Chromosomes of the antelope genus Kobus (Artiodactyla, Bovidae): karyotypic divergence by centric fusion rearrangements

G- and C-banded karyotypes of four species of the genus Kobus were compared using the standard karyotype of Bos taurus. Chromosomal complements were 2 n = 50-54 in K. ellipsiprymnus, 2n = 50 in K. kob, 2n = 48 in K. leche, and 2n = 52 in K. megaceros. The number of autosomal arms in all karyotypes wa s 58. Fifteen autosomal pairs were conserved among these four species, incl uding the 1;19 and 2;25 centric fusions. and autosomal differences involved eight centric fusion rearrangements. Five centric fusions were each unique to a particular taxon: 3;10 (K. leche), 3;11 and 6;29 (K. kob), and 5;17 a nd 7;11 (K. ellipsiprymnus). The 4;7 fusion occurred in K. leche and K. meg aceros, whereas the 5;13 fusion occurred in K. kob and K. leche; the 6;18 f usion was found in three species but was absent in fi: kob. Differences bet ween the X chromosomes of the four Kobus species were attributed to heteroc hromatic additions or deletions, and Y-chromosome differences may have been the result of pericentric inversion. G-banded karyotypes of putative K. l. leche and K. l. kafuensis appeared identical, as did C-banded karyotypes o f the two subspecies. Karyotypes of K. e. ellipsiprymnus and K. e. defassa differed as a result of the 6;18 centric fusion, which was polymorphic in K . e. defassa, and the 7;11 centric fusion, which was polymorphic in K. e. e llipsiprymnus but absent in K. e. defassa. Several centric fusions were rel ated by monobrachial chain-IV complexes: however, records of hybridization indicate that reproductive isolation between at least certain species of Ko bus is incomplete. Karyotypic differences between K. ellipsiprymnus (includ ing K. e. ellipsiprymnus and K. e. defassa), K. kob, K. leche, and K. megac eros support the validity of these taxa, as well as the need to manage them as separate populations. Copyright (C) 2001 S. Karger AG, Basel.