Two-trait Selection and the Genetic Correlation II. Changes in the Genetic Correlation During Two-trait Selection

Although there is little experimental information on the effect of simultaneous selection for two quantitative characters on the magnitude of the genetic correlation between them, it is apparently generally expected that such selection for the two characters in the same direction will cause a negative change in the genetic correlation, and selection in opposite directions a positive change. Selection using independent culling levels was done for each of the four combinations of high or low third coxal bristle number with high or low sternopleural bristle number in Drosophila melanogaster for 22 generations. To estimate changes in the genetic correlation, realized genetic parameters were estimated from single-trait lines started from the base population, and from the two-trait lines after 10 and 22 generations of selection. Changes in the genetic correlation in individual two-trait selection lines were variable and unpredictable. At generation 22 concurrent two-trait selection had resulted in significantly larger realized genetic correlations than divergent two-trait selection, so that results were contrary to the generally accepted expectation.

Download Full-text

Two-trait Selection and the Genetic Correlation I. Prediction of Responses in Single-trait and in Two-trait Selection

Australian Journal of Biological Sciences ◽

10.1071/bi9740075 ◽

1974 ◽

Vol 27 (1) ◽

pp. 75 ◽

Cited By ~ 5

Author(s):

AK Sheridan ◽

JSF Barker

Keyword(s):

Genetic Correlation ◽

Reasonable Agreement ◽

Genetic Parameters ◽

Genetic Correlations ◽

Diallel Analysis ◽

Selection Intensity ◽

Base Population ◽

Selection Responses ◽

Bristle Number ◽

Independent Culling

Selection using independent culling levels (20% overall selection intensity) was done for the four combinations of high or low third coxal bristle number with high or low sternopleural bristle number in Drosophila melanogaster. Single-trait lines from the base population were selected at 20 % selection intensity for 10 generations for high or low bristle number. Realized heritabilities and genetic correlations were estimated after 10 and 22 generations of selection in the two-trait lines, and also from the single-trait lines. There was considerable variation among replicate lines within treatments in selection responses, and in realized heritabilities and genetic correlations. Although average estimates of the realized parameters were all less than those made from a diallel analysis of the base population, the average base population genetic correlation and the average realized genetic corre-lations from single-trait and two-trait selection lines were reasonably similar. Predicted selection responses in both single-trait and two-trait lines using genetic parameters derived from a diallel analysis of the base population were greater than average realized responses. However, predicted selection responses in the two-trait lines using realized genetic parameters from the single-trait lines were in reasonable agreement with average realized responses.

Download Full-text

PSVIII-38 Late-Breaking Abstract: Estimating genetic parameters of feed efficiency traits in American mink

Journal of Animal Science ◽

10.1093/jas/skaa278.612 ◽

2020 ◽

Vol 98 (Supplement_4) ◽

pp. 347-347

Author(s):

Pourya Davoudi ◽

Duy Ngoc Do ◽

Guoyu Hu ◽

Siavash Salek Ardestani ◽

Younes Miar

Keyword(s):

Body Weight ◽

Genetic Correlation ◽

Feed Intake ◽

Feed Efficiency ◽

Fixed Effects ◽

Genetic Parameters ◽

American Mink ◽

Genetic Correlations ◽

Final Body Weight ◽

Selection For

Abstract Feed cost is the major input cost in the mink industry and thus improvement of feed efficiency through selection for high feed efficient mink is necessary for the mink farmers. The objective of this study was to estimate the heritability, phenotypic and genetic correlations for different feed efficiency measures, including final body weight (FBW), daily feed intake (DFI), average daily gain (ADG), feed conversion ratio (FCR) and residual feed intake (RFI). For this purpose, 1,088 American mink from the Canadian Center for Fur Animal Research at Dalhousie Faculty of Agriculture were recorded for daily feed intake and body weight from August 1 to November 14 in 2018 and 2019. The univariate models were used to test the significance of sex, birth year and color as fixed effects, and dam as a random effect. Genetic parameters were estimated via bivariate models using ASReml-R version 4. Estimates of heritabilities (±SE) were 0.41±0.10, 0.37±0.11, 0.33±0.14, 0.24±0.09 and 0.22±0.09 for FBW, DFI, ADG, FCR and RFI, respectively. The genetic correlation (±SE) was moderate to high between FCR and RFI (0.68±0.15) and between FCR and ADG (-0.86±0.06). In addition, RFI had low non-significant (P > 0.05) genetic correlations with ADG (0.04 ± 0.26) and BW (0.16 ± 0.24) but significant (P < 0.05) high genetic correlation with DFI (0.74 ± 0.11) indicating that selection for lower RFI will reduce feed intake without adverse effects on the animal size and growth rate. The results suggested that RFI can be implemented in genetic/genomic selection programs to reduce feed intake in the mink production system.

