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Article #423 South African Journal of Science 90

6 into 6,17 and into and 1,2,3,4,5 They are 9 . 15,16 C. t. taurinus kg a Research Letter and this study evidence ni 27,28

a 6 a goal of this study 29 and 260 er although is brown in colour with colour in brown is 7 cr kg h

although the actual extent actual the although 20 10,11,12 n ), Burchell, 1823) and the black (Rushworth I 2000, personal a 23 S Afr J Sci kg furt li

a , ~170 , Zimmermann, Zimmermann, 1780). In recent , , but following their initial divergence, cm C. taurinus, mm a C. gnou, C. gnou m

provide Hybrids between these two species that have been 21 ) and weighing between 210 in 8 e

a as well as a handful of other , Zimmermann, 1780). Molecular analyses and estimates ABSTRACT 24,25,26 INTRODUCTION ovid In addition, the blue has a large, long head, with horns C. gnou, 8 B

This article is available at: http://www.sajs.co.za : Following this initial divergence, the lineage leading to the modern blue modern the to leading lineage the divergence, initial this Following 8,22 2,6 dmixture a tall at the shoulder Although their distributions overlapped during the the during overlapped distributions their Although Lichtenstein, 1814, contains two extant species, the a cm

Lichtenstein, 1814, is part of the family (Order: Artiodactyla), which 6,10,13,14 Superficial morphological separation of the two species of wildebeest is based 6 of The primary goal of this paper is to briefly describe unusual dental and sutural ctyl

22 Today, the blue wildebeest occurs in a variety of savannah habitat types, including 6 a habitat preferences and behavioural differences have kept them largely separate. Connochaetes, 14 Vol. 106 No. 11/12 Page 1 of 5 106 No. 11/12 Vol. , Burchell, 1823) and the ( Connochaetes, Indeed, a substantial proportion of the black wildebeest population in South may tures 8,19 This forced sympatry in confined areas has led to interbreeding, and the production of fertile rtiod 18 a The black wildebeest, in contrast, is smaller (males ~120 (males smaller is contrast, in wildebeest, black The 6 C. taurinus The ( forced sympatry in confined areas within has led to interbreeding between these taxa and to fertile offspring. Here we report wildebeest on population a culled series at of Spioenkop cranial Dam characteristics Nature of Dental, Reserve, sutural a KwaZulu-, and hybrid South morphological anomalies Africa. occur at high frequency within these Similar . cranial morphological anomalies have been shown in other mammalian study hybrids provides further and evidence that this such anomalies may characterise hybridisation more broadly across phylogenetically divergent mammalian groups, although in the their expression anomalies across taxa. appear An increased to ability to differ identify hybrids of the endemic black wildebeest. applications in the conservation may also have important © 2010. The Authors. Licensee: OpenJournals Publishing. This work is licensed under the Creative CommonsAttribution License. (A two extant species, the blue wildebeest (or the brindled gnu, wildebeest (or white-tailed gnu, from the fossil record indicate that these two species diverged around one million years ago forms. southern and northern wildebeest black southerly the while form, ancestral the from morphologically little changed wildebeest which time many morphological changes accumulated. adapted to an open niche, during Today, five of the blue wildebeest occur on the African continent, The genus includes , , and other even-toed horned . Within this genus, there are contain a significant number of introgressed genes from the blue wildebeest, blue the from genes introgressed of number significant a contain of admixture between the two taxa is not known. well as species, both of traits displaying variable, highly as described been have phenotypically studied as intermediate traits (Table 1). . cream-to-black manes and a very long cream-tipped tail, and has characteristic horns with expanded before curving up at the tips. bases that curve primarily forwards and downwards It is uncertain whether geographically separated wildebeest the at of species the two the time of divergent occurrence of sympatric speciation the allowed of evolutionary conditions environmental and climatic lineages that led to in . these two forms open and were grassland, while the black wildebeest is restricted to the plateau. inland open central of the historic times, Yet despite these different habitat preferences, these two species have come recent into years frequent on contact many in private farms and on government-controlled reserves Africa. throughout South hybrids. is the only subspecies living in South Africa. The black wildebeest is endemic to South Africa and has no extant subspecies. primarily on horn curvature and pelage, especially the colour and length of the fur on the tail, as well as facial, neck and limb length and overall size (Table 1). The blue wildebeest is the larger of the species, two with males ~130 on hair long and stripes brindled with sheen), blue silvery a have can they (although colour in grey dark their manes, chin, throat and tails. the towards back sometimes and ends the at up curve then downwards, slightly and laterally sweep that Here we report on a series of anomalous cranial morphological characteristics displayed in a hybrid (blue hybrid a in displayed characteristics morphological cranial anomalous of series a on report we Here Africa. South KwaZulu-Natal, Reserve, Nature Dam Spioenkop at culled population wildebeest black) x These hybrids were identified initially from their external phenotype, communication, March 08), based primarily on horn morphology and pelage, and have been reported in detail elsewhere. anomalies, as well as other unusual morphological traits a over present diverged have that in lineages between hybrids primate these of skeletons the hybrids. in demonstrated been have Similar anomalies comparable time frame (i.e. Pleistocene), provides further evidence that cranial morphological anomalies characterise mammalian hybridisation more broadly. Because mammalian hybrids are also known to be polymorphic, sign

