Comparative gene and QTL mapping in aquaculture species

Abstract

Mapping genes and quantitative trait loci (QTLs) is of fundamental and applied interest in aquaculture species. Such studies can pro- vide essential information about rates and patterns of evolutionary change and may pro- vide tools which can be used in marker-assist- ed selection (MAS; e.g., Groenen et al., 2000). Mapping typically involves producing divergent crosses and analyzing segregation patterns in the offspring of hybrids between the divergent crosses. The more divergent the cross is, the greater the potential for finding useful marker and trait differences that can be mapped. The basic goal of mapping is to understand the position of loci on chromo- somes and how the positions change during evolution. The applied goal of mapping is to understand the position of loci associated with phenotypic traits which could be important in breeding programs. Correspondingly, QTL mapping seeks to identify the number and location of loci associated with phenotypic traits (e.g., Mackay, 2001; Mauricio, 2001; Burt and Hocking, 2002; Erickson et al., 2004) while applied QTL studies seek to identify candidate genes or markers for use in MAS.