Category: Evolution

Conservation Success To Boy’s Club: The Hawaii Creeper In Danger Of Extinction

The beautifully diverse honeycreepers. Cover art for Current Biology, volume 21, issue 22

Though most people focus on Darwin’s famous birds, I would argue that the Hawaiian honeycreepers are the most dazzling example of adaptive radiation, especially by a finch. From a single finch ancestor arose a stunning diversity of honeycreepers, from the brilliant red I’iwi with its long, curved bill to the small, rotund ʻAkikiki. Over 50 species of these colorful forest birds once brightened the islands from Hawaii to Laysan, putting the 14 Galapagos finches to shame. Their tale is not just one of rapid evolution, though; it’s one of a brief and fleeting existence on this planet. All but eighteen are extinct, and of those that remain, ten are endangered or critically endangered and five are listed as vulnerable, leaving only three species that seem to be holding their own against the every-growing list of threats to their survival. Continue reading “Conservation Success To Boy’s Club: The Hawaii Creeper In Danger Of Extinction”

Here Be Dragons: The Mythic Bite of the Komodo

Here Be Dragons: first written on the Hunt-Lenox Globe c. 1510 as the latin phrase HC SVNT DRACONES.

To a mediaeval mapmaker, the world was a vast and scary place. Explorers that braved the seemingly endless oceans in search of new worlds often didn’t return, and those that did carried with them nightmarish tales of monsters and serpents. It was the mapmaker’s task to warn future travelers of the dangers that awaited them in far-off lands. Based on their drawings, I cannot even begin to imagine the beasts that haunted these cartographer’s dreams. Their creative expressions of fear were eventually distilled into a single, ominous phrase: here be dragons.

Lands that still deserve this cartographer’s omen, however, can be counted on one hand. They are the Indonesian islands of Rinca, Gili Motang, Flores, and Komodo — the only places in the world where dragons still roam. Continue reading “Here Be Dragons: The Mythic Bite of the Komodo”

Why did the chicken cross the road? Maybe it was looking for its penis.

Warning: the following may be considered NSFW, particularly if your employer finds avian genitalia inappropriate. 

Thanks to the detailed research of Patricia Brennan and the fluent coverage of it by Ed Yong and Carl Zimmer, a lot of people have not only heard of the impressive duck penis, they’ve seen it in all its explosive glory (if you don’t know what I’m talking about, take a moment to click on the links above — trust me, it’s worth it).

Why do chickens and other birds lack the fancy phalluses of their relatives? Good question. At least, now, we know how…
Image from Herrera et al., Fig 1.

But while ducks and their fellow water fowl boast these impressive, large penises, the penes of most birds are nothing to squawk about. Ninety-seven percent — over 10,000 species of birds — have either reduced or non-existant penises that are incapable of penetration. “One of the most puzzling events in evolution is the reduction and loss of the phallus in birds,” explains biologist Marty Cohn in a Cell Press Video Abstract. “It’s remarkable that a group of animals would eliminate a structure that is so important for reproduction.” Given that, like us, birds conceive through internal fertilization, you would think a penis would be essential. How else is the male’s sperm supposed to get all up in the female’s vagina?

While scientists still debate about why the chicken lost most of its penis, a new study published this week in Current Biology finally explains how it was lost, a crucial first step in unraveling this evolutionary enigma. Continue reading “Why did the chicken cross the road? Maybe it was looking for its penis.”

Dolphin-Assisted Birth—Possibly The Worst Idea, Ever.

I consider myself to be a fairly grounded person, so I’m rarely shocked by anything I see on the internet. But then, this tweet by Emily Anthes appeared in my stream:

O_o.

The couple planning to do this are entirely serious—and they won’t be the first to travel to Hawaii for a dolphin-assisted birth. My professional opinion: this has to be, hands down, one of the worst natural birthing ideas anyone has ever had (and that is saying a lot). Continue reading “Dolphin-Assisted Birth—Possibