Optimum selection age for wood density in loblolly pine

2002 ◽  
Vol 32 (8) ◽  
pp. 1393-1399 ◽  
Author(s):  
D P Gwaze ◽  
K J Harding ◽  
R C Purnell ◽  
F E Bridgwater
Keyword(s):  
Linear Relationship ◽  
Wood Density ◽  
Genetic Correlations ◽  
Core Density ◽  
Individual Tree ◽  
Phenotypic Correlations ◽  
Age Related ◽  
Optimum Selection ◽  
Heritability Estimates ◽  
Optimum Selection Age

Genetic and phenotypic parameters for core wood density of Pinus taeda L. were estimated for ages ranging from 5 to 25 years at two sites in southern United States. Heritability estimates on an individual-tree basis for core density were lower than expected (0.20–0.31). Age–age genetic correlations were higher than phenotypic correlations, particularly those involving young ages. Age–age genetic correlations were high, being greater than 0.75. Age–age genetic correlations had a moderately linear relationship, while age–age phenotypic correlations had a strong linear relationship with natural logarithm of age ratio. Optimum selection age for core density was estimated to be 5 years when calculations were based on both genetic and phenotypic correlations. However, age 5 was the youngest examined in this study and optimum selection age may be younger than 5. Generally, the optimum selection age was robust to changes in breeding phase and assumptions concerning age-related variation in heritability estimates. Early selection for core density would result in a correlated increase in earlywood density but little progress in latewood density or latewood proportion at maturity.

scholarly journals Realized Sampling Variances of Estimates of Genetic Parameters and the Difference Between Genetic and Phenotypic Correlations

Genetics ◽  
1996 ◽  
Vol 143 (3) ◽  
pp. 1409-1416 ◽  
Author(s):  
Kenneth R Koots ◽  
John P Gibson
Keyword(s):  
Genetic Correlation ◽  
Genetic Parameters ◽  
Genetic Parameter ◽  
Genetic Correlations ◽  
Phenotypic Correlation ◽  
Parameter Estimates ◽  
Sampling Variance ◽  
Phenotypic Correlations ◽  
Genetic And Phenotypic Correlations ◽  
Heritability Estimates

Abstract A data set of 1572 heritability estimates and 1015 pairs of genetic and phenotypic correlation estimates, constructed from a survey of published beef cattle genetic parameter estimates, provided a rare opportunity to study realized sampling variances of genetic parameter estimates. The distribution of both heritability estimates and genetic correlation estimates, when plotted against estimated accuracy, was consistent with random error variance being some three times the sampling variance predicted from standard formulae. This result was consistent with the observation that the variance of estimates of heritabilities and genetic correlations between populations were about four times the predicted sampling variance, suggesting few real differences in genetic parameters between populations. Except where there was a strong biological or statistical expectation of a difference, there was little evidence for differences between genetic and phenotypic correlations for most trait combinations or for differences in genetic correlations between populations. These results suggest that, even for controlled populations, estimating genetic parameters specific to a given population is less useful than commonly believed. A serendipitous discovery was that, in the standard formula for theoretical standard error of a genetic correlation estimate, the heritabilities refer to the estimated values and not, as seems generally assumed, the true population values.

Genetic parameter estimates (full sib and half sib analysis) of fertility and hatchability in two strains of Rhode Island chickens

2021 ◽  
Vol 38 (1) ◽  
pp. 14-22
Author(s):  
M. Orunmuyi ◽  
I. A. Adeyinka ◽  
O.O Oni
Keyword(s):  
Rhode Island ◽  
Additive Genetic Variance ◽  
Genetic Parameter ◽  
Genetic Correlations ◽  
Reproductive Traits ◽  
Parameter Estimates ◽  
Phenotypic Correlations ◽  
Poultry Breeding ◽  
Genetic And Phenotypic Correlations ◽  
Heritability Estimates

