Data from: Rapid, complete reproductive isolation in two closely-related Zosterops White-eye bird species despite broadly overlapping ranges

Examining what happens when two closely-related species come into
secondary contact provides insight into the later stages of the speciation
process. The Zosteropidae family of birds is one of the most rapidly
speciating vertebrate lineages. Members of this family are highly vagile
and geographically widespread, raising the question of how divergence can
occur if populations can easily come into secondary contact. On the small
island of Kolombangara, two closely-related non-sister species of
White-eyes, Zosterops kulambangrae and Z. murphyi, are distributed along
an elevational gradient and come into secondary contact at mid-elevations.
We captured 134 individuals of both species along two elevational
transects. Using genotyping-by-sequencing data and a mitochondrial marker,
we found no evidence of past hybridization events and strong persistence
of species boundaries, even though the species have only been diverging
for approximately two million years. We explore potential reproductive
barriers that allow the two species to coexist in sympatry, including
premating isolation based on divergence in plumage and song. We also
conducted a literature review to determine the time it takes to evolve
complete reproductive isolation in congeneric avian species/subspecies in
secondary contact (restricted to cases where congeneric taxa are
parapatric or have a hybrid zone), finding our study is one of the
youngest examples of complete reproductive isolation studied in a genomic
context reported in birds.