EVOLUTION OF DIMORPHIC TRAITS - EFFECT OF DIRECTIONAL SELECTION ON HERITABILITY

Authors
Citation
Da. Roff, EVOLUTION OF DIMORPHIC TRAITS - EFFECT OF DIRECTIONAL SELECTION ON HERITABILITY, Heredity, 72, 1994, pp. 36-41
Citations number
27
Categorie Soggetti
Genetics & Heredity
Journal title
ISSN journal
0018067X
Volume
72
Year of publication
1994
Part
1
Pages
36 - 41
Database
ISI
SICI code
0018-067X(1994)72:<36:EODT-E>2.0.ZU;2-Y
Abstract
Directional selection on a quantitative character is predicted to decr ease genetic variance and lead to rapid fixation of alleles. However, many traits vary in a dichotomous manner although the underlying genet ic determination is polygenic. This paper presents a theoretical exami nation of the effects of directional selection on a dimorphic trait. S uch selection can change the incidence of the selected morph from 50 p er cent to 99 per cent within 20 generations. However, after an initia l decline heritability is predicted to rise back to its original value . The consequences of a finite number of alleles and loci on this pred iction are examined using a simulation model. These simulations show t hat, unlike the case of directional selection on a continuously distri buted trait, there is little loss of genetic variance even when the tr ait is controlled by only three loci with two alleles per locus.