Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “quantitative genetics”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 541 records · Page 30Linked to original sources
PubMed1982

Relationships among ontogenetic, static, and evolutionary allometry.

The relationship between ontogenetic, static, and evolutionary levels of allometry is investigated. Extrapolation from relative size relationships in adults to relative growth in ontogeny depends on the variability of slopes and intercepts of ontogenetic vectors relative to variability in length of the vector. If variability in slopes and intercepts is low relative to variability in length, ontogenetic and static allometries will be similar. The similarity of ontogenetic and static allometries was tested by comparing the first principal component, or size vector, for correlations among 48 cranial traits in a cross-sectional ontogenetic sample of rhesus macaques from Cayo Santiago with a static sample from which all age- and sex-related variation had been removed. The vector correlation between the components is high but significantly less than one while two of three allometric patterns apparent in the ontogenetic component are not discernable in the static component. This indicates that there are important differences in size and shape relationships among adults and within ontogenies. Extrapolation from intra-or interspecific phenotypic allometry to evolutionary allometry is shown to depend on the similarity of genetic and phenotypic allometry patterns. Similarity of patterns was tested by comparing the first principal components of the phenotypic, genetic, and environmental correlation matrices calculated using standard quantitative genetic methods. The patterns of phenotypic, genetic, and environmental allometry are dissimilar; only the environmental allometries show ontogenetic allometric patterns. This indicates that phenotypic allometry may not be an accurate guide to patterns of evolutionary change in size and shape.

Aging↗
PubMed2001

Courtship songs of Drosophila pseudoobscura and D. persimilis. II. Genetics of species differences.

Although male courtship songs have been repeatedly implicated in sexual isolation between numerous Drosophila species, no genetic studies have evaluated the genetic basis of differences between species beyond using quantitative genetic analyses of hybrids or surveying associations of song characters to five or fewer genetic markers. Here, we dissect the genetic basis of the difference between D. pseudoobscura and D. persimilis in two courtship song elements (interpulse interval and intrapulse frequency) using 15 molecular markers. We also evaluate the association between song elements and sexual isolation in these backcross hybrid males of these species. We find that song differences between these species are associated with at least two or three genomic regions, and the species difference in interpulse interval may be oligogenic. Courtship song differences are especially strongly associated with two inversions that differentiate these species. Further, we found that interpulse interval is strongly associated with mating success to D. pseudoobscura females, while intrapulse frequency is associated with mating success to D. persimilis females. Implications of these findings are discussed.

Animals↗
PubMed2003

Divergent selection maintains adaptive differentiation despite high gene flow between sympatric rainbow smelt ecotypes (Osmerus mordax Mitchill).

In this study, we investigate the relative role of historical factors and evolutionary forces in promoting population differentiation in a new case of sympatric dwarf and normal ecotypes of the rainbow smelt (Osmerus mordax Mitchill) in Lac Saint-Jean (Québec, Canada). Our first objective was to test the hypothesis that the evolution of sympatric smelt ecotypes in Lac Saint-Jean has been contingent upon the secondary contact between two evolutionary lineages in postglacial times. Secondly, the QST method was applied to test the null hypothesis that the extent of phenotypic differences relative to that of neutral marker variation would be similar in comparisons involving populations within and among ecotypes. Thirdly, we applied a quantitative-genetic method as an exploratory assessment as to whether the amount of gene flow observed between populations could affect divergence in adaptive traits under specific conditions. This study revealed a unique situation of dwarf and normal smelt ecotypes that are, respectively, characterized by selmiparous and iteroparous life histories and the occurrence in each of two genetically distinct populations that synchronously use the same spawning habitat in two tributaries. Historical contingency has apparently played little role in the origin of these populations. In contrast, an important role of divergent natural selection in driving their phenotypic divergence was suggested. While divergent selection has apparently been strong enough to maintain phenotypic differentiation in the face of migration, this study suggests that gene flow has been sufficiently important to modulate the extent of adaptive differentiation being achieved between ecotypes, unless the extent of stabilizing selection acting on smelt ecotypes is much more pronounced than usually reported in natural populations.

Adaptation, Biological↗
PubMed2005

The evolutionary origin and elaboration of sociality in the aculeate Hymenoptera: maternal effects, sib-social effects, and heterochrony.

