Taxonomic Status of the African Buffalo

BackgroundTick-borne diseases (TBDs) are very important in relation to domestic ruminants, but their occurrence among wild ruminants, mainly in the African buffalo Syncerus caffer, remains little known.MethodsMolecular diagnostic methods were applied to detect Anaplasma marginale, Anaplasma centrale, Anaplasma phagocytophilum, Ehrlichia ruminantium and Ehrlichia chaffeensis in 97 blood samples of African buffalo captured at the Marromeu Reserve in Mozambique. Molecular detection of agents belonging to the family Anaplasmataceae were based on conventional and qPCR assays based on msp5, groEL, 16S rRNA, msp2, pCS20 and vlpt genes. Phylogenetic reconstruction of new Anaplasma isolates detected in African buffalo was evaluated based on msp5, groEL and 16S rRNA genes.ResultsAll the animals evaluated were negative for specific PCR assays for A. phagocytophilum, E. ruminantium and E. chaffeensis, but 70 animals were positive for A. marginale, showing 2.69 × 100 up to 2.00 × 105msp1β copies/μl. This result overcomes the conventional PCR for A. marginale based on msp5 gene that detected only 65 positive samples. Sequencing and phylogenetic analyses were performed for selected positive samples based on the genes msp5, groEL and 16S rRNA. Trees inferred using different methods separated the 29 msp5 sequences from buffalo in two distinct groups, assigned to A. centrale and A. marginale. The groEL sequences determined for African buffalo samples revealed to be more heterogeneous and inferred trees could not assign them to any species of Anaplasma despite being more related to A. marginale and A. centrale. The highly conserved 16S rRNA gene sequences suggested a close relationship of the new 16 sequences with A. centrale/A. marginale, A. platys and A. phagocytophilum.ConclusionsOur analysis suggests that different species of Anaplasma are simultaneously present in the African buffalo. To the best of our knowledge, this is the first study that diagnosed Anaplasma spp. in the African buffalo and inferred the taxonomic status of new isolates with different gene sequences. The small fragment of msp5 sequences revealed to be a good target for phylogenetic positioning of new Anaplasma spp. isolates.

The African buffalo (Syncerus caffer) exhibits extreme morphological variability, which has led to controversies about the validity and taxonomic status of the various recognized subspecies. The present study aims to clarify these by inferring the pan-African spatial distribution of genetic diversity, using a comprehensive set of mitochondrial D-loop sequences from across the entire range of the species. All analyses converged on the existence of two distinct lineages, corresponding to a group encompassing West and Central African populations and a group encompassing East and Southern African populations. The former is currently assigned to two to three subspecies (S. c. nanus, S. c. brachyceros, S. c. aequinoctialis) and the latter to a separate subspecies (S. c. caffer). Forty-two per cent of the total amount of genetic diversity is explained by the between-lineage component, with one to seventeen female migrants per generation inferred as consistent with the isolation-with-migration model. The two lineages diverged between 145 000 to 449 000 years ago, with strong indications for a population expansion in both lineages, as revealed by coalescent-based analyses, summary statistics and a star-like topology of the haplotype network for the S. c. caffer lineage. A Bayesian analysis identified the most probable historical migration routes, with the Cape buffalo undertaking successive colonization events from Eastern toward Southern Africa. Furthermore, our analyses indicate that, in the West-Central African lineage, the forest ecophenotype may be a derived form of the savanna ecophenotype and not vice versa, as has previously been proposed. The African buffalo most likely expanded and diverged in the late to middle Pleistocene from an ancestral population located around the current-day Central African Republic, adapting morphologically to colonize new habitats, hence developing the variety of ecophenotypes observed today.

1 Department of Biology, University of Washington, Seattle, WA, USA 2 Department of Fisheries and Wildlife Sciences, Virginia Polytechnic Institute and State University, Blacksburg, VA, USA 3 Department of Biology, Valdosta State University, Valdosta, GA, USA 4 New Mexico Museum of Natural History, Albuquerque, NM, USA 5 Department of Environmental, Population, and Organismic Biology, University of Colorado, Boulder, CO, USA 6 School of Molecular and Life Sciences, University of Limpopo, Sovenga, South Africa

