African Rift Valley Research Papers (original) (raw)

Le Nyiragongo (3 469 m) et le Nyamulagira (3 058 m) sont les deux volcans actifs de la chaîne des Virunga, qui s'étend entre la République démocratique du Congo (R.d.c.), l'Ouganda et le Rwanda. Alors que le premier, bien connu pour abriter le plus grand lac de lave du monde, est imprévisible, le deuxième entre en éruption en moyenne tous les deux ans et il était somme toute assez prévisible qu'il entre en éruption après vingt-deux longs mois de sommeil. Cependant, l'éruption du 6 novembre 2011 ayant eu lieu à 11 km du cratère principal du Nyamulagira, on pouvait penser à la naissance d'un nouveau volcan. Cet article paru dans le numéro 154 de LAVE (Janvier 2012) relate une visite sur les lieux de l'éruption du Nyamulagira du 6 novembre 2011.

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- Volcanology, Democratic Republic of Congo, African Rift Valley, Nyiragongo

The Australopithecus afarensis partial skeleton A.L. 288-1, popularly known as “Lucy” is associated with
nine vertebrae. The vertebrae were given provisional level assignments to locations within the vertebral
column by their discoverers and later workers. The continuity of the thoracic series differs in these assessments,
which has implications for functional interpretations and comparative studies with other
fossil hominins. Johanson and colleagues described one vertebral element (A.L. 288-1am) as uniquely
worn amongst the A.L. 288-1 fossil assemblage, a condition unobservable on casts of the fossils. Here, we
reassess the species attribution and serial position of this vertebral fragment and other vertebrae in the
A.L. 288-1 series. When compared to the other vertebrae, A.L. 288-1am falls well below the expected size
within a given spinal column. Furthermore, we demonstrate this vertebra exhibits non-metric characters
absent in hominoids but common in large-bodied papionins. Quantitative analyses situate this vertebra
within the genus Theropithecus, which today is solely represented by the gelada baboon but was the most
abundant cercopithecoid in the KH-1s deposit at Hadar where Lucy was discovered. Our additional
analyses confirm that the remainder of the A.L. 288-1 vertebral material belongs to A. afarensis, and we
provide new level assignments for some of the other vertebrae, resulting in a continuous articular series
of thoracic vertebrae, from T6 to T11. This work does not refute previous work on Lucy or its importance
for human evolution, but rather highlights the importance of studying original fossils, as well as the
efficacy of the scientific method.

- by Marc Meyer and +1
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- Evolutionary Biology, Paleoanthropology, Human Evolution, Evolution

The site of Mwanganda's Village, located along a paleochannel in northern Malawi, is one of only a few sites that have characterized the Middle Stone Age (MSA) of Malawi for decades (Clark & Haynes, 1970; Clark et al., 1970; Kaufulu, 1990). The Malawi Earlier-Middle Stone Age Project has re-examined the site using new mapping and chronometric tools in order to reinterpret the site's significance within the context of current debates surrounding human origins and the potential role the environment played in shaping human behavior. The new data do not support the previous hypothesis that the site was an elephant butchery location (contra Clark & Haynes, 1970; Clark et al., 1970; Kaufulu, 1990). Instead, the evidence shows successive colonization of riparian corridors by MSA hunter-gatherers focused on exploiting localized resources during periods of generally humid climates while other lakes desiccated across Africa. We challenge the hypothesis that stable and intermediately high lake levels within the African Rift Valley System (sensu Trauth et al., 2010) catalyzed the evolution of regional interaction networks between 42 and 22 ka. Instead, we interpret the evidence to suggest that regional variants of technology persist into the late MSA as foragers focused on exploiting resources from local catchments.

- by David Wright and +2
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- Archaeology, Geomorphology, Human Evolution, Humanities

