Reproductive ecology of Commerson's leaf-nosed bats Hipposideros commersoni (Chiroptera: Hipposideridae) in South-Central Africa: interactions between seasonality and large body size; and implications for conservation

The annual cycle and reproductive ecology of a large population of Commerson's leaf-nosed bats, Hipposideros commersoni, was studied in central Zimbabwe. The influence of the extremely large body size of this microchiropteran, interrelating with a seasonal, tropical environment, was the central theme of this study. Adaptive responses to seasonal environmental changes differed between reproducing adults of the sexes. Reproductive females dispersed twice during the annual cycle, while in contrast adult males reduced activity during the cool, dry season. A polygynous mating system was characterised by breeding males defending demarcated territories within the daylight roost. Synchronized parturitions within maternity roosts (in late October) created a hot, humid microclimate which facilitated rapid post-natal development of neonates. The large body size of H. commersoni is suggested to have evolved in response to different selective agents, including: availability of large, hard shelled arthropods as prey; energetic constraints; and availability of fat reserves to ‘ride out’ inclement periods when food is limiting. Sexual selection may be the ultimate cause of a large body size. The conservation of H. commersoni is discussed given the history and pressures for guano exploitation of their breeding caves and the keystone role of these large bats in transferring nutrients and energy into the cavernicolous ecosystems where they roost and breed

Taxonomic status and conservation importance of the avifauna of Katanga (south-east Congo Basin) and its environs

A re-appraisal of published knowledge of the birds recorded in Katanga (Democratic Republic of Congo) focussed on the status of 56 taxa, to reveal a high endemism (14 species of a total of at least 642). In addition, 33 taxa were also revealed as possible south-central African endemics but need thorough taxonomic appraisal. All are geographically isolated populations, with ranges restricted within, or centred on, Katanga. These taxonomic enigmas await thorough re-appraisal. The majority of these newly-recognised Katanga endemics were traditionally lumped into polytypic species in classifications based on the Biological Species Concept (BSC). These synonymised taxa have therefore been ignored repeatedly in recent conservation assessments of African birds. This failure illustrates how the BSC can obfuscate patterns of species diversity in its classifications, which lump evolutionarily-distinct lineages into imprecisely-diagnosed taxa. An unfortunate historical legacy is to forget that a distinct population exists, after it has been classified as a subspecies, synonym or race in a polytypic species. These discoveries exemplify the research opportunities that Katanga's birds present for avian systematists. The assessment of any taxon of Afrotropical birds is hamstrung by the fragmented state of taxonomic information in the literature. This constraint impinges on any taxonomic study of any African avifauna and will be removed if an accessible database summarises all published taxonomic information in an exhaustive classification, accounting for synonomy, authority and context of each described taxon. Availability of such a complete taxonomic catalogue is quintessential if phylogeographic and systematic research is to determine precisely which populations have been named, and where these occur. This is critical to compile refined biogeographical knowledge for scientifically-sound conservation plans and actions. Objective evaluation of the endemism of the Katanga avifauna requires complementary datasets for other regional avifaunas across Africa. Their unavailability exemplifies the gravity of this taxonomic impediment, given the immense effort involved in compiling and comparing such fine-grained taxonomic data. Deficiencies aside, the data compiled in this review point to a recent suite of speciation events (most likely late Cenozoic) centred on Katanga. The strident biogeographical signal in these data emphasises the hitherto poorly-appreciated significance of Katanga's unique and rich biodiversity, which ranks alongside better-known sites in Africa of global conservation importance. Copyright © NISC Pty Ltd.Revie

The Upemba lechwe, Kobus anselli: An antelope new to science emphasizes the conservation importance of Katanga, Democratic Republic of Congo

