Contemporary geophysical, climatic and ecological setting of West Africa.(a) Elevational map with major rivers. Legend for elevation profile on the upper right is altitude in metres. Course of major rivers modified from Food and Agriculture Organisation of the United Nations (https://data.apps.fao.org/catalog/iso/b891ca64-4cd4-4efd-a7ca-b386e98d52e8). Numbers refer to major rivers sorted from west to east: 1: Cavally; 2: Sassandra; 3: Bandama; 4: Comoé; 5: Volta; 6: Niger; 7: Cross. Location of Lake Bosumtwi and other fossil pollen records are indicated with a star (taken from Dupont et al. (2000));(b) Average annual precipitation for the years 1970–2000 (Fick and Hijmans 2017). Legend with colour-shading in the upper right in millimetres. West African forests delimitation in white contour;(c) Present-day ecoregions modified from Olson et al. (2001) grouped into biomes: a) tropical and subtropical moist broadleaf forests; b) tropical and subtropical grasslands, savannah and shrublands; c) montane grasslands and shrublands; d) mangroves. West African forests delimitation in black contour.