Tag: evolution

Attack of the Babysitters: Ant Slaves Strike Back

By Ashley P. Taylor | October 1, 2012 11:35 am

ant

Here’s the latest lesson from the ant world: kidnapped babysitters may not be the most reliable. Evolutionary myrmecologist Susanne Foitzik studies a species of ants that, instead of using its own workers to raise its young, kidnaps larvae from another species and puts them to work as babysitters. But, she’s found, the free labor has a price.

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Bad News for Roosters: If You Aren't King of the Henhouse, Your Ejaculate Will Be Ejected

By Veronique Greenwood | August 26, 2011 12:23 pm

rooster
WHAT? Noooooooo!

If you haven’t heard about the corkscrew kookiness that is duck genitalia by now, you need to check that stuff out ASAP.

Ducks’ twisting vaginas and telescoping penises are well-known part of an evolutionary arms race between the sexes that’s been going on for millennia, with each side trying to exert control over which males’ sperm fertilize the female’s eggs—a battle that, especially in birds, is fierce, occasionally violent, and weird as all-get-out. The most recently discovered example of what biologists deem “sexual conflict,” a little behavior hens have developed called sperm ejection, upholds that fine tradition.

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The Better to Ignore You With: Female Frogs Deaf to Males' Ultrasonic Calls

By Joseph Castro | June 17, 2011 3:06 pm

The concave-eared torrent frog.

Wouldn’t it be nice if we could hear each other over the low-frequency roar of jetliners and subway trains? For some rodents, bats, and marine mammals, environmental noise doesn’t normally pose a problem, as they can communicate at ultrasonic frequencies (greater than 20 kHz, just above our maximum hearing range). There are also a couple of amphibians that exhibit this trait, but in an odd twist, researchers have now learned that female concave-eared torrent frogs are deaf to the ultrasonic components of the males’ calls.

The concave-eared frog is a tree-loving native of the Huangshan Mountains in China. In choosing this woodsy area, the nocturnal amphibians must put up with one minor annoyance: streams that produce constant ambient noise. In 2006, Jun-Xian Shen, a biophysicist at the Chinese Academy of Science in Beijing, and his research team discovered that the frogs get around this sonic clutter by adding ultrasonic frequencies to their normal calls (pdf). The frogs were the first non-mammalian vertebrate found to do this, and scientists have since learned that Borneo’s hole-in-the-head frogs (yes, that’s the actual name) also chirp in ultrasonic frequencies. After finding these ultrasonic noises, researchers wanted to know what they were saying with these super-high-pitched croaks.

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How Global Warming Caused the Attack of the Giant Ants

By Patrick Morgan | May 4, 2011 2:32 pm

It sounds like the opening plot to a made-for-TV horror flick: Global warming renders an Arctic land bridge habitable, spurring a race of  “monstrously big ants” to blaze a trail between Europe and America. This particular horror story actually played out 50 million years ago, and the monstrously big ants were only about 2 inches long, about the size of the smallest known hummingbird. Archeologists recently unearthed the fossilized remains of this new giant ant species—one of the largest ant species ever seen—in Wyoming, making it the first complete giant ant fossil found in America. And because similar giant ants have been found in Europe, they think this is the first reported example of a tropical insect traipsing across the Arctic.

It all started when paleoentomologist Bruce Archibald spied a fossil that was sitting in a drawer at the Denver Museum of Nature and Science. “I immediately recognized it and said, ‘Oh my god, this is a giant ant and it looks like it’s related to giant ants that are known from about this time in Germany,’” as he told Live Science. The fossil they found was a queen ant, so we still don’t know how large the average worker was. Because of its whopping 2-inch length, he included the word “titan” into the new species, dubbing it Titanomyrma lubei.

