scholarly journals Pattern of inbreeding depression, condition dependence, and additive genetic variance in Trinidadian guppy ejaculate traits

2013 ◽  
Vol 3 (15) ◽  
pp. 4940-4953 ◽  
Author(s):  
Clelia Gasparini ◽  
Alessandro Devigili ◽  
Ryan Dosselli ◽  
Andrea Pilastro
Keyword(s):  
Inbreeding Depression ◽  
Genetic Variance ◽  
Additive Genetic Variance ◽  
Condition Dependence ◽  
Trinidadian Guppy

Additive Genetic Variance, Heritability, and Inbreeding Depression in Male Extra-Pair Reproductive Success

2011 ◽  
Vol 177 (2) ◽  
pp. 177-187 ◽  
Author(s):  
Jane M. Reid ◽  
Peter Arcese ◽  
Rebecca J. Sardell ◽  
Lukas F. Keller
Keyword(s):  
Reproductive Success ◽  
Inbreeding Depression ◽  
Genetic Variance ◽  
Additive Genetic Variance

scholarly journals Genomic dissection of maternal, additive and non-additive genetic effects for growth and carcass traits in Nile tilapia

2019 ◽  
Author(s):  
Rajesh Joshi ◽  
John Woolliams ◽  
Theodorus Meuwissen ◽  
Hans Magnus Gjøen
Keyword(s):  
Inbreeding Depression ◽  
Nile Tilapia ◽  
Genetic Variance ◽  
Additive Genetic Variance ◽  
Genomic Data ◽  
Genetic Effects ◽  
Phenotypic Variance ◽  
Breeding Schemes ◽  
Additive Genetic Effects ◽  
The Impact

AbstractBackgroundThe availability of both pedigree and genomic sources of information for animal breeding and genetics has created new challenges in understanding how best they may be utilized and how they may be interpreted. This study computed the variance components obtained using genomic information and compared these to the variances obtained using pedigree in a population generated to estimate non-additive genetic variance. Further, the impact of assumptions concerning Hardy-Weinberg Equilibrium (HWE) on the component estimates was examined. The magnitude of inbreeding depression for important commercial traits in Nile tilapia was estimated for the first time, here using genomic data.ResultsThe non-additive genetic variance in a Nile tilapia population was estimated from fullsib families and, where present, was found to be almost entirely additive by additive epistatic variance, although in pedigree studies this source is commonly assumed to arise from dominance. For body depth (BD) and body weight at harvest (BWH), the estimates of the additive by additive epistatic ratio (P<0.05) were found to be 0.15 and 0.17 in the current breeding population using genomic data. In addition, we found maternal variance (P<0.05) for BD, BWH, body length (BL) and fillet weight (FW), explaining approximately 10% of the observed phenotypic variance, which are comparable to the pedigree-based estimates. This study also disclosed detrimental effects of inbreeding in commercial traits of tilapia, which were estimated to cause 1.1%, 0.9%, 0.4% and 0.3% decrease in the trait value with 1% increase in the individual homozygosity for FW, BWH, BD and BL, respectively. The inbreeding depression and lack of dominance variance was consistent with an infinitesimal dominance modelConclusionsAn eventual utilisation of non-additive genetic effects in breeding schemes is not evident or straightforward from our findings, but inbreeding depression suggests for cross-breeding, although commercially this conclusion will depend on cost structures. However, the creation of maternal lines in Tilapia breeding schemes may be a possibility if this variation is found to be heritable.

Effects of inbreeding and estimates of additive genetic variance within seven summer oilseed rape cultivars

Genome ◽  
1989 ◽  
Vol 32 (1) ◽  
pp. 115-119 ◽  
Author(s):  
J. E. Brandle ◽  
P. B. E. McVetty
Keyword(s):  
Brassica Napus ◽  
Inbreeding Depression ◽  
Oilseed Rape ◽  
Genetic Variance ◽  
Additive Genetic Variance ◽  
Inbred Lines ◽  
Brassica Napus L ◽  
Genetic Determination ◽  
The Mean

Seven groups of inbred lines derived from the summer oilseed rape (Brassica napus ssp. oleifera) cultivars 'Westar', 'Regent', 'Lergo', 'Marnoo', 'Ariel', 'Karat', and 'R83-11' were evaluated at three sites over 2 years, for agronomic characters and seed oil and protein concentrations. Estimates of additive genetic variance and heritability were calculated. Comparison of the mean of inbred lines with the mean of their respective source cultivars indicated little, if any, inbreeding depression in all cultivars except 'Ariel'. It was concluded that dominance is not a major factor in the genetic determination of the characters studied. For every trait in every cultivar, individual inbred lines were identified that exceeded or equaled their respective source cultivar means, indicating that neither heterozygosity per se nor genetic heterogeneity is required to maintain maximum performance in summer oilseed rape. Therefore, the oilseed rape cultivars used in this study were considered to be genetically heterogeneous populations, consisting of some number of generally homozygous lines. Significant additive genetic variance was detected for most traits in most cultivars, indicating that superior inbred lines could be extracted from within cultivars.Key words: inbreeding depression, heritability, Brassica napus L.

scholarly journals SNP-based mate allocation strategies to maximize total genetic value in pigs

2019 ◽  
Vol 51 (1) ◽  
Author(s):  
David González-Diéguez ◽  
Llibertat Tusell ◽  
Céline Carillier-Jacquin ◽  
Alban Bouquet ◽  
Zulma G. Vitezica
Keyword(s):  
Inbreeding Depression ◽  
Genetic Gain ◽  
Variance Components ◽  
Genetic Variance ◽  
Additive Genetic Variance ◽  
Genetic Effects ◽  
Breeding Values ◽  
Genetic Merit ◽  
Additive Genetic Effects ◽  
Allocation Strategies

