Birds-of-paradise genomes target sexual selection

A new study published in the open access journal GigaScience explores the genomes of a fascinating group of birds, birds-of-paradise, with work providing genome sequences from 5 birds-of-paradise species: 3 that did not have available genome sequences. Birds-of-paradise, with their elaborate and colorful feathers as well as complex courtship displays, have a special place in natural history. They serve as a school-book example of sexual selection, which is the outcome of generations of female mate choice of males that have "attractive" features. The result is an unparalleled radiation of species where males exhibit extreme morphological features and behaviors with no other evolutionary meaning than to attract females for mating. However, very little is known about the genetic variants that distinguish the lavishly colored birds-of-paradise from their less conspicuous relatives, such as the collared flycatcher. Whole genome availability of multiple species provides a rich resource for molecular evolutionary to identify genes that came under the influence of sexual selection, and a way to assess how these genes transformed the males' plumage into a colorful asset for mating purposes.

The famous evolutionary biologist Ernst Mayr (1904-2005) once said about the birds-of-paradise: "Every ornithologist and birdwatcher has his favourite group of birds. Frankly, my own are the birds of paradise and bowerbirds. If they do not rank as high in world-wide popularity as they deserve it is only because so little is known about them."

Taking on the task of addressing the limited amount of information available for these exotic birds were researchers from the Swedish Museum of Natural History, American scientists, and first author Stefan Prost from the Senckenberg Museum in Frankfurt. They selected three species that did not yet have available genomes sequences: the paradise crow (Lycocorax pyrrhopterus) from Obi Island in Indonesia; the paradise riflebird (Ptiloris paradiseus) from New South Wales, Australia; and the huon astrapia (Astrapia rothschildi) from Papua New Guinea. They further provided new genome sequence data to improve currently available genomic information for two other birds-of-paradise species from Papua New Guinea: the King of Saxony bird-of-paradise (Pteridophora alberti) and the red bird-of-paradise (Paradisaea rubra).

Martin Irestedt, senior curator at the Swedish Museum of Natural History, said that "Birds-of-paradise constitute one of the most famous examples on how sexual selection has driven the evolution of male plumage ornamentation and mating behaviors to its extreme. It is thus extremely exciting that we are able to present genomic data that provide the first glimpse to how genomic evolution is linked to the extraordinary phenotypic variation found in this fascinating group of birds."

Using these five bird-of-paradise datasets, Prost and colleagues identified genes that show signs of past influence of selection and evolution, some of which appear to be important for coloration, morphology, and feather and eye development. For example, they identified a gene called ADAMTS20 that is potentially involved in producing the exquisite birds-of-paradise colorful feathers. ADAMTS20 is known to influence the development of melanocytes, specialized cells for the production of pigmentation patterns.

Thanks to modern genomics and the availability of these new datasets in the GigaScienceDataBase, GigaDB, we are about to learn much more about these fascinating animals.