Elevational Differentiation Increases Rates of Trait Evolution but not Diversification in Neotropical Passerine Birds

The importance of ecologically-mediated divergent selection in elevating rates of trait evolution has been poorly studied in the most species-rich biome of the planet, the continental tropics. I performed a macroevolutionary analysis of trait divergence and diversification rates across closely-related pairs of passerine birds, belonging to the Amazon basin and adjacent Andean slopes, to assess whether the difference in elevational range separating species pairs influences the speed of trait evolution and diversification rates. Difference in elevation was used as a proxy for the degree of ecological divergence. I found that the amount of elevational separation is associated with faster differentiation of song frequency, a trait important for premating isolation, and several morphological traits, which may contribute to extrinsic postmating isolation. However, ecological differentiation does not primarily drive bird diversification and, thus, may have limited influence on patterns of species richness along the eastern slope of the tropical Andes.M.Sc.2020-11-15 00:00:0