![Afrixalus paradorsalis, Cameroon][1]
[1]: http://danielportik.com/DP/Home_files/shapeimage_3.png
This project page contains data, input files, analysis instructions, and results for the study:
**Sky, sea, and forest islands: diversification in the African leaf-folding frog Afrixalus paradorsalis (Anura: Hyperoliidae) of the Lower Guineo-Congolian rainforest**
*Kristin L. Charles, Rayna C. Bell, David C. Blackburn, Marius Burger, Matthew K. Fujita, Václav Gvoždík, Gregory F.M. Jongsma, Marcel Talla Kouete, Adam D. Leaché, and Daniel M. Portik*
**Aim** To investigate how putative barriers, forest refugia, and ecological gradients across the Lower Guineo-Congolian rainforest shape genetic and phenotypic divergence in the leaf-folding frog Afrixalus paradorsalis, and examine the role of adjacent land-bridge and sky-islands in diversification.
Location The Lower Guineo-Congolian Forest, the Cameroonian Volcanic Line, and Bioko Island, Central Africa.
**Taxon** *Afrixalus paradorsalis* (Family: Hyperoliidae), an African leaf-folding frog
**Methods** We used molecular and phenotypic data to investigate diversity and divergence among the A. paradorsalis species complex distributed across lowland rainforests, land-bridge islands, and high elevations in Central Africa. We examined the coincidence of population boundaries, landscape features, divergence times, and spatial patterns of connectivity and diversity, and subsequently performed demographic modeling using genome-wide SNP variation to distinguish among divergence mechanisms in mainland (riverine barriers, forest refugia, ecological gradients) and land-bridge island populations (vicariance, overwater dispersal).
**Results** We detected four genetically distinct allopatric populations corresponding to Bioko Island, the Cameroonian Volcanic Line, and two lowland rainforest populations split by the Sanaga River. Although lowland populations are phenotypically indistinguishable, pronounced body size evolution occurs at high elevation, and the timing of the formation of the high elevation population coincides with mountain uplift in the Cameroonian Volcanic Line. Spatial analyses and demographic modeling revealed population divergence across mainland Lower Guinea is best explained by forest refugia rather than riverine barriers or ecological gradients, and that the Bioko Island population divergence is best explained by vicariance (marine incursion) rather than overseas dispersal.
**Main conclusions** We provide growing support for the important role of forest refugia in driving intraspecific divergences in the Guineo-Congolian rainforest. In *A. paradorsalis*, sky-islands in the Cameroonian Volcanic Line have resulted in greater genetic and phenotypic divergences than marine incursions of the land-bridge Bioko Island, highlighting important differences in patterns of island-driven diversification in Lower Guinea.