Download Full-text

Genetic parameters for egg weight v. age curve, and other egg production and egg weight traits, in synthetic lines of chickens

Australian Journal of Agricultural Research ◽

10.1071/ar9830085 ◽

1983 ◽

Vol 34 (1) ◽

pp. 85 ◽

Cited By ~ 5

Author(s):

BH Yoo ◽

BL Sheldon ◽

RN Podger

Keyword(s):

Standard Deviation ◽

Genetic Correlation ◽

Egg Production ◽

Genetic Parameters ◽

Genetic Correlations ◽

Egg Mass ◽

Control Line ◽

Egg Weight ◽

Egg Number ◽

Selection For

An exponential curve, W = P-Qexp(- Rt), where W is egg weight at age t, was fitted to egg weights of individual pullets, and genetic parameters were estimated for P, Q and R, the residual standard deviation and other egg weight and egg production characters. The data consisted of records collected over six generations on more than 4000 pullets in two selection lines and a control line which originated from a synthetic gene pool of White Leghorn x Australorp crosses. The half-sib and offspring-on-parent regression estimates of heritability pooled over the lines were 0.23 and 0.33 for P, 0.14 and 0.20 for Q, and 0.14 and 0.25 for R. Genetic correlations were estimated to be -0.10 between P and Q, -0.46 between P and R, and 0.90 between Q and R. These estimates suggest that the egg weight v. age curve may be modified to increase the proportion of eggs in desirable weight grades and reduce the incidence of oversized eggs later in the production year. The genetic correlation between mean weight of first 10 eggs and egg weight at 62 weeks of age was estimated to be 0.68, further suggesting that early egg weight may be improved partly independently of late egg weight. The heritability estimates of egg mass output were not higher than those of egg number in spite of the highly heritable average egg weight being an important component of egg mass, probably because of the negative genetic correlation (r = -0.49) between egg number and average egg weight. The standard deviation of individual pullet's egg weights was moderately heritable and genetically correlated positively with egg weight characters and negatively with egg production; these estimates were consistent with the responses to selection for reduced egg weight variability observed elsewhere

Download Full-text

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

Genetics ◽

10.1093/genetics/143.3.1409 ◽

1996 ◽

Vol 143 (3) ◽

pp. 1409-1416 ◽

Cited By ~ 1

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.

Download Full-text

Genetic correlation between traits in the ESALQ-PB1 maize population divergently selected for tassel size and ear height

Scientia Agricola ◽

10.1590/s0103-90162001000100018 ◽

2001 ◽

Vol 58 (1) ◽

pp. 119-123 ◽

Cited By ~ 8

Author(s):

Austeclínio Lopes Farias Neto ◽

José Branco de Miranda Filho

Keyword(s):

Genetic Correlation ◽

Correlation Coefficients ◽

Divergent Selection ◽

Phenotypic Correlation ◽

Base Population ◽

Branch Number ◽

Maize Population ◽

Tassel Branch Number ◽

Ear Height ◽

Selection For

Full-sib and selfed (S1) progenies were obtained from sub-populations of ESALQ-PB1, divergently selected for tassel size (T+ and T-) and ear height (E+ and E-), and used for estimating genetic and phenotypic correlation coefficients between traits. The analyzed traits were: EW- total ear weight (g/plant), PH- plant height (cm), EH- ear height (cm), TB- tassel branch number and TL- tassel length. The highest genetic (rG) and phenotypic (rF) correlation was observed for the combination PH x EH, as expected, with average of 0.800 and 0.778, respectively over sub-populations and locations. It is apparent that divergent selection for tassel size did not affect greatly the correlation between PH and EH in the full sib progenies, but in the inbred progenies the correlation was smaller in the sub-population selected for larger tassels. Genetic correlation between PH and EH with tassel traits was always positive but ranged from 0.020 to 0.668 in Piracicaba and from 0.06 to 0.309 in Rio Verde. Genetic correlation between PH and EH with yield (EW) also was positive in the range of 0.087 to 0.503. EH showed higher correlation with EW in relation to PH x EW and differences were larger in the sub-populations divergently selected for ear height. Correlation between tassel traits with other traits was positive in most of instances and a lack of consistency was observed among sub-populations. Generally the coefficients of genetic and phenotypic correlation differed substantially from the estimates in the base population ESALQ-PB1 before divergent selection for tassel size and ear placement. Divergent selection affected the correlation between traits under unpredicted and varying magnitudes.

