A microsatellite-based linkage map of the honeybee, Apis mellifera L

A linkage map for the honeybee (Apis mellifera) was constructed mainly from the progeny of two hybrid queens (A. m. ligustica × A. m. mellifera). A total of 541 loci were mapped; 474 were microsatellite loci; a few were additional bands produced during PCRs, one of the two rDNA loci (using ITS), the MDH locus, and three sex-linked markers (Q and FB loci and one RAPD band). Twenty-four linkage groups were estimated of which 5 were minute (between 7.1 and 22.8 cM) and 19 were major groups (>76.5 cM). The number of major linkage groups exceeded by three the number of chromosomes of the complement (n = 16). The sum of the lengths of all linkage groups amounts to 4061 cM to which must be added at least 320 cM to link groups in excess, making a total of at least 4381 cM. The length of the largest linkage group I was 630 cM. The average density of markers was 7.5 cM and the average resolution was about one marker every 300 kb. For most of the large groups, the centromeric region was determined genetically, as described in Baudry et al. (2004, accompanying article in this issue), using half-tetrad analysis of thelytokous parthenogens in which diploid restoration occurs through central fusion. Several cases of segregation distortion that appreared to result from deleterious recessives were discovered. A low positive interference was also detected.