Use of genetic markers in animal breeding

Abstract

Following some recent major advances in molecular genetics, particularly the discovery of microsatellite sequences in all animal genomes and of the DNA amplification with the PCR reaction, many genetic markers are now available in most animal domestic species and are located in genetic maps. The properties of genetic markers are presented. Out of them, polymorphism and linkage make it possible to trace chromosomal segments across generations. This paper describes the potential applications of genetic markers for population management and analysis of genetic variability. Emphasis is put on detection of loci (quantitative trait loci = QTL) involved in the genetic determinism of economically important traits. QTL detection is a first step toward marker- assisted selection or marker-assisted introgression. This paper also briefly presents some methods, often based on comparative mapping, to identify the causal genes detected through genetic markers. This final step paves the road toward a better comprehension of the mechanisms involved and to simpler, more general, and more efficient selection procedures.