The Pachycephalidae are a family of bird species that includes the whistlers, shrike-thrushes, and three of the pitohuis, and is part of the ancient Australo-Papuan radiation of songbirds. Its members range from small to medium in size, and occupy most of Australasia. Australia and New Guinea are the centre of their diversity.
There are five subspecies of the Grey Shrike-thrush, corresponding to five regional populations across Australia: rufiventris, brunnea, superciliosa, harmonica and strigata. At locations where populations overlap, researchers detected low levels of gene flow (Lamb et al., 2019)
During the Pleistocene ice ages, large parts of the world’s seawater was locked up in ice, resulting in worldwide drop in sea levels. In some regions, such as Australasia, this led to the formation of land bridges between islands. These land bridges might have facilitated gene flow between subspecies of the golden whistler (Pachycephala pectoralis) on the islands Taliabu and Peleng (Garg et al. 2018).
Garg, K.M., Chattopadhyay, B., Wilton, P.R., Prawiradilaga, D.M. & Rheindt, F.E. (2018) Pleistocene land bridges act a semipermeable agents of avian gene flow in Wallacea. Molecular Phylogenetics and Evolution, 125:196-203.
Lamb, A.M., da Silva, A.G., Joseph, L., Sunnucks, P. & Pavlova, A. (2019) Pleistocene-dated biogeographic barriers drove divergence within the Australo-Papuan region in a sex-specific manner: an example in a widespread Australian songbird. Heredity.