red 1 ha s

4 5 wildebeest 2,3

; conservation; for ybrid Florisbad Quaternary Centre for Environmental Institute for Human Biodiversity Planning Department of Accepted: Sept. 07 2010 2010 Published: Nov. 12 hybridisation; South Africa Dates: 2010 Mar. Received: 11 Keywords: Connochaetes cranial anomalies; dental anomalies; gene flow; Archaeology, University of Private X1, Bag Cape Town, Rondebosch 7701, South Africa ac.za Postal address: Department of Correspondence to: Rebecca Ackermann email: becky.ackermann@uct. of theof Witwatersrand, , South Africa Bloemfontein, South Africa 5 SchoolEvolution, of Geosciences, University & Research Component, Department Economic of Development, Tourism & Environmental Affairs, of theof , Bloemfontein, South Africa 4 National Museum, Bloemfontein, South Africa 3 Management, University Archaeology, University of SouthCape Africa Town, 2 Research Department, Bonita Klerk de Affiliations: 1 Authors: Rebecca R. Ackermann James Brink S. Savvas Vrahimis H crania. S Afr J Sci. Art. #423, 2010;106(11/12), 5 pages. DOI: 10.4102/sajs. v106i11/12.423 (Artiodactyla: Bovidae) provide further evidence for shared signatures of admixture in mammalian How to cite this article: Ackermann RR, Brink VrahimisJS, deS, Klerk B. Hybrid wildebeest http://www.sajs.co.za Evidence for hybridisationin wildebeest crania Research Letter Ackermann, Brink, Vrahimis & De Klerk

TABLE 1 Phenotypic characteristics of the first generation (F1) hybrid wildebeest (Connochaetes taurinus x C. gnou) from South Africa Blue wildebeest Black wildebeest F1 hybrid Horn shape Horns smooth, arising from swollen bosses and Horns smooth with expanded bases, directed Horns project down at an angle of 30 degrees directed outwards and slightly downwards before forward and downwards before curving up sharp- and then curl outward, away from the head, or curving up; horn tips pointed inwards and often ly. Adult males have heavy horns with prominent can be similar to either black or blue wildebeest slightly backwards. Horns of females are more bosses, while horns of females are more lightly horn shape lightly built than horns of males built Pelage colour Bluish-grey in colour with dark brindle stripes on Rich, dark-brown colour. Mature males have a Either bluish-grey or dark-brown in colour the neck and shoulders black face and a darker, almost black appear- ance Tail colour Black tail almost reaching the ground Characteristic creamy white, horse-like tail, dark Tail black, brown and white in most instances at the base, almost reaching the ground