The Melka Wakena archaeological site-complex is located at the eastern rift margin of the central sector of the Main Ethiopian Rift (MER), in south central Ethiopia. This wide, gently sloping rift shoulder, locally called the “Gadeb plain” is underlain by a succession of primary pyroclastic deposits and intercalated fluvial sediments as well as reworked volcaniclastic rocks, the top part of which is exposed by the Wabe River in the Melka Wakena area. Recent archaeological survey and excavations at this site revealed important paleoanthropological records. An integrated stratigraphic, petrological, and major and trace element geochemical study has been conducted to constrain the petrogenesis of the primary pyroclastic deposits and the depositional history of the sequence. The results revealed that the Melka Wakena pyroclastic deposits are a suite of mildly alkaline, rhyolitic pantellerites (ash falls, pumiceous ash falls and ignimbrites) and slightly dacitic ash flows. These rocks were deposited by episodic volcanic eruptions during early to middle Pleistocene from large calderas along the Wonji Fault Belt (WFB) in the central sector of the MER and from large silicic volcanic centers at the eastern rift shoulder. The rhyolitic ash falls, pumiceous ash falls and ignimbrites have been generated by fractional crystallization of a differentiating basaltic magma while the petrogenesis of the slightly dacitic ash flows involved some crustal contamination and assimilation during fractionation. Contemporaneous fluvial activities in the geomorphologically active Gadeb plain deposited overbank sedimentary sequences (archaeology bearing conglomerates and sands) along meandering river courses while a dense network of channels and streams have subsequently down-cut through the older volcanic and sedimentary sequences, redepositing the reworked volcaniclastic sediments further downstream.

- by Erella Hovers and +1
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- Early Pleistocene, Pyroclastic Rocks, African Rift Valley, main ethiopian rift

The Southern Montane Forest-Grassland mosaic ecosystem in the humid subtropics southern Rift Valley of Africa comprised the environmental context for a large area in which modern human evolution and dispersal occurred. Variable climatic conditions during the Late Pleistocene have ranged between humid and hyperarid, changing the character of the ecosystem and transforming it at different points in time into a barrier, a refuge, and a corridor between southern and eastern African populations. Alluvial fans presently blanket the areas adjacent to major river systems, which were key areas of prehistoric human habitation. These sets of variables have created conditions that are both challenging and advantageous to conduct archaeological research. Lateritic soil development has resulted in poor organic preservation and facilitated insect bioturbation, which has demanded an integrated micro-macro scale approach to building a reliable geochronology. An integrated field and analytical methodology has also been employed to identify the nature and degree of post-depositional movement in alluvial deposits, which preserve a wide range of spatial integrity levels in buried stone artifact assemblages between 47 and 30 ka in Karonga, northern Malawi. This paper describes the methodological advances taken toward understanding open-air Middle Stone Age archaeology in subtropical Africa, and explores the inferential potential for understanding Pleistocene human ecology in the important southern Rift Valley region.

- by Flora C Schilt and +5
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- Geomorphology, Landscape Archaeology, Paleoenvironment, Archaeological Soil Micromorphology

Why did humans walk upright? Previous models based on adaptations to forest or savannah are challenged here in favour of physical incentives presented by steep rugged terrain-the kind of tectonically varied landscape that has produced early hominin remains. "Scrambler man" pursued his prey up hill and down dale and in so doing became that agile, sprinting, enduring, grasping, jumping two-legged athlete that we know today.

- by Geoffrey King
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- Archaeology, Paleoanthropology, Human Evolution, Landscape Archaeology

An expanded model of the 3-D shear wave velocity structure of the uppermost mantle beneath eastern Africa has been developed using earthquakes recorded by the AfricaArray East African Seismic Experiment in conjunction with data from permanent stations and previously deployed temporary stations. The combined data set comprises 331 earthquakes recorded on a total of 95 seismic stations spanning Kenya, Uganda, Tanzania, Zambia and Malawi. In this study, data from 149 earthquakes were used to determine fundamental-mode Rayleigh wave phase velocities at periods ranging from 20 to 182 s using the two-plane wave method, and then combined with the similarly processed published measurements and inverted for a 3-D shear wave velocity model of the uppermost mantle. New features in the model include (1) a low-velocity region in western Zambia, (2) a high-velocity region in eastern Zambia, (3) a low-velocity region in eastern Tanzania and (4) low-velocity regions beneath the Lake Malawi rift. When considered in conjunction with mapped seismicity, these results support a secondary western rift branch striking southwestwards from Lake Tanganyika, likely exploiting the relatively weak lithosphere of the southern Kibaran Belt between the Bangweulu Block and the Congo Craton. We estimate a lithospheric thickness of ∼150–200 km for the substantial fast shear wave anomaly imaged in eastern Zambia, which may be a southward subsurface extension of the Bangweulu Block. The low-velocity region in eastern Tanzania suggests that the eastern rift branch trends southeastwards offshore eastern Tanzania coincident with the purported location of the northern margin of the proposed Ruvuma microplate. Pronounced velocity lows along the Lake Malawi rift are found beneath the northern and southern ends of the lake, but not beneath the central portion of the lake.

