Evolution takes time. Or does it?

Evolution can happen rapidly—it all depends upon how strong selection is and how much genetic variation there is in the trait being selected.  We tend to look at fossil bones, for example those along the horse lineage, and it seems like only a few millimeters of length are added per hundreds of thousands of years.  But in fact, these traits can vary quite a bit—even within populations—and if you have lots of individuals and lots of points in time, sometimes you can see really noticeable changes in short times.  The classic examples are Darwin’s Finches, that can significantly evolve larger or smaller bills during times of great stress.

That’s the Academy’s bird expert Jack Dumbacher. I asked him about a paper published this week in Current Biology about birds evolving shorter wings over a time-span of a mere thirty years. The evolutionary advantage? To avoid becoming roadkill.

In the US alone, an estimated 80 million birds are killed each year by cars. But the paper’s two authors, Nebraska researchers Charles and Mary Brown, noticed that fewer of the swallows they’ve studied for the past 30 years were becoming roadkill. This finding was surprising, since there are more cars on the road now than in the 1980s, and more of the swallows make their homes near the highways.

The researchers recently collected hundreds of dead cliff swallows from roadways, railroad tracks and other nesting areas, and noticed that “there were fewer road kills, and the birds found dead along highways had longer wing spans,” Charles Brown says. “I wanted to know if there was selection for particular characteristics in those dead birds.”

So he and his colleagues began a retrospective analysis, measuring the specimens in his 30-year collection. According to ScienceNOW:

The birds that were being killed, further analysis revealed, weren’t representative of the rest of the population. On average, they had longer wings. In 2012, for example, the average cliff swallow in the population had a 106-millimeter wingspan, whereas the average swallow killed on the road had a 112-millimeter wingspan.

The results suggested cliff swallows were undergoing morphological changes through natural selection.

Jack explains this adaptation. “Shorter wings—just like shorter cars – usually means a shorter turning radius. So if the birds need to make a rapid change in course, smaller wings might help facilitate this.”

The cliff swallows aren’t the first bird species to evolve quickly in response to human impacts. “One of my favorite examples is bird song in human habitats,” Jack says. “Our roads and neighborhoods are full of noises—air conditioners, traffic and other machines. Some of these produce noise in certain frequencies that can drown out or obscure bird song.  Researchers here and abroad have shown that many birds have noticeably shifted their song frequencies to avoid our ‘white noise’ and be better heard in human environments.”

Jack appreciates the work of the Browns in determining these shorter wingspans. “We often drive our commute and watch this or that, and sometimes we even ask ourselves whether, ‘Hmm, sure does seem like there are fewer roadkill than last year.’  Even a simple question like this can be incredibly difficult to even verify, but then to do all of the work to find the cause of the change—that can be very difficult to do.  They clearly have that restless scientific mind that doesn’t rest until they find a solid answer…”

I guess it takes one to know one.

Image: Ingrid Taylar/Wikipedia

Environmental Groups Need Reform

An independent review panel reported to the United Nations early this week that the Intergovernmental Panel on Climate Change (IPCC) should be fundamentally reformed. According to ScienceInsider, the review gave the IPCC

a solid B+ for its two decades of assessments of the global climate system. But the panel assembled by the InterAcademy Council, which is made up of science academies from around the world, says that there are plenty of areas in which IPCC could do better. Its 113-page report, issued today, calls for a new leadership structure with shorter terms, tighter review procedures, and better lines of communication.

The IPCC shared the Nobel Peace prize with Al Gore in 2007, but errors in a report that year, per the New York Times,

threatened to overshadow the United Nations’ message that climate change is a significant threat requiring urgent collective action.

Another organization formed to protect the environment, in this case marine fisheries, came under attack this week in the journal Nature. You’ll need a subscription to read the article, but the New York Times has a great summary of how the Marine Stewardship Council is “giving its stamp of approval to industrial fisheries that some scientists say are anything but environmentally sustainable.”

Evolutionary Teamwork

There were two recent stories in the news about creature self-sacrifice and evolution.

The first to break was about the idea of kin selection—wherein certain species have sterile members who take one for their relations, such as ants and bees whose workers do everything for the queen’s offspring and have none of their own. Last week scientists, including the venerable E.O. Wilson, disputed the idea of kin selection in the journal Nature. This week, two articles in the New York Times and Science News had scientists taking sides and putting on their boxing gloves over this. Controversies keep science fun and interesting!

“Charitable” might not be the first word that comes to mind when you think of E. coli bacteria, but the second story describes how charitable bacteria share with others to become resistant to antibacterial agents. Studying E. coli, scientists found that “just a few drug-resistant bacteria can release a protective substance that makes a whole population resilient to drugs.” [Science News]  The protective substance is a molecule called indole, which is known to help E. coli handle stress. And as Ed Yong reports in Discover, even though it takes the E. coli a lot of energy to produce indole,

Having multiplied from common ancestors, the bacteria in the group are all related to one another and carry virtually the same genes. In this light, making a small sacrifice for the sake of genetically identical others is a good move.

I wonder where that puts them in the kin selection argument?

Sour Babies

This one is purely for fun but does relate to a Science in Action video we produced a while ago describing how facial expressions are innate and not learned. Scientists studying babies’ faces found that babies make the same expressions whether they are tasting something sour, sweet, salty, or bitter for the first time. This video of babies tasting lemons and limes on YouTube will probably make you laugh—and perhaps give you some observational data to judge whether the babies’ reactions seem innate or learned.  Or it might inspire you to perform the innocent experiment on a baby you know…

What did you find fun in science news this week? Share with us!

Baby image by Chris Denbow