We integrated observations or morphology, behaviour (vocalizations) with a whole-genome resequencing of the three traditional subspecies of the Limestone Wren Babbler Napothera crispifrons, and a distinct leucistic population of one of these subspecies. We were able to recognize three deeply diverged lineages, N. crispifrons from Myanmar and western Thailand, N. annamensis from Vietnam, and N. calcicola from north-eastern Thailand., Mitochondrial divergences of 5-6.4% among these taxa were roughly twice as great as those between typical bird sister species pairs.
Despite its great phenotypic distinctness, the leucistic population of N. crispifrons (to the west of the Salween River) was characterized by shallow genomic differentiation from its dark-plumaged neighbour to the east. These two colour morphs only differed at a few genomic loci. Such extreme colour differences may arise and subside rapidly in evolutionary terms.
Gwee, Chyi Yin; Lee, Qiao Le; Mahood, Simon ; Le, Hung; Tizard, Robert ; Eiamampai, K., Round, P..&; Rheindt, F. 2021. The interplay of color and bioacoustic traits in the differentiation of a Southeast Asian songbird complex. Molecular Ecology 30 (1):297–309. DOI: 10.1111/mec.15718