Simulated glacial and interglacial vegetation across Africa: implications for species phylogenies and trans‐African migration of plants and animals

Abstract

The paleoenvironmental context of plant and animal species evolution (including glacial migrations and population separations) is based on a very patchy and incomplete paleophytogeographic record. It was our objective, therefore, to provide an additional source for paleovegetation comparison by presenting simulations from a state-of-the-art fully coupled earth system model (HadCM3LC). We simulated potential paleovegetation distributions following pre-Industrial and last glacial maximum (LGM) climate forcing for the continent of Africa. Our LGM simulations indicate that tropical broadleaf forest was not severely displaced by expanding grasslands within central Africa, although the outer extent of closed forest decreases, particularly in the north. Our simulations indicate that the structure of glacial forests may have been much different from today, in thatLGM simulations indicate that forests were likely characterized by lower leaf area indexes, lower tree heights and lower vegetation carbon content. On the other hand, warmer interglacial climate (like our pre-Industrial climate scenario) results in simulated expansion of tropical forest from coast to coast across central Africa that we postulate could have acted as a barrier to plant and animal species migrations. We suggest that our modeling experiments have implications for the interpretation of phylogenetic data, including that of our own species, Homo sapiens sapiens.

Plio-Pleistocene history and phylogeography of Acacia senegal in dry woodlands and savannahs of sub-Saharan tropical Africa: evidence of early colonisation and recent range expansion

“…In Southern Africa, the presence of a private trnH-psbA haplotype suggests long-term persistence and isolation of the population in this region. The expansion and contraction of moist rainforest across East Africa is likely to have been the driving force behind isolation of Southern African populations (Cowling et al, 2008). Similar patterns have been found in phylogeographic studies of other savannah-adapted species, such as the plains zebra (Lorenzen et al, 2008).…”

Strong influence of palaeoclimate on the structure of modern African mammal communities

“…Africa is also home to a great diversity of species in 17 of the world's 20 orders of terrestrial mammals [19][20][21], and is virtually the only continent relatively unscathed by the late Quaternary extinction events [22,23]. Nevertheless, late Quaternary palaeoclimate change has been noted as a particularly important time period in the evolution and biogeography of African mammals [24][25][26][27][28][29][30][31][32][33][34][35], especially recurrent expansions and contractions of major vegetation biomes as climates changed [29,[36][37][38][39][40].…”

Untitled

“…Sediment cores from Lake Malawi have been interpreted as indicating recurring megadroughts Scholz et al 2007) and the formation of refugia the southern Cape, the Ethiopian highlands, and the immediate environs of major East African lakes and rivers (Basell 2008;Brandt 2006). Other studies suggest an overall reduction of vegetation throughout the subcontinent (Cowling et al 2008). Whether or not such refugia actually existed, the periodic episodes of hyper-aridity that repeatedly afflicted African humans from Plio-Pleistocene times onwards (Trauth et al 2007), combined with equato-these artifacts as reflecting either an independent, if belated, development of projectile weaponry or diffusion of the projectile technology from dispersing Homo sapiens populations to indigenous Neandertals.…”