Abstract Background Mate allocation strategies that account for non-additive genetic effects can be used to maximize the overall genetic merit of future offspring. Accounting for dominance effects in genetic evaluations is easier in a genomic context, than in a classical pedigree-based context because the combinations of alleles at loci are known. The objective of our study was two-fold. First, dominance variance components were estimated for age at 100 kg (AGE), backfat depth (BD) at 140 days, and for average piglet weight at birth within litter (APWL). Second, the efficiency of mate allocation strategies that account for dominance and inbreeding depression to maximize the overall genetic merit of future offspring was explored. Results Genetic variance components were estimated using genomic models that included inbreeding depression with and without non-additive genetic effects (dominance). Models that included dominance effects did not fit the data better than the genomic additive model. Estimates of dominance variances, expressed as a percentage of additive genetic variance, were 20, 11, and 12% for AGE, BD, and APWL, respectively. Estimates of additive and dominance single nucleotide polymorphism effects were retrieved from the genetic variance component estimates and used to predict the outcome of matings in terms of total genetic and breeding values. Maximizing total genetic values instead of breeding values in matings gave the progeny an average advantage of − 0.79 days, − 0.04 mm, and 11.3 g for AGE, BD and APWL, respectively, but slightly reduced the expected additive genetic gain, e.g. by 1.8% for AGE. Conclusions Genomic mate allocation accounting for non-additive genetic effects is a feasible and potential strategy to improve the performance of the offspring without dramatically compromising additive genetic gain.

scholarly journals Nature and magnitude of genetic variability, heterosis and inbreeding depression in Amaranthus

Genetika ◽  
2007 ◽  
Vol 39 (2) ◽  
pp. 251-258
Author(s):  
R.M. Pandey
Keyword(s):  
Genetic Variability ◽  
Grain Yield ◽  
Inbreeding Depression ◽  
Combining Ability ◽  
Harvest Index ◽  
Genetic Variance ◽  
Additive Genetic Variance ◽  
Grain Weight ◽  
The Other ◽  
Panicle Length

Combining ability, heterosis and inbreeding depression were estimated in grain amaranths for ten characters. Non-additive genetic variance was predominant for majority of characters in both F1 and F2 generations. The parent AG-21 was good general combiner for yield/plant also showed high GCA effects for panicles/plant and harvest index in both F1 and F2 generations. Seven characters, the best F2s on the basis of SCA involves one parent with high GCA effect and the other with poor or average GCA effects. The hybrids which exhibited highest heterosis also showed high inbreeding depression. Heterosis over better parent was highest for economic grain yield (145.047%), followed by panicles/plant (113.675%), panicle length (33.656%) and grain weight/panicle (23.566%).

scholarly journals SELECTION FOR BLOOD PRESSURE LEVELS IN MICE

Genetics ◽  
1974 ◽  
Vol 76 (3) ◽  
pp. 537-549
Author(s):  
Gunther Schlager
Keyword(s):  
Blood Pressure ◽  
Systolic Blood Pressure ◽  
Genetic Variance ◽  
Additive Genetic Variance ◽  
Population Bottleneck ◽  
Control Line ◽  
Selected Lines ◽  
High Line ◽  
Selection For ◽  
Random Control

ABSTRACT Response to two-way selection for systolic blood pressure was immediate and continuous for about eight generations. In the twelfth generation, the High males differed from the Low males by 38 mmHG; the females differed by 39 mmHg. There was little overlap between the two lines and they were statistically significant from each other and from the Random control line. There appeared to be no more additive genetic variance in the eleventh and twelfth generations. Causes for the cessation of response are explored. This is probably due to a combination of natural selection acting to reduce litter sizes in the Low line, a higher incidence of sudden deaths in the High line, and loss of favorable alleles as both selection lines went through a population bottleneck in the ninth generation.—In the eleventh generation, the selected lines were used to produce F1, F2, and backcross generations. A genetic analysis yielded significant additive and dominance components in the inheritance of systolic blood pressure.

scholarly journals Selection Response in Finite Populations

Genetics ◽  
1996 ◽  
Vol 144 (4) ◽  
pp. 1961-1974 ◽  
Author(s):  
Ming Wei ◽  
Armando Caballero ◽  
William G Hill
Keyword(s):  
Linkage Disequilibrium ◽  
Inbreeding Depression ◽  
Genetic Variance ◽  
Relative Rate ◽  
Selection Response ◽  
Rate Of Change ◽  
Effective Population ◽  
Short Term ◽  
Model Account

Formulae were derived to predict genetic response under various selection schemes assuming an infinitesimal model. Account was taken of genetic drift, gametic (linkage) disequilibrium (Bulmer effect), inbreeding depression, common environmental variance, and both initial segregating variance within families (σAW02) and mutational (σM2) variance. The cumulative response to selection until generation t(CRt) can be approximated asCRt≈R0[t−β(1−σAW∞2σAW02)t24Ne]−Dt2Ne,where Ne is the effective population size, σAW∞2=NeσM2 is the genetic variance within families at the steady state (or one-half the genic variance, which is unaffected by selection), and D is the inbreeding depression per unit of inbreeding. R  0 is the selection response at generation 0 assuming preselection so that the linkage disequilibrium effect has stabilized. β is the derivative of the logarithm of the asymptotic response with respect to the logarithm of the within-family genetic variance, i.e., their relative rate of change. R  0 is the major determinant of the short term selection response, but σM2, Ne and β are also important for the long term. A selection method of high accuracy using family information gives a small Ne and will lead to a larger response in the short term and a smaller response in the long term, utilizing mutation less efficiently.

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