A study was conducted to estimate the genetic parameters of fertility and hatchability in two strains of Rhode Island Red (RIR) Chickens denoted as Strain A and Strain B respectively using the full-sib (sire +dam variance) and maternal half-sib (dam variance) components. The birds were obtained from the selected populations of RIR Chickens kept at the poultry breeding programme of National Animal Production Research Institute, Shika, Zaria, Nigeria. Settable eggs were collected from mating 28 cocks to 252 hens in a ratio of 1cock:9 hens from each strain. Eggs were pedigreed according to sire and dam. Results showed that values obtained for number of egg set (EGGSET), number of fertile eggs (NFERT), number of hatched chicks (NHATCH), percentage of chicks hatched from total eggs set (PHATCH) and percentage of chicks hatched from fertile eggs (PHATCHBL) were all higher in strain A than strain B. Heritability estimates obtained from the full-sib and maternal half-sib analysis ranged from medium to high for the two strains (0.24-0.96). The maternal half sib estimates were higher (0.40-0.96) than the estimates obtained from full sibs (0.24- 0.48). Genetic and phenotypic correlations obtained for both strains were positive and similar regardless of method of estimation. Genetic correlations between EGGSET and PFERT were low in strain A using both full-sib and maternal half-sib analyses (0.09-0.14). Phenotypic correlations between EGGSET and PFERT, PHATCH and PHATCHBL were also low in both strains and regardless of method of analyses. Moderate to high heritability estimates suggest that genetic improvement can be obtained by selection of these reproductive traits. The full-sib analysis for estimating heritability will be preferred since it is assumed that only additive genetic variance contributes to the covariance between family members.

Estimates of genetic and phenotypic parameters of some weight and fleece traits in a coarse-wool breed of sheep

1982 ◽  
Vol 99 (2) ◽  
pp. 277-285 ◽  
Author(s):  
R. A. Guirgis ◽  
E. A. Afifi ◽  
E. S. E. Galal
Keyword(s):  
Body Weight ◽  
Genetic Correlations ◽  
Phenotypic Correlations ◽  
Body Weights ◽  
Heritability Estimates ◽  
Fleece Weight ◽  
Staple Length

SUMMARYA study using 1150 lambs to estimate genetic and phenotypic parameters of some weight and fleece traits was carried out on coarse-wool Barki sheep. The weight traits were birth, weaning, yearling weights and daily gains whereas fleece traits included kemp score, staple length and greasy-fleece weight.Heritability estimates of weight traits were within the range 0·25–0·30. Those of fleece traits were 0·16, 0·21 and 0·43. The repeatability estimates of fleece traits were 0·18, 0·38 and 0·53 for staple length, greasy-fleece weight and kemp score respectively.Phenotypic correlations between body weight and fleece traits were mostly positive. Genetic correlations between greasy-fleece weight and body weights were mostly positive and of medium values. Those between kemp score and body weights were mostly negative, ranging from medium-high to high.

scholarly journals Genetic Control of Growth Traits in Shortleaf Pine in Missouri

2005 ◽  
Vol 29 (4) ◽  
pp. 200-204 ◽  
Author(s):  
David P. Gwaze ◽  
Ross Melick ◽  
Charly Studyvin ◽  
Mark Coggeshall
Keyword(s):  
Growth Traits ◽  
Genetic Correlations ◽  
Selection Criterion ◽  
Seed Orchard ◽  
Direct Selection ◽  
Pinus Echinata ◽  
Shortleaf Pine ◽  
Individual Tree ◽  
High Heritability ◽  
Heritability Estimates

Abstract Genetic parameters for height (HT), diameter (diameter at breast height [dbh]), and volume for a shortleaf pine (Pinus echinata Mill.) population in Missouri were estimated from a single progeny test comprising 44 half-sibling families assessed at 3, 5, 7, 10, and 17 years. Individual tree heritability estimates for growth traits at age 10 years and younger were high (0.30–0.43), and those at age 17 years were low (0.11–0.24). Heritability estimates for dbh were lower than those for HT. Family mean heritability estimates were moderate to high (0.32–0.66). Genetic correlations were higher than their phenotypic counterparts for all growth traits. Age-age genetic correlations for growth traits were moderate to high (0.68–0.98), indicating opportunity for early selection. Genetic correlations between different growth traits were high (0.81–1.00). Indirect selection on age 5- or 7-year HTs may be expected to produce over 25% more volume at 17 years compared with direct selection for volume at age 17 years. Efficiencies of selection suggest that early HT is a better selection criterion for volume at older ages than dbh because of the high heritability at young ages and strong juvenile-mature genetic correlations. Genetic gain in an unrogued seed orchard was predicted to be 6.7 and 27.2% for 10- and 17-year volume, respectively. These results suggest that growth traits in shortleaf pine in Missouri have high genetic variation, and genetic improvement was effective. South. J. Appl. For. 29(4):200–204.

