An international team of scientists has sequenced and analyzed the genomes of representatives from all five major clades within the birds-of-paradise family (Paradisaeidae): the paradise crow (Lycocorax pyrrhopterus) from Obi Island in Indonesia, the paradise riflebird (Ptiloris paradiseus) from New South Wales, Australia, the huon astrapia (Astrapia rothschildi), the King of Saxony bird-of-paradise (Pteridophora alberti) and the red bird-of-paradise (Paradisaea rubra) from Papua New Guinea.
Drawing of the male and female huon astrapia (Astrapia rothschildi), also known as the Rothschild’s bird-of-paradise, by Ellis Rowan.
Birds-of-paradise, with their elaborate and colorful feathers as well as complex courtship displays, have a special place in natural history.
“Every ornithologist and birdwatcher has his favorite 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,” the famous evolutionary biologist Ernst Mayr once said about these exotic birds.
Birds-of-paradise 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.
“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,” said Dr. Martin Irestedt, senior curator at the Swedish Museum of Natural History.
“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.”
For the study, Dr. Irestedt and co-authors selected three species that did not yet have available genomes sequences: the paradise crow, the paradise riflebird and the huon astrapia.
They further provided new genome sequence data to improve currently available genomic information for two other birds-of-paradise species: the King of Saxony bird-of-paradise and the red bird-of-paradise.
Using these five datasets, the researchers 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, we are about to learn much more about these fascinating animals,” the scientists said.
The findings appear in the journal GigaScience.
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Stefan Prost et al. Comparative analyses identify genomic features potentially involved in the evolution of birds-of-paradise. GigaScience, published online January 24, 2019; doi: 10.1093/gigascience/giz003
