The Colors of Paradise
Art by Juli Badics
By Marlena Tyldesley
If you, like me, found yourself absentmindedly working your way through Netflix’s film selection over the last year, you may have come across my now-favorite movie: Dancing with the Birds. The movie occupied a good few hours of quarantine, but, far more importantly, it introduced me to birds-of-paradise. If you’ve never had the pleasure of seeing a bird-of-paradise in action, here are some pictures for you:
While the birds have a very large fan base among scientists and bird enthusiasts (and me), relatively little is known about the genetics that made them so glorious. So, in a 2019 study, researchers from the Swedish Museum of Natural History and several universities set out to conduct a comparative analysis of the genomes of different birds-of-paradise. There have been previous attempts to dig through the evolutionary history of this family of birds, but the results, according to the authors, have been “largely incongruent” (Prost et al., 2019).
As far as their coloring goes, male birds-of-paradise bear the beauty responsibility in this species. In fact, another study showed that because the birds’ sexual selection depends so heavily on the ornamentation of the males, males were getting increasingly ornamented and ‘beautiful’ while females were getting less so and starting to look similar between species.
Because only about 50% of all species of birds-of-paradise are represented in the live tissue samples that had been collected at the time of the study, the authors took advantage of new technology that allowed them to sequence genomes from specimens in museum collections. Altogether, the authors used three live tissue samples and two from museum samples to create a group of genomes representative of the five clades of birds-of-paradise.
Upon completion of the comparative analysis of these genomes, the authors identified three genes thought to play a role in coloration. The first, ADAMTS20, is crucial for melanocyte development. For reference, melanocytes are responsible for skin color in humans, and are known to affect pigmentation in other birds. Specific types of mutations in the ADAMTS20 gene have been shown to interrupt the processes of a second gene, KIT. KIT regulates pigment cell development, which we know have to do with melanocytes in mammals and birds. So, the logic goes: if we know melanocytes (made with ADAMTS20) affect pigments (made with KIT), then we can reasonably assume that these two genes, and the mutations that affect them, may be responsible for the plethora of beautiful colors represented in the birds-of-paradise family .
The third gene the authors identified is ATP7B, a gene thought to encode an enzyme that transports copper. Copper plays a crucial role in melanin synthesis, once again playing back into coloration pathways that have already been documented in other species.
There are several more genes that the authors identified as possibly having similar functions in birds-of-paradise as they do in chickens and mammals, but these ties are not discussed in detail.
These observations suggest promising pathways for future research, including on ornamentation - traits that don’t directly contribute to the survival of individual animals, but rather to the sexual selection exhibited by animals like birds-of-paradise (“Birds of Paradise”). The authors also expressed excitement at the continuing advancement of technologies that may be used to investigate evolutionary traits and genome analysis of my new favorite bird.
Prost, S., Armstrong, E., Nylander, J., Thomas, G., Suh, A., Petersen, B., Dalen, L., Benz, B., Blom, M., Palkopoulou, E., Ericson, P., & Irestedt, M. (2019). Comparative analyses identify genomic features potentially involved in the evolution of birds-of-paradise. Giga Science. https://academic.oup.com/gigascience/article/8/5/giz003/5300102
“Birds of Paradise.” National Geographic, https://www.nationalgeographic.com/animals/birds/facts/birds-of-paradise.