Download Full-text

HERITABILITIES AND GENETIC CORRELATIONS FOR ULTRASONIC BACKFAT MEASUREMENTS, GROWTH AND CARCASS TRAITS IN SWINE

Canadian Journal of Animal Science ◽

10.4141/cjas82-081 ◽

1982 ◽

Vol 62 (3) ◽

pp. 665-670 ◽

Cited By ~ 3

Author(s):

D. C. JEFFRIES ◽

R. G. PETERSON

Keyword(s):

Key Words ◽

Genetic Correlation ◽

Genetic Parameters ◽

Average Daily Gain ◽

Genetic Correlations ◽

Phenotypic Correlation ◽

Ultrasonic Measurements ◽

Yorkshire Pigs ◽

Daily Gain ◽

Season Interaction

Genetic parameters were estimated for 2403 purebred Yorkshire pigs over a 2-yr period, representing 21 sires. The traits studied included average daily gain, age adjusted to 90 kg, ultrasonic measurements of backfat at the mid-back and loin positions, total and adjusted total ultrasonic backfat and corresponding carcass backfat measurements. Least squares analyses were used to estimate and adjust for the effects of sex, year-season and sex by year-season interaction. Heritabilities and genetic correlations were calculated for all traits using both half- and full-sib estimates. Adjusted age and adjusted total ultrasonic backfat measurements were found to have the highest heritabilities of the live traits in this study. Estimates of heritability for adjusted age and adjusted total ultrasonic backfat were 0.24 ± 0.10 and 0.26 ± 0.10 based on half-sib and 0.56 ± 0.07 and 0.41 ± 0.06 from full-sib analyses. The genetic correlation between these two traits was −0.07 ± 0.28 based on the half-sib method. The total phenotypic correlation was −0.01 ± 0.02. Key words: Swine, ultrasonic backfat, heritabilities, genetic correlations

Download Full-text

Genetic parameters of production and reproduetive traits in on a farm tested Danish Large White and Landrace swine in Greece

Archives Animal Breeding ◽

10.5194/aab-43-287-2000 ◽

2000 ◽

Vol 43 (3) ◽

pp. 287-298

Author(s):

J. Bizelis ◽

A. Kominakis ◽

E. Rogdakis ◽

F. Georgadopoulou

Keyword(s):

Maximum Likelihood ◽

Genetic Correlation ◽

Genetic Parameters ◽

Genetic Correlations ◽

Production Traits ◽

Likelihood Methods ◽

Large White ◽

Reproduction Traits ◽

Maximum Likelihood Methods ◽

Genetic And Phenotypic Correlations

Abstract. Production and reproduetive traits in Danish Landrace (LD) and Large White (LW) swine were analysed by restricted maximum likelihood methods to obtain heritabilities as well as genetic and phenotypic correlations. Production traits were: age, backfat thickness (BT), muscle depth (MD) and the ratio BT/MD, adjusted to Standard bodyweight of 85 kg. Reproduction traits were: number of pigs born (NB) and number of pigs weaned (NW) per sow and parity. Heritabilities for age, BT, MD and BT/MD were 0.60, 0.44, 0.51 and 0.42 for LD and 0.36, 0.44, 0.37 and 0.45 for LW, respectively. Genetic correlations between age and BT were −0.22 in LD and – 0.44 in LW. The genetic correlation between age and MD was close to zero in both breeds. Genetic correlation between BT and MD were −0.36 and −0.25 in LD and LW, respectively. Heritabilities for NB were 0.25 in LD and 0.13 in LW while heritabilities for NW were close to zero in both breeds. Genetic correlation between NB and NW was 0.46 and 0.70 in LD and LW, respectively.

Download Full-text

Phenotypic and genetic parameters for lamb weights in a synthetic line of sheep

Animal Science ◽

10.1017/s0003356100024041 ◽

1980 ◽

Vol 30 (2) ◽

pp. 261-269 ◽

Cited By ~ 22

Author(s):

T. G. Martin ◽

D. I. Sales ◽

C. Smith ◽

D. Nicholson

Keyword(s):

Least Squares ◽

Genetic Parameters ◽

Genetic Correlations ◽

Animal Breeding ◽

Research Organization ◽

Correction Factors ◽

Component Method ◽

Breeding Research ◽

Selection For ◽

Synthetic Line

ABSTRACTData on 2120 lambs produced over 7 years in the Animal Breeding Research Organization synthetic Dam Line (49% Finn, 22% East Friesian, 16 % Border Leicester and 13 % Dorset Horn) were analysed by least squares. The effects of sex, age of dam, year of birth, birthrearing class, and age of lamb on weights at birth and at 4, 8, 12 and 16 weeks of age were all appreciable. However, pooled within-year correction factors should be adequate in adjusting records for selection. Heritability estimates for weights at the five ages ranged from 0·17 to 0·24 by the sire component method and from 0·18 to 0·28 by regression of offspring on dam. Previous reports of differences in heritability in singles and in twins were not confirmed. Estimates of the genetic correlations among the various lamb weights were high (0·62 to 1·04) indicating that selection for weight at one age should result in increased weights at all ages.

