ◽  
Michael J. Walsh ◽  
Ken C. Flower ◽  
Martin M. Vila-Aiub ◽  
Stephen B. Powles
Keyword(s):  
Flowering Time ◽  
Adaptive Evolution ◽  
Directional Selection ◽  
Wild Radish ◽  
Selection For

Effects of artificial stabilizing selection on Drosophila populations subjected to directional selection for another trait

Genetica ◽  
1991 ◽  
Vol 83 (3) ◽  
pp. 247-256
Author(s):  
A. G. Imasheva ◽  
L. A. Zhivotovsky ◽  
O. E. Lazebny
Keyword(s):  
Directional Selection ◽  
Stabilizing Selection ◽  
Selection For
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