Say what you will about the parasitic lifestyle, but in the evolution of life on Earth, it is a winner.
Offered that about half of all identified species are parasites, biologists have extended hypothesized that the approach of leeching off other organisms is a major driver of biodiversity. Studying populations of Galápagos hawks (Buteo galapagoensis) and feather lice that reside in their plumage (Degeeriella regalis), a group led by University of Arizona ecologists and evolutionary biologists has gathered some of the initial field evidence suggesting that a phenomenon named co-divergence in between parasites and hosts is indeed an vital mechanism driving the evolution of biodiversity.
"The idea is really easy," said the study's lead author, Jennifer Koop, who is a postdoctoral fellow in the lab of Noah Whiteman in the UA's Department of Ecology and Evolutionary Biology. "Every time a host population splits into separate populations that potentially turn into distinct species, we predict that their parasites could do the exact same factor."
On the other hand, biologists have lengthy struggled to test this hypothesis, as parasites are elusive.
"Usually, the evolutionary trees of parasites and their hosts are congruent – they appear like mirror photos of a single an additional," said Whiteman, who is an assistant professor in EEB, a joint assistant professor in the Department of Entomology and the College of Plant Sciences, and a member of the UA's BIO5 Institute. "But for the reason that parasites tend to be inside or attached to hosts, their distributions are tricky to study."
"We identified the lice are passed on from mother to babies for the duration of brooding, nearly like genes," Whiteman stated. "They're evolutionary heirlooms, like your family's silverware or engagement ring diamond."
Because the hawks pass on the feather lice from generation to generation, the researchers wanted to know no matter whether the louse populations diverge between populations of hawks and involving person hawks, or no matter if the populations of the birds and the lice diverged independently of every other.Enlarge Noah Whiteman is shown processing lice for DNA analysis. Credit: Jenny Bollmer
Remarkably, the findings, which are published in the journal Biology Letters of the Royal Society, revealed that the population structure of the lice matched that of the birds across the archipelago, even although the two are pretty distinct species.
"To the lice, each and every bird is an island, and their populations are really unique from bird to bird," Whiteman stated. "The very same pattern is repeated among bird populations on distinctive islands. It is like Russian dolls."
In other words, the lice living on any 1 bird and its offspring are additional closely connected than the lice living on a unique bird. As the birds diversify into distinct populations on each island, their parasites diversify with them. The findings support clarify the speedy price of parasite evolution, according to the research group.
"You have to be in the appropriate spot at the proper time to see this approach taking place," Koop mentioned. "Our study empirically demonstrates an critical evolutionary approach in which the hawks separate into unique populations, and the lice living on them do the exact same."
This course of action is hypothesized to lead to the formation of distinctive species, in this case different species of hawks and lice, and could explain some of the extraordinary diversity observed amongst parasites, she said.
The group chose the Galápagos Islands, situated 575 miles off the west coast of Ecuador, for the study for the reason that the species that colonized the geologically young group of islands have evolved in isolation, creating the location an ideal organic laboratory.
"Of all the vertebrate species native to the Galápagos, the Galápagos hawk is the most current arrival," Whiteman stated. "So what ever is taking place in terms of evolution of the bird population and the parasite population is most most likely in the earliest stages of that method."Enlarge Noah Whiteman is shown with a Galápagos hawk. Credit: Jenny Bollmer
In four years of fieldwork on eight main islands, the group caught hundreds of Galápagos hawks – which later were released unharmed – and collected blood samples and feather lice for genomic evaluation, in a partnership with the Galápagos National Park. Whiteman stated the hawks' lice are specialized on their host species and the feathers they consume, and unable to survive on any other species.
Co-authors Karen DeMatteo and Patricia Parker, each at the Department of Biology at the University of Missouri-St. Louis, then utilised the DNA from the samples to create a genetic fingerprint of each population. Parker helped with the fieldwork.
A far better understanding of how parasites and their hosts coevolve has implications for biomedical sciences, according to Whiteman. In addition, it can enable researchers who study parasites as evolutionary tags of the host species.
"The fact that we had been able to operate with these birds, which are the major predators in their habitat, and reveal some answers to fundamental inquiries in biology shows why such locations need to continue to be preserved," Whiteman stated.
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