scholarly journals ATTAINMENT OF QUASI LINKAGE EQUILIBRIUM WHEN GENE FREQUENCIES ARE CHANGING BY NATURAL SELECTION

Genetics ◽  
1965 ◽  
Vol 52 (5) ◽  
pp. 875-890 ◽  
Author(s):  
Motoo Kimura
Keyword(s):  
Natural Selection ◽  
Linkage Equilibrium ◽  
Gene Frequencies ◽  
Quasi Linkage Equilibrium

scholarly journals REMARKS ON THE EVOLUTIONARY EFFECT OF NATURAL SELECTION

Genetics ◽  
1976 ◽  
Vol 83 (3) ◽  
pp. 601-607
Author(s):  
W J Ewens
Keyword(s):  
Natural Selection ◽  
Present Note ◽  
Great Majority ◽  
Linkage Equilibrium ◽  
Evolutionary Effect ◽  
Mathematical Theorem ◽  
Fitness Parameters ◽  
Mean Fitness ◽  
The Mean ◽  
Quasi Linkage Equilibrium

ABSTRACT The so-called "Fundamental Theorem of Natural Selection", that the mean fitness of a population increases with time under natural selection, is known not to be true, as a mathematical theorem, when fitnesses depend on more than one locus. Although this observation may not have particular biological relevance, (so that mean fitness may well increase in the great majority of interesting situations), it does suggest that it is of interest to find an evolutionary result which is correct as a mathematical theorem, no matter how many loci are involved. The aim of the present note is to prove an evolutionary theorem relating to the variance in fitness, rather than the mean: this theorem is true for an arbitrary number of loci, as well as for arbitrary (fixed) fitness parameters and arbitrary linkage between loci. Connections are briefly discussed between this theorem and the principle of quasi-linkage equilibrium.

scholarly journals General Models of Multilocus Evolution

Genetics ◽  
2002 ◽  
Vol 161 (4) ◽  
pp. 1727-1750 ◽  
Author(s):  
Mark Kirkpatrick ◽  
Toby Johnson ◽  
Nick Barton
Keyword(s):  
Sexual Selection ◽  
Natural Selection ◽  
Evolutionary Dynamics ◽  
Linkage Equilibrium ◽  
Sex Linkage ◽  
Genetic Composition ◽  
Evolutionary Forces ◽  
And Migration ◽  
The Web ◽  
Quasi Linkage Equilibrium

Abstract In 1991, Barton and Turelli developed recursions to describe the evolution of multilocus systems under arbitrary forms of selection. This article generalizes their approach to allow for arbitrary modes of inheritance, including diploidy, polyploidy, sex linkage, cytoplasmic inheritance, and genomic imprinting. The framework is also extended to allow for other deterministic evolutionary forces, including migration and mutation. Exact recursions that fully describe the state of the population are presented; these are implemented in a computer algebra package (available on the Web at http://helios.bto.ed.ac.uk/evolgen). Despite the generality of our framework, it can describe evolutionary dynamics exactly by just two equations. These recursions can be further simplified using a “quasi-linkage equilibrium” (QLE) approximation. We illustrate the methods by finding the effect of natural selection, sexual selection, mutation, and migration on the genetic composition of a population.

Moving Targets

2012 ◽  
Author(s):  
Stephen J. Simpson ◽  
David Raubenheimer
Keyword(s):  
Life History ◽  
Natural Selection ◽  
Growth And Development ◽  
Early Growth ◽  
Evolutionary Change ◽  
Life History Strategies ◽  
Moving Targets ◽  
Gene Frequencies ◽  
Epigenetic Effects ◽  
As Species

This chapter studies intake and growth targets. For clarity, earlier chapters have treated intake and growth targets as static points integrated across a particular period in the life of an animal. In reality they are, of course, not static but rather trajectories that move in time. In the short term, the requirements of the animal change as environmental circumstances impose differing demands for nutrients and energy. At a somewhat longer timescale, targets move as the animal passes through the various stages of its life, from early growth and development to maturity, reproduction, and senescence. On an even longer timescale, nutritional traits are subject to natural selection and move as species evolve to exploit new or changing nutritional environments and to adopt differing life-history strategies. Presaging such evolutionary change in gene frequencies within populations are epigenetic effects, whereby the nutritional experiences of parents influence the behavior and metabolism of their offspring without requiring changes in gene frequencies.

3. How behaviour develops

2017 ◽  
Author(s):  
Tristram D. Wyatt
Keyword(s):  
Gene Expression ◽  
Gene Regulation ◽  
Natural Selection ◽  
Phenotypic Plasticity ◽  
Mate Choice ◽  
Social Influences ◽  
Future Generations ◽  
Gene Frequencies ◽  
Brain Gene Expression ◽  
Genes And Environment

Behaviours evolve by natural selection. As genes influence how behaviours develop, selection on behaviour will alter gene frequencies in subsequent generations: genes that lead to successful behaviours in foraging, parental care, or mate choice, for example, will be represented in more individuals in future generations. If conditions change, then mutations of the genes that give rise to advantageous behaviours will be favoured by selection. ‘How behaviour develops’ explains that the environment is equally important: both genes and environment are intimately and interactively involved in behaviour development. Behavioural imprinting is also discussed along with co-opting genes, gene regulation, social influences on brain gene expression, phenotypic plasticity, and play.

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.

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