RELATIONSHIPS OF REPRODUCTION TRAITS, BODY WEIGHT AND MILK YIELD IN DAIRY CATTLE

1986 ◽  
Vol 66 (1) ◽  
pp. 53-65 ◽  
Author(s):  
T. R. BATRA ◽  
A. J. LEE ◽  
A. J. McALLISTER
Keyword(s):  
Body Weight ◽  
Dairy Cattle ◽  
Milk Yield ◽  
Fixed Effects ◽  
Genetic Correlations ◽  
Calving Interval ◽  
Phenotypic Correlations ◽  
Reproduction Traits ◽  
Heritability Estimates ◽  
National Cooperative

The relationships between reproduction traits, body weight and milk yield were investigated using data from 1611 heifers and 733 cows from two lines of the National Cooperative Dairy Cattle Breeding Project. The data were analyzed separately for heifers and cows within lines using a mixed linear model containing fixed effects for station, year of birth, season of birth and random effect of sires. Heritability estimates and genetic correlations were estimated by a paternal half-sib analysis. Heritability estimates for heifer and cow reproduction traits ranged between 0 and 26% while those of body weights at calving and 112 d postpartum and milk yield ranged from 24 to 43%. Heifers with difficult calving had a higher incidence of retained placenta than those with normal calving. Phenotypic correlations between heifer reproduction traits and milk yield during first lactation were small. High milk production in cows was associated with longer calving interval. Phenotypic correlations between heifer's and cow's reproduction traits were small. Difficult calving in heifers impairs reproductive performance after calving resulting in greater number of days from calving to first and last breeding and leading to a longer calving interval. Key words: Reproduction traits, heifers, cows, milk yield, dairy cattle

scholarly journals Exploring Phenotypic and Genetic Overlap Between Cannabis Use and Schizotypy

2020 ◽  
Vol 23 (4) ◽  
pp. 221-227 ◽  
Author(s):  
James Vaissiere ◽  
Jackson G. Thorp ◽  
Jue-Sheng Ong ◽  
Alfredo Ortega-Alonso ◽  
Eske M. Derks
Keyword(s):  
Multiple Testing ◽  
Association Studies ◽  
Genetic Correlations ◽  
Cannabis Use ◽  
Exact Nature ◽  
Social Anhedonia ◽  
Multiple Testing Correction ◽  
Phenotypic Correlations ◽  
Genetic Overlap ◽  
Heritability Estimates

AbstractThere is a well-established relationship between cannabis use and psychosis, although the exact nature of this relationship is not fully understood. Recent studies have observed significant genetic overlap between a diagnosis of schizophrenia and lifetime cannabis use. Expanding on this work, the current study aimed to examine whether genetic overlap also occurs for subclinical psychosis (schizotypy) and cannabis use, as well as examining the phenotypic association between the traits. Phenotypic correlations were calculated for a variety of schizotypy and cannabis phenotypes in the UK Biobank (UKB), and single nucleotide polymorphism (SNP)-based heritability estimates and genetic correlations were calculated for these UKB phenotypes as well as for several other variables taken from recent genomewide association studies. Positive phenotypic correlations were observed between 11 out of 12 pairs of the cannabis use and schizotypy phenotypes (correlation range .05–.18), indicating a robust association between increased symptoms of schizotypy and cannabis use. SNP-based heritability estimates for two schizotypy phenotypes remained significant after multiple testing correction: social anhedonia (h2SNP = .08, SE = .02, N = 4025) and ever seen an unreal vision (h2SNP = .35, SE = .10, N = 150,717). Finally, one significant genetic correlation was observed between schizotypy and cannabis use, a negative correlation between social anhedonia and number of times used cannabis (rg = −.30, p = .012). The current study suggests the relationship between cannabis use and psychosis is also seen in subclinical symptoms of psychosis, but further research with larger samples is needed to determine the biological mechanisms underlying this association.

