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The pteropodid fruit bat genus Eidolon is comprised of two extant species: E. dupreanum on Madagascar and E. helvum on the African mainland and offshore islands. Recent population genetic studies of E. helvum indicate widespread panmixia across the continent, although island populations off western Africa show genetic structure. Little is known about the genetic connectivity of E. dupreanum or the divergence time between these two sister species. We examine sequence data for one mitochondrial (cyt-b) and three nuclear regions (β-fib, RAG1, and RAG2) to assess population genetic structure within E. dupreanum and divergence between the two Eidolon spp. In addition, we characterize the demographic history of both taxa using coalescent-based methods. We find little evidence for population structure within E. dupreanum, and suggest that this reflects dispersal based on seasonal fruit availability and a preference for roosting sites in exposed rock outcrops. However, despite apparent panmixia in both Eidolon spp. and large dispersal distances reported in previous studies for E. helvum, these two taxa diverged in the mid-to-late Miocene. Both species are also characterized by population expansion and young, Pleistocene clade ages, although slower population growth in E. dupreanum is likely explained by its divergence via colonization from the mainland. Finally, we discuss the implications of population connectivity in E. dupreanum in the context of its potential role as a reservoir host for pathogens capable of infecting humans.
The straw-coloured fruit bat, Eidolon helvum, is a common and conspicuous migratory species, with an extensive distribution across sub-Saharan Africa, yet hunting and habitat loss are thought to be resulting in decline in some areas. Eidolon helvum is also a known reservoir for potentially zoonotic viruses. Despite E. helvum's importance, ecological and behavioural traits are poorly described for this species. Here we present extensive data on the distribution, migration patterns, roost size, age and sex composition of 29 E. helvum roosts from nine countries across tropical Africa, including roosts not previously described in the literature. Roost age and sex composition were dependent on timing of sampling relative to the annual birth pulse. Rather than a single ‘breeding season’ as is frequently reported for this species, regional asynchrony of reproductive timing was observed across study sites (with birth pulses variably starting in March, April, September, November or December). Considered together with its genetic panmixia, we conclude that the species has a fluid, fission-fusion social structure, resulting in different roost ‘types’ at different times of the year relative to seasonal reproduction. Bat-human interactions also varied across the species' geographical range. In the absence of significant hunting, large urban colonies were generally tolerated, yet in regions with high hunting pressure, bats tended to roost in remote or protected sites. The extensive quantitative and qualitative data presented in this manuscript are also valuable for a wide range of studies and provide an historical snapshot as its populations become increasingly threatened.
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