Phenotypic Variances
Mostrando 13-24 de 35 artigos, teses e dissertações.
-
13. Analysis of Conditional Genetic Effects and Variance Components in Developmental Genetics
A genetic model with additive-dominance effects and genotype X environment interactions is presented for quantitative traits with time-dependent measures. The genetic model for phenotypic means at time t conditional on phenotypic means measured at previous time (t - 1) is defined. Statistical methods are proposed for analyzing conditional genetic effects and
-
14. Realized Sampling Variances of Estimates of Genetic Parameters and the Difference between Genetic and Phenotypic Correlations
A data set of 1572 heritability estimates and 1015 pairs of genetic and phenotypic correlation estimates, constructed from a survey of published beef cattle genetic parameter estimates, provided a rare opportunity to study realized sampling variances of genetic parameter estimates. The distribution of both heritability estimates and genetic correlation estim
-
15. A Genetic Analysis of Targeted Growth in Mice
Effects of normal growth regulation on components of phenotypic variance and covariance of body weight were examined in a cross-fostering study of growth between 2 and 10 wk of age in ICR randombred mice. Different early growth rates caused genetic, postnatal maternal and residual environmental variances to increase, but these variances were subsequently red
-
16. The Effects of Disruptive and Stabilizing Selection on Body Size in DROSOPHILA MELANOGASTER. I. Mean Values and Variances
Disruptive and stabilizing selection were applied to thorax and wing length in Drosophila melanogaster. Disruptive selection with negative assortative mating (D-) practiced on thorax length caused a large increase of the phenotypic variance; practiced on wing length the increase was less striking. Disruptive selection with random mating (DR) caused in most l
-
17. The Evolution of Continuous Variation. III. Joint Transmission of Genotype, Phenotype and Environment
Evolutionary models of continuous traits are developed. The models are based on the ideas that: (1) the phenotype is the result of the interaction between genotype and environment; (2) the phenotype is the object of natural selection; (3) not only the genotype but also environmental variables and even phenotypes can be directly transmitted. The phenotype of
-
18. Phenotypic diversity and ecosystem functioning in changing environments: A theoretical framework
Biodiversity plays a vital role for ecosystem functioning in a changing environment. Yet theoretical approaches that incorporate diversity into classical ecosystem theory do not provide a general dynamic theory based on mechanistic principles. In this paper, we suggest that approaches developed for quantitative genetics can be extended to ecosystem func
The National Academy of Sciences.
-
19. Pleiotropy and Multilocus Polymorphisms
It is demonstrated that systems of two pleiotropically related characters controlled by additive diallelic loci can maintain under Gaussian stabilizing selection a stable polymorphism in more than two loci. It is also shown that such systems may have multiple stable polymorphic equilibria. Stabilizing selection generates negative linkage disequilibrium, as a
-
20. Evolution of continuous variation: direct approach through joint distribution of genotypes and phenotypes.
The evolutionary dynamics of the joint distribution of genotypes and phenotypes is studied. The model, originally devised to study the joint effects of Mendelian and other types of transmissions, provides results of interest also to the theory of direct Mendelian transmission with natural selection. Assuming bivariate normal distributions, it is shown that i
-
21. How Informative Is Wright's Estimator of the Number of Genes Affecting a Quantitative Character?
S. Wright suggested an estimator, m, of the number of loci, m, contributing to the difference in a quantitative character between two differentiated populations, which is calculated from the phenotypic means and variances in the two parental populations and their F(1) and F(2) hybrids. The same method can also be used to estimate m contributing to the geneti
-
22. Evaluation of the Culling Variate Used by Breeders in Actual Selection
The theoretical basis and computational procedures for estimating the culling variate utilized by breeders in actual selection are presented. The essential part of this procedure is to derive the unknown culling variate in terms of a linear combination of traits based on realized indirect selection differentials of those traits and phenotypic variances and c
-
23. Quantitative Genetics of DROSOPHILA MELANOGASTER. I. Sexual Dimorphism in Genetic Parameters for Wing Traits
Sexual dimorphism in genetic parameters is examined for wing dimensions of Drosophila melanogaster. Data are fit to a quantitative genetic model where phenotypic variance is a linear function of additive genetic autosomal variance (common to both sexes), additive genetic X-linked variances distinct for each sex, variance due to common rearing environment of
-
24. Correcting the Bias of Wright's Estimates of the Number of Genes Affecting a Quantitative Character: A Further Improved Method
Wright's method of estimating the number of genes contributing to the difference in a quantitative character between two populations involves observing the means and variances of the two parental populations and their hybrid populations. Although simple, Wright's method provides seriously biased estimates, largely due to linkage and unequal effects of allele