Variation and Covariation of Gene Frequencies in Subdivided Populations

Evolution ◽  
1965 ◽  
Vol 19 (2) ◽  
pp. 256 ◽  
Author(s):  
Massatoshi Nei
Keyword(s):  
Gene Frequencies ◽  
Subdivided Populations

scholarly journals LINKAGE DISEQUILIBRIUM IN SUBDIVIDED POPULATIONS

Genetics ◽  
1973 ◽  
Vol 75 (1) ◽  
pp. 213-219
Author(s):  
Masatoshi Nei ◽  
Wen-Hsiung Li
Keyword(s):  
Linkage Disequilibrium ◽  
Migration Rate ◽  
Random Mating ◽  
Isolated Populations ◽  
Gene Frequencies ◽  
Average Linkage ◽  
Subdivided Population ◽  
Overdominant Selection ◽  
Subdivided Populations ◽  
Recombination Value

ABSTRACT The linkage disequilibrium in a subdivided populaton is shown to be equal to the sum of the average linkage disequilibrium for all subpopulations and the covariance between gene frequencies of the loci concerned. Thus, in a subdivided population the linkage disequilibrium may not be 0 even if the linkage disequilibrium in each subpopulation is 0. If a population is divided into two subpopulations between which migration occurs, the asymptotic rate of approach to linkage equilibrium is equal to either r or 2(m  1 + m  2) - (m  1 + m  2)2, whichever is smaller, where r is the recombination value and m  1 and m  2 are the proportions of immigrants in subpopulations 1 and 2, respectively. Thus, if migration rate is high compared with recombination value, the change of linkage disequilibrium in subdivided populations is similar to that of a single random mating population. On the other hand, if migration rate is low, the approach to lnkage equilibrium may be retarded in subdivided populations. If isolated populations begin to exchange genes by migration, linkage disequilibrium may increase temporarily even for neutral loci. If overdominant selection operates and the equilibrium gene frequencies are different in the two subpopulations, a permanent linkage disequilibrium may be produced without epistasis in each subpopulation.

Gene-Frequencies and Mendelian Ratios

1951 ◽  
Vol 85 (823) ◽  
pp. 268-269
Author(s):  
H. P. Riley
Keyword(s):  
Gene Frequencies

scholarly journals Effects of Inbreeding on Genetic Characteristic, Growth, Survival Rates, and Immune Responses of a New Inbred Line of Exopalaemon carinicauda

2020 ◽  
Vol 2020 ◽  
pp. 1-11
Author(s):  
Jiajia Wang ◽  
Jitao Li ◽  
Qianqian Ge ◽  
Zhao Chen ◽  
Jian Li
Keyword(s):  
Immune Responses ◽  
Inbred Line ◽  
Survival Rates ◽  
The Body ◽  
Exopalaemon Carinicauda ◽  
Economic Traits ◽  
Gene Frequencies ◽  
Research Fields ◽  
Ssr Loci ◽  
Genetic Detection

The Exopalaemon carinicauda could be a useful crustacean laboratory animal in many research fields. We newly established an inbred line of Exopalaemon carinicauda named EC4 inbred line by brother×sister mating and keeping to F11 generation. Trends in heterozygosity in the process of producing EC4 inbred line were examined through the characterization of polymorphisms based on gene frequencies of SNP and EST-SSR loci. The results demonstrated that the number of alleles (N), observed heterozygosity (Ho), expected heterozygosity (He), and polymorphism information content (PIC) gradually decreased with the increase of inbreeding generations. The genetic detection results indicated that 9 (29.03%, 9/31) of the SNP loci and 15 (32.61%, 15/46) of the EST-SSR loci were homozygous in F11 generation of EC4 inbred line. The variation of the growth-related traits, the immune responses, and antioxidant status were described in experimental full-sibling inbred populations of E. carinicauda at five levels of inbreeding coefficient (F=0.785, F=0.816, F=0.859, F=0.886, F=0.908) under controlled laboratory conditions. The body weight, body length, and survival rate in EC4 inbred line of all generations were less than the control population. Inbreeding affected the antibacterial activity, phenoloxidase (PO) activity, and superoxide dismutase (SOD) which decreased at the eleventh generation of EC4 inbred line. This study demonstrated that inbreeding had a negative effect on the economic traits and immune response, but our inbred line was established successfully until F11 and confirmed by genetic detection using SNP and EST-SSR loci.

scholarly journals Analysis of Genetic Structure and Dispersal Patterns in a Population of Sea Beet

Genetics ◽  
1998 ◽  
Vol 149 (4) ◽  
pp. 1975-1985
Author(s):  
Jarle Tufto ◽  
Alan F Raybould ◽  
Kjetil Hindar ◽  
Steinar Engen
Keyword(s):  
Equilibrium Distribution ◽  
Pollen Dispersal ◽  
Migration Pattern ◽  
Likelihood Ratio Tests ◽  
Frequency Data ◽  
Gene Frequencies ◽  
Dispersal Patterns ◽  
Parametric Bootstrapping ◽  
Estimated Parameters ◽  
Multivariate Stochastic Process

Abstract A model of the migration pattern in a metapopulation of sea beet (Beta vulgaris L. ssp. maritima), based on the continuous distributions of seed and pollen movements, is fitted to gene frequency data at 12 isozyme and RFLP loci by maximum likelihood by using an approximation of the simultaneous equilibrium distribution of the gene frequencies generated by the underlying multivariate stochastic process of genetic drift in the population. Several alternative restrictions of the general model are fitted to the data, including the island model, a model of complete isolation, and a model in which the seed and pollen dispersal variances are equal. Several likelihood ratio tests between these alternatives are performed, and median bias in the estimated parameters is corrected by using parametric bootstrapping. To assess the fit of the selected model, the predicted covariances are compared with covariances computed from the data directly. The dependency of estimated parameters on the ratio between effective and absolute subpopulation sizes, which is treated as a known parameter in the analysis, is also examined. Finally, we note that the data also appear to contain some information about this ratio.

scholarly journals Spatial and space-time correlations in systems of subpopulations with genetic drift and migration.