Mane Shaggy mane of long black hair Stiff, upright, trim mane, creamy-white with dark Mane black and white, upright and shaggy to- tips wards the back

Brindle stripes Present Absent Present Face or nose morphology Head and face elongated; chin with long beard Head and face is less elongated than in the blue Head and face can be either elongated or less and limp black hair wildebeest, with a broad muzzle, erect facial tuft, elongated. Facial tuft often directed downwards and a distinct tuft of hair under the chin. Another tuft of hair is found on the chest, between the forelegs Height of males at shoulder ~ 1.3 m ~ 1.2 m ~ 1.3 m Source: Adapted from Fabricius et al.8 , with additional observations by authors

TABLE 2 Description of dental and sutural morphological anomalies in sub-adult and adult male and female hybrids (Connochaetes taurinus x C. gnou) from South Africa Specimen Sex Age Dental morphological anomalies Sutural morphological anomalies NMB12054 male adult none none NMB12051 male adult none right premaxillary suture extending slightly into maxilla NMB12048 female adult none small bilateral premaxillary suture remnants, extension of left premaxillary suture across maxilla NMB12052 male adult none small additional suture in left zygomatic, with pathology NMB12060 male sub-adult none none NMB12049 male adult unusual root right mandibular second premolar (p4), remnant of premaxillary suture bilaterally projecting into adjacent socket NMB12046 male sub-adult none none NMB12047 male adult none bilateral premaxillary sutures, extending completely around maxilla on right NMB12043 male adult rotated right maxillary second premolar (P4), 90 degrees none counter-clockwise NMB12042 male adult none none

Article #423 NMB12050 male sub-adult none none NMB12044 female adult none right remnant (but fused) premaxillary suture NMB12053 male adult none none NMB, National Museum Bloemfontein. South African Journal of Science was to qualitatively assess the range of phenotypic variation supernumerary teeth, extra sutures or ossicles in the maxillary in the hybrid sample. These results may assist in identification or premaxillary region, rotated teeth and dental crowding.26 of regions in South Africa with high versus low levels of The expression of supernumerary teeth was also recorded, as hybridisation, as it has been shown that the identification of such this has been shown to vary across mammalian hybrids.26,27 anomalies allows detection of hybridisation on the landscape.25 Additionally, the crania were examined for other evidence of This has important implications for conservation of the rarer, developmental abnormalities or abnormal trait variation. endemic black wildebeest. Data were compared to known trait variation in the blue and 6 MATERIALS AND METHODS black wildebeest. The comparative unhybridised sample included 20 blue wildebeest (11 male, 9 female) and 20 black All examined hybrid wildebeest crania (n = 13) are housed at the wildebeest (10 male, 10 female). The black wildebeest sample Florisbad Quaternary Research Station of the National Museum, included only historic and subfossil specimens, which predate Bloemfontein (NMB), and are listed in Table 2. The sample is the present hybridisation problem, while the blue wildebeest dominated by male adults, although there are two females and sample included both historic and modern specimens.6,17,22 two sub-adult individuals. These crania were prepared and curated at the Florisbad Quaternary Research Station after a large culling of wildebeest hybrids in the Spioenkop Dam Nature RESULTS AND DISCUSSION Reserve near the northern Drakensburg Mountains of KwaZulu- The dental and sutural morphological anomalies found in the Natal province, South Africa. The present study sample was 13 hybrid wildebeest are listed and briefly described in Table selected in the field at the time of the culling, based on author 2. None of the hybrids has supernumerary teeth, although one observations of deviations from the known black wildebeest 22,23 adult male individual (NMB12043) has a unilateral rotated phenotype. Further details of the examined cranial sample, premolar (Figure 1a). The only other dental anomaly is an as well as its associated postcranial remains, have been reported unusual premolar root (Figure 1b), also in an adult male. This previously.22 individual is old and it is possible that the root was damaged as a result of dental attrition. Sutural anomalies are more Individual hybrid wildebeest crania were examined and scored common in the hybrid wildebeest; six individuals (46%) had for the presence of a suite of qualitative (non-metric) cranial sutural anomalies, five of which were additional sutures in traits, with emphasis on dental and sutural morphometric the premaxillary region. These sutural anomalies occur in anomalies comparable to what is known to be present in hybrid primates.24,25,26 Qualitative cranial traits scored included: both males and females. The additional premaxillary sutures

