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Maternal Genetic Effects (maternal + genetic_effects)
Selected AbstractsMaternal genetic effects on adaptive divergence between anadromous and resident brook charr during early life historyJOURNAL OF EVOLUTIONARY BIOLOGY, Issue 5 2005G. M. L. PERRY Abstract The importance of directional selection relative to neutral evolution may be determined by comparing quantitative genetic variation in phenotype (QST) to variation at neutral molecular markers (FST). Quantitative divergence between salmonid life history types is often considerable, but ontogenetic changes in the significance of major sources of genetic variance during post-hatch development suggest that selective differentiation varies by developmental stage. In this study, we tested the hypothesis that maternal genetic differentiation between anadromous and resident brook charr (Salvelinus fontinalis Mitchill) populations for early quantitative traits (embryonic size/growth, survival, egg number and developmental time) would be greater than neutral genetic differentiation, but that the maternal genetic basis for differentiation would be higher for pre-resorption traits than post-resorption traits. Quantitative genetic divergence between anadromous (seawater migratory) and resident Laval River (Québec) brook charr based on maternal genetic variance was high (QST > 0.4) for embryonic length, yolk sac volume, embryonic growth rate and time to first response to feeding relative to neutral genetic differentiation [FST = 0.153 (0.071,0.214)], with anadromous females having positive genetic coefficients for all of the above characters. However, QST was essentially zero for all traits post-resorption of the yolk sac. Our results indicate that the observed divergence between resident and anadromous brook charr has been driven by directional selection, and may therefore be adaptive. Moreover, they provide among the first evidence that the relative importance of selective differentiation may be highly context-specific, and varies by genetic contributions to phenotype by parental sex at specific points in offspring ontogeny. This in turn suggests that interpretations of QST - FST comparisons may be improved by considering the structure of quantitative genetic architecture by age category and the sex of the parent used in estimation. [source] Variance components due to direct genetic, maternal genetic and permanent environmental effect for growth and feed-efficiency traits in young male Japanese Black cattleJOURNAL OF ANIMAL BREEDING AND GENETICS, Issue 3 2007M. A. Hoque Summary Variance components and genetic parameters were estimated using data recorded on 740 young male Japanese Black cattle during the period from 1971 to 2003. Traits studied were feed intake (FI), feed-conversion ratio (FCR), residual feed intake (RFI), average daily gain (ADG), metabolic body weight (MWT) at the mid-point of the test period and body weight (BWT) at the finish of the test (345 days). Data were analysed using three alternative animal models (direct, direct + maternal environmental, and direct + maternal genetic effects). Comparison of the log likelihood values has shown that the direct genetic effect was significant (p < 0.05) for all traits and that the maternal environmental effects were significant (p < 0.05) for MWT and BWT. The heritability estimates were 0.20 ± 0.12 for FI, 0.14 ± 0.10 for FCR, 0.33 ± 0.14 for RFI, 0.19 ± 0.12 for ADG, 0.30 ± 0.14 for MWT and 0.30 ± 0.13 for BWT. The maternal effects (maternal genetic and maternal environmental) were not important in feed-efficiency traits. The genetic correlation between RFI and ADG was stronger than the corresponding correlation between FCR and ADG. These results provide evidence that RFI should be included for genetic improvement in feed efficiency in Japanese Black breeding programmes. [source] Estimates of direct and maternal genetic effects for weights from birth to 600 days of age in Nelore cattleJOURNAL OF ANIMAL BREEDING AND GENETICS, Issue 2 2001Galvão de Albuquerque Estimates of direct and maternal variance and heritability for weights at each week (up to 280 days of age) and month of age (up to 600 days of age) in Zebu cattle are presented. More than one million records on 200 000 animals, weighed every 90 days from birth to 2 years of age, were available. Data were split according to week (data sets 1) or month (data sets 2) of age at