A COMPREHENSIVE MAP OF THE PORCINE GENOME

We report the highest density genetic linkage map for a livestock spec ies produced to date. Three published maps for Sus scrofa were merged by genotyping virtually every publicly available microsatellite across a single reference population to yield 1042 linked loci, 536 of which are novel assignments, spanning 2286.2 cM (average interval 2.23 cM) in 19 linkage groups (18 autosomal and X chromosomes, n=19). Linkage g roups were constructed de novo and mapped by locus content to avoid pr opagation of errors in older genotypes. The physical and genetic maps were integrated with 123 informative loci assigned previously by fluor escence in situ hybridization (FISH). Fourteen linkage groups span the entire length of each chromosome. Coverage of chromosomes 11, 12, 15, and 18 will be evaluated as more markers are physically assigned. Mar ker-deficient regions were identified only on 11q1.7-qter and 14 cen-q 1.2. Recombination rates (cM/Mbp) varied between and within chromosome s. Short chromosomal arms recombined at higher rates than long arms, a nd recombination was more frequent in telomeric regions than in perice ntric regions. The high-resolution comprehensive map has the marker de nsity needed to identify quantitative trait loci (QTL), implement mark er-assisted selection or introgression and YAC contig construction or chromosomal microdissection.