91 S Afr J Sci Vol. 106 No. 11/12 Page 2 of 5 http://www.sajs.co.za Article #423 South African Journal of Science 92

n 27 The e d 26,29 Research Letter and for sutural for and 26 in lineages that are

with individuals showing a

29 S Afr J Sci and recent and Pleistocene squirrels, 25 he high variability seen here is consistent is here seen variability high he While hybrid morphology is typically 22 the variation in horn morphology among the among morphology horn in variation the There is also considerable variation in the 21

25 ) from South Africa. Specimen numbers: NMB12047, b) a) Extreme genetic differences (e.g. differentially c during the Pleistocene. Hybridisation is expected 30,31 wild gorillas 26 morphological anomalies in mammalian hybrids. Previously, it has been hypothesised that such morphological traits, which have been observed in the hybrids of known pedigree and wild , are broadly characteristic of mammalian hybridisation. presence of these morphological anomalies in hypothesis. provides further evidence in support of this the wildebeest These results also traits indicate occur that in anomalous separated fairly recently morphological diverged to lineages have very that different phenotypic have effects distantly divergent, compared with those that are more recently separated. and is comparable to what was observed for dental anomalies i anomalies dental for observed was what to comparable is and (50%) baboons F1 male hybrid known-pedigree anomalies in an identified hybrid zone within eastern lowland gorillas (45%). expression of these sutures across the hybrids (unilateral versus inferior; see Figure 2). bilateral, superior versus In addition anomalies, there are to also three individuals with abnormal horn these sheath morphology, one dental of which also has a pronounced and horn asymmetry (Figure 3). sutural hybrid Although in the observed been presence has morphology of morphological horn unusual intermediate often and wildebeest, and used to detect the presence of hybridisation in populations, wild is nonetheless striking. hybrids examined here Substantial cranial variation is also present across the sample, both in terms of size and shape (Figure 4); this variation (both cranial and postcranial) has been described more elsewhere. fully quantified and depicted as intermediate, in highly variable, reality or polymorphic, hybrid populations range are of phenotypes that can be outside fall can or other, intermediate the or parent one resemble can morphs, to the parental T range. parental the of with such expectations. Although this is a features preliminary in the report crania documenting of results hybrid wildebeest, are the implications nonetheless of significant.wildebeest the provide Most additional evidence of importantly, dental and these sutural FIGURE 2 Connochaetes taurinus x C. gnou b b Moreover, = 20) or black Vol. 106 No. 11/12 Page 3 of 5 106 No. 11/12 Vol.

n suggesting that their frequency a ) from South Africa: a rotated a) maxillary 6,22 FIGURE 1 a root on specimen number NMB12049 = 20) samples,

n No comparable dental or sutural anomalies were Sutural anomalies (indicated by circles and arrows) in wildebeest hybrids ( premolar on specimen number NMB12034 and an atypical b) premolar Dental anomalies (indicated by a circle and arrow) in wildebeest hybrids Connochaetes taurinus x C. gnou ( NMB12048, NMB12049, c) d) NMB12051 and NMB12052. e) Specimen number NMB12044 is not shown. Refer to Table 2 for descriptions of these morphological anomalies in the hybrids qualitative greatly trait variation in mammals (generally less than 5%), exceeds ‘normal’ levels of atypical found in the non-hybridised blue wildebeest ( wildebeest ( across non-hybridised wildebeest is low or absent. the high frequency of sutural morphological anomalies seen but are instead new atypical variants. It is possible premaxillary that sutures these provide some disadvantage in fitnessby terms altering the of physical properties of the snout in these hybrids. do not represent sutures that are seen earlier in ontogeny, http://www.sajs.co.za Evidence for hybridisationin wildebeest crania Research Letter Ackermann, Brink, Vrahimis & De Klerk Article #423

