Data for: Faster evolution of a premating reproductive barrier is not associated with faster speciation rates in New World passerine birds

Why are speciation rates so variable across the tree of life? One
hypothesis is that this variation is explained by how rapidly reproductive
barriers evolve. We tested this hypothesis by conducting a comparative
study of the evolution of bird song, a premating barrier to reproduction.
Speciation in birds is typically initiated when geographically isolated
(allopatric) populations evolve reproductive barriers. We measured the
strength of song as a premating barrier between closely related allopatric
populations by conducting 2,339 field experiments to measure song
discrimination for 175 taxon pairs of allopatric or parapatric New World
passerine birds, and estimated recent speciation rates from a global
molecular phylogeny of birds. Taxon pairs with high song discrimination in
allopatry failed to regularly interbreed in parapatry, evidence that song
discrimination is indeed an important reproductive barrier. However,
evolutionary rates of song discrimination were not associated with recent
speciation rates, and song discrimination evolves faster in suboscine
passerines than their more species-rich sister clade, the oscines. Our
findings support the long-held idea that song is a key premating
reproductive barrier in birds, but show that faster evolution of this
reproductive barrier between populations does not result in faster
diversification betweeen species.