- by Aubreya Adams
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- East Africa, Tomography, Surface Waves, African Rift Valley

Lake Naivasha was designated as a RAMSAR site in 1995. The lake environment is fragile and critically threatened by human-induced factors. The study presented a steady and transient numerical modeling. The long-term and system flux over time interaction between the lake and the surficial aquifer is represented in the Lake Package LAK3 with in the advanced 3-D simulation sofware (GMS). The model covers an area of 1817 km2. Model calibration was constrained by the observed groundwater and lake levels using PEST. The effect of excessive abstraction was rigorously analyzed via scenario analysis. The simulation was evaluated “with abstraction” and “without abstraction” scenarios. The abstraction scenario was simulated using range of combination assuming that all the abstraction was from the lake or the groundwater and in the ratio of groundwater and lake water. The effect of the stress was evaluated based on the observed aquifer heads and lake stage at the end of the simulation time. The development of low groundwater-level anomalies in the well field is explained. The result indicates that the one of the well fields is not in direct hydraulic connection to the main recharging water body. Apparently, similar development of cone of depression was not generated in the other two well fields, and this could have several reasons including due to the fact that these well fields are located relatively close by to the main recharging zones and concluded to have additional source of recharge, and this was supported by previous studies, whereby the isotopic composition of the boreholes has their source of recharge from precipitation and river and was also confirmed from the isotopic composition of unsaturated zone, which is a mixture of river and rain. The study reveals that seasonal variability of groundwater–surface water exchange fluxes and its spatially and temporally variable impact substantially on the water resource availability. Such analysis can be used as a basis to quantify the linkages between the surface water and groundwater regime and impacts in the basin. The model output is expected to serve as a basis via linking/coupling with others to incorporate the ecology and biodiversity of the lake to safeguard this high-value world heritage water feature.

The relationship between mantle perturbation, penetrative magmatism, crustal uplift and the processes of rifting and rift propagation was studied. Quasi-scale model experiments and theoretical analyses by Boussinesq's three function method were used. Three dimensional stress analyses around a rising mantle intrusion and semiquantitative model experiments on mantle upwelling and magma penetration into brittle and brittle-ductile lithospheric materials indicate the origin of ridges, rifts, and rift-basin structures. These structures are commonly initiated by broad domal or plateau uplift. The magnitude and nature of the uplift, fissure or rift development, branching and pattern(s) are controlled primarily by flexural rigidity, magnitude of stress development due to mantle intrusion and magma penetration, and the degree of preferred orientation of weakness (anisotropy) in the lithosphere. Continued magma penetration into the crust produces en echelon fissures, vertical and lateral dike propagation, graben and graben and horst structures with step or block faulting. This is followed by axial subsidence, fault opening and periodic volcanism with continued crustal extension, stretching and slow spreading. Mantle and magma penetration into the crust are shown to be important in developing in situ lateral compressive stress adjacent to and around the active rift zones. Transverse fissures, dike swarms, volcanoes and anticlines between two rifts (as in Iceland) result from such lateral compressive stress. This stress is also important in the development of marginal fissures and faults (as in fast-spreading centers). Time progressive model experiments on magma formation and magma penetration from the asthenosphere-lithosphere boundary show the importance of magma chambers. These chambers cause thinning and stretching of the composite lithosphere, vertical and lateral propagation of dikes and dike swarms, and initiate rifts with or without significant uplift. This study also suggests that multiple dike wedging with rapid extension fracturing can generate excess magma pressure and push force, and may contribute seismicity to spreading centers.

Alongside the eusocial naked mole-rat, Heterocephalus glaber, Heliophobius argenteocinereus represents the second oldest lineage within the African mole-rat family Bathyergidae, and phylogenetically intermediate between the East African Het. glaber and the South African genera Bathyergus and Georychus. Across its geographic range, Hel.. argenteocinereus is widely distributed on both sides of the East African Rift System (EARS), and is a key taxon for understanding the phylogeographic patterns of divergence of the family as a whole. Phylogenetic analysis of 62 mitochondrial cyt b sequences, representing 48 distinct haplotypes from 26 geographic locations across the range of Heliophobius, consistently and robustly resolved six genetically divergent clades that we recognize as distinct evolutionary species. Early species descriptions of Heliophobius were synonymized into a monotypic taxonomy that recognized only Hel. argentocinereus. These synonyms constitute available names for these rediscovered cryptic lineages, for which combined morphological and genetic evidence for topotypical populations endorses the recognition of six to eight distinct taxa. Bayesian estimates of divergence times using the fossil Proheliophobius as a calibration for the molecular clock suggest that the adaptive radiation of the genus began in the early Miocene, and that cladogenesis, represented in the extant species, reflects a strident signature of tectonic activity that forged the principal graben in the EARS.

