Contribution of small rodent communities (Muridae) to the history of West Central African savannas (case of Gabonese savannas): diversity, biogeographic affinities, phylogeography and paleoenvironmental analyses

Abstract

Savannas of West Central Africa stand around or inside the large rainforest block. They result from paleo-climatic fluctuations, but the details of their history remain poorly known. The aim of the present study is to explain the present distribution of savannas in West Central Africa, considering the two classic anthropic or paleoclimatic hypotheses about their origin. The study was focused on Gabonese savannas and based on small terrestrial mammal patterns. The phylogeography of small species of strictly savanicolous rodents was compared using nested clade analysis of haplotype networks based on cytochrome b mitochondrial DNA, coupled with other approaches. The data were also compared with literature data on vegetation changes in tropical West Africa over the last 150,000 years to test scenarios on the origin and history of Gabonese savannas. The results showed several fragmentation events of small rodent populations and revealed redundant biogeographic relationships. These events were dated, and the results about the history of rodent species were congruent with palaeobiological data about the successive phases of savanna expansion and fragmentation: the results support the hypothesis of a paleoclimatic origin of the Western Congolian forest-savanna mosaic. These rodent population fragmentation events occurred more than 50,000 years ago.