W G Hill

..The results can be applied to predict multi-locus identity in, for example, gene mapping...

..For descendants of full-sibs, the variation is reduced in later generations, but for descendants of half-sibs, it is increased...

..We demonstrate that these highly pleiotropic models can give results similar to those obtained in analyses of experimental data and that conclusions on limits to evolvability through pleiotropy are not robust...

..The fertility of a chicken's egg is a trait which depends on both the hen that lays the egg and on her mate. It is also known that fertility of an individual changes over the laying period...

..The results can be applied to detection of quantitative trait loci (QTL) by computing the probability of IBD at candidate loci in terms of identity-by-state at neighboring markers...

..The evidence for and implications of such variability in variance are discussed...

..Approximate sampling errors of the estimates are given. Methods are extended to estimate genetic distances and their sampling errors. The AFLP data from samples of breeds of pig are used for illustration...

..We conclude that interactions at the level of genes are not likely to generate much interaction at the level of variance...

..This appears to be a straightforward and potentially effective means of product tracing...

..Methods based on summary statistics and predictions rather than at the individual gene level seem likely to prevail for some time yet...

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..Results from long-term selection experiments in mice in this laboratory are described and related to the theoretical analyses with the aim of reconciling the evidence for substantial standing variation with the low rate of response...

..We also evaluate the opportunities for reducing VE in breeding programmes. Although empirical and theoretical studies have increased our understanding of genetic control of environmental variance, many issues remain unresolved...

..Analytical formulas are given for one or two loci, and simulation is used for more. It is shown that the method could have substantial discriminating ability and thus potential practical value...

..Extensions to these techniques allow reconstruction of half sibships when some or all of the maternal genotypes are known...

..Dominance effects in the females were found to be non-significant. No significant X-linked effect on carcass fat percentage was detected, but a single X-linked QTL appears to explain almost the entire X-linked body weight effect...

..Cows use body lipid to support lactation over 3 lactations and the profile of that use varies according to genotype and diet...

..The modified form shows less bias in its estimates of heritability than the likelihood technique originally proposed...

..7-6.4%) and CU (2-15%) animals. While sensitivity to leptin remains in the fat line, response appears to vary among animals at the dose level used...

..The simulations results are in general compatible with empirical observations...

..Litter size, food intake, and fat content also differ substantially. These inbred extreme selected lines are a uniquely valuable resource for QTL or gene mapping, candidate gene identification, and elucidation of epistatic effects...

..In this model, only a few parameters need to be estimated, and the residual variance is then a continuous function of time. The analysis of a sample data set illustrates this methodology...

..It is therefore concluded that testosterone metabolism has not contributed disproportionately to the response to artificial selection in spite of its known effects on growth and body composition...

..The simulation results and their implications are discussed in the context of biological conservation and tests for purging...

..8. Thus, in order to avoid continued selection for body weight reducing egg production to a point where natural selection offsets selection gains, alternative selection strategies should be considered...

..The interactions between the effects of the transgene and of the lit gene and the genetic background were, nevertheless, relatively small and therefore these results support a polygenic model of selection response...

..The interactions between the effects of the lit gene and the genetic background were, however, relatively small compared with these main effects and again indicate that other systems contributed most of the selection response...

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..We show by simulation that genetic drift, leptokurtosis of mutational effects, and pleiotropy can increase the mean-optimum deviation greatly, however, and that the apparent directional selection thereby caused can be substantial...

..If the magnitude of the environmental variance is not under genetic control, there is a complementary relationship between the levels of environmental and genetic variance such that the level of phenotypic variance is little affected...

..This conclusion is not robust for small populations because some mutants may become fixed, which indicates that other selective forces must be involved, such as an intrinsic cost of homogeneity...

..important, why do we age, which genetic processes can generate new species or drive endangered species to extinction, and how should policy on levels of potentially harmful mutagens introduced into the environment by humans be determined?..

..In this study, we use the Price equation to derive many such well-known results for the dynamics and equilibria of variances in a straightforward way and to develop them further...

..Estimates of variance component are biased, with the direction and magnitude of bias being dependent upon the underlying errors made during pedigree reconstruction...

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..This finding provides some promise that a high heritability can be explained under strong total stabilizing selection for what are regarded as typical values of mutation and selection parameters...

..Comparison with data from laboratory selection experiments shows that, overall, the analysis did not provide clear support for the joint-effect model or a clear case for rejection...

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..It is shown that a small homogeneity cost is enough to maintain the observed levels of environmental variance, whereas a large amount of temporal variation in the optimal phenotype and the strength of selection would be necessary...

..Thus considerations of dominance coefficients of mutations lend further support to our previous conclusion that mutation-selection balance is a plausible mechanism of the maintenance of the genetic variance in natural populations...

..Correlations between leptin level and fat amount were high (over 0.86) in fed or fasted animals of the F line, indicative of leptin resistance...

..We discuss here common themes, specific problems and pointers for future research...

..This line, when congenic, will be a useful resource in gene expression studies and for finding modifying genes...

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..The assumptions made in developing the theory and methods and the applications of MAS in conservation are discussed...

..This article suggests that dominance is the main cause for increased genetic variances for fitness components and fitness-related traits after bottlenecks observed in various experiments...

..Breeding values for energy balance can be calculated from single observations of BCS and linear type traits on daughters of a sire; data that can routinely be collected in national conformation assessment schemes...

..A higher frequency of inbreeding was estimated among the parasites that survived the dry season compared to the wet season...

..We also discuss the effects of population bottlenecks on covariances among relatives...

..These models offer a substantial flexibility for the correlation structure, even in the case of complex non-stationary patterns, and perform better than multivariate random regression models, with fewer parameters...

..Furthermore, it may be that the best indications of selection will come from population-specific F(ST) values rather than the usually reported population-average values...

..Genetic improvement of uniformity is particularly interesting for traits where the current population mean is near an intermediate optimum...

..Recent reports of substantial heritability for gene expression and new estimation methods using marker data highlight the relevance of heritability in the genomics era...

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..This paper presents a generalization of their approach to genetic analyses. The methodology is applied to daily records for milk production in dairy cattle and data on age-specific fertility in Drosophila...