recording, creating 54 and 21 data sets, respectively. The model of analysis included contemporary groups as fixed effects, and age of dam (linear and quadratic) and age of calf (linear) effects as covariables. Random effects fitted were additive direct and maternal genetic effects, and maternal permanent environmental effect. Direct heritability estimates decreased from 0.28 at birth, to 0.12,0.13 at about 150 days of age, stayed more or less constant at 0.14,0.16 until 270 days of age and increased with age after that, up to 0.25,0.26. Maternal heritability estimates increased from birth (0.01) to a peak of 0.14 for data sets 1 and 0.07,0.08 for data sets 2 at about 180,210 days of age, before decreasing slowly to 0.07 and 0.05, respectively, at 300 days, and then rapidly diminished after 300 days of age. Permanent environmental effects were 1.5 to four times higher than genetic maternal effects and showed a similar trend. Schätzung von direkten und maternal genetischen Effekten für Gewichte von der Geburt bis zum 600. Lebenstag beim Nelore-Rind Es werden Schätzwerte für die direkte und maternale Varianz sowie für Heritabilitäten der Gewichte in jeder Woche (bis zum 280. Lebenstag) und für jeden Monat (bis zum 600. Lebenstag) beim Zebu Rind gezeigt. Mehr als eine Million Datensätze vom 200.000 Tieren standen zur Verfügung, die alle 90 Tage bis zum zweiten Lebensjahr gewogen wurden. Die Daten wurden entsprechend dem Alter in Wochen (Datenset 1) oder Monaten (Datenset 2) aufgeteilt, woraus 54 bzw. 21 Datensets entstanden. Die Modelle beinhalteten Tiergruppen, die zur gleichen Zeit gelebt haben, als fixen Effekt, das Alter der Mutter (linear und quadratisch) und das Alter des Kalbes (linear) als Kovariablen. Als zufällige Effekte wurden der additive direkte, maternal genetische Effekt und maternal permanente Umwelteffekt berücksichtigt. Direkte Heritabilitätsschätzungen nahmen von 0,28 von Geburt auf 0,12,0,13 bei ca. 150 Lebenstagen ab, blieben mehr oder weniger konstant bei 0,14,0,16 bis zum 270. Lebenstag und nahmen ab dem 270. Lebenstag auf 0,25,0,26 zu. Maternale Heritabilitätsschätzungen nahmen von Geburt (0,01) zu einem Peak von 0, 14 beim Datenset 1 und 0,07,0,8 beim Datenset 2 bis ca. 180,210 Lebenstagen zu, bevor sie langsam wieder auf 0,07 bzw. 0,05 bei einem Alter von 300 Tagen sanken. Nach 300 Lebenstagen sanken sie rapide ab. Permanente Umwelteffekte waren 1,5 bis vierfach höher als genetisch maternale Effekte und zeigten einen ähnlichen Trend. [source] Genetic parameters for individual birth and weaning weight and for litter size of Large White pigsJOURNAL OF ANIMAL BREEDING AND GENETICS, Issue 3 2000D. Kaufmann Summary Data from a French experimental herd recorded between 1990 and 1997 were used to estimate genetic parameters for individual birth and weaning weight, as well as litter size of Large White pigs using restricted maximum likelihood (REML) methodology applied to a multivariate animal model. In addition to fixed effects the model included random common environment of litter, direct and maternal additive genetic effects. The data consisted of 1928 litters including individual weight observations from 18151 animals for birth weight and from 15360 animals for weaning weight with 5% of animals transferred to a nurse. Estimates of direct and maternal heritability and proportion of the common environmental variance for birth weight were 0.02, 0.21 and 0.11, respectively. The corresponding values for weaning weight were 0.08, 0.16 and 0.23 and for litter size 0.22, 0.02 and 0.06, respectively. The direct and the maternal genetic correlations between birth and weaning weight were positive (0.59 and 0.76). Weak positive (negative) genetic correlations between direct effects on weight traits and maternal effects on birth weight (weaning weight) were found. Negative correlations were found between direct genetic effect for litter size and maternal genetic effects on all three traits. The negative relationship between litter size and individual weight requires a combined selection for litter size and weight. Zusammenfassung Daten einer französischen Versuchsherde aus den Jahren 1990 bis 1997 wurden für die Schätzung von genetischen Parametern für individuelles Geburts-, Absetzgewicht und Wurfgrösse bei französischen Large White verwendet. Die Schätzung der Parameter erfolgte mit der Restricted Maximum Likelihood Methode (REML) angewandt auf ein multivariates Tiermodell. Neben