The monophyly of the raptorial Circus genus (harriers) has never been in question, but the specific status of many, often vulnerable island endemic, taxa remains uncertain. Here we utilise one mitochondrial and three nuclear loci from all currently recognised Circus taxa (species and subspecies) to infer a robust phylogeny, to estimate the divergence date and to reconstruct the biogeographic origins of the Circus group. Our phylogeny supports both the monophyly of Circus and polyphyly of the genus Accipiter. Depending on the rate of molecular clock used, the emergence of the harrier clade took place between 4.9 and 12.2mya which coincides with the worldwide formation of open habitats which extant harriers now exploit. The sister relationship of the Northern Harrier C. cyaneus hudsonius and the Cinereous Harrier C. cinereus contradicts previous classifications that treated the former as conspecific with the Hen Harrier C. cyaneus cyaneus. Thus both should be elevated to species status: C. hudsonius and C. cyaneus. Further, the African Marsh C. ranivorus and the European Marsh C. aeruginosus Harriers emerge as sister species. The remaining marsh harriers exhibit very little genetic diversity, and are all recently diverged taxa that exhibit allopatric distributions. Considering their sister relationship and geographic proximity, we recommend treating C. approximans and C. spilonotus spilothorax as subspecies of C. approximans. For C. spilonotus spilonotus C. maillardi maillardi and C. maillardi macrosceles, their plumage and morphometric differences, phylogenetic relationship and geographic distributions make lumping of these taxa as a single species complicated. We thus propose to recognise as separate, recently evolved species: C. spilonotus, C. maillardi and C. macrosceles. Biogeographic inferences on the ancestral origin of harriers are uncertain, indicating that the harriers emerged in either the Neotropics, Palearctic or Australasia. We are, however, able to show that speciation within the harriers was driven by long range dispersal and migration events.

Department of Zoology and Lab of Ornithology Faculty of Science Palacky University Tř 17 Listopadu 50 77146 Olomouc Czech Republic

DST NRF Centre of Excellence Percy FitzPatrick Institute University of Cape Town Rondebosch 7701 South Africa

Institut de Systématique Évolution Biodiversité ISYEB UMR 7205 CNRS MNHN UPMC EPHE

Muséum national d'Histoire naturelle Sorbonne Universités 57 rue Cuvier CP5175005 Paris France

UMS MNHN CNRS 2700 Outils et Méthodes de la Systématique Intégrative Muséum National d'Histoire Naturelle 57 rue Cuvier F 75231 Paris Cedex 05 France

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