We discuss the evolutionary origin and elaboration of sociality using an indirect genetic effects perspective. Indirect genetic effects models simultaneously consider zygotic genes, genes expressed in social partners (especially mothers and siblings), and the interactions between them. Incorporation of these diverse genetic effects should lead to more realistic models of social evolution. We first review haplodiploidy as a factor that promotes the evolution of eusociality. Social insect biologists have doubted the importance of relatedness asymmetry caused by haplodiploidy and focused on other predisposing factors such as maternal care. However; indirect effects theory shows that maternal care evolves more readily in haplodiploids, especially with inbreeding and despite multiple mating. Because extended maternal care is believed to be a precondition for the evolution of eusociality, the evolutionary bias towards maternal care in haplodiploids may result in a further bias towards eusociality in these groups. Next, we compare kin selection and parental manipulation and then briefly review additional hypotheses for the evolutionary origin of eusociality. We present a verbal model for the evolutionary origin and elaboration of sib-social care from maternal care based on the modification of the timing of expression of maternal care behaviors. Specifically, heterochrony genes cause maternal care behaviors to be expressed prereproductively towards siblings instead of postreproductively towards offspring. Our review demonstrates that both maternal effect genes (expressed in a parental manipulation manner) and direct effect zygotic genes (expressed in an offspring control manner) are likely involved in the evolution of eusociality. We conclude by describing theoretical and empirical advances with indirect genetic effects and sociogenomics, and we provide specific quantitative genetic and genomic predictions from our heterochrony model for the evolutionary origin and elaboration of eusociality.

Animals↗
PubMed2000

Selective genotyping with epistasis can be utilized for a major quantitative trait locus mapping in hypertension in rats.

Epistasis used to be considered an obstacle in mapping quantitative trait loci (QTL) despite its significance. Numerous epistases have proved to be involved in quantitative genetics. We established a backcross model that demonstrates a major QTL for hypertension (Ht). Seventy-eight backcrossed rats (BC), derived from spontaneously hypertensive rats (SHR) and normotensive Fischer 344 rats, showed bimodal distribution of systolic blood pressure (BP) values and a phenotypic segregation ratio consistent with 1:1. In this backcross analysis, sarco(endo)plasmic reticulum Ca(2+)-dependent ATPase (Serca) II heterozygotes showed widespread bimodality in frequency distribution of BP values and obviously demonstrated Ht. First, in genome-wide screening, Mapmaker/QTL analysis mapped Ht at a locus between D1Mgh8 and D1Mit4 near Sa in all 78 BC. The peak logarithm of the odds (LOD) score reached 5.3. Second, Serca II heterozygous and homozygous BC were analyzed separately using Mapmaker/QTL. In the 35 Serca II heterozygous BC, the peak LOD score was 3.8 at the same locus whereas it did not reach statistical significance in the 43 Serca II homozygotes. Third, to map Ht efficiently, we selected 18 Serca II heterozygous BC with 9 highest and 9 lowest BP values. In these 18 BC, the peak LOD score reached 8.1. In 17 of the 18, D1Mgh8 genotypes (homo or hetero) qualitatively cosegregated with BP phenotypes (high or low) (P < 0.0001, by chi-square analysis). In conclusion, selective genotyping with epistasis can be utilized for a major QTL mapping near Sa on chromosome 1 in SHR.

Animals↗
PubMed2000

Genetic determinants of acute hypoxic ventilation: patterns of inheritance in mice.

Acutely lowering ambient O(2) tension increases ventilation in many mammalian species, including humans and mice. Inheritance patterns among kinships and between mouse strains suggest that a robust genetic influence determines individual hypoxic ventilatory responses (HVR). Here, we tested specific genetic hypotheses to describe the inheritance patterns of HVR phenotypes among two inbred mouse strains and their segregant and nonsegregant progeny. Using whole body plethysmography, we assessed the magnitude and pattern of ventilation in C3H/HeJ (C3) and C57BL/6J (B6) progenitor strains at baseline and during acute (3-5 min) hypoxic [mild hypercapnic hypoxia, inspired O(2) fraction (FI(O(2))) = 0.10] and normoxic (mild hypercapnic normoxia, FI(O(2)) = 0.21) inspirate challenges in mild hypercapnia (inspired CO(2) fraction = 0.03). First- and second-filial generations and two backcross progeny were also studied to assess response distributions of HVR phenotypes relative to the parental strains. Although the minute ventilation (VE) during hypoxia was comparable between the parental strains, breathing frequency (f) and tidal volume were significantly different; C3 mice demonstrated a slow, deep HVR relative to a rapid, shallow phenotype of B6 mice. The HVR profile in B6C3F(1)/J mice suggested that this offspring class represented a third phenotype, distinguishable from the parental strains. The distribution of HVR among backcross and intercross offspring suggested that the inheritance patterns for f and VE during mild hypercapnic hypoxia are consistent with models that incorporate two genetic determinants. These results further suggest that the quantitative genetic expression of alleles derived from C3 and B6 parental strains interact to significantly attenuate individual HVR in the first- and second-filial generations. In conclusion, the genetic control of HVR in this model was shown to exhibit a relatively simple genetic basis in terms of respiratory timing characteristics.