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Can Your Dog Cut a Rug? The DISCOVER Dancing Pet Challenge

By Veronique Greenwood | April 14, 2011 3:21 pm

Snowball the dancing, Backstreet Boys-loving cockatoo is more than a web meme: he is a scientific conundrum. Bobbing in time to music is a shockingly rare behavior, and even monkeys, capable of learning very complex tasks, find it impossible to get down to the beat even after more than a year of training. It’s marvelous evolutionary serendipity that humans dance, thinks neurobiologist Aniruddh Patel, who has found that our hearing system and motor control are intimately linked. In DISCOVER’s 2011 special issue on the brain, Patel discusses his idea that that animals needed a vocal-learning brain in order to get their groove on:

The implication is that dogs and cats can never do it, horses and chimps can never do it, but maybe other vocal-learning species can do it. I proposed that idea, but it was purely hypothetical until a few years after, when along came Snowball [in 2007].

But more importantly (drumroll), he issues a challenge:

If your pet really does have rhythm, he wants to know about it. “If someone has a dog that can dance to the beat, it will totally refute my hypothesis,” he says, “and that’s progress in science.”

If you think your pet proves Patel wrong, collect some video evidence, upload it to YouTube, and e-mail the link to webmaster@discovermagazine.com. We will post the best videos on May 1 (along with footage of Snowball shaking his groove thang).

What the Duck? Lady Mallards May Get Down With Bright-Billed Drakes to Avoid STDs

By Patrick Morgan | April 13, 2011 3:57 pm

When it comes to mallard bills, brighter is better: A bright yellow bill is duck-speak for “I’m healthy,” attracting more female ducks than dingy green ones. After discovering that avian semen has antibacterial properties, scientists then found that the semen of brighter-billed males killed more bacteria than the semen of darker-billed ones. It implies that by seeking out bright-billed males, female ducks are protecting themselves against bacteria-related sexually transmitted diseases.

In her experiment, University of Oslo researcher Melissah Rowe collected semen from ducks (a feat unto itself—the videos in this link are amazing, but watch at your own risk) of various bill colors, and then tested how well the semen killed bacteria such as E. coli. She found that ducks whose bills had more carotenoids—an organic pigment that brightens bills—also had semen that more effectively killed E. coli. However, they discovered that the semen’s effectiveness against the bacteria S. aureus wasn’t associated with bill color, possibly implying that this bacteria doesn’t pose much harm to ducks.

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For Fruit Flies, There's Such a Thing as "Too Sexy"

By Patrick Morgan | February 15, 2011 4:02 pm

Beauty doesn’t only fade within a lifetime–it also fades genetically over the course of several generations, according to new research. Scientists studying populations of sexually attractive male fruit flies have found that there’s a limit to their evolutionary success–and that there may actually be a disadvantage to being too sexy.

For the study, published in the Proceedings of the National Academy of Sciences, researchers genetically modified male fruit flies, causing them to give off excessive amounts of attractive pheromones. The scientists then introduced a flock of these foxy fellows to a normal fruit fly population. They discovered that the female flies mated with these modified flies more often initially, and the proportion of super-sexy males increased for a while–but the proportions returned to normal after seven generations.

As The New York Times reports:

“Even though we were able to make males more attractive, there must have been a fitness cost,” said Katrina McGuigan, a biologist at the University of Queensland and one of the study’s authors. “While sexual selection is really powerful, there are consequences to nonsexual traits.”

It’s not yet clear what genetic disadvantage these fruit fly ladykillers may have had. But let’s turn to the more urgent question: Is there any carryover implications for humans? The New York Times quotes McGuigan:

“Hard to say, but only that very attractive individuals may well have something wrong with them — they may not be as good as they seem to be at first glance.”

Related Content:
Discoblog: Do Women Prefer a Scarred Face? Yes, But Not for Long.
80beats: How Gut Bacteria Rule the Sex Lives of Fruit Flies
80beats: A Gory Aphrodisiac: Spiders Feast on Blood to Get Their Sexy On
DISCOVER: Raw Data: Do Beautiful Parents Have More Daughters?

