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

Abstract

G- and C-banded karyotypes of four species of the genus Kobus were compared using the standard karyotype of Bos taurus. Chromosomal complements were 2n = 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 was 58. Fifteen autosomal pairs were conserved among these four species, including 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 and 7;11 (K. ellipsiprymnus). The 4;7 fusion occurred in K. leche and K. megaceros, whereas the 5;13 fusion occurred in K. kob and K. leche; the 6;18 fusion was found in three species but was absent in K. kob. Differences between the X chromosomes of the four Kobus species were attributed to heterochromatic 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 of 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. ellipsiprymnus but absent in K. e. defassa. Several centric fusions were related by monobrachial chain-IV complexes; however, records of hybridization indicate that reproductive isolation between at least certain species of Kobus is incomplete. Karyotypic differences between K. ellipsiprymnus (including K. e. ellipsiprymnus and K. e. defassa), K. kob, K. leche, and K. megaceros support the validity of these taxa, as well as the need to manage them as separate populations.

Phylogeny and vicariant speciation of the Grey Rhebok, Pelea capreolus

“…Although there is some variation in extent of C-positive material within and among species, the location is invariably conserved. Previous studies have identified a series of Rb fusions in Redunca and Kobus species (Kingswood et al, 2000;Rubes et al, 2007;Pagacova et al, 2011) all of which were confirmed by cross-species FISH in the present investigation. Based on these data, and the new information presented for Pelea (Table 1), we can conclude that Rb 2;25 is a synapomorphy that unites Pelea þ Kobus þ Redunca, thus firmly placing Pelea within Reduncinae.…”

“…The supermatrix initially included all six DNA fragments in combination with the P. capreolus chromosomal characters presented above, as well as those reported for R. fulvorufula, K. kob, K. ellipsiprymnus, K. leche, and K. megaceros (Kingswood et al, 2000;Rubes et al, 2007;Pagacova et al, 2011-see Table 1) and confirmed by cross-species FISH in the present study. Species for which chromosomal information was not available were coded as missing data.…”

“…Chromosomal data (based on G-banding and/or Q-banding) are available for four of five Kobus species (K. ellipsiprymnus 2n ¼ 50, K. kob 2n ¼ 50, K. leche 2n ¼ 48, K. megaceros 2n ¼ 52 Kingswood et al, 2000) and one of three Redunca species (R. fulvorufula (RFU) 2n ¼ 56, Rubes et al, 2007). Since these data form the basis for our comparison with Pelea, a point of taxonomic clarification is required.…”

Karyotype, centric fusion polymorphism and chromosomal aberrations in captive-born mountain reedbuck <i>(Redunca fulvorufula)</i>

“…The biarmed chromosomes result from centric fusions involving chromosomes 2 and 25, and 6 and 10, respectively. Four species of the genus Kobus of the same subfamily Reduncinae , which has been described in detail by Kingswood et al (2000), have four to six fusions. The fusion 2; 25 was also found in all four investigated species of the genus Kobus (K. ellipsiprymnus, K. kob, K. leche, K. megaceros) .…”

Homologous fission event(s) implicated for chromosomal polymorphisms among five species in the genus <i>Equus</i>

“…Balanced chromosome polymorphisms have been identified in other mammalian species as well, such as oryx (Oryx dammah and O. leucocryx) (Kumamoto et al, 1999), gazelle (Gazella subgutturosa marica, G. bennetti, and G. saudiya) (Vassart et al, 1993;Kumamoto et al, 1995), the rock wallaby (Petrogale lateralis pearsoni) (Eldridge and Pearson, 1997), domestic sheep (Ovis aries) (Koop et al, 1983), and the owl monkey (Aotus) (Ma et al, 1976), but in all cases are relatively uncommon. One out of four species in the genus Kobus (K. ellipsiprymnus) exhibited two polymorphic centric fusions (Kingswood et al, 2000). Interestingly, a balanced chromosomal polymorphism has been reported in another Perissodactyl, the northern white rhinoceros (Ceratotherium simum) (Houck et al, 1994), and research is underway to determine if the rhinoceros polymorphism is homologous to the equids (Lear, personal communication).…”