Acute Disease↗
PubMed2004

Mapping quantitative trait Loci interactions from the maternal and offspring genomes.

The expression of most developmental or behavioral traits involves complex interactions between quantitative trait loci (QTL) from the maternal and offspring genomes. The maternal-offspring interactions play a pivotal role in shaping the direction and rate of evolution in terms of their substantial contribution to quantitative genetic (co)variation. To study the genetics and evolution of maternal-offspring interactions, a unifying statistical framework that embraces both the direct and indirect genetic effects of maternal and offspring QTL on any complex trait is developed. This model is derived for a simple backcross design within the maximum-likelihood context, implemented with the EM algorithm. Results from extensive simulations suggest that this model can provide reasonable estimation of additive and dominant effects of the QTL at different generations and their interaction effects derived from the maternal and offspring genomes. Although our model is framed to characterize the actions and interactions of maternal and offspring QTL affecting offspring traits, the idea can be readily extended to decipher the genetic machinery of maternal traits, such as maternal care. Our model provides a powerful means for studying the evolutionary significance of indirect genetic effects in any sexually reproductive organisms.

Animals↗
PubMed2006

Identifying quantitative trait locus by genetic background interactions in association studies.

Association studies are designed to identify main effects of alleles across a potentially wide range of genetic backgrounds. To control for spurious associations, effects of the genetic background itself are often incorporated into the linear model, either in the form of subpopulation effects in the case of structure or in the form of genetic relationship matrices in the case of complex pedigrees. In this context epistatic interactions between loci can be captured as an interaction effect between the associated locus and the genetic background. In this study I developed genetic and statistical models to tie the locus by genetic background interaction idea back to more standard concepts of epistasis when genetic background is modeled using an additive relationship matrix. I also simulated epistatic interactions in four-generation randomly mating pedigrees and evaluated the ability of the statistical models to identify when a biallelic associated locus was epistatic to other loci. Under additive-by-additive epistasis, when interaction effects of the associated locus were quite large (explaining 20% of the phenotypic variance), epistasis was detected in 79% of pedigrees containing 320 individuals. The epistatic model also predicted the genotypic value of progeny better than a standard additive model in 78% of simulations. When interaction effects were smaller (although still fairly large, explaining 5% of the phenotypic variance), epistasis was detected in only 9% of pedigrees containing 320 individuals and the epistatic and additive models were equally effective at predicting the genotypic values of progeny. Epistasis was detected with the same power whether the overall epistatic effect was the result of a single pairwise interaction or the sum of nine pairwise interactions, each generating one ninth of the epistatic variance. The power to detect epistasis was highest (94%) at low QTL minor allele frequency, fell to a minimum (60%) at minor allele frequency of about 0.2, and then plateaued at about 80% as alleles reached intermediate frequencies. The power to detect epistasis declined when the linkage disequilibrium between the DNA marker and the functional polymorphism was not complete.

Animals↗
PubMed1998

Developmental loss of effect of a Chromosome 15 QTL on alcohol acceptance.

