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Ecological Genetics and the Evolution of Trace Element Hyperaccumulation in Plants
Published in Norman Terry, Gary Bañuelos, of Contaminated Soil and Water, 2020
A. Joseph Pollard, Keri L. Dandridge, Edward M. Jhee
It is often useful to estimate the relative contributions of genotype and environment to the phenotype. This is done using a statistic called heritability, symbolized h2, which varies between zero and one. The ratio VG/VP, known as “broad-sense heritability,” reflects the fraction of the population’s variability that is caused genotypically and, by extension, the probable fraction of an individual’s phenotype determined by its genes. The ratio VA/VP is termed “narrow-sense heritability.” Because of the definition of additive variation, narrow-sense heritability can be said to reflect the degree to which phenotypes are determined by the genes of parents (i.e., the importance of inheritance in controlling the phenotype). In either case, heritability is a characteristic of a particular population in a particular environmental setting. Heritability estimates made under uniform conditions will usually be higher than those measured in a variable environment, because of the decreased contribution of VE to the denominator, VP.
Personalizing Environmental Health for the Military—Striving for Precision
Published in Kirk A. Phillips, Dirk P. Yamamoto, LeeAnn Racz, Total Exposure Health, 2020
As older GWAS have been done with early, less capable platforms, this implies that the DNA measurements of many GWAS may need to be redone in order to obtain structural variants and SNPs in low-complexity genomic regions. Prime candidates for reassessment would be studies in which the sum of the statistically significant SNPs does not reach the level of known genetic heritability measured in monozygotic twins. An example would be type 2 diabetes. This complex trait has ~42 SNPs that have been associated with it through GWAS. Interestingly, most SNP risk is cumulative (Manolio et al. 2009). Essentially, one can potentially sum the risk (i.e., odds ratio) of each SNP associated with a complex trait or disease and compare to the level of heritability as measured by H2 = Var (G)/Var (P), where H =Heritability, G = Genetics, and P =Phenotype. The difference between the two may provide a measure of how much variability is remaining that is heritable but has not been accurately measured by SNP arrays. In other words, this ‘missing heritability’ (Fisher 1918) could very likely be comprised of structural variants missed by SNP arrays, which could be measured by OxNan and other long-read sequence typing technologies.
Glossary of scientific and technical terms in bioengineering and biological engineering
Published in Megh R. Goyal, Scientific and Technical Terms in Bioengineering and Biological Engineering, 2018
Heritability is the proportion of total phenotypic variation within a population that is due to individual genetic variation (HB; broad sense heritability). Heritability is more commonly referred to as the proportion of phenotypic variation within a population that is due to additive genetic variation (HN; narrow sense heritability).
Towards a science of the acquisition of expert performance in sports: Clarifying the differences between deliberate practice and other types of practice
Published in Journal of Sports Sciences, 2020
Most of the current knowledge about the degree of influence of genetic factors is based on studies of twins and the finding that identical twins are more similar than fraternal twins. The most common measure is heritability, namely the percentage of variance in individual differences of a characteristic that can be accounted for by genetic factors. It is, however, important to recognize that “heritability describes ‘what is’ in a particular sample; it does not connote innateness or immutability” (Plomin, Shakeshaft, McMillan, & Trzaskowski, 2014, p. 47). It is not valid to extrapolate heritability estimates for the performance of individuals, who lead mostly sedentary lives with recreational activities, to heritability estimates for expert performers, who have engaged in extensive training for years and even decades (Ericsson, 2007). The expert performer represents what Plomin et al. (2014) refer to as “what could be”. Research has shown that expert performance is mediated by acquired cognitive skills and physiological adaptations, which beginners do not have. In a review, Ericsson (2014) showed that the performance of beginners correlates with scores on tests of general cognitive ability whereas among skilled performers the correlations with such test scores are dramatically reduced, often to a chance level. In a more recent meta-analysis of the correlation between cognitive-ability tests and chess performance, Burgoyne, Sala, Gobet, Macnamara, Campitelli, and Hambrick (2016) found this pattern with substantial correlation for beginners and less skilled players but not for highly skilled players.