What geological and ecological processes explain the distribution of this species?
At the moment, I am enjoying a well-deserved holiday with my family in Belgium. Apart from writing blog posts for the Avian Hybrids Project, I fill my free time with reading books and watching some Netflix-series (for those interested: I am currently watching The Walking Dead and Titans). Nothing more relaxing than immersing yourself in good story. But you don’t need to switch in your television or dive into the writings of Stephen King or George R. R. Martin to find these stories. Nature is full of amazing stories on a huge variety of species. For example, a recent study in the Journal of Ornithology used genetic analyses and ancestral area reconstructions to tell the evolutionary story of the Blue-backed Manakin (Chiroxiphia pareola) across South America. Sit back, relax and enjoy this epic journey from the Amazon to the Atlantic Forest.
Our story starts about 3 million years ago in the Amazon region where an ancestral population of the Blue-backed Manakin resides. At the end of the Pliocene (ca. 2.8 million years ago), massive erosion events changed the river dynamics in this area and split the ancestral population in two. Later on, the resulting western population gave rise to the subspecies regina and napensis, which became isolated on opposite sides of the Marañon River and Ucayali River. The eastern population, on the other hand, moved into the Guiana Shield (a mountain range in the northeast of South America), evolving into the subspecies pareola. These events nicely show how different processes – vicariance and dispersal – come into play during the evolutionary history of a bird species.
Fast forward to about 0.5 million years ago and we can see that the eastern population has colonized the Atlantic Forest. In previous blog posts – on the Variable Antshrike (Thamnophilus caerulescens) and Buff-browed Foliage Gleaner (Syndactyla rufosuperciliata) – I described several routes into the Atlantic Forest. But how did the Blue-backed Manakin get there? Based on ecological niche modelling, the authors argue that this species followed “a scenario in which a connection between the Amazonian and northeastern Atlantic Forest occurred in the early/middle Pleistocene via routes that extended through the interior of the Brazilian northeast.” This connection is supported by studies on other bird species and analyses of plant fossils.
And there you have it, the evolutionary story of the Blue-backed Manakin. Currently, this species is classified into four subspecies: napensis, regina, atlantica and pareola. However, the genetic analyses in this study uncovered five distinct lineages, not four. It seems that the subspecies atlantica and pareola are composed of more genetic groups than currently thought. A taxonomic revision might thus be warranted. And if these changes in classification are published, you can read the entire taxonomic story at the Avian Hybrids Project.
do Nascimento, N. F. F., Agne, C. E. Q., Batalha-Filho, H., & de Araujo, H. F. P. (2021). Population history of the Blue-backed Manakin (Chiroxiphia pareola) supports Plio-Pleistocene diversification in the Amazon and shows a recent connection with the Atlantic Forest. Journal of Ornithology, 162(2), 549-563.
Featured image: Blue-backed Manakin (Chiroxiphia pareola) © Steve Garvie | Wikimedia Commons