GENETIC-DIFFERENCES IN RECOMBINATION FREQUENCY IN THE PIG (SUS SCROFA)

A comparison has been performed on 3 recently published linkage maps o f the pig, hereafter designated as the American (A), European (E), and Swedish (S) maps. The cumulated distances between common markers in t hese 3 maps were in the ratio 1.00 (A):0.88 (E):0.77 (S), in keeping w ith the ratio of the percentages of domestic genome in the reference f amilies used to build the corresponding maps, i.e., 1.00 (A):0.81 (E): 0.50 (S). From further recombination frequencies reported in wild boar s (in the S report), the wild pig genome length (in centimorgans) is e xpected to represent 66% of the domestic pig genome length. These obse rvations tend to confirm a general result of Burt and Bell (Nature (Lo ndon), 326: 803-805 (1987)), showing higher chiasma frequencies in dom estic mammalian species compared with wild species. Consequences for m apping studies are discussed.