The Plumage Evolution of Crimson Rosellas (Platycercus elegans)

Abstract

The Crimson Rosella (Platycercus elegans) species complex is one of great plumage diversity. This study aims to describe the plumage of all 7 subspecies, while also using reflectance values to ask questions about their classification and evolutionary history. For the first time ever, the plumage of each subspecies of the P. elegans complex were plotted on an avian tetrahedral colour space (Goldsmith, 1990). Our statistical findings give reasons why the classification of 3 intermediate/orange subspecies (P. e. fleurieuensis, P. e. adelaidae, and P. e. subadelaidae) should be reduced to 2 subspecies, merging P. e. adelaidae and P. e. subadelaidae. The study also argues that P. e. elegans and P. e. melanoptera, two crimson subspecies, should remain as distinct subspecies based on their difference in long wavelength light reflectance and their geographic isolation from one another. Finally, the data produced by this study rejects an ideal ring species hypothesis, however further research must be done to determine if this complex evolved as a ring species some time ago before it was broken up by environmental conditions.