The Effect of Overlapping Generations and Population Structure on Gene-Frequency Clines

1997 ◽  
pp. 355-369 ◽  
Author(s):  
Oscar E. Gaggiotti ◽  
Carol E. Lee ◽  
Glenda M. Wardle
Keyword(s):  
Population Structure ◽  
Gene Frequency ◽  
Overlapping Generations

scholarly journals On sojourn times at particular gene frequencies

1975 ◽  
Vol 25 (2) ◽  
pp. 89-94 ◽  
Author(s):  
Edward Pollak ◽  
Barry C. Arnold
Keyword(s):  
Markov Chains ◽  
Gene Frequency ◽  
Overlapping Generations ◽  
Finite Population ◽  
Diffusion Method ◽  
Gene Frequencies ◽  
Sojourn Times ◽  
The Mean ◽  
Number Of Visits ◽  
Finite Markov Chains

SUMMARYThe distribution of visits to a particular gene frequency in a finite population of size N with non-overlapping generations is derived. It is shown, by using well-known results from the theory of finite Markov chains, that all such distributions are geometric, with parameters dependent only on the set of bij's, where bij is the mean number of visits to frequency j/2N, given initial frequency i/2N. The variance of such a distribution does not agree with the value suggested by the diffusion method. An improved approximation is derived.

Patterns of allozyme variation within and among Douglas-fir breeding zones in southwest Oregon

1987 ◽  
Vol 17 (5) ◽  
pp. 402-407 ◽  
Author(s):  
S. A. Merkle ◽  
W. T. Adams
Keyword(s):  
Genetic Diversity ◽  
Population Structure ◽  
Gene Frequency ◽  
Quantitative Traits ◽  
Allozyme Variation ◽  
Douglas Fir ◽  
Expected Heterozygosity ◽  
Breeding Zone ◽  
Southwest Oregon ◽  
Environmental Distance

Gametophytes from wind-pollinated seeds of Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco var. menziesii) parent trees (mean 56) in each of 22 breeding zones in southwest Oregon were analyzed electrophoretically for gene frequency patterns at 27 loci. Allozyme variability levels were high, as shown by breeding-zone averages for the percentage of polymorphic loci (71.7%, 0.99 criterion), mean number of alleles per locus (2.46), and expected heterozygosity (0.178). Differences among zones in allele frequency were significant (p < 0.05) for only 2 of the 27 loci surveyed, and analysis of hierarchical population structure showed that less than 1% of genetic diversity was attributable to differences among breeding zones. Genetic distance between zones was small [Formula: see text] and, in general, bore no relation to geographical or environmental distance. The limited allozyme differentiation among zones contrasts strikingly with the environment-related variation in seedling quantitative traits previously reported for southwest Oregon Douglas-fir. Allozymes do not appear to be useful for mapping patterns of adaptive variation or for certifying Douglas-fir seed in this region.

GENETIC LOADS IN HETEROGENEOUS ENVIRONMENTS

Genetics ◽  
1975 ◽  
Vol 80 (3) ◽  
pp. 621-635
Author(s):  
Charles E Taylor
Keyword(s):  
Population Structure ◽  
Genetic Variation ◽  
Gene Frequency ◽  
Phase Plane ◽  
Genetic Load ◽  
Sufficient Conditions ◽  
Heterogeneous Environments ◽  
Niche Space ◽  
Necessary And Sufficient ◽  
Existence Of Equilibria

ABSTRACT A model of population structure in heterogeneous environments is described with attention focused on genetic variation at a single locus. The existence of equilibria at which there is no genetic load is examined.—The absolute fitness of any genotype is regarded as a function of location in the niche space and the population density at that location. It is assumed that each organism chooses to live in that habitat in which it is most fit ("optimal habitat selection").—Equilibria at which there is no segregational load ("loadless equilibria") may exist. Necessary and sufficient conditions for the existence of such equilibria are very weak. If there is a sufficient amount of dominance or area in which the alleles are selectively neutral, then there exist equilibria without segregational loads. In the N, p phase plane defined by population size, N, and gene frequency, p, these equilibria generally consist of a line segment which is parallel to the p axis. These equilibria are frequently stable.

scholarly journals A TEST OF SPATIAL AUTOCORRELATION ANALYSIS USING AN ISOLATION-BY-DISTANCE MODEL

Genetics ◽  
1983 ◽  
Vol 105 (1) ◽  
pp. 219-237
Author(s):  
Robert R Sokal ◽  
Daniel E Wartenberg
Keyword(s):  
Population Structure ◽  
Spatial Autocorrelation ◽  
Process Parameters ◽  
Gene Frequency ◽  
Isolation By Distance ◽  
Neighborhood Size ◽  
Spatial Autocorrelation Analysis ◽  
Autocorrelation Analysis ◽  
Natural Systems ◽  
Distance Model

ABSTRACT Using the isolation-by-distance model as an example, we have examined several assumptions of spatial autocorrelation analysis applied to gene frequency surfaces. Gene frequency surfaces generated by a simulation of Wright's isolation-by-distance model were shown to exhibit spatial autocorrelation, except in the panmictic case. Identical stochastic generating processes result in surfaces with characteristics that are functions of the process parameters, such as parental vagility and neighborhood size. Differences in these parameters are detectable as differences in spatial autocorrelations after only a few generations of the simulations. Separate realizations of processes with identical parameters yield similar spatial correlograms. We have examined the inferences about population structure that could have been made from these observations if they had been real, rather than simulated, populations. From such inferences, we could have drawn conclusions about the presence of selection, migration and drift in given natural systems.

A general theory of the distribution of gene frequencies - I. Overlapping generations

1958 ◽  
Vol 149 (934) ◽  
pp. 102-112 ◽  
Keyword(s):  
General Theory ◽  
Gene Frequency ◽  
Overlapping Generations ◽  
Random Mating ◽  
Phenotypic Selection ◽  
Single Locus ◽  
Heuristic Methods ◽  
Gene Frequencies ◽  
Mating Population

The distribution of gene frequency at a single locus in a population of diploid individuals, with two sexes, subject to mutation, non-random mating and phenotypic selection, is obtained in the case where the generations are overlapping so that individuals die one by one. This distribution is of the same form as that obtained by heuristic methods by S. Wright in a randomly mating population but the coefficients are altered both by the non-randomness of the mating and the overlapping of the generations.

A general theory of the distribution of gene frequencies - II. Non-overlapping generations

1958 ◽  
Vol 149 (934) ◽  
pp. 113-116 ◽  
Keyword(s):  
General Theory ◽  
Gene Frequency ◽  
Overlapping Generations ◽  
Random Mating ◽  
Phenotypic Selection ◽  
Single Locus ◽  
Gene Frequencies ◽  
New Generation

The distribution of gene frequency at a single locus in a population of diploid individuals with two sexes, subject to mutation, non-random mating and phenotypic selection, is obtained in the case where all the population dies at the same time and is replaced by a new generation. The distribution is similar to that obtained by Wright with a correction due to the non-randomness of the mating.

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