Thirty-five museum specimens collected in 1926 and 1947-48 vouch for the distinctiveness of an undescribed large mammal, a form of lechwe antelope. Their preservation has allowed comparative analyses of morphological characters to reveal this new species, the Upemba lechwe Kobus anselli sp. nov. It is most similar to the black lechwe K. smithemani and quite distinct from all other known taxa, including topotypical red lechwes K. leche. Prevailing threats and conservation concerns underwrite its formal description after neglect by science for decades. This lechwe is restricted to the Upemba wetlands, Kamalondo depression, south-east Congo basin (Katanga Province, Democratic Republic of Congo), and has declined greatly since the 1970s. Commercial poaching through the 1980s reduced c. 20 000 individuals to under 1000 estimated today. Recognition of K. anselli as a distinct evolutionary entity was previously ignored, because the entrenched taxonomy assumed it was just another red lechwe. Its speciation seems to be recent, probably Pleistocene. Lechwes evolved in an archipelago of wetlands formed through vicariance of a more extensive drainage system, the Palaeo-Chambeshi, which extended from Katanga and north-east Zambia across the south-central African plateau, into the Kalahari basin. The Palaeo-Chambeshi was a major endoreic tributary of Palaeo-Lake Makgadikgadi. Its fragmentation isolated lechwes in the Kamalondo depression from wetlands in the Upper Zambezi-Okavango, Upper Kafue, and the Chambeshi and Luapula drainages. The belated discovery of K. anselli emphasizes the region's conservation significance. Because of its high species richness and high endemism, Katanga is a biodiversity hotspot within the encompassing Katanga-Chambeshi region, also covering eastern Angola and much of Zambia. A secure future for the critically endangered Upemba lechwe hinges on reducing adverse human impact and maintaining the integrity of its wetland habitat. Support for protected areas is critical. Maintenance of ecological processes, focused on aquatic systems, is especially important to conserve biodiversity. Recognition of the complex evolutionary history of the region (since the Late Neogene) underpins the scientific foundation for all conservation plans and activities. It prescribes why a regional conservation strategy should encompass the landscape mosaic, structured across neighbouring drainage systems (Lufira, Upper Lualaba and Chambeshi-Luapula rivers). A trans-frontier conservation area will consolidate the protected areas and land use systems of the region in an ecological context.Articl

Taxonomic anarchy or an inconvenient truth for conservation? Accelerated species discovery reveals evolutionary patterns and heightened extinction threat in Afro-Malagasy small mammals

We respond to recent criticisms of supposed “taxonomic anarchy” which is said to hamper conservation efforts. Using examples from African small mammals, we document recent increases of 13% (rodents) and 18% (bats) over the past three decades in the number of recognized species of Afro-Malagasy rodents and bats. By reference to a number of case studies involving Afro-Malagasy taxa (predominantly from montane habitats), and a suggested four-criterion approach to delimiting species accurately, we show that these increases are a genuine reflection of speciation in cryptic species complexes. Moreover, we show that some of these cryptic species are subject to increased extinction risks due to small population size and anthropogenic changes (habitat degradation and climate change). These changes were captured accurately in a recent Mammal Red List of South Africa, Lesotho and Swaziland, indicating that taxonomists and conservationists can work together to assess the Red List status of cryptic species based on robust taxonomic revisions

The evolution and ages of Makgadikgadi paleo-lakes: consilient evidence from Kalahari drainage evolution south-central Africa

The Makgadikgadi Pans in northern Botswana are the desiccated relicts of a former major inland lake system, with fossil shorelines preserved at five distinct elevations (~995 m, 945 m, 936 m, 920 m and 912 m). These lakes persisted in the Makgadikgadi Basin, which evolved in the Okavango-Makgadikgadi Rift Zone: the south-western extension of the East African Rift System (EARS) into northern Botswana. This paper synthesizes cross-disciplinary evidence, which reveals that the antiquity of this lake complex has been widely underestimated. It presents a Regional Drainage Evolution Model that invokes tectonically initiated drainage reorganizations as the underlying control over lake evolution. Lake formation was initiated by rift-flank uplift along the Chobe Fault, across the course of the Zambezi River, which diverted the regional drainage net into the Makgadikgadi Basin. Filling of the basin initiated a major climatic feedback mechanism that locally increased rainfall and lowered evaporation rates. This progressively enhanced water input to the basin, and most likely led to overtopping of the Chobe Horst barrier during the three highest lake stands, with outflow into the Zambezi River. During this period, the hydrology of the basin would have been closely analogous to modern, shallow Lake Victoria. Fragmentation of the regional drainage network by successive river captures resulted in sequential contractions of the lake to lower elevation shorelines. In turn, resultant decreases in areas of these successive lakes modulated the magnitude of the feedback mechanism. Thus, loss of the Upper Chambeshi catchment caused the lake to drop from the 990 to the 945 m level. Severance of the former link between the Kafue and Zambezi resulted in a further drop to the 936 m shoreline. Inflow declined further after the impoundment of a major lake (Palaeo-Lake Bulozi) on the Upper Zambezi River, causing contraction to the 920 m shoreline. Continued incision of the Zambezi channel into the Chobe horst barrier ultimately terminated input from this river to the Makgadikgadi depression, causing contraction of the lake below 920 m, sustained by the Cuando and Okavango prior to final desiccation. This Regional Drainage Evolution Model contradicts previous proposals that have invoked Late Pleistocene climatic forcing to explain inferred fluctuations in lake levels. The timeframe developed for the drainage reorganizations requires that the lake was initiated by ~1.40 to 0.51 Ma at the most recent (Early – Mid-Pleistocene), while archaeological evidence shows that it had contracted below the 936 m shoreline before 500 ka. This contrasts with 14C and quartz luminescence dates (generally <100 ka), which require that the 945 m lake stage was extant during much of the Upper Pleistocene. The calcareous radiocarbon dates reflect multiple episodes of calcrete formation, while the young luminescence dates are ascribed to the extensive bioturbation of older Kalahari landforms

