Effect of barriers and distance on song, genetic, and morphological divergence in the highland endemic Timberline Wren (Thryorchilus browni, Troglodytidae)

Mountain passes and distance significantly reduce gene flow between populations of the Timberline Wren (Thryorchilus browni), leading to notable divergence in genetic, vocal, and morphological traits. Researchers analyzed four Costa Rican populations using microsatellites and song recordings, revealing that a lowland mountain pass caused the greatest differences—likely due to reduced gene flow. Cultural drift and female assortative mating, where females prefer songs from their own population, further accentuated these effects. This pattern of divergence, observed over smaller scales than previously documented in Neotropical highland birds, underscores how geographic barriers and limited movement shape evolution in highland species with restricted distributions.

Camacho-Alpízar, A., Fuchs, E. J., & Barrantes, G. (2018). Effect of barriers and distance on song, genetic, and morphological divergence in the highland endemic Timberline Wren (Thryorchilus browni, Troglodytidae). Plos One, 13(12), e0209508. https://doi.org/10.1371/journal.pone.0209508