Nav: Home

One species to four: New analysis documents new bird diversity in the Pacific

March 06, 2020

In the 1930s, famed biologist Ernst Mayr became the first to study Pacific Robins. Based on his observations of the robins and other birds on Australia and its outlying islands, he developed foundational concepts that continue to inform the study of evolution. He took copious notes on the birds' physical characteristics, behaviors, and habitats. Always, he described the robin populations as a single species, albeit with significant variation from island to island.

Ernst Mayr made lasting contributions to evolutionary biology--but like most scientists, he wasn't right about everything.

Bold new claims

Anna Kearns is a former UMBC postdoctoral fellow now at the Smithsonian Institution's Conservation Biology Institute. With her UMBC postdoc advisor Kevin Omland and other colleagues, she has conducted new investigations into the relationships among Pacific Robins on various islands using many of the same bird specimens Mayr himself used. The difference is, "He would have mainly been just using his eyes" to compare specimens, Kearns says. She and her colleagues have had the advantage of major advances in technology since Mayr's time.

Kearns has built on Mayr's work by using techniques like DNA sequencing and spectrophotometry, which quantitatively compares the hue, brightness, and saturation of feathers. She has come to a more nuanced understanding of the relationships between, say, a robin on Fiji and one on the Solomon Islands.

As a result of this research, Kearns and colleagues from UMBC, the Australian National Wildlife Collection, Australian Centre for Ancient DNA, and the Smithsonian National Museum of Natural History are making bold new claims about the relationships between these birds. In a 2015 paper in Conservation Genetics, Kearns demonstrated that robins living on Norfolk Island, directly east of mainland Australia, are a distinct species from the rest. A new paper in the Journal of Avian Biology published this month indicates two more unique species--one that inhabits the Solomon and Bougainville Islands, and another that lives on Fiji, Vanuatu, and Samoa.

Preserving biodiversity

The new work demonstrates just how much is still unknown about avian biodiversity. "Even in this well-studied group of birds, that's been a textbook example since 1942, we did not really know what the units of biodiversity were," says Omland, professor of biological sciences at UMBC, and senior author on the new paper.

Understanding those "units of biodiversity" is critical for conservation. When all the Pacific Robins and mainland Australia's Scarlet Robin were considered a single species (a single unit of biodiversity), the loss of the birds on one or two islands would be unfortunate, but not necessarily very impactful. If those birds were actually the only remaining members of a unique species, however, the same loss becomes catastrophic.

"What Anna's work is showing is that the bird populations on these islands have very distinctive traits," Omland adds, "so just knowing what the biodiversity is that we want to conserve is super important."

Unpredictable patterns

The team's work indicates that all the Pacific Robins are descended from an ancestral Australian population where males were brightly-colored and females were dull-colored. But as small groups of robins colonized the outlying islands, the population on each island took its own evolutionary path. Today, some island groups still maintain the bright male and dull female pattern, but on other islands both sexes have evolved bright coloration. On other islands, both sexes have evolved dull coloration.

"When you look at the genetics, you find two distinct lineages" leading from the common ancestor to all the island populations that exist today, Kearns says. "So that means these patterns have evolved independently multiple times."

Kearns and Omland think the changes have more to do with random forces than evolutionary adaptation. "If we flipped two coins, this is about what we'd expect," Omland says.

For example, the pattern an island's population ended up with could depend on the color of the individuals that happened to get blown onto that island initially. Also, in a very small population, the random way genes are redistributed from generation to generation can have a significant impact--as much of an effect or more than natural selection.

Detective work

Kearns and Omland are both excited to have the opportunity to suggest names for the new species they've identified. Kearns suggests "Mayr's Robin" for the Fiji/Vanuatu/Samoa population, in honor of Ernst Mayr's pioneering study of these birds.

But their contribution to ornithology is more than a name. "Because these birds are all on very small isolated islands, and Pacific birds are often on many, many, many isolated islands, collecting is very difficult. So there haven't actually been that many comprehensive studies," Kearns says. Revealing the complexity of the relationships among these robins adds much-needed information to the field. It also raises the prospect that other birds--especially those on islands--might have undergone similar, as-yet-unstudied, evolutionary processes.