Image: Wikimedia Commons / A. O’Toole

Devious Mating 101: The Lesson of the Fairy Wren and the Butcherbird

By Patrick Morgan | January 28, 2011 1:11 pm

You’d think birds would hush up at the sound of a predator, especially if that predator’s name is the “butcherbird.” But that’s not the style of the male splendid fairy-wren, and it turns out he has a good reason for raising a ruckus when the butcherbird calls: it helps him get a mate.

Researchers studied this wren-butcherbird interaction in Southern Australia by playing iPod bird songs for wild wrens to hear. As the press release reports, the researchers determined the the males were engaging in a form of “vocal hitchhiking”:

“We have shown that females do, in fact, become especially attentive after hearing butcherbird calls,” said Emma Greig, PhD, first author of the study and currently a postdoctoral researcher at Cornell University. “So, it seems that male fairy-wrens may be singing when they know they will have an attentive audience, and, based on the response of females, this strategy may actually work!”

But how do you tell if a bird is paying attention? The scientists calculated attention by whether the female wren looked towards the call and responded with her own song. Female wrens responded overwhelmingly when the researchers played the male wren’s distinctive “Type II” call immediately following the cry of a butcherbird. From the press release:

“The most exciting possibility is that Type II songs have a sexual function, and that females are more easily stimulated by, or receptive to, displays after being alerted by a predator, such that the male’s song is especially attractive,” Greig said.

Their study, published in the journal Behavioral Ecology, should spur research into other bird species–like the white-throated magpie jay and the fairy gerygone–whose males display a similar post-predator call. And birds may not be the only ones who use fear as an aphrodisiac–anyone headed to a horror movie for Friday date night?

Related Content:
80beats: How Male Antelopes Lie to Get More Sex: With False Alarm Calls
Not Exactly Rocket Science:The Bird That Cries Hawk: Fork-Tailed Drongos Rob Meerkats With False Alarms
DISCOVER: The Best Ways To Sell Sex
DISCOVER: The Mating Game’s Biggest Cheaters (photo gallery)

Image: flickr / dicktay2000


The Platypus Can Poison You 80 Different Ways

By Jennifer Welsh | October 13, 2010 4:50 pm

platypusThe platypus is a bit like a fruitcake. Shove a bunch of leftover genes in there, mix it up and send it to your relatives see what kind of animal you get.

That’s kind of the approach evolution used when designing this odd creature’s venom; scientists have just determined that the venom contains over 80 different toxins in 13 different classes. The poison can kill small animals, and can leave humans in pain for weeks. The venom is delivered through a barb on the male’s foot–it’s thought that the fellas use the poison during mating season to show dominance.

At least three of the toxins are unique to the platypus and the rest are strikingly similar to proteins from a variety of animals including snakes, lizards, starfish, and sea anemones. It seems that some of these toxins have evolved separately in different animal lineages to perform the same function, a process called convergent evolution. The study‘s lead author, Wesley Warren, told Nature News:

Warren says that this probably happens when genes that perform normal chores, such as blood coagulation, become duplicated independently in different lineages, where they evolve the capacity to carry out other jobs. Animals end up using the same genes as building blocks for venom because only a subset of the proteins the genes encode have the structural and functional properties to become venoms, he adds.

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The Fruit That Hit Newton's Head Is Down With the Fruit of Darwin's Head

By Jennifer Welsh | September 22, 2010 2:23 pm

CircularTimetreelargeApple may not allow porn on its product line, but it has no problem with another source of controversy: evolution. A new, free iPad/iPhone application called Timetree, distributed by Arizona and Penn State Universities, allows users to map how long ago two living creatures separated on the tree of life, a subject that can get a bit sticky with creationists, says The Register:

Now, Apple has taken a stance which will upset a lot of Americans: it has allowed an app which specifies quite clearly that evolution is real and that humans and monkeys share a common ancestor some 30 million years in the past.

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