Fig. 1

Reticulate speciation history of North American ravens. a Geographic range of distinct mtDNA lineages within Common and Chihuahuan Ravens based on previous mtDNA studies^18,19,20,21 and range records²⁹. b Hypothesis of speciation reversal where the Common Raven is formed from the fusion of non-sister California (orange) and Holarctic (purple) lineages following secondary contact, while Chihuahuan Ravens (black) remained reproductively isolated despite sympatry with the Common Raven. Dashed lines in b show the mtDNA gene tree topology from this and previous studies^18,19,20,21. Solid grey background in b traces the changing taxonomic boundaries as the Holarctic lineage first split from the ancestor of the California and Chihuahuan lineages, and then the California and Holarctic lineages fused into a single admixed lineage