Amphistomosis is a poorly understood trematode disease of domestic and wild ruminants whose effect has been underestimated. To date, there is limited information on the taxonomic status of amphistome species, particularly in sub-Saharan Africa which is home to diverse species infecting domestic and wild ruminants. In view of this, a survey was conducted in wildlife conservancies and national parks located in Beitbridge, Nyamandlovu, and Hwange in the Matebeleland region of Zimbabwe during the 2019-2021 game hunting seasons. Gastrointestinal tract of 329 carcasses of wild ruminants were examined for amphistome infections and 33/329 (10%) of the animals were infected and the highest prevalence per locality was in Hwange (35%; 7/20). A high prevalence of 63% was recorded in Kobus ellipsiprymnus (waterbuck) from Beitbridge, accompanied with a high parasitic burden of more than 10000 parasites per animal. The lowest parasitic burden was observed in Connochaetes taurinus taurinus (blue wildebeest) and Hippotragus niger (sable), each with less than 10 amphistomes. A total of 86 amphistome specimens from Syncerus caffer (African buffalo) (n=27), Aepyceros melampus (impala) (n=17), Tragelaphus strepsiceros (kudu) (n=16), waterbuck (n=10), sable (n=7), Redunca arundinum (reedbuck) (n=7), and Connochaetes taurinus taurinus (blue wildebeest) (n=2) were randomly selected for morphological and molecular identification. Using a combination of both histological technique and ITS-2 rDNA marker, the following seven amphistome species were identified; Leiperocotyle (L.) gretillati, Calicophoron (C.) microbothrium, C. raja, C. clavula, C. phillerouxi, Gigantocotyle (Gi.) symmeri, and Gastrothylax (G.) crumenifer which are pouched amphistome species. Orthocoelium dicranocoelium identification was based on morphological characters only. Although the ITS-2 is a widely used marker, it may not be useful in discriminating cryptic species in the Calicophoron genus. Orthocoelium (O.) dicranocoelium, G. crumenifer and L. gretillati are first records in wild ruminants in Zimbabwe.

-The systematic relationships of genera in the artiodactyl tribe Bovini were evaluated using two sets of mitochondrial DNA (mtDNA) sequences available for Bison, Bos, and Bubalus. One of these sets included 2,726 aligned positions from the two relatively conserved ribosomal RNA genes and three flanking transfer RNA genes; the other consisted of 247 base pairs from the rapidly evolving D-loop region. Most-parsimonious cladograms derived from the two data sets indicated that Bison and Bos are more closely related to each other than either is to Bubalus, as suggested from morphological, paleontological, and reproductive data. However, the traditional arrangement of the genus Bos is seriously challenged, as Bos grunniens groups first with Bison bison rather than with its congener Bos taurus. These results, when coupled with reproductive and other molecular data, strongly suggest that Bison should be treated as a congener of Bos rather than as a distinct genus in the tribe Bovini. [DNA sequences; mitochondrial DNA; molecular systematics; Bovini.] The mitochondrial genome of animals provides an excellent system to infer phylogenetic relationships at lower taxonomic levels (Wilson et al., 1985). Its rapid rate of nucleotide change ensures that a large number of reliable sequence differences accumulate for the resolution of evolutionary events within the last 20 million years or so (Miyamoto and Boyle, 1989). At the lower hierarchical levels, mitochondrial DNA (mtDNA) divergence exhibits little (Moritz et al., 1987), because insufficient time is available to accumulate parallel and back mutations (Miyamoto and Boyle, 1989). As a strong transition to transversion bias exists (Brown et al., 1982), transitions in the absence of saturation are responsible for most of the observed base differences at these levels. In spite of their obvious economic importance, the systematic relationships and taxonomic status of Recent genera in the artiodactyl tribe Bovini (subfamily Bovinae, family Bovidae) remain unclear, as reflected by the different classifications available for this group. Typically, four extant genera are recognized (Bison H. Smith [bison], Bos Linnaeus [cattle], Bubalus H. Smith [Asian water buffalo], and Syncerus Hodgson [African buffalo]) (McDonald, 1981; Kingdon, 1982; Walker et al., 1983; Simpson, 1984), but other classifications exist. Haltenorth (1963) and Lawlor (1979) recognize only one genus of buffalo (Bubalus) rather than two. Van Gelder (1977) and Gentry (1978) acknowledge only a single genus (Bos) for bison and cattle. Given its outstanding attributes for studying recent evolutionary events, the mtDNA system is therefore of potential importance to the resolution of systematic and taxonomic problems in the tribe Bovini (Miyamoto and Boyle, 1989). The relatively recent origin of the tribe (five to six million years ago in the upper Miocene to lower Pliocene [Romer, 1966; Sinclair, 1977; Kingdon, 1982] falls well within the time range in which mtDNA variation exhibits its greatest utility and resolving power (Moritz et al., 1987). We have employed mtDNA sequences to evaluate the molecular systematics and current taxonomic status of the two closely related genera Bison and Bos (Tanhauser, 1985). This study is restricted to a discussion of the systematic and taxonomic implications of the sequence data. Other aspects of our ongoing work with artiodactyl