Human alcohol abuse and alcoholism have clear developmental features, suggesting the possibility of changes over time in heritability and in quantitative genetic architecture, and raising prospects of identifying individual genes or quantitative trait loci (QTLs) that display different influence on alcohol-related phenotypes at different ages. The identification of specific loci showing such age-related changes will open up opportunities of focused association studies and of genotype manipulation by various mating procedures. Most animal model research in alcohol assesses the phenotypes of the animals at an early age; developmental studies are rare. Here we report on a QTL on Chromosome (Chr) 15 of the mouse that has been shown in several populations, including BXD recombinant inbred strains, an F2, and genotypically selected lines, to affect a measure of alcohol consumption. In the present study, we measured alcohol acceptance in the genotypically selected animals and in an F4 sample at about 100 days and again at about 300 days of age. In both groups, and in both sexes, significant differences were observed at 100 days between animals that were homozygous for the "increasing" haplotype defining the QTL region and those homozygous for the "decreasing" haplotype. At 300 days of age, the effect is absent in females and has diminished or disappeared in males. The results provide a further confirmation of the Chr 15 QTL in young mice, offer a new perspective on the development of alcohol-related phenotypes, and have strong implications for research design.

Alcohol Drinking↗
PubMed2005

Environmental quality and evolutionary potential: lessons from wild populations.

An essential requirement to determine a population's potential for evolutionary change is to quantify the amount of genetic variability expressed for traits under selection. Early investigations in laboratory conditions showed that the magnitude of the genetic and environmental components of phenotypic variation can change with environmental conditions. However, there is no consensus as to how the expression of genetic variation is sensitive to different environmental conditions. Recently, the study of quantitative genetics in the wild has been revitalized by new pedigree analyses based on restricted maximum likelihood, resulting in a number of studies investigating these questions in wild populations. Experimental manipulation of environmental quality in the wild, as well as the use of naturally occurring favourable or stressful environments, has broadened the treatment of different taxa and traits. Here, we conduct a meta-analysis on recent studies comparing heritability in favourable versus unfavourable conditions in non-domestic and non-laboratory animals. The results provide evidence for increased heritability in more favourable conditions, significantly so for morphometric traits but not for traits more closely related to fitness. We discuss how these results are explained by underlying changes in variance components, and how they represent a major step in our understanding of evolutionary processes in wild populations. We also show how these trends contrast with the prevailing view resulting mainly from laboratory experiments on Drosophila. Finally, we underline the importance of taking into account the environmental variation in models predicting quantitative trait evolution.

Animals↗
PubMed1992

Remating effects on the genetic structure of female life histories in populations of Drosophila mojavensis.

A quantitative genetic analysis of nine adult fitness components was performed in two populations of cactophilic Drosophila mojavensis under natural conditions of fermenting cactus and ethanol vapour. Female progeny from 18 sires and 36 dams were treated to a range of six exposure periods to males to assess effects of remating frequency on female fitness. Lifetime fecundity increased with increasing male exposure, but longevity showed an intermediate optimum with temporary exposure to males of 2-4 days. Narrow-sense heritabilities were significant for egg production traits while broad-sense heritabilities were significant for longevity-related traits. Positive genetic correlations between components of fitness were expressed among functionally related traits, e.g. longevity was positively correlated with lifetime fecundity, the number of clutches laid, clutch size, and the number of eggs laid per day. Negative genetic correlations were detected between early and late life fecundity suggesting genetic tradeoffs among components of adult fitness.

Animal Nutritional Physiological Phenomena↗
PubMed2005

Quantitative genomics of starvation stress resistance in Drosophila.

BACKGROUND: A major challenge of modern biology is to understand the networks of interacting genes regulating complex traits, and the subset of these genes that affect naturally occurring quantitative genetic variation. Previously, we used P-element mutagenesis and quantitative trait locus (QTL) mapping in Drosophila to identify candidate genes affecting resistance to starvation stress, and variation in resistance to starvation stress between the Oregon-R (Ore) and 2b strains. Here, we tested the efficacy of whole-genome transcriptional profiling for identifying genes affecting starvation stress resistance. RESULTS: We evaluated whole-genome transcript abundance for males and females of Ore, 2b, and four recombinant inbred lines derived from them, under control and starved conditions. There were significant differences in transcript abundance between the sexes for nearly 50% of the genome, while the transcriptional response to starvation stress involved approximately 25% of the genome. Nearly 50% of P-element insertions in 160 genes with altered transcript abundance during starvation stress had mutational effects on starvation tolerance. Approximately 5% of the genome exhibited genetic variation in transcript abundance, which was largely attributable to regulation by unlinked genes. Genes exhibiting variation in transcript abundance among lines did not cluster within starvation resistance QTLs, and none of the candidate genes affecting variation in starvation resistance between Ore and 2b exhibited significant differences in transcript abundance between lines. CONCLUSIONS: Expression profiling is a powerful method for identifying networks of pleiotropic genes regulating complex traits, but the relationship between variation in transcript abundance among lines used to map QTLs and genes affecting variation in quantitative traits is complicated.

