Tectonic Uplift and Eastern Africa Aridification

Abstract

The history of Eastern African hominids has been linked to a progressive increase of open grassland during the past 8 million years. This trend was explained by global climatic processes, which do not account for the massive uplift of eastern African topography that occurred during this period. Atmosphere and biosphere simulations quantify the role played by these tectonic events. The reduced topographic barrier before 8 million years ago permitted a zonal circulation with associated moisture transport and strong precipitation. Our results suggest that the uplift itself led to a drastic reorganization of atmospheric circulation, engendering the strong aridification and paleoenvironmental changes suggested by the data.

Transposable elements and an epigenetic basis for punctuated equilibria

“…As predicted by the epi-transposon hypothesis, analysis of 75 SINE loci indicates that this haplochromine lineage has experienced repeated bouts of cichlid-specific SINE insertions followed by extensive radiations within each lake. (108) Moreover, geological evidence of aridification in East Africa 2.5-3 Mya (94) and extreme lake level fluctuations of several hundreds of meters over the last 1.1 My (109) is consistent with epigenetic regulation of cichlid TEs breaking down in response to environmentally induced physiological stress.…”

Cenozoic extension in the Kenya Rift from low‐temperature thermochronology: Links to diachronous spatiotemporal evolution of rifting in East Africa

“…This spatiotemporal pattern of extension is inconsistent with tectonic models of rifting in East Africa that are based on a southward-directed migration of volcanism and cogenetic extension [McConnell, 1972;Ebinger and Sleep, 1998;Ebinger et al 2000;Nyblade and Brazier, 2002;Morley, 2010]. In light of the pronounced geophysical anomalies, evidence for mantle advection, and the evolution of dynamic topography associated with regional domal uplift [i.e., White and McKenzie, 1989;Simiyu and Keller, 1997;Prodehl et al, 1997;Achauer and Masson, 2002;Mechie et al, 1997;Sepulchre et al, 2006;Moucha and Forte, 2011;Wichura et al, 2015], the timing of extension throughout East Africa likely reflects a large-scale, mantle-driven process that generated differential stresses [e.g., Crough, 1983;Zeyen et al, 1997] and the formation of rift basins in areas characterized by pronounced lithospheric and crustal-scale anisotropies and weaknesses [i.e., Ashwal and Burke, 1989;Ebinger and Sleep, 1998;Smith and Mosley, 1993;Smith, 1994]. As such, our new data from the Kenya Rift, combined with the synopsis of geological and thermo-chronological studies in East Africa, is compatible with recent numerical modeling results [Koptev et al, 2015] that predict a regionally overlapping initiation of amagmatic and magmatic rifting sectors in East Africa following the asymmetric impingement of a single mantle plume [i.e., Halldórsson et al, 2014] at the base of the lithosphere of the eastern sector of the Tanzania Craton.…”

The role of ecological opportunity in shaping disparate diversification trajectories in a bicontinental primate radiation

“…In this case, a dearth of EO may explain why colobines did not radiate as strongly in Africa. First, suitable tropical rainforest covered East Africa 12.6 Ma [75] close to the divergence of African colobines but contracted and was partially replaced with grasslands several millions of years later because of aridification from the uplift of the central Tanganyikan plateau [76,77]. Second, because historically more cercopithecine primates have co-occurred with colobines in Africa than Asia [23,24], interspecific competition for habitat and dietary resources may have depressed diversification of the African lineage despite the availability of potential niches.…”