Inferences on the Genetics of Quantitative Traits from Long‐Term Selection in Laboratory and Domestic Animals

Hill, William G.; Bünger, L.

doi:10.1002/9780470650288.ch6

Cited by 23 publications

(23 citation statements)

References 51 publications

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“…Differences between means within sex are indicated as P , 0.05 (*), P , 0.01 (**). likely explanation for our findings (Hill and Bunger 2004;Hill and Zhang 2004). Our hypotheses of sex linkage on dispersion in urinary calcium are as follow: female F 2 rats had higher dispersion in urinary calcium than males (P , 0.05), and QTL for phenotypic dispersion were detected only in female F 2 s (P , 0.05), while male WKY animals and male congenics in each RNO1 subcongenic line (being .1 -0.5 6 98% WKY genome) had significantly higher CVs for urinary calcium than females (P , 0.001), suggesting differences in sex linkage between GHS and WKY rather than sex limitation.…”

Section: Discussionmentioning

confidence: 83%

“…However, further examination of Hoopes et al (2003) revealed that female GHS rats also had a variance 40 times and a coefficient of variation (CV ¼ s/m) 2.3 times that of male GHS rats and that nearly the reverse was true in male and female WKY progenitors, implicating genotypeby-sex interaction in the generation of random variation. Further, there was increasing generation-to-generation variability in urinary calcium over the selective development of the GHS line, a pattern suggestive of increasing variation in selection lines of Drosophila bred by Clayton and Robertson (1957) (see Hill and Bunger 2004;Hill and Zhang 2004). The architecture of urinary calcium and stone formation differs markedly between the sexes in mammals: males and females have different urinary calcium in rats (Hoopes et al 2003) and humans (Coe 1988;Curhan et al 1997), which have more stones than females (Monk and Bushinsky 2003;Alaya et al 2010).…”

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confidence: 99%

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Sex Modifies Genetic Effects on Residual Variance in Urinary Calcium Excretion in Rat (Rattus norvegicus)

et al. 2012

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Conventional genetics assumes common variance among alleles or genetic groups. However, evidence from vertebrate and invertebrate models suggests that residual genotypic variance may itself be under partial genetic control. Such a phenomenon would have great significance: high-variability alleles might confound the detection of "classically" acting genes or scatter predicted evolutionary outcomes among unpredicted trajectories. Of the few works on this phenomenon, many implicate sex in some aspect of its control. We found that female genetic hypercalciuric stone-forming (GHS) rats (Rattus norvegicus) had higher coefficients of variation (CVs) for urinary calcium (CV ¼ 0.14) than GHS males (CV ¼ 0.06), and the reverse in normocalciuric Wistar-Kyoto rats (WKY) (CV ♂ ¼ 0.14; CV ♀ ¼ 0.09), suggesting sex-by-genotype interaction on residual variance. We therefore investigated the effect of sex on absolute-transformed residuals in urinary calcium in an F 2 GHS · WKY mapping cohort. Absolute residuals were associated with genotype at two microsatellites, D3Rat46 (RNO3, 33.9 Mb) and D4Mgh1 (RNO4, 84.8 MB) at Bonferroni thresholds across the entire cohort, and with the microsatellites D3Rat46, D9Mgh2 (RNO9, 84.4 Mb), and D12Rat25 (RNO12, 40.4 Mb) in females (P , 0.05) but not males. In GHS chromosome 1 congenic lines bred onto a WKY genomic background, we found that congenic males had significantly (P , 0.0001) higher CVs for urinary calcium (CV ¼ 0.25) than females (CV ¼ 0.15), supporting the hypothesis of the inheritance of sex-by-genotype interaction on this effect. Our findings suggest that genetic effects on residual variance are sex linked; heritable, sex-specific residuals might have great potential implications for evolution, adaptation, and genetic analysis.

