Galapagos Hawks Hand Down Feather Lice to Offspring Like Heirlooms

Being a parasite may not be the most glamorous of lifestyles in the animal kingdom, but it's certainly one of the most effective. Scientists have found that feather lice that live in the plumage of Galapagos hawks are passed down from one generation to another like family heirlooms, evolving with different populations of hawks.

Scientists have long hypothesized that leeching off other organisms is a major driver of biodiversity. Yet until now, it's been difficult to test this theory.

"The idea is really simple," said Jennifer Koop, the lead author of the new study, in a news release. "Each time a host population splits into separate populations that potentially become different species, we predict that their parasites could do the same thing."

The researchers examined hawks on the Galapagos Islands, which are located 575 miles off of the west coast of Ecuador. The species that colonized these islands have evolved in isolation, which makes this a natural laboratory for scientists. Over the course of four years, the scientists caught hundreds of Galapagos hawks and collected blood samples and feather lice for genomic analysis.

"We found the lice are passed on from mother to babies during brooding, almost like genes," said Noah Whiteman, one of the researchers. "They're evolutionary heirlooms, like your family's silverware or engagement ring diamond."

This means that the lice living on any bird and its offspring are more closely related than the lice living on a different bird. When these birds diversify into distinct populations on each island, their parasites also diversify.

"You have to be in the right spot at the right time to see this process happening," said Koop. "Our study empirically demonstrates an important evolutionary process in which the hawks separate into different populations, and the lice living on them do the same."

The findings reveal a little bit more about how parasites and their hosts co-evolve. This, in particular, has implications for biomedical scientists, and helps researchers who study parasites.

The findings are published in the journal Biology Letters.