Genetics ◽  
1993 ◽  
Vol 133 (3) ◽  
pp. 711-727
Author(s):  
B K Epperson
Keyword(s):  
Population Genetics ◽  
Time Correlation ◽  
Space Time ◽  
Spatial Correlations ◽  
Gene Frequencies ◽  
Migration Patterns ◽  
Migration Rates ◽  
Space And Time ◽  
Time Correlations ◽  
And Migration

Abstract The geographic distribution of genetic variation is an important theoretical and experimental component of population genetics. Previous characterizations of genetic structure of populations have used measures of spatial variance and spatial correlations. Yet a full understanding of the causes and consequences of spatial structure requires complete characterization of the underlying space-time system. This paper examines important interactions between processes and spatial structure in systems of subpopulations with migration and drift, by analyzing correlations of gene frequencies over space and time. We develop methods for studying important features of the complete set of space-time correlations of gene frequencies for the first time in population genetics. These methods also provide a new alternative for studying the purely spatial correlations and the variance, for models with general spatial dimensionalities and migration patterns. These results are obtained by employing theorems, previously unused in population genetics, for space-time autoregressive (STAR) stochastic spatial time series. We include results on systems with subpopulation interactions that have time delay lags (temporal orders) greater than one. We use the space-time correlation structure to develop novel estimators for migration rates that are based on space-time data (samples collected over space and time) rather than on purely spatial data, for real systems. We examine the space-time and spatial correlations for some specific stepping stone migration models. One focus is on the effects of anisotropic migration rates. Partial space-time correlation coefficients can be used for identifying migration patterns. Using STAR models, the spatial, space-time, and partial space-time correlations together provide a framework with an unprecedented level of detail for characterizing, predicting and contrasting space-time theoretical distributions of gene frequencies, and for identifying features such as the pattern of migration and estimating migration rates in experimental studies of genetic variation over space and time.

The sociobiological aspects of the National Survey on Fecundity and Fertility in Belgium

1969 ◽  
Vol 1 (4) ◽  
pp. 369-388 ◽  
Author(s):  
R. L. Cliquet
Keyword(s):  
National Survey ◽  
Evaluation Method ◽  
Modern Society ◽  
Western Society ◽  
Gene Frequencies ◽  
Potential Fecundity ◽  
Preliminary Results ◽  
Human Needs ◽  
Belgian Population

SummaryIn 1966, a National Survey on Fecundity and Fertility was organized in Belgium. Approximately 3000 married women under 41 years of age and living with their husbands were interviewed and asked about their reproductive histories. The present paper records the sociobiological aims and methods and some preliminary results of this survey. The aims were to:(1) study the influences of contraception on human needs and qualities, in this case mainly potential fecundity;(2) study the influence of attempts to increase the potential fecundity level in modern society on fecundity gene frequencies;(3) study the influences of the overall socio-cultural environment on fecundity and fertility variables with particular reference to differences in social status in Western society;(4) analyse the role of social assortment of fecundity and fertility variables on the biological structure, and possibly the composition, of modern populations.A relatively large, but far from complete body of data has been collected on a number of individual fecundity and fertility variables, on the medical processes employed to increase fecundity, on contraception, and on a number of conventional sociological and demographic variables.The principles underlying the present approach to the study of fecundity are explained, and a few preliminary results for one of the general fecundity classifications are shown.The information collected on contraception has been qualitatively analysed and a correction and evaluation method is described. Data on the use of the different contraceptive methods show that substantial sections of the Belgian population are limiting their family size in a way which is inefficient, from both sexual and familial standpoints.

scholarly journals Selection, Subdivision and Extinction and Recolonization

Genetics ◽  
2004 ◽  
Vol 166 (2) ◽  
pp. 1105-1114 ◽  
Author(s):  
Joshua L Cherry
Keyword(s):  
Frequency Dependence ◽  
Allele Frequency ◽  
Deleterious Alleles ◽  
Subdivided Population ◽  
Theoretical Predictions ◽  
Subdivided Populations ◽  
Fixation Probabilities ◽  
Selection Parameters ◽  
To Come ◽  
Do So

Abstract In a subdivided population, the interaction between natural selection and stochastic change in allele frequency is affected by the occurrence of local extinction and subsequent recolonization. The relative importance of selection can be diminished by this additional source of stochastic change in allele frequency. Results are presented for subdivided populations with extinction and recolonization where there is more than one founding allele after extinction, where these may tend to come from the same source deme, where the number of founding alleles is variable or the founders make unequal contributions, and where there is dominance for fitness or local frequency dependence. The behavior of a selected allele in a subdivided population is in all these situations approximately the same as that of an allele with different selection parameters in an unstructured population with a different size. The magnitude of the quantity Nese, which determines fixation probability in the case of genic selection, is always decreased by extinction and recolonization, so that deleterious alleles are more likely to fix and advantageous alleles less likely to do so. The importance of dominance or frequency dependence is also altered by extinction and recolonization. Computer simulations confirm that the theoretical predictions of both fixation probabilities and mean times to fixation are good approximations.

Sign in / Sign up

Export Citation Format

Share Document