fixen Effekten berücksichtigte das Modell die zufällige gemeinsame Wurfumwelt und direkte und maternale additiv genetische Effekte. Der Datensatz bestand aus 1928 Wurfaufzeichnungen mit Angaben zum individuellen Geburtsgewicht von 18151 Tieren und zum Absetzgewicht von 15360 Tieren. Nach der Geburt wurden 5% der Ferkel in einen anderen Wurf versetzt. Die geschätzten Werte für die direkte, die maternale Heritabilität und den Varianzanteil der Wurfumwelt waren für das Geburtsgewicht 0.02, 0.21 und 0.11. Die entsprechenden Werte für das Absetzgewicht waren 0.08, 0.16 und 0.23 und für die Wurfgrösse 0.22, 0.02 und 0.06. Die direkten und die maternalen genetischen Korrelationen zwischen Geburts-und Absetzgewicht waren positiv (0.59 und 0.76). Schwache positive (negative) genetische Korrelationen wurden zwischen den direkten genetischen Effekten auf die Gewichtsmerkmale und dem maternalen genetischen Effekt auf das Geburtsgewicht (Absetzgewicht) gefunden. Negative Korrelationen gab es zwischen dem direkten genetischen Effekt auf die Wurfgrösse und den maternalen genetischen Effekten auf alle drei Merkmale. Die negative Beziehung zwischen Wurfgrösse und individuellem Gewicht verlangt nach einer kombinierten Selektion für Wurfgrösse und Gewicht. [source] Contribution of direct and maternal genetic effects to life-history evolutionNEW PHYTOLOGIST, Issue 3 2009Laura F. Galloway Summary ,,Maternal effects are ubiquitous in nature. In plants, most work has focused on the effects of maternal environments on offspring trait expression. Less is known about the prevalence of genetic maternal effects and how they influence adaptive evolution. Here, we used multivariate genetic models to estimate the contributions of maternal and direct genetic (co)variance, the cross-generation direct-maternal covariance, and M, the matrix of maternal effect coefficients, for life-history traits in Campanulastrum americanum, a monocarpic herb. ,,Following a three-generation breeding design, we grew paternal half-sib families with full-sib relatives of each parent and measured juvenile and adult traits. ,,Seed size was influenced exclusively by maternal environmental effects, whereas maternal genetic effects influenced traits throughout the life cycle, including strong direct and maternal additive genetic correlations within and between generations for phenological and size traits. Examination of M suggested that both juvenile and adult traits in maternal plants influenced the expression of offspring traits. ,,This study reveals substantial potential for genetic maternal effects to contribute to adaptive evolution including cross-generation direct-maternal correlations that may slow selection response, maternal effects on phenology that reinforce genetic correlations, and within- and between-generation genetic correlations that may influence life-history polymorphism. [source] Using Case-parent Triads to Estimate Relative Risks Associated with a Candidate HaplotypeANNALS OF HUMAN GENETICS, Issue 3 2009Min Shi Summary Estimating haplotype relative risks in a family-based study is complicated by phase ambiguity and the many parameters needed to quantify relative risks for all possible diplotypes. This problem becomes manageable if a particular haplotype has been implicated previously as relevant to risk. We fit log-linear models to estimate the risks associated with a candidate haplotype relative to the aggregate of other haplotypes. Our approach uses existing haplotype-reconstruction algorithms but requires assumptions about the distribution of haplotypes among triads in the source population. We consider three levels of stringency for those assumptions: Hardy-Weinberg Equilibrium (HWE), random mating, and no assumptions at all. We assessed our method's performance through simulations encompassing a range of risk haplotype frequencies, missing data patterns, and relative risks for either offspring or maternal genetic effects. The unconstrained model provides robustness to bias from population structure but requires excessively large sample sizes unless there are few haplotypes. Assuming HWE accommodates many more haplotypes but sacrifices robustness. The model assuming random mating is intermediate, both in the number of haplotypes it can handle and in robustness. To illustrate, we reanalyze data from a study of orofacial clefts to investigate a 9-SNP candidate haplotype of the IRF6 gene. [source] | ||||||||||