The work is a unique blend of past and present. "You really wouldn't be able to do this study without using these old collections," Kearns says. At the same time, discovering the new species also wouldn't have been possible without modern techniques. "It's kind of like detective work in a way," Kearns says. "I feel like there's just so much more we need to know about it. But we feel like we have made a big step forward."

University of Maryland Baltimore County

Related Biodiversity Articles:

Using the past to maintain future biodiversity
New research shows that safeguarding species and ecosystems and the benefits they provide for society against future climatic change requires effective solutions which can only be formulated from reliable forecasts.
Changes in farming urgent to rescue biodiversity
Humans depend on farming for their survival but this activity takes up more than one-third of the world's landmass and endangers 62% of all threatened species.
Predicting the biodiversity of rivers
Biodiversity and thus the state of river ecosystems can now be predicted by combining environmental DNA with hydrological methods, researchers from the University of Zurich and Eawag have found.
About the distribution of biodiversity on our planet
Large open-water fish predators such as tunas or sharks hunt for prey more intensively in the temperate zone than near the equator.
Bargain-hunting for biodiversity
The best bargains for conserving some of the world's most vulnerable salamanders and other vertebrate species can be found in Central Texas and the Appalachians, according to new conservation tools developed at the National Institute for Mathematical and Biological Synthesis (NIMBioS) at the University of Tennessee, Knoxville.
Researchers solve old biodiversity mystery
The underlying cause for why some regions are home to an extremely large number of animal species may be found in the evolutionary adaptations of species, and how they limit their dispersion to specific natural habitats.
Biodiversity offsetting is contentious -- here's an alternative
A new approach to compensate for the impact of development may be an effective alternative to biodiversity offsetting -- and help nations achieve international biodiversity targets.
Biodiversity yields financial returns
Farmers could increase their revenues by increasing biodiversity on their land.
Biodiversity and wind energy
The location and operation of wind energy plants are often in direct conflict with the legal protection of endangered species.
Mapping global biodiversity change
A new study, published in Science, which focuses on mapping biodiversity change in marine and land ecosystems shows that loss of biodiversity is most prevalent in the tropic, with changes in marine ecosystems outpacing those on land.
More Biodiversity News and Biodiversity Current Events

Trending Science News

Current Coronavirus (COVID-19) News

Top Science Podcasts

We have hand picked the top science podcasts of 2020.
Now Playing: TED Radio Hour

Debbie Millman: Designing Our Lives
From prehistoric cave art to today's social media feeds, to design is to be human. This hour, designer Debbie Millman guides us through a world made and remade–and helps us design our own paths.
Now Playing: Science for the People

#574 State of the Heart
This week we focus on heart disease, heart failure, what blood pressure is and why it's bad when it's high. Host Rachelle Saunders talks with physician, clinical researcher, and writer Haider Warraich about his book "State of the Heart: Exploring the History, Science, and Future of Cardiac Disease" and the ails of our hearts.
Now Playing: Radiolab

Insomnia Line
Coronasomnia is a not-so-surprising side-effect of the global pandemic. More and more of us are having trouble falling asleep. We wanted to find a way to get inside that nighttime world, to see why people are awake and what they are thinking about. So what'd Radiolab decide to do?  Open up the phone lines and talk to you. We created an insomnia hotline and on this week's experimental episode, we stayed up all night, taking hundreds of calls, spilling secrets, and at long last, watching the sunrise peek through.   This episode was produced by Lulu Miller with Rachael Cusick, Tracie Hunte, Tobin Low, Sarah Qari, Molly Webster, Pat Walters, Shima Oliaee, and Jonny Moens. Want more Radiolab in your life? Sign up for our newsletter! We share our latest favorites: articles, tv shows, funny Youtube videos, chocolate chip cookie recipes, and more. Support Radiolab by becoming a member today at Radiolab.org/donate.