- by Chris Faulkes
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- Evolutionary Biology, Zoology, Phylogeography, Landscape genetics

The Wonji Fault Belt (WFB), Main Ethiopian Rift, forms a network of faults oriented NNE-SSW with a Quaternary direction of extension oriented c. N958 E. Faults are spaced between 0.5 and 2 km, show a fresh steep scarp, recent activity and slip rates of up to 2.0 mm a 21 . This high value of deformation along the rift floor with respect to the plate separation rates suggests that most of the active strain could be accommodated by magma-induced faulting within the rift. However, the mountain front morphology associated with a displacement of 300-400 m since the Middle Pleistocene, tilted-blocks, brittle-seismic fault rock fabric and historical earthquakes with M.6 support a tectonic origin of the Asela boundary fault. Therefore, we propose a model that considers the possible coexistence of both magmatic deformation at the rift floor and brittle faulting at the rift margin. We also report the data relative to a GPS network installed in December 2004, along two transects across the WFB, between Asela and the Ziway Lake.

- by Riccardo Salvini and +1
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- GPS Applications, African Rift Valley

Recent archaeology of Mursiland's past takes into account its present and is concerned with the impact that archaeological dialogue has upon Mursi engagements with what we, at least, regard as archaeological sites and narrative. We contend that this allows for a tripartite investigation into cultural mixing whereby the example of a series of megalithic platforms acts as a dynamic contact zone.

- by Tim Clack
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- Archaeology, Ethnoarchaeology, Ethnography, Material Culture Studies

- by Leonardo Disperati and +1
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- Earth Sciences, GPS Applications, Quaternary Geology, Neotectonics
- by Elizabeth Chindebvu
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- Archaeology, Earth Sciences, Geomorphology, Human Evolution

The Australopithecus afarensis partial skeleton A.L. 288-1, popularly known as…

- by Marc Meyer
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- Evolutionary Biology, Archaeology, Paleoanthropology, Anthropology

Scattered populations of the same tree species in montane forests through Africa have led to speculations on the origins of distributions. Here, we inferred the colonization history of the Afromontane tree Prunus africana using seven chloroplast DNA loci to study 582 individuals from 32 populations sampled in a range-wide survey from across Africa, revealing 22 haplotypes. The predominant haplotype, HT1a, occurred in 13 populations of eastern and southern Africa, while a second common haplotype, HT1m, occurred in populations of western Uganda and western Africa. The high differentiation observed between populations in East Africa was unexpected, with stands in western Uganda belonging with the western African lineage. High genetic differentiation among populations revealed using ordered alleles (N ST = 0.840) compared with unordered alleles (G ST = 0.735), indicated a clear phylogeographic pattern. Bayesian coalescence modelling suggested that 'east' and 'west' African types likely split early during southward migration of the species, while further more recent splitting events occurred among populations in the East of the continent. The high genetic similarity found between western Uganda and west African populations indicates that a former Afromontane migration corridor may have existed through Equatorial Africa.

- by Alice Muchugi
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- Botany, Evolutionary Biology, Conservation Biology, Phylogeography