Adaptation, Physiological↗
PubMed1979

A review of research on genetic variation in physiological characteristics related to performance in dairy cattle.

Genetic influence on physiological characteristics ranges from single gene effects on amino acid substitutions in alternative forms of proteins to quantitative genetic effects on the amounts of enzymes and hormones. The number of loci involved in the control of quantitative variation in physiologically important substances is not known. A number of marker genes that affect blood antigens, serum and milk proteins, and enzymes have been identified in dairy cattle. However, relatively little is known about genetic effects on quantitative physiological traits in dairy cattle. Much more is known about the genetic control of hormones in laboratory animals. About 25% of the variation in milk production of dairy cows results from genetic differences. We need more studies of genetic influences on the various physiological and biochemical processes involved in the secretion of milk to reveal the mechanisms by which genetics influences the quantity and quality of milk produced by individual cows.

Animals↗
PubMed2003

Heritability of energetics in a wild mammal, the leaf-eared mouse (Phyllotis darwini).

As a first examination of the additive genetic variance of thermoregulatory traits in a natural population of endotherms, we studied the quantitative genetics of key physiological ecology traits in the leaf-eared mouse, Phyllotis darwini. We measured basal metabolic rate (BMR), nonshivering thermogenesis (NST), maximum metabolic rate for thermoregulation (MMR), thermal conductance (CT), body temperature (Tb), and factorial aerobic scope (FAS) in individuals acclimated to cold and warm conditions. For comparability with previous studies, we included the following morphological traits: foot length (FL), total length (TL), body mass (mb, at birth, sexual maturity, 6 months, and 8 months). Variance components were obtained from two different procedures: the expected variance component in an ANOVA Type III sum of squares and an animal model approach using restricted maximum likelihood. Results suggest the presence of additive genetic variance in FL (h2 = 0.47, P = 0.045), CT of cold-acclimated animals (h2 = 0.66, P = 0.041), and night body temperature, measured in cold-acclimated animals (h2 = 0.68, P = 0.080). Heritabilities of mb were near zero at all ages, but maternal effects and common environment effects were high and significant. We found no evidence of additive genetic variance in BMR, NST, MMR, or FAS (i.e., estimates were not significantly different from zero for all tests). Our results are in general agreement with previous studies of mammals that reported low heritability for: (1) BMR and MMR; (2) daytime body temperature; and (3) body mass for wild, but not laboratory or domestic, populations.

Acclimatization↗
PubMedDate not supplied

Genotypic selection provides experimental confirmation for an alcohol consumption quantitative trait locus in mouse.

Quantitative genetic research has produced a wealth of basic information concerning genetic influence on alcohol-related processes. Recent developments in quantitative trait locus (QTL) methodology were promptly applied to the task of individuating polygenes affecting alcohol-related attributes in animal models and a body of reliable data is gradually coming into focus as a result of replication and convergence of evidence from a variety of methods. A key issue in QTL research is the need to distinguish true positive results from the false positive results that are inherent in analytical procedures requiring large numbers of significance tests. One school of thought holds that stringent significance levels should be imposed; another suggests more modest criteria for QTL nomination, with subsequent confirmation trials with independent samples. Recombinant inbred strains and various types of intercrosses have been used in correlational designs, both for nomination and confirmation studies. Alternative experimental procedures include knockout preparations and short-term phenotypic selective breeding. We present here results from a third experimental method-that of marker-based genotypic selection--in evaluation of two nominated QTLs for alcohol acceptance in mice.

Alcohol Drinking↗
PubMed2001

When sources become sinks: migrational meltdown in heterogeneous habitats.

