Dec 06, 2013 This feature is not available right now. Please try again later. Por ende, los individuos que las poseen tienen mayores probabilidades de aprovechar los recursos del ambiente, de sobrevivir, y de dejar.
(1)where µ o and µ are the population means before and after selection, respectively. If the trait is completely inherited, µ 1, the population mean of the offspring of selected individuals will be close to µ. On the contrary, a trait for which the genetic contribution is too low (i.e., only environmentally determined) will have a µ 1 very close to µ o. This measureis called the narrow-sense heritability (h 2) (0 £ h 2 £ 1).Hence, if h 2 »1, then µ 1 »µ; similarly if h 2 »0, µ 1 »µ o (see ).
Narrow-sense heritability indicates the relative proportion of additive genetic variance to phenotypic variance. Additivity of gene effects relates to the fact that each gene is inherited individually. In evolutionary terms the important fact is the individual contribution of each gene to the phenotype. Effects that depend on the interaction among genes (e.g., dominance, epistasis) are less important in the long term (and in large, panmitic populations) because these are properties of genotypes, not of genes. The additive genetic variance (V A) contains the variance of breeding values which are those properties of individual genes. Together, V A and V P make up h 2: h 2 = V A / V P. (4)Equation (4), known as the 'breeders equation', shows that natural selection translates into evolution only if there is some degree of inheritance in the selected trait.
The breeders equation has been empirically demonstrated and its components in many cases are different from zero (i.e., evolution by natural selection is occuring). Two of the most important advances in evolutionary theory are the Fundamental Theorem of Natural Selection and the Robertson-Price Identity(, ), also referred as the Secondary Theorem of Natural Selection (Caswell 1989).
The important contributions of these models are that S can be equated to the covariance between a trait of interest (z), and to relative fitness (w) (see ),S = Cov (z,w).