The shear wave velocity structure of the upper mantle beneath the East African plateau has been investigated using teleseismic surface waves recorded on new broadband seismic stations deployed in Uganda and Tanzania, as well as on previously deployed stations in Tanzania and Kenya. Rayleigh wave phase velocities at periods between 20 and 182 s, measured with a two-plane wave method, have been used to create phase velocity maps, and dispersion curves extracted from the maps have been inverted to obtain a quasi-3-D shear wave velocity model of the upper mantle. We find that phase velocities beneath the Tanzania Craton and areas directly north and west of the craton are faster, at all periods, than those beneath the Western and Eastern branches of the East African Rift System. At periods <50 s, the western branch is slower than the Eastern Branch, but at periods greater than 50 s, this relationship is reversed. Anisotropy is found at all periods, with a generally north-south fast polarization direction. The shear wave velocity model shows a seismically fast lithosphere (lid) beneath the Tanzania Craton to depths between 150 and 200 km. The fast velocities in this depth range extend to the north beneath the Uganda Basement Complex and to the east beneath the northern Tanzania divergence zone, indicating that these regions together form a rigid block around which rifting has occurred within weaker mobile belt lithosphere. The Eastern and Western branches are slower than the craton at lithospheric mantle depths, and both branches show variable structure in the upper 200 km of the mantle, with the lowest velocities found beneath areas of Cenozoic volcanism. At depths greater than ∼225 km, a low velocity anomaly is present beneath the entire East African plateau that may extend into the mantle transition zone. Velocities in the low velocity region are reduced by ≥10 per cent relative to lid velocities, and if attributed only to temperature variations, would represent an unrealistic thermal perturbation of >400 K. Consequently, it is likely that the velocity reduction reflects a combination of thermal and compositional changes, and also possibly the presence of partial melt. The width and thickness of the low velocity anomaly is greater than typically expected for a plume head and is more easily attributed to an upward continuation of the lower mantle African superplume structure into the upper mantle.

- by Dayanthie Weeraratne and +1
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- East Africa, Tomography, Surface Waves, African Rift Valley

- by Cheledi Kadu
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- Botany, Evolutionary Biology, Conservation Biology, Ecology

About 1800 krn of reconnaissance echo-sounder data have been collected from Lake Victoria. The prof'des show a maximum open-basin thickness of 8 m of latest Pleistocene and Holocene fine-grained muds. Their distribution mimics bathymetry, except for locally thicker patches around bathymetric highs, which serve as current and seiche breaks. The ~ansparent sediment blanket overlies an acoustic basement that ranges from crystalline basement to a late-Tertiary, boulder-studded peneplain to coarser-grained lacustrine sediments and dewatered fine-grained mudstones, depending upon position in the lake. Correlation to discontinuities in core data suggest that the boundary between the fine-grained, acoustically transparent muds and acoustic basement represents a 14,000 year old desiccation surface of essentially lakewide extent. Many curious signatures are noted in the Lake Victoria echograms, including spiky diffractions that may represent buried boulders or gas escape structures; megaripples and sediment wave bedforms associated with current activity in the SW comer of the lake; and a tilted-block terrain in the Speke Gulf that is probably caused by recent submergence of subaefially eroded Archean crystalline rocks along uniformly-spaced joints and fractures.

- by Crisantos Obama
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- Botany, Evolutionary Biology, Conservation Biology, Phylogeography

When continents are stretched over a long period of time, deep elongated rift valleys form at Earth's surface and zones of ponded magma, centred beneath the rift, form at the crust-mantle boundary 1,2 . Ascending magma sometimes erupts within the rift valley 3,4 or, counterintuitively, at volcanic fields away from the rift valley that are o set by tens of kilometres from the source of magma at depth 5-8 . The controls on the distribution of this o -rift volcanism are unclear. Here we use a numerical model of magmatic dyke propagation during rifting to investigate why some dykes reach the surface outside the rift valley, whereas others are confined to the valley. We find that the location of magmatism is governed by the competition between tectonic stretching and gravitational unloading pressure, caused by crustal thinning and faulting along the rift borders. When gravitational unloading dominates over tectonic stretching forces, dykes ascending from the ponded magma are steered towards the rift sides, eventually causing o -rift eruptions. Our model also predicts the formation of stacked magma sills in the lower crust above the magma-ponding zone, as well as the along-rift propagation of shallow dykes during rifting events, consistent with observations of magmatism and volcanism in rift zones globally. We conclude that rift topography-induced stress changes provide a fundamental control on the transfer of magma from depth to the surface.