Download Full-text

Genetic parameter estimations and genomic insights for teat and udder structure in young and mature Canadian Angus cows

Journal of Animal Science ◽

10.1093/jas/skab087 ◽

2021 ◽

Author(s):

K Devani ◽

J J Crowley ◽

G Plastow ◽

K Orsel ◽

T S Valente

Keyword(s):

Animal Model ◽

Genetic Correlation ◽

Genetic Parameters ◽

Genetic Parameter ◽

Genetic Correlations ◽

Age Groups ◽

Morbidity And Mortality ◽

Parameter Estimations ◽

Angus Cattle ◽

Genetic Evaluations

Abstract Poor teat and udder structure, frequently associated with older cows, impact cow production and health, as well as calf morbidity and mortality. However, producer culling, for reasons including age, production, feed availability, and beef markets, creates a bias in teat and udder scores assessed and submitted to the Canadian Angus Association for genetic evaluations towards improved mammary structure. In addition, due to the infancy of the reporting program, repeated scores are rare. Prior to adoption of genetic evaluations for teat and udder scores in Canadian Angus cattle, it is imperative to verify that teat and udder scores from young cows are the same trait as teat and udder scores estimated on mature cows. Genetic parameters for teat and udder scores from all cows (n=4,192), and then from young cows (parity 1 and 2) and from mature cows (parity ≥ 4) were estimated using a single trait animal model. Genetic correlations for the traits between the two cow age groups were estimated using a two-trait animal model. Estimates of heritability (PSD) were 0.32 (0.07) and 0.45 (0.07) for young teat and udder score, and 0.27 (0.07) and 0.31 (0.07) for mature teat and udder score, respectively. Genetic correlation (PSD) between the young and mature traits was 0.87 (0.13) for teat score and 0.40 (0.17) for udder score. GWAS were used to further explore the genetic and biological commonalities and differences between the two groups. Although there were no genes in common for the two udder scores, 12 genes overlapped for teat score in the two cow age groups. Interestingly, there were also 23 genes in common between teat and udder scores in mature cows. Based on these findings, it is recommended that producers collect teat and udder score on their cow herd annually.

Download Full-text

Estimation of Genetic Parameters for Peak Yield, Yield and Persistency Traits in Murciano-Granadina Goats Using Multi-Traits Models

Animals ◽

10.3390/ani9070411 ◽

2019 ◽

Vol 9 (7) ◽

pp. 411

Author(s):

Judith C. Miranda ◽

José M. León ◽

Camillo Pieramati ◽

Mayra M. Gómez ◽

Jesús Valdés ◽

...

Keyword(s):

Multivariate Analysis ◽

Selection Criteria ◽

Genetic Parameters ◽

Genetic Correlations ◽

Multiple Trait ◽

Lactation Curve ◽

Derivative Free ◽

Selection For ◽

Estimated Breeding Values ◽

Estimation Of Genetic Parameters

This paper studies parameters of a lactation curve such as peak yield (PY) and persistency (P), which do not conform to the usual selection criteria in the Murciano-Granadina (MG) breed, but are considered to be an alternative to benefit animal welfare without reducing production. Using 315,663 production records (of 122,883 animals) over a period of 24 years (1990–2014), genetic parameters were estimated with uni-, bi- and multivariate analysis using multiple trait derivative free restricted maximum likelihood (MTDFREML). The heritability (h2)/repeatability (re) of PY, yield (Y) and P was estimated as 0.13/0.19, 0.16/0.25 and 0.08/0.09 with the uni-trait and h2 of bi- and multi-traits analysis ranging from 0.16 to 0.17 of Y, while that of PY and Y remained constant. Genetic correlations were high between PY–Y (0.94 ± 0.011) but low between PY–P (–0.16 ± 0.054 to –0.17 ± 0.054) and between Y–P (–0.06 ± 0.058 to –0.05 ± 0.058). Estimates of h2/re were low to intermediate. The selection for Y–PY or both can be implemented given the genetic correlation between these traits. PY–P and Y–P showed low to negligible correlation values indicating that if these traits are implemented in the early stages of evaluation, they would not be to the detriment of PY–Y. The combination of estimated breeding values (EBVs) for all traits would be a good criterion for selection.

Download Full-text