Wikimedia Commons // CC BY-SA 2.0
Wikimedia Commons // CC BY-SA 2.0

As Darwin's Finches Face Extinction, Study Offers New Hope of Saving Them

Wikimedia Commons // CC BY-SA 2.0
Wikimedia Commons // CC BY-SA 2.0

In the past few years, the Galapagos birds that helped inspire Darwin's theory of evolution by natural selection have hit hard times. A parasitic fly has brought their population numbers to dangerous new lows. This threat could wipe out Darwin's finches within 50 years. However, a new study suggests that certain preventative measures could help these rare birds gain back some ground in the islands.

Published today in the Journal of Applied Ecology, the collaborative study examined three viability models based on five years' worth of data on Geospiza fortis, or the medium ground finch, one of the islands' more common species. The goal was to determine the birds' longterm outlook for survival while plagued with parasitic Philornis downsi flies. Introduced to the islands by human visitors, the flies begin life as larvae hatched from eggs laid in the nests of Galapagos finches, and spend their first days eating away at the inside of baby finches' nasal cavities before migrating to the bottom of nests and emerging at night to feed on chicks' blood, Yale Environment 360 explains—a process that kills young finches or leaves them with deformed beaks, making it difficult for them to feed themselves.

University of Utah biology professor Dale Clayton, the study's senior author, noted in a press release that two of three viability models tested showed that the fly could potentially drive this and other finch species into extinction within the next several decades, but that the team's results were not "all doom and gloom." He explained, "Our mathematical model also shows that a modest reduction in the prevalence of the fly—through human intervention and management—would alleviate the extinction risk."

Voyage of the Beagle, 1845. Image credit: Wikimedia Commons // Public Domain

Methods of human intervention that could help save the approximately 14 to 18 species of Darwin's finch include removing chicks from nests for safer hand-rearing; releasing sterile male flies and fly-parasitizing wasps into the islands' ecosystems; and even getting finches to pitch in by self-fumigating their own nests. The latter idea comes from a 2014 study Clayton did in which researchers set out cotton balls treated with the mild insecticide Permethrin, hoping the finches would use the cotton in nest-building. They did. In the nests with Permethrin-treated cotton balls, half of the fly larvae died, reported. "We are trying to help birds help themselves," Clayton told the site.

Jennifer Koop, an assistant professor of biology at the University of Massachusetts Dartmouth and the study's first author, noted that a 40 percent reduction of flies in finch nests could extend the birds' predicted extinction date from being several decades away to perhaps a full century, during which time finch populations would have more time to adapt and recover. If that goal could be met, she said, researchers "predict they will no longer go extinct."

Koop also stressed the importance of keeping these rare and uniquely illustrative birds around. "Darwin's finches are one of the best examples we have of speciation," she said in a release. "They were important to Darwin because they helped him develop his theory of evolution by natural selection."

Andreas Trepte via Wikimedia Commons // CC BY-SA 2.5
Climate Change Has Forced Mussels to Toughen Up
Andreas Trepte via Wikimedia Commons // CC BY-SA 2.5
Andreas Trepte via Wikimedia Commons // CC BY-SA 2.5

Researchers writing in the journal Science Advances say blue mussels are rapidly evolving stronger shells to protect themselves against rising acid levels in sea water.

Bivalves like mussels, clams, and oysters aren’t good swimmers, and they don’t have teeth. Their hard shells are often the only things standing between themselves and a sea of dangers.

But even those shells have been threatened lately, as pollution and climate change push the ocean's carbon dioxide to dangerous levels. Too much carbon dioxide interferes with a bivalve’s ability to calcify (or harden) its shell, leaving it completely vulnerable.

A team of German scientists wondered what, if anything, the bivalves were doing to cope. They studied two populations of blue mussels (Mytilus edulis): one in the Baltic Sea, and another in the brackish waters of the North Sea.

The researchers collected water samples and monitored the mussel colonies for three years. They analyzed the chemical content of the water and the mussels’ life cycles—tracking their growth, survival, and death.

The red line across this mussel larva shows the limits of its shell growth. Image credit: Thomsen et al. Sci. Adv. 2017

Analysis of all that data showed that the two groups were living very different lives. The Baltic was rapidly acidifying—but rather than rolling over and dying, Baltic mussels were armoring up. Over several generations, their shells grew harder.

Their cousins living in the relatively stable waters of the North Sea enjoyed a cushier existence. Their shells stayed pretty much the same. That may be the case for now, the researchers say, but it definitely leaves them vulnerable to higher carbon dioxide levels in the future.

Inspiring as the Baltic mussels’ defiance might be, the researchers note that it’s not a short-term solution. Tougher shells didn’t increase the mussels’ survival rate in acidified waters—at least, not yet.

"Future experiments need to be performed over multiple generations," the authors write, "to obtain a detailed understanding of the rate of adaptation and the underlying mechanisms to predict whether adaptation will enable marine organisms to overcome the constraints of ocean acidification."

University of Adelaide
Scientists Find Potential Diabetes Drug in Platypus Venom
University of Adelaide
University of Adelaide

The future of diabetes medicine may be duck-billed and web-footed. Australian researchers have found a compound in platypus venom (yes, venom) that balances blood sugar. The team published their results in the journal Scientific Reports.

So, about that venom. The platypus (Ornithorhynchus anatinus) may look placid and, frankly, kind of goofy, but come mating season, the weaponry comes out. Male platypuses competing for female attention wrestle their opponents to the ground and kick-stab them with the venom-tipped, talon-like spurs on their back legs. It’s not a pretty sight. But it is an interesting one, especially to researchers.

Animal venoms are incredible compounds with remarkable properties—and many of them make excellent medicine. Many people with diabetes are already familiar with one of them; the drug exenatide was originally found in the spit of the venomous gila monster. Exenatide works by mimicking the behavior of an insulin-producing natural compound called Glucagon-like peptide 1 (GLP-1). The fact that the lizard has both venom and insulin-making genes is not a coincidence; many animal venoms, including the gila monster’s, induce low blood sugar in their prey in order to immobilize them.

It’s a good strategy with one flaw: GLP-1 and compounds like it break down and stop working very quickly, and people who have trouble making insulin really need their drug to keep working.

With this issue in mind, Australian researchers turned their attention to our duck-billed friends. They knew that platypuses, like people, made GLP-1 in their guts, and that platypuses, like gila monsters, make venom. The real question was how these two compounds interacted within a platypus’s body.

The researchers used chemical and genetic analysis to identify the chemical compounds in the guts and spurs of platypuses and in the guts of their cousins, the echidnas.

They found something entirely new: a tougher, more resilient GLP-1, one that breaks down differently—and more slowly—than the compounds in gila monster spit. The authors say this uber-compound is the result of a "tug of war" between GLP-1’s two uses in the gut and in venom.

"This is an amazing example of how millions of years of evolution can shape molecules and optimise their function," co-lead author Frank Gutzner of the University of Adelaide said in a statement.

"These findings have the potential to inform diabetes treatment, one of our greatest health challenges, although exactly how we can convert this finding into a treatment will need to be the subject of future research."


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