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Section: Discussionmentioning

confidence: 83%

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confidence: 99%

Sex Modifies Genetic Effects on Residual Variance in Urinary Calcium Excretion in Rat (Rattus norvegicus)

et al. 2012

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“…For the estimated parameters, according to prediction formulas given by Mulder et al (2007), with intense mass selection entirely on means the variance is expected to increase over generations, but because the rate of increase in SD would be lower than for the mean, the CV would therefore be decreased by selection. In the selection experiment by Dunnington and Siegel (1996) in Virginia, the CV decreased in the line selected for high BW and increased in the low line (Hill and Bünger, 2004), also indicative of a negative correlation between mean and variance.…”

Section: Discussionmentioning

confidence: 89%

Genetic variability in residual variation of body weight and conformation scores in broiler chickens

et al. 2009

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The aim of the study was to estimate genetic variance in residual variation of BW and body conformation scores of 34-d-old male and female broiler chickens. The data set included performance records of 52,349 female and 49,001 male birds. Two models were used: an iterative mean-variance restricted maximum likelihood sire plus dam model and a Bayesian sire plus dam model, in each case with heterogeneity in residual variances across sire families. They gave similar results. Estimates of heritability for BW in females and males were, respectively, 0.25 and 0.21, and for conformation score were 0.24 and 0.15, and genetic correlations for the same trait between sexes were high. Estimates of genetic correlations between means and variances were positive for both sexes and both traits. Estimates of the heritability of residual variation were low, between 0.023 and 0.038 for both traits, but genetic CV were substantial (between 0.25 and 0.40), indicating the possibility of improving uniformity of BW and conformation by means of selection.

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“…Worsening of fitness-associated traits such as fertility in dairy cattle and leg defects in broilers have been reversed by increasing emphasis on these traits (Kapell et al 2012). In contrast, judging by the winning times of classic flat races, Thoroughbred racehorses and Greyhounds have hardly increased in speed for well over half a century; but it is not clear why (Hill 1988;Hill and Bunger 2004).…”

Section: Progress and Perspectivesmentioning

confidence: 99%

“…Very substantial and continued genetic improvement has been made in livestock over the past several decades (Hill and Bunger 2004;Hill 2008). Broiler chickens increased in 8-week weight over fourfold as shown by a contemporary comparison of 1957 control and 2001 commercial stock, with a further twofold difference in breast meat yield, and response continues.…”

Section: Progress and Perspectivesmentioning

confidence: 99%

Applications of Population Genetics to Animal Breeding, from Wright, Fisher and Lush to Genomic Prediction

Hill

2014

Genetics

106

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Although animal breeding was practiced long before the science of genetics and the relevant disciplines of population and quantitative genetics were known, breeding programs have mainly relied on simply selecting and mating the best individuals on their own or relatives' performance. This is based on sound quantitative genetic principles, developed and expounded by Lush, who attributed much of his understanding to Wright, and formalized in Fisher's infinitesimal model. Analysis at the level of individual loci and gene frequency distributions has had relatively little impact. Now with access to genomic data, a revolution in which molecular information is being used to enhance response with "genomic selection" is occurring. The predictions of breeding value still utilize multiple loci throughout the genome and, indeed, are largely compatible with additive and specifically infinitesimal model assumptions. I discuss some of the history and genetic issues as applied to the science of livestock improvement, which has had and continues to have major spin-offs into ideas and applications in other areas.

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Inferences on the Genetics of Quantitative Traits from Long‐Term Selection in Laboratory and Domestic Animals

Cited by 23 publications

References 51 publications

Sex Modifies Genetic Effects on Residual Variance in Urinary Calcium Excretion in Rat (Rattus norvegicus)

Sex Modifies Genetic Effects on Residual Variance in Urinary Calcium Excretion in Rat (Rattus norvegicus)

Genetic variability in residual variation of body weight and conformation scores in broiler chickens

Applications of Population Genetics to Animal Breeding, from Wright, Fisher and Lush to Genomic Prediction

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