Divergent selection experiments in poultry.

摘要

The importance of quantitative genetics is obvious for poultry breeders as most traits of economic value are quantitative. To better understand quantitative traits, much research has been conducted using short- and long-term divergent selection experiments in chickens and quails over the last decades. In the past, divergent selection experiments were conducted for a variety of reasons such as estimating genetic parameters, testing alternate breeding schemes, measuring selection limits and plateaus, testing theoretical basis relating population sizes and selection intensities, searching for correlated responses to selection on a focal trait, ascertaining the symmetry of responses in a particular trait, etc. Genetically correlated traits are known to respond to indirect selection pressures caused by directional selection on other traits. Thus correlations are of great interest to the breeders. Additionally, information on genetic correlations between traits may provide insight into the biological mechanisms involved in generating differences between selection lines. Divergent selection experiments resulted in a wealth of unique populations of chickens/quails that are very useful for subsequent biochemical or physiological studies, and for studying of genotype by environment (G x E) interactions. G x E interactions are of fundamental importance in poultry breeding because their involvement influences breeding procedure. Geneticists have long been concerned with identifying key genes responsible for variation in quantitative traits. Intercrosses between divergently selected chicken/quail lines have led to the identification of several quantitative trait loci affecting for growth, egg production and quality, feed consumption, disease resistance and other traits.