Age trends in genetic parameters of wood density in young Norway spruce

1999 ◽  
Vol 29 (1) ◽  
pp. 135-143 ◽  
Author(s):  
Gro Hylen
Keyword(s):  
Norway Spruce ◽  
Wood Density ◽  
Additive Genetic Variance ◽  
Genetic Correlations ◽  
Steady Increase ◽  
Environmental Variance ◽  
Cambial Age ◽  
Latewood Density ◽  
Age Trends ◽  
Heritability Estimates

Age trends of phenotypic, environmental, and additive genetic variance and heritability were estimated for overall density and its components earlywood and latewood densities and latewood proportion. The objective was to acquire information for both individual and cumulated rings from ring number 3 to 12 counted from the pith. Age-age correlations were calculated for cumulated density traits only. The wood density data were obtained with X-ray analysis of increment cores from 47 open-pollinated families of Norway spruce (Picea abies (L.) Karst.). The families had earlywood and latewood with significant differences in density for individual and cumulated rings and consequently for overall density. The latewood proportion had significant family variation for cumulated rings but not for all individual rings. Large fluctuations in environmental variance caused fluctuations in heritability estimates for successive rings. A strong decrease in environmental variance for all cumulated traits, especially from ring 3 to 5, resulted in a steady increase in heritability estimates. The latewood density had the highest heritability estimates and latewood proportion the lowest for both individual and cumulated rings. Overall density and the cumulated components at cambial age 12 showed strong genetic correlations with their respective traits at all younger ages.

The genetic evaluation of beef sires used for crossing with dairy cows in the UK 2. Genetic parameters and sire merit predictions for calving survey traits

1998 ◽  
Vol 66 (1) ◽  
pp. 47-54 ◽  
Author(s):  
B. J. McGuirk ◽  
I. Going ◽  
A. R. Gilmour
Keyword(s):  
Genetic Parameters ◽  
Threshold Model ◽  
Genetic Correlations ◽  
Gestation Length ◽  
Strongly Correlated ◽  
Genetic Merit ◽  
Phenotypic Correlations ◽  
Heritability Estimates ◽  
Difficulty Score ◽  
Calving Difficulty

AbstractGenetic parameters were estimated for traits recorded in a calving survey for beef sires used in commercial dairy herds in England and Wales. The five traits included in the survey were calving difficulty score, calf mortality to 48 h after birth, gestation length, and subjectively assessed calf size and conformation. The data file examined included over 88 000 records, on 323 sires of eight beef sire breeds, namely Aberdeen Angus, Belgian Blue, Blonde d'Aquitaine, Charolais, Hereford, Limousin, Piedmontese and Simmental.Estimates of heritability and genetic and phenotypic correlations were obtained for all traits by REML procedures using a sire model. The effects of cow age, calf sex, year and season of the calving and sire breed were included in the model, together with interactions.Heritability estimates were 0·09 (s.e. 0·01) for calving difficulty score, 0·32 (s.e. 0·03) for gestation length, 0·02 (s.e. 0·003) for mortality, 0·09 (s.e. 0·01) for calf size and 0·06 (s.e. 0·01) for calf conformation.Heritability estimates for the scored categorical and binomial (mortality) traits were also obtained using threshold model analysis. As expected, these estimates were higher than the REML estimates; 0·16 (s.e. 0·01) for calving difficulty score, 0·08 (s.e. 0·01) for mortality, 0·14 (s.e. 0·01) for calf size and 0·09 (s.e. 0·01) for calf conformation. Calving difficulty score was strongly correlated genetically with calf size (-0·84), mortality (0·74) and calf conformation (-0·72), and moderately correlated with gestation length (0·26). Calf size and conformation were very highly correlated genetically (0·86), and both were also strongly correlated with mortality (-0·63 and -0·52 respectively). In all cases, the genetic correlations were stronger than the phenotypic correlations.Sire genetic merit was predicted for all traits and the distribution of these predictions is described. Sire predictions of genetic merit for calving difficulty score on the underlying scale were backtransformed to predict the expected incidence of serious difficulties in future calvings and these predictions are illustrated for the major sire breeds.

