The genus Caloenas is represented by a single living species, the Nicobar Pigeon ( Caloenas nicobarica), which has a circum-Indonesian distribution (from the Andaman to the Solomon Islands) and has a tendency to live on small and remote islands. This extended Dodo clade includes, in order of closeness to the Dodo and the Rodrigues Solitaire, the genera Caloenas, Goura and Didunculus, of which all living species posses the ability to fly but show at least some degree of terrestrial habits. More recent genetic analyses have revealed that the Dodo from Mauritius and the closely related Rodrigues Solitaire ( Pezophaps solitaria), both extinct flightless island endemics in the subfamily Raphinae, fall in a clade of morphologically very diverse Pigeon species. The morphological distinctiveness of the Dodo has severely complicated the investigation of its relationship to other bird species. The Dodo ( Raphus cucullatus) is an icon of extinction as well as extreme morphological evolution. This set of traits supports the stepping stone hypothesis, which states that the Raphinae got to their respective localities by island hopping from India or Southeast Asia. The phylogenetic placement of the Spotted Green Pigeon indicates that the ancestors of both Caloenas and therefore Raphinae displayed and shared the following traits: ability of flight, semi-terrestrial habits and an affinity towards islands. The distance observed for the Spotted Green Pigeon and Nicobar Pigeon is larger than that observed within other Pigeon species, indicating that the Spotted Green pigeon is a unique taxon, thereby also indicating it is a genuine addition to the list of extinct species. Maximum Likelihood phylogenetic analyses reveal that the Spotted Green Pigeon is a unique lineage and together with the Nicobar Pigeon, is basal to the Dodo and Rodrigues Solitaire. A novel extraction method with the ability to retain and purify heavily fragmented DNA is used to investigate two feathers from the sole surviving specimen. We use ancient DNA methodologies to investigate the phylogeny and authenticity of the Spotted Green Pigeon. Due to its potential close relationship, the Spotted Green Pigeon may hold clues to the historical migration, isolation and morphological evolution of the Dodo and its kindred. Today only one of the original two specimens survives and nothing is known about the origin of the taxon. The relationship between both taxa has occasionally been questioned, leading some ornithologists to suggest that the two may in fact be different taxa. Soon however the taxon fell into obscurity, as it was regarded as simply an abnormal form of the Nicobar Pigeon. The Spotted Green Pigeon ( Caloenas maculata) was described in 1783 and showed some similarities to the Nicobar Pigeon. Genetic analyses have revealed that the Nicobar Pigeon ( Caloenas nicobarica) is the closest living relative of these birds, thereby highlighting their ancestors’ remarkable migration and morphological evolution. The closely related and extinct Dodo ( Raphus cucullatus) and Rodrigues Solitaire ( Pezophaps solitaria), both in the subfamily Raphinae, are members of a clade of morphologically very diverse pigeons.
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