Geography of African Rubiaceae with reference to glacial rain forest refuges

Bio‐indicator species and Central African rain forest refuges in the Campo‐Ma'an area, Cameroon

“…Robbrecht (1996) argued that although most Rubiaceae species have fleshy fruits (drupes or berry-like) that allow for long-distance dispersal by birds, they possess some advanced morphological syndromes by which cross-pollination becomes obligatory. As a consequence, their breeding system probably renders isolated cases of long-distance dispersal of single diaspores ineffective, because a self-incompatibility system is present in the majority of the species (Robbrecht, 1988(Robbrecht, , 1996.…”

“…Robbrecht (1996) argued that although most Rubiaceae species have fleshy fruits (drupes or berry-like) that allow for long-distance dispersal by birds, they possess some advanced morphological syndromes by which cross-pollination becomes obligatory. As a consequence, their breeding system probably renders isolated cases of long-distance dispersal of single diaspores ineffective, because a self-incompatibility system is present in the majority of the species (Robbrecht, 1988(Robbrecht, , 1996. Therefore, one may expect that relict Rubiaceae populations will need a long time to recolonise the expanding spread of forest when favourable climatic conditions return after a period of forest reduction during a glacial period (Robbrecht, 1996).…”

“…As a consequence, their breeding system probably renders isolated cases of long-distance dispersal of single diaspores ineffective, because a self-incompatibility system is present in the majority of the species (Robbrecht, 1988(Robbrecht, , 1996. Therefore, one may expect that relict Rubiaceae populations will need a long time to recolonise the expanding spread of forest when favourable climatic conditions return after a period of forest reduction during a glacial period (Robbrecht, 1996).…”

“…In Central Africa, a number of these so-called Pleistocene forest refuges are found in Gabon and Cameroon, amongst them the Campo-Ma'an area (Aubréville, 1962;White, 1979White, , 1983Hamilton, 1982;Maley, 1987;Sosef, 1994). However, there is a disagreement about the exact location of these refuges within these areas (Robbrecht, 1996;Sosef, 1996;Leal, 2001). This is probably because tropical rain forest refuges are often studied on a large scale (Maley, 1987(Maley, , 1989.…”

“…Understanding the presentday location of tropical rain forest refuges requires the use of direct evidence or 'palaeo-evidence' such as palynological or palaeobotanical data, or indirect evidence, such as the distribution patterns of endemic and slow dispersal species, or genetic studies (Hardy et al, 2003). More often, endemism and patterns in the distribution of slow dispersal taxa have been used to identify the location and extent of regional forest refuges (Rietkerk et al, 1996;Robbrecht, 1996;Sosef, 1996;Achoundong, 2000). These studies interpreted locations with a high degree of endemism and plant diversity to coincide with former forest refuge areas.…”