The genetic evaluation of UK Holstein Friesian sires for calving ease and related traits

1999 ◽  
Vol 68 (3) ◽  
pp. 413-422 ◽  
Author(s):  
B. J. McGuirk ◽  
I. Going ◽  
A. R. Gilmour
Keyword(s):  
Threshold Model ◽  
Genetic Correlations ◽  
Subjective Assessment ◽  
Gestation Length ◽  
Phenotypic Correlations ◽  
Holstein Friesian ◽  
Regional Location ◽  
Heritability Estimates ◽  
Difficulty Score ◽  
Calving Difficulty

AbstractRecords were analysed on more than 75 000 calvings by 685 Holstein-Friesian bulls tested in commercial dairy herds in England and Wales. The data were collected from 1988 to 1994. The traits analysed were the degree of difficulty at calving, assessed from no difficulty to serious difficulty, calf mortality to 48 h, gestation length and a subjective assessment of calf size. Information was available for the percentage Holstein genes in the sire, dam age (heifer or mature), sex of the calf and the year and month of the calving for all records, while lactation number of the dam and the regional location of the herd were also recorded in 1993 and 1994 (14988 records). Estimates of heritability and genetic and phenotypic correlations were obtained for all traits by restricted maximum likelihood (REML) procedures using a sire model, while also fitting the effects of dam age, calf sex, year and season of calving and significant interations.Heifers had more difficult calvings, higher calf losses and shorter gestations than mature cows while seriously difficult calvings and mortality were higher for male calves (all P < 0·05). Summer months were associated with lower incidences of difficult calvings, lower mortality and shorter gestations. Heritability estimates were 0·05 (s.e. <0·01) for calving difficulty score, 0·45 (s.e. 0·02) for gestation length, 0·02 (s.e. <0·01) for mortality and 0·08 (s.e. <0·01) for calf size score. Heritability estimates for the scored categorical and binomial (mortality) traits were also obtained using threshold model analysis. As expected, these estimates were higher than the REML estimates; 0·12 (s.e. 0.01) for calving difficulty score, 0·08 (s.e. 0·01) for mortality and 0·14 (s.e. 0·01) for calf size score. Calving difficulty score was genetically correlated with calf size score (-0.81), mortality (0.40) and gestation length (0.34) and calf size score was moderately correlated with mortality (-0.40). In all cases, the genetic correlations were stronger than the corresponding phenotypic correlations.Sire genetic merit was predicted for calving difficulty score and the distribution of these predictions is described. Sire predictions for calving difficulty score on the underlying scale were backtransformed to predict the expected incidence of serious difficulties in future calvings.

Studies on Western Australian Merino sheep. II. Genetic and phenotypic parameter estimates for objectively measured traits on ram and ewe hoggets using different model types

1994 ◽  
Vol 45 (4) ◽  
pp. 829 ◽  
Author(s):  
RP Lewer ◽  
RR Woolaston ◽  
RR Howe
Keyword(s):  
Environmental Effects ◽  
Genetic Correlations ◽  
Fibre Diameter ◽  
Parameter Estimates ◽  
Merino Sheep ◽  
Phenotypic Correlations ◽  
Average Fibre Diameter ◽  
Heritability Estimates ◽  
Fleece Weight ◽  
Western Australian

Data from a Western Australian experimental flock of Merino sheep were used to estimate genetic and phenotypic parameters for clean fleece weight (CFW), greasy fleece weight (GFW), average fibre diameter (FD), and clean yield (Y) from hogget fleeces as well as liveweights at birth (BWT), weaning (3WT), 8-9 months (8WT), 11-12 months (11WT) and 14-15 months (14WT) of age. The estimates were derived for male and female hoggets using restricted maximum likelihood REML. Simple models were fitted in which most environmental effects were omitted for comparison with results from models containing all recorded significant environmental effects. There were no significant differences amongst heritability estimates between models or sexes. Genetic correlations were calculated between sexes for each trait, with none being significantly different to unity. Ranges of heritability estimates across models and sexes were: GFW, 0.30-0-42; CFW, 0.26-0.44; Y, 0.46-0.59; FD, 0.47-0.59; BWT, 0.16-0.33; 3WT, 0.32-0.39; 8WT, 0.22-0.36; llWT, 0-27-0.44; 14WT, 0.27-0.50. Estimates of genetic and phenotypic correlations were in reasonable agreement with other literature values. As with the heritability estimates, the model fitted did not result in important differences in either genetic or phenotypic correlations.

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