How many allospecies are there within the Accipiter gentilis superspecies?
Birds of prey are often classified as “superspecies”. You might think that taxonomists do this because they consider these birds so cool. However, “superspecies” is a taxonomic term that refers to “monophyletic groups of allo- or semispecies that are less differentiated from one another than closely related species usually are. Allospecies are allopatric, while semispecies are connected by a stable hybrid zone.” I have written about the Common Buzzard (Buteo buteo) superspecies. A recent study in the Journal of Zoological Systematics and Evolutionary Research focuses on another raptorial superspecies: the Northern Goshawk (Accipiter gentilis).
The Northern Goshawk forms a superspecies with three other allospecies: the Black Sparrowhawk (A. melanoleucus), the Meyer’s Goshawk (A. meyerianus) and the Henst’s Goshawk (A. henstii). As you can deduce from the terminology, these four allospecies occur in different parts of the world. The Northern Goshawk is widely distributed across the Holarctic (i.e. Eurasia, North Africa and North America). You can find the Black Sparrowhawk in sub-Saharan Africa. The Henst’s Goshawk is confined to Madagascar and the Meyer’s Goshawk to New Guinea including its surrounding islands. The map below gives a nice overview of this superspecies’ distribution.
Holartic = Nearctic + Palearctic
Florian Kunz and his colleagues collected samples from these four allospecies, including all 10 recognized subspecies of the Northern Goshawk. Based on two mitochondrial genes – the control region and cytochrome b – they determined the relationships between these birds of prey.
The analyses revealed that the Northern Goshawk is not monophyletic. The different populations in this allospecies cannot be traced back to one common ancestor. Instead, the Northern Goshawk is comprised of two unrelated groups: one in the Nearctic (i.e. North America) and one in the Palearctic (i.e. Eurasia and North Africa). The Palearctic group is nested within Meyer’s Goshawk, while the Nearctic group represents a separate lineage.
This result indicates that the taxonomy of this superspecies needs revision. The most plausible solution would be to split the Northern Goshawk into two allospecies. However, more research – based on nuclear DNA and morphology – is needed to gain more insights into this superspecies. One thing is certain though, it will be super-interesting!
Kunz, F., Gamauf, A., Zachos, F.E. & Haring, E. (2019) Mitochondrial phylogenetics of the goshawk Accipiter [gentilis] superspecies. Journal of Zoological Systematics and Evolutionary Research, Early View.