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I show that fine-scale localization of a survival-related locus call be accomplished on the basis of deviations from Hardy-Weinberg equilibrium and linkage disequilibrium at closely linked marker loci. The method is based on [X.sup.2]-tests and they can be performed for age-specific samples of alive (or dead) individuals, as for combined samples of alive and dead individuals.

An exact stratified test is developed for Hardy-Weinberg equilibrium (HWE) for diallelic markers, such as single-nucleotide polymorphisms (SNPs) and an exact test for homogeneity of Hardy-Weinberg disequilibrium. These new methods are found to be useful for samples composed of multiple ethnic groups.

A computationally feasible approach that does not assume Hardy-Weinberg equilibrium, along with graphic displays and a statistical comparison of pair wise matrices of linkage disequilibrium (LD) between case and control samples is presented. The LD-contrast tests demonstrate substantially higher power under certain haplotype-driven disease models.

When the classical [chi square] goodness-of-fit test for Hardy-Weinberg (HW) equilibrium is used on samples with related individuals, the type I error can be greatly inflated. In particular the test is inappropriate in population isolates where the individuals are related through multiple lines of descent. In this article, we propose a new test for HW (the QL-HW test) suitable for any sample with related individuals, including large inbred pedigrees, provided that their genealogy is known. Performed conditional on the pedigree structure, the QL-HW test detects departures from HW that are not due to the genealogy. Because the computation of the QL-HW test becomes intractable for very polymorphic loci in large inbred pedigrees, a simpler alternative, the GCC-HW test, is also proposed. The statistical properties of the QL-HW and GCC-HW tests are studied through simulations considering a sample of independent nuclear families, a sample of extended outbred genealogies, and samples from the Hutterite population, a North American highly inbred isolate. Finally, the method is used to test a set of 143 biallelic markers spanning 82 genes in this latter population.

While nonrandom associations between zygotes at different loci (zygotic associations) frequently occur in Hardy-Weinberg disequilibrium populations, statistical analysis of such associations has received little attention. In this article, we describe the joint distributions of zygotes at multiple loci, which are completely characterized by heterozygosities at individual loci and various multilocus zygotic associations. These zygotic associations are defined in the same fashion as the usual multilocus linkage (gametic) disequilibria on the basis of gametic and allelic frequencies. The estimation and test procedures are described with details being given for three loci. The sampling properties of the estimates are examined through Monte Carlo simulation. The estimates of three-locus associations are not free of bias due to the presence of two-locus associations and vice versa. The power of detecting the zygotic associations is small unless different loci are strongly associated and/or sample sizes are large (>100). The analysis of zygotic associations not only offers an effective means of packaging numerous genic disequilibria required for a complete characterization of multilocus structure, but also provides opportunities for making inference about evolutionary and demographic processes through a comparative assessment of zygotic association vs. gametic disequilibrium for the same set of loci in nonequilibrium populations.

Results reveal significant population differentiation for life cycle, karyotype, and 17-locus microsatellite genotype differences in the spring populations of Myzus persicae. High clonal diversity and overall conformance to the Hardy-Weinberg law are discussed.

We develop models that describe the cytonuclear structure for either a cytoplasmic and nuclear marker in a haplodiploid species or a cytoplasmic and X-linked marker in a diploid species. Sex-specific disequilibrium statistics that summarize nonrandom cytonuclear associations in such systems are defined, and their basic Hardy-Weinberg dynamics and admixture formulae are delimited. We focus on the context of hybrid zones and develop continent-island models whereby individuals from two genetically differentiated source populations migrate into and mate within a single zone of admixture. We examine the effects of differential migration of the sexes, assortative mating by pure type females, and census time (relative to mating and migration), as well as special cases of random mating and migration subsumed under the general models. We show that pure type individuals and nonzero cytonuclear disequilibria can be maintained within a hybrid zone if there is continued migration from both source populations, and that females generally have a greater influence over these cytonuclear variables than males. The resulting theoretical framework can be used to estimate the rates of assortative mating and sex-specific gene flow in hybrid zones and other zones of admixture involving haplodiploid or sex-linked cytonuclear data.

Allozyme electrophoresis facilitated the determination of the specific status of two morphs of the scleractinian coral Montipora digitata. The occurrence of sexual reproduction is suggested by the population of both morphs, which are in the Hardy-Weinberg equilibrium. The genetic diversity ratio reveals the occurrence of asexual reproduction, which influences genetic differentiation between different populations.

Hardy-Weinberg principle contradicts the conventional theory of genetic revitalization proposed by the eugenicists. The conventional theory indicates that segregating individuals affected by physical and psychological disorder from the process of reproduction will result in a society with near-perfect individuals. The Hardy-Weinberg principle reveals that such characteristics of individuals are not inherited but acquired from the environment under which they are subjected to.

Studies are conducted to examine whether breeds and subbreeds comply with Hardy-Weinberg equilibrium (HWE) as a useful indicator of genotype frequencies within a population. Results indicate that canine case-control association studies would be reasonable if performed within defined breeds.

Allozyme electrophoresis is used to estimate deviations from expected levels of heterozygosity under Hardy-Weinberg equilibrium to infer selfing rates in 10 species from 36 New Zealand populations. It is found that while there are deficiencies of heterozygotes compared to expectation in both monoicous and dioicous mosses, monoicous species had considerably higher levels of heterozygote deficiency than diocous species.

The genetic structure of the Sardina pilchardus population in the Bay of Biscay was investigated and analyzed to identify genetic clines between geographic factors and genetic indices. It is found that the process driving the cline throughout the Bay of Biscay for Sardina pilchardus is difficult to compute from the usual analysis of genetic structure.

Much forensic inference based upon DNA evidence is made assuming that the Hardy-Weinberg equilibrium (HWE) is valid for the genetic loci being used. Several statistical tests to detect and measure deviation from HWE have been devised, each having advantages and limitations. The limitations become more obvious when testing for deviation within multiallelic DNA loci is attempted. Here we present an exact test for HWE in the biallelic case, based on the ratio of weighted likelihoods under the null and alternative hypotheses, the Bayes factor. This test does not depend on asymptotic results and minimizes a linear combination of type I and type II errors. By ordering the sample space using the Bayes factor, we also define a significance (evidence) index, P value, using the weighted likelihood under the null hypothesis. We compare it to the conditional exact test for the case of sample size n = 10. Using the idea under the method of [chi square] partition, the test is used sequentially to test equilibrium in the multiple allele case and then applied to two short tandem repeat loci, using a real Caucasian data bank, showing its usefulness.

The usual approach to characterizing and estimating multilocus associations in a diploid population assumes that the population is in Hardy-Weinberg equilibrium. The purpose of this study is to develop a set of summary statistics that can be used to characterize and estimate the multilocus associations in a nonequilibrium population. The concept of 'zygotic associations' is first expanded to facilitate the development. The summary statistics are calculated using the distribution of a random variable, the number of heterozygous loci (K) found in diploid individuals in the population. In particular, the variance of K consists of single-locus and multilocus components with the latter being the sum of zygotic associations between pairs of loci. Simulation results show that the multilocus associations in the variance of K are detectable in a sample of moderate size ([is greater than or equal to] 30) when the sum of all pairwise zygotic associations is greater than zero and when gene frequency is intermediate. The method presented here is a generalization of the well-known development for the Hardy-Weinberg equilibrium population and thus may be of more general use in elucidating the multilocus organizations in nonequilibrium and equilibrium populations.