With their short wings relative to body size, hummingbirds are built for hovering. Their relatives, swifts, have super-long wings, built for gliding and high-speed flight. Their common ancestor, Eocypselus rowei, had wings sized between the two and they were built for… well, it’s hard to say.

“[Based on its wing shape] it probably wasn’t a hoverer like a hummingbird, and it probably wasn’t as efficient at fast flight as a swift,” says Daniel Ksepka of the National Evolutionary Synthesis Center.

Ksepka and his colleagues discovered a fossil of E. rowei in southwestern Wyoming at a fossil site known as the Green River Formation. The small bird—only twelve centimeters from head to tail—lived about 50 million years ago. Feathers account for more than half of the bird’s total wing length.

The researchers compared the specimen to extinct and modern day species. Their analyses suggest that the bird was an evolutionary precursor to the group that includes today’s swifts and hummingbirds. “This fossil bird represents the closest we’ve gotten to the point where swifts and hummingbirds went their separate ways,” says Ksepka.

Their study was published last week in the Proceedings of the Royal Society B.

The shape of the E. rowei’s wings, coupled with its tiny size, suggest that the ancestors of today’s swifts and hummingbirds got small before each group’s unique flight behavior came to be. “Hummingbirds came from small-bodied ancestors, but the ability to hover didn’t come to be until later,” Ksepka explains.

Closer study of the feathers under a scanning electron microscope revealed that carbon residues in the fossils—once thought to be traces of bacteria that fed on feathers—are fossilized melanosomes, tiny cell structures containing melanin pigments that give birds and other animals their color. The findings suggest that the ancient bird was probably black and may have had a glossy or iridescent sheen, like swifts living today. Based on its beak shape it probably ate insects, the researchers say.

Hummingbirds and swifts are two of many animals built for speed. Later this week, the Academy will open a new exhibit called Built for Speed, that will feature fast fishes and marine mammals. Learn more here.

Image: Mdf/Wikipedia

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

Researchers out of the University of Wisconsin Madison published an article in Nature this week with the possible answer, at least for fruit flies: the Wingless morphogen.

Wingless what?

In studying wing patterns of certain North American spotted fruit flies, the scientists discovered a morphogen (a substance that determines the development of cells and the position of those cells within a tissue) encoded with the Wingless gene (a specific gene that affects wing and limb development during the embryonic and metamorphosis stages).

Late in wing development, the Wingless morphogen diffuses through tissue where it prompts cells in certain areas of the wing to make pigment. “It acts by triggering responding cells to do things, in this case make color,” explains Sean Carroll, the senior author of the report.

“The Wingless molecule is deployed in this species at specific points in time and in specific places — the places where the spots are going to be.”

So the team began experimenting. Three years and thousands of fruit fly embryos later, they found that by inserting the Wingless gene into different parts of the fly’s genome, they were able to successfully manipulate the decoration of the fly’s wing, creating stripes instead of spots, and patterns not seen in nature. “We can make custom flies,” notes Carroll. By manipulating the gene, “we can make striped flies out of spotted flies.”

Although the study was conducted in teeny fruit flies, the principles uncovered by Carroll’s group, he argues, very likely apply to many animals, everything from butterflies to boa constrictors. “This is animal color patterning, how they are generated, how they evolved.”

Creative Commons image by photoholic1