- by Francesco Maccaferri
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- Volcanology, Lake Baikal, Tectonics, Extensional Tectonics

- by Geoffrey Muluvi
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- Botany, Evolutionary Biology, Geography, Conservation Biology

Gorongosa National Park in central Mozambique offers an unparalleled setting for the study of primate adaptations to complex and highly dynamic environments. Located at the southern end of the East African Rift System, Gorongosa hosts a mosaic of forests, woodlands, grasslands, swamps, rivers, and a major lake, Lake Urema, which fluctuates extensively with the seasonal cycles. Renowned biologist E.O. Wilson has described Gorongosa as “ecologically the most diverse park in the world”. The park is home to five species of nonhuman primates, among them 219 troops of baboons, whose phenotypic diversity suggests an extended history of admixture between chacmas (Papio ursinus) and yellow baboons (P. cynocephalus). With its dynamic mix of environments in the African Rift Valley, and highly adaptable primates, Gorongosa brings to mind the vegetation mosaics in which Pliocene and Pleistocene hominins evolved. Gorongosa thus provided an ideal setting to bring together a broad interdisciplinary group of scientists to discuss “New perspectives on primate adaptations to complex environments and implications for early human evolution.” The occasion was a workshop funded by the Wenner-Gren Foundation and hosted by Gorongosa National Park on 23-25 July 2019. The Wenner-Gren Foundation has sponsored about 165 symposia and workshops over the past 67 years, but this was only the third time such an event was held in Africa. The workshop included 36 researchers and students (from 20 institutions in 11 countries) with expertise in primatology, zoology, natural history, ecology, botany, genetics, genomics, paleontology, paleoanthropology, archeology, and geology. The event was open to the public, so researchers, students, and staff working in the park, among them many young Mozambicans, attended the workshop and participated in the discussions. Holding such an event in Mozambique was a milestone for a country with great potential in primatology, paleontology, and paleoanthropology, and allowed Mozambican scholars and students to establish new collaborations for future research and training.

- by René Bobe and +1
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- Baboons, African Rift Valley

- by Geoff Bailey
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- Archaeology, Paleoanthropology, Human Evolution, Landscape Archaeology

Conjectures on the effects of four supervolcanoes on very early man in the middle Ethiopian rift valley. Proposal to defend and valorize a splendid environment sapiens developed into, and loved. In an age in which an insipient offspring... more

African mole-rats are subterranean Hystricomorph rodents, distributed widely throughout sub-Saharan Africa, and displaying a range of social and reproductive strategies from solitary dwelling to the 'insect-like' sociality of the naked mole-rat, Heterocephalus glaber . Both molecular systematic studies of Rodentia and the fossil record of bathyergids indicate an ancient origin for the family. This study uses an extensive molecular phylogeny and mitochondrial cytochrome b and 12s rRNA molecular clocks to examine in detail the divergence times, and patterns of speciation of the five extant genera in the context of rift valley formation in Africa. Based on a value of 40 -48 million years ago (Myr) for the basal divergence of the family ( Heterocephalus ), we estimate divergence times of 32 -40 Myr for Heliophobius , 20 -26 Myr for Georychus / Bathyergus and 12-17 Myr for Cryptomys , the most speciose genus. While early divergences may have been independent of rifting, patterns of distribution of later lineages may have been influenced directly by physical barriers imposed by the formation of the Kenya and Western Rift, and indirectly by accompanying climatic and vegetative changes. Rates of chromosomal evolution and speciation appear to vary markedly within the family. In particular, the genus Cryptomys appears to have undergone an extensive radiation and shows the widest geographical distribution. Of the two distinct clades within this genus, one exhibits considerable karyotypic variation while the other does not, despite comparatively high levels of sequence divergence between some taxa. These different patterns of speciation observed both within the family and within the genus Cryptomys may have been a result of environmental changes associated with rifting.

- by Chris Faulkes
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- Evolutionary Biology, Geography, Phylogeography, Phylogenetics
- by Susanne Epple
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- Anthropology, Languages and Linguistics, Ethiopian Studies, Island Studies

- by C. Katsvanga
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- Botany, Evolutionary Biology, Conservation Biology, Phylogeography

- by Caroline Kadu and +2
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- Botany, Evolutionary Biology, Conservation Biology, Phylogeography
- by Steven Forman
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- Archaeology, Earth Sciences, Geomorphology, Human Evolution

We show that fractures produced in an elastic, homogeneous lithospheric plate by stress generated by wedging of deepseated igneous mass(es) are comparable with the major fracture geometry and rift valley formation associated with the Red Sea, Gulf of Aden and East African Ridges; and that the formation and evolution of certain triple junction fracture geometry (FFR to RRR types) can also be related to stress generated around an oblate magmatic body.

- by Hitoshi Koide
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- Fracture Mechanics, Plate Tectonics, Midoceanic Ridges, Magma Chambers