Data from: Female, but not male, tropical sparrows respond more strongly to the local song dialect: implications for population divergence.

In addition to the observed high diversity of species in the tropics,
divergence among populations of the same species exists over short
geographic distances in both phenotypic traits and neutral genetic
markers. Divergence among populations suggests great potential for the
evolution of reproductive isolation and eventual speciation. In birds,
song can evolve quickly through cultural transmission resulting in
regional dialects, which can be a critical component of reproductive
isolation through variation in female preference. We examined female and
male behavioral responses to local and non-local dialects in two
allopatric populations of rufous-collared sparrows (Zonotrichia capensis)
in the Andes of Ecuador. Here we show that female sparrows prefer their
natal song dialect to the dialect from an allopatric population just 25 km
away and separated by unsuitable higher elevation habitat (pass 4200 m),
thus providing evidence of prezygotic reproductive isolation among
populations. Males showed similar territorial responses to all conspecific
dialects, with no consistent difference with respect to distance, making
male territoriality uninformative for estimating reproductive isolation.
This study provides novel evidence for culturally-based prezygotic
isolation over very short distances in a tropical bird.