We consider the evolution of ecological specialization in a landscape with two discrete habitat types connected by migration, for example, a plant-insect system with two plant hosts. Using a quantitative genetic approach. we study the joint evolution of a quantitative character determining performance in each habitat together with the changes in the population density. We find that specialization on a single habitat evolves with intermediate migration rates, whereas a generalist species evolves with both very low and very large rates of movement between habitats. There is a threshold at which a small increase in the connectivity of the two habitats will result in dramatic decrease in the total population size and the nearly complete loss of use of one of the two habitats through a process of "migrational meltdown." In some situations, equilibria corresponding to a specialist and a generalist species are simultaneously stable. Analysis of our model also shows cases of hysteresis in which small transient changes in the landscape structure or accidental demographic disturbances have irreversible effects on the evolution of specialization.

Animal Migration↗
PubMed2000

Mapping a quantitative trait locus via the EM algorithm and Bayesian classification.

Mapping a locus controlling a quantitative genetic trait (e.g., blood pressure) to a specific genomic region is of considerable interest. Data on the quantitative trait under consideration and several codominant genetic markers with known genomic locations are collected from members of families and statistically analyzed to draw inferences on the genomic position of the trait locus. The vector of parameters of interest comprises the pairwise recombination fractions, theta, between the putative quantitative trait locus and the marker loci. One of the major complications in estimating theta for a quantitative trait in humans is the lack of haplotype information on members of families. The purpose of this study was to devise a computationally simple and efficient method of estimation of theta in the absence of haplotype information. We have proposed a two-stage estimation procedure using the expectation-maximization (EM) algorithm. In the first stage, parameters of the QTL are estimated based on data of a sample of unrelated individuals. From estimates thus obtained, we have used a Bayes' rule to infer QTL genotypes of parents in families. Finally, in the second stage of the procedure, we have proposed an EM algorithm for obtaining the maximum likelihood estimate of theta based on data of informative families (which are identified upon inferring parental QTL genotypes performed in the first stage). We have shown, using simulated data, that the proposed procedure is cost-effective, computationally simple, and statistically efficient. As expected, analysis of data on multiple markers jointly is more efficient than the analysis based on single markers.

Algorithms↗
PubMed2003

Congenic strains of mice for verification and genetic decomposition of quantitative trait loci for femoral bone mineral density.

Peak femoral volumetric bone mineral density (femoral bone mineral density) in C57BL/6J (B6) 4-month-old female mice is 50% lower than in C3H/HeJ (C3H) and 34% lower than in CAST/EiJ (CAST) females. Genome-wide analyses of (B6 x C3H)F2 and (B6 x CAST)F2 4-month-old female progeny demonstrated that peak femoral bone mineral density is a complex quantitative trait associated with genetic loci (QTL) on numerous chromosomes (Chrs) and with trait heritabilities of 83% (C3H) and 57% (CAST). To test the effect of each QTL on femoral bone mineral density, two sets of loci (six each from C3H and CAST) were selected to make congenic strains by repeated backcrossing of donor mice carrying a given QTL-containing chromosomal region to recipient mice of the B6 progenitor strain. At the N6F1 generation, each B6.C3H and B6.CAST congenic strain (statistically 98% B6-like in genomic composition) was intercrossed to obtain N6F2 progeny for testing the effect of each QTL on femoral bone mineral density. In addition, the femoral bone mineral density QTL region on Chr 1 of C3H was selected for congenic subline development to facilitate fine mapping of this strong femoral bone mineral density locus. In 11 of 12 congenic strains, 6 B6.C3H and 5 B6.CAST, femoral bone mineral density in mice carrying c3h or cast alleles in the QTL regions was significantly different from that of littermates carrying b6 alleles. Differences also were observed in body weight, femoral length, and mid-diaphyseal periosteal circumference among these 11 congenic strains when compared with control littermates; however, these latter three phenotypes were not consistently correlated with femoral bone mineral density. Analyses of eight sublines derived from the B6.C3H-1T congenic region revealed two QTLs: one located between 36.9 and 49.7 centiMorgans (cM) and the other located between 73.2 and 100.0 cM distal to the centromere. In conclusion, these congenic strains provide proof of principle that many QTLs identified in the F2 analyses for femoral bone mineral density exert independent effects when transferred and expressed in a common genetic background. Furthermore, significant differences in femoral bone mineral density among the congenic strains were not consistently accompanied by changes in body weight, femur length, or periosteal circumference. Finally, decomposition of QTL regions by congenic sublines can reveal additional loci for phenotypes assigned to a QTL region and can markedly refine genomic locations of quantitative trait loci, providing the opportunity for candidate gene testing.

Alleles↗