The genome of the gray, short-tailed opossum, Monodelphis domestica, will be the first of any marsupial to be fully sequenced. The utility of this sequence will be greatly enhanced by construction and integration of detailed genetic and physical maps. Therefore, it is important to verify the unusual recombinational characteristics that were suggested by the ‘first-generation’ M. domestica linkage map; specifically, very low levels of recombination and severely reduced female recombination, both of which are contrary to patterns in other vertebrates. We constructed a new linkage map based on a different genetic cross, using a new and much larger set of map markers, and physically anchored and oriented the linkage groups onto chromosomes via fluorescence in-situ hybridization mapping. This map includes 150 loci in eight autosomal linkage groups corresponding to the eight autosome pairs, and spans 86–89% of the autosomal genome. The sex-averaged autosomal map covers 715 cM, with a full-length estimate of 866 cM; the shortest full-length linkage map reported for any vertebrate. The sex-specific maps confirmed severely reduced female recombination in all linkage groups, and an overall F/M map ratio = 0.54. These results greatly extend earlier findings, and provide an improved microsatellite-based linkage map for this species.
Figure S1Sub-pedigree structures for the BBBX mapping panel. The single, complex BBBX pedigree of 571 animals was subdivided into the 8 sub-pedigrees shown in this figure to facilitate computation for linkage analysis. Circles and squares represent females and males, respectively, in the grandparental and parental (reproductive) generations. The numbers within the circles and squares are the unique identification numbers for each animal as stored in the Southwest Foundation for Biomedical Research M. domestica research colony pedigree database (see main paper). Shaded shapes indicate animals that occur in more than one of the eight sub-pedigrees. Diamonds represent the terminal offspring generation; figures within the diamonds indicate the number of offspring in the particular sibship (PPT 1,310 KB)