Dynamic evolution of the Zambezi-Limpopo watershed, Central Zimbabwe

Prospecting carried out to the south of the Zambezi-Limpopo drainage divide in the vicinity of Bulawayo, Zimbabwe, led to the recovery of a suite of ilmenites with a chemical "fingerprint" that can be closely matched with the population found in the early Palaeozoic Colossus kimberlite, which is located to the north of the modern watershed. The ilmenite geochemistry eliminates other Zimbabwe Kimberlites as potential sources of these pathfinder minerals. Geophysical modelling has been used to ascribe the elevation of southern Africa to dynamic topography sustained by a mantle plume; however, the evolution of the modern divide between the Zambezi and Limpopo drainage basins is not readily explained in terms of this model. Rather, it can be interpreted to represent a late Palaeogene continental flexure, which formed in response to crustal shortening, linked to intra-plate transmission of stresses associated with an episode of spreading reorganization at the ocean ridges surrounding southern Africa. It is proposed that the formation of the flexure was a dynamic process, with the initial locus of flexure located to the north of the Colossus, resulting in the dispersal of ilmenites to the south of this kimberlite. Subsequently, the axis of flexure migrated to its present position, to the south of Colossus

Species definitions and conservation: a review and case studies from African mammals

The nature of species, especially as applied to large mammals, is of major concern in conservation. Here, we briefly comment on recent thinking in alpha taxonomy, and assert that species are in essence evolutionary lineages, and that the most effective way of recognising them is by their diagnosability, i.e. the so-called Phylogenetic Species Concept. We further assert that the amount of genetic distance is not a relevant datum for distinguishing species, and that the ability to interbreed is not relevant. We consider a few case studies, especially that of the Northern White Rhinoceros Ceratotherium cottoni, and also species in Loxodonta, Giraffa and Oreotragus

Molecular and morphological evidence for a Pleistocene radiation of laminate-toothed rats (Otomys: Rodentia) across a volcanic archipelago in equatorial Africa

West African Mountains of the Cameroon Volcanic Line harbour two montane-endemic species of laminated-toothed rats (Otomys), which represent the most westerly occurrence of the genus. We explore here through mtDNA sequencing and cranial morphometrics the taxonomic status and phylogenetic relationships of O. burtoni (Mt Cameroon) and O. occidentalis (Mts Oku and Gotel). We conclude that both species are valid and can be discriminated by molecular data, as well as quantitative and qualitative cranial characters. From molecular data, O. occidentalis and O. burtoni are closest neighbours (p-distance = 7.5–8.5%) and weakly associated sister species (suggesting a single West African radiation) and both are sister clades to a well supported clade of central, East and northeast African members of the O. typus s.l. and O. tropicalis s.l. species complexes from mountain ranges comprising the East African ‘Montane Circle’ and Ethiopian Highlands. Re-evaluation of the evolutionary origins of the allopatric Otomys populations in equatorial Africa is undertaken in light of fossil evidence of a southern African origin of the genus. We can conclude that Otomys reached the Cameroon Volcanic Line via corridors of temperate grasslands during the Late Pliocene. Our data support the hypothesis that, following major peripatric speciation events at around 2.3 to 2.03 Ma (from East Africa into West and North Africa respectively), further speciation occurred across neighbouring mountain ranges in West, Central-East and North-East Africa. Estimated molecular dates of speciation events in Otomys reveal close congruence with well-constrained geochronological estimates, pertinently the uplift of the Albertine Rift in the Early Pleistocene. These regional analyses reveal how peripatric speciation events established narrow-range endemics of Otomys on principal stratovolcanoes across the East African plateau and Cameroon