Title: Heritability of Body Measurements in Turkeys ,
Abstract: IT IS now recognized that aside from its genetic basis, the phenotypic expression of a characteristic depends on the environmental modification of the genetic potential for that characteristic. In this connection, several methods of estimating heritability have been devised to evaluate the relative importance of environmental and hereditary influences in determining the phenotype. By a broad definition, heritability is that fraction of the observed phenotypic variance which can be ascribed to known genetic differences between individuals. A narrow definition of heritability can be limited to include only the average gene effects, such as would be expected to appear if the genes were acting additively. This latter definition is a more useful one from the standpoint of applied genetics because it excludes genetic effects that are not likely to be recovered in successive generations. In terms of variances, heritability in the narrow sense can be expressed as while the corresponding broader . . .