The overall recombinational landscape of porcine X chromosome and intervals with individual heterogeneity of recombination. The top part of this figure represents the genetic position of makers placed on both genetic maps of INRA and JXAU populations compare to the physical position of pig clone map. Markers with a star were used in the initial genotyping experiment. SW259 is located near the centromere. The slope of the curves provides an estimate of the local recombination rate. The patterns for the two populations are similar over the whole chromosome, except for the region from SW980 to SW1903 (gray lines). A (SW2456-UMNP1174), C (SW1426-MCSE347J6) and D (SW1608-S 0218-SW2588) delimit three regions of high recombination rates; B (SW259-SW1994-UMNP71) is a recombination coldspot. Heterogeneity of recombination fraction among F1 females was observed for four intervals, including LH-C (UMNP71-SW1943), LH-1 (SW1903-SW2456), LH-2 (SW1608-S0218) and LH-3 (SW1943-SW1608). LH-1 and LH-2 were observed only in the INRA population, and LH-3 was specific to JXAU population, while LH-C was detected in both populations. The lower part presents a more detailed analysis of the recombination patterns in the LH-C interval among 4 F1 full-sisters from INRA population. Females 910002, 910009, 910010 who inherited the same maternal haplotype showed higher recombination rates compared with 910013, who inherited the other maternal haplotype, or compared with the average of the whole population. Number of meioses analysed for each female is presented between parentheses. LH-C could be further narrowed down to a sub-interval UMNP891-UMNP93, flanked by two vertical dash lines.