The objective of this study was to investigate whether dispersal ability, as measured by a proxy of hand-wing index 2, influenced diversification of the birds of Madagascar at two scales. Madagascar is home to several avian lineages that have diversified greatly while other lineages are only represented by a single species. a key question in evolutionary biology is why some of these lineages diversified while others did not. One way to address this is to examine what features of these lineages promotes their diversification. Recent studies have focused on the relative importance of dispersal ability to diversification at the continental and island scales. to further test this relationship, I investigated whether dispersal ability, as measured by hand-wing index 2, influenced diversification in the birds of Madagascar at a large regional scale and smaller local scale within Madagascar. to assess whether dispersal ability influenced diversification of the birds of Madagascar I compared hand-wing index 2 of Malagasy and source (closest non-Malagasy relatives) clades of five radiating and three non-radiating lineages. I treated each lineage as an independent case study in the hopes of identifying a pattern reflecting a shift in dispersal ability upon colonization of Madagascar in radiating lineages. at a smaller local scale of macrohabitats within Madagascar, I examined whether variation in dispersal ability (HWI2) within widespread Malagasy species differed between subspecies restricted to macrohabitats reflecting local adaptation and divergence across macrohabitats. My study found that Malagasy species did not shift in their dispersal ability after colonizing Madagascar and thus, dispersal ability is not critical to the diversification of Malagasy endemics from their source clade in radiating or non-radiating lineages. However, at a smaller local scale of macrohabitats, I found variation in dispersal ability was likely due to local adaptations to macrohabitats. This study adds to our knowledge of dispersal ability and diversification patterns in Malagasy avifauna. This is a leading step towards additional studies to investigate the impact of potential geographic barriers to dispersal ability in the birds of Madagascar and could provide further insights into diversification patterns
