How many babies in the bush? Systematics of cryptic dwarf bushbabies (Galagoides spp)

Background: Species are often distributed discontinuously across their total geographic range. Understanding how these patterns originated is a major question in systematics and biogeography. Habitat fragmentation has often been invoked to explain population isolation. which. over prolonged periods of time. can lead to speciation [1]. One example of a region where species patterns may have been shaped by historical habitat fragmentation is the humid Guineo-Congolean evergreen and semi-evergreen forests of West and West-central Africa. In this region. lowland rainforests are separated by a zone of low rainfall known as the Dahomey gap. Because this gap is supposedly unsuitable for forest-dwelling organisms. several animal and plant species seem to have a disjunct distribution around the Dahomey gap. However. local species often have unclear ranges and taxonomic identities [2]. Due to subtle phenotypic variation and limited phylogenetic information. species diversity may be underestimated [3]. As a result. we know little about regional biogeographic patterns and the evolutionary processes that generated them. A case in point are the western dwarf bushbabies (genus Galagoides) [4]. a widely distributed group of elusive nocturnal primates (Figure 1) that show low phenotypic divergence in fur coloration and skull morphology [5]. Historically. only two species are recognized: G. demidoff???with six subspecies never confirmed???and G. thomasi. Recently. a third species. G. kubirensis. was described based on acoustics and morphology [6]. Although some Galagoides lineages seem to tolerate the dry conditions of the Dahomey gap. it is hard to confidently assign these populations to any of these taxa. For instance. the new IUCN red list assessment [7] relied on anecdotal acoustic surveys to determine that G. thomasi is present in the Dahomey gap. while G. demidoff is absent ??? the exact opposite of what was previously proposed based on morphology [8]. Therefore. it is unclear whether Galagoides populations may be locally adapted and if habitat boundaries impose restrictions to gene flow. These knowledge gaps have implications for the systematics. evolution. and conservation of a highly neglected primate clade [9].
 
 Scope of the Project: The main goals of this research project are to 1) characterize the genetic diversity and structure of Galagoides species across their geographic range; 2) elucidate the evolutionary relationship among bushbaby populations; 3) test putative new species (e.g.. G. kumbirensis); and 4) clarify the diversity of dwarf bushbabies and their distribution in the Congolean forests.