Phylogeography of Bornean land snails suggests long-distance dispersal as a cause of endemism

Aim: Islands are often hotspots of endemism due to their isolation, making colonization a rare event, and hence facilitating allopatric speciation. Dispersal usually occurs between nearby locations according to a stepping-stone model. We aimed to reconstruct colonization and speciation processes in an endemic-rich system of land-based islands that does not seem to follow the obvious stepping-stone model of dispersal. Location: Five land-based habitat archipelagos of limestone outcrops in the floodplain of the Kinabatangan River in Sabah, Malaysian Borneo. Methods: We studied the phylogeography of three species complexes of endemic land snails, using multiple genetic markers. We calculated genetic distances between populations, applied BEAST2 to reconstruct phylogenies for each taxon, and subsequently reconstructed ancestral ranges using ‘BIOGEOBEARS’. Results: We found spatial genetic structure among nearby locations to be highly pronounced for each taxon. Genetic correlation was presen...