FIGURE 3

South African Journal of Science Specimen number NMB12053, a male wildebeest hybrid (Connochaetes taurinus x C. gnou) from South Africa, displaying pronounced horn asymmetry as well as unusual sheath morphology, where the horn ‘pinches off’ or abruptly changes direction (indicated by the arrows)

FIGURE 4 Four male wildebeest hybrid specimens (Connochaetes taurinus x C. gnou) from South Africa, demonstrating the range of morphological variation in cranial and horn morphology of wildebeest hybrids, including both size and shape variation

fixed alleles and different diploid numbers of ) in This study also demonstrates that the expression of such the more divergent species could potentially result in extremely anomalies may differ across phylogenetically divergent anomalous or even inviable hybrids, while limited differentiation mammalian groups. In primate , the morphological in more recently separated species may lead to hybrids with anomalies associated with hybridisation were predominantly relatively few signs of morphological anomalies. The range of mandibular distomolars, although unusual zygomaxillary phenotypic expression under such different scenarios remains, sutures were also fairly common.24,25,26 For squirrels, distomolars however, to be empirically demonstrated for most mammals.29 were also present, although they were maxillary.27 In both

93 S Afr J Sci Vol. 106 No. 11/12 Page 4 of 5 http://www.sajs.co.za Article #423 South African Journal of Science 94 . ) Connochaetes Research Letter Connochaetes gnou and black wildebeest Spermophilus richardsonii ) population from the Abe S Afr J Sci . Eur J Wildl Res. 2007;53:90–99. Connochaetes taurinus Connochaetes gnou ). Mamm Biol. 2005;70:35–45. ). MSc thesis, Johannesburg, University of the New York: Dover Publications; 1997. Stelkens RB, Schmid C, Selz O, novelty Seehausen in experimental O. hybrids is predicted Phenotypic by the genetic distance between species of cichlid 2009;9:283. fish. BMC Evol Biol. Friedmann Y. hybridisation Black action Conservation wildebeest Breeding plan. Specialist ( Trust; 2003. CBSG Southern Africa, Endangered Wildlife Group (SSC/IUCN) Final / De workshop Klerk B. ( wildebeest black on bearing its and wildebeest report: An osteological documentation gnou of hybrid Witwatersrand, 2007. Langley N. 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Connochaetus Genetic taurinus cytogenetic divergence study. in MSc the thesis, Pretoria, wildebeest, University of Brink JS. The taphonomy of an Early/Middle Pleistocene 13. 12. 10. 11. 9. 8. 7. 6. 5. 4. 2. 3. 1. molecular data, could play conserve this endemic South African species. an important role in efforts to from a conservation perspective. There is an ongoing effort to minimise the impact of introgression of blue wildebeest genes into black wildebeest populations and such increased powers of identification, applied either alone or in conjunction with populations, as well as the recent historical and/or evolutionary and/or historical recent the as well as populations, past of the and groups Bishop under investigation hybrids wildebeest Identifying collected. ( Finally, this study shows the potential for wildebeest identifying hybrid and zones when animal of provenance introgression is hybrid zones can provide on known. insights into the dynamics of the extant landscape morphological trait variation in range of variation in the to more fully understand the mammals skeletal collections of other mammalian hybrid phenotype. taxa. In the wildebeest sample, morphological anomalies were largely sutural, with limited and considerable evidence variation of in horn dental shape. understanding anomalies, It of will hybrid morphology benefit to our continue to examine cases, the pattern of expression differed from the parental http://www.sajs.co.za Evidence for hybridisationin wildebeest crania Copyright of South African Journal of Science is the property of African Online Scientific Information System PTY LTD and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use.