MGR parsimony tree of syntenic block rearrangements. (a) Syntenic blocks are colored according to homology for the karyotype of the last common ancestor (represented by T. thetis, see KEY). The diploid number is indicated in grey below the karyotype. The number of rearrangements is indicated on branches as fissions (/), fusions (^), and translocations (*). Unmarked branches have no changes. Estimated ancestral karyotypes, constructed by MGR, are included at marked nodes α, β, and γ, without sex chromosome inference. Note that the M. rufus karyotype is equivalent to ancestral α, the M. eugenii karyotype is equivalent to ancestral β, and the ancestral γ karyotype has no extant counterpart. Nine rearrangements reconstruct all six karyotypes of the genus. The M. eugenii autosomal karyotype is equivalent to those of the true wallabies; the M. robustus autosomal karyotype is equivalent to the wallaroos herein. Spacers on the X chromosomes represent the positions of the nucleolous orgranizer regions . (b) Syntenic blocks active in rearrangements: C1 (dark pink), C2 (grey), C8 (light yellow), C10 (aqua), C15 (dark orange), C18 (orange). The syntenic block numbering is based on the relation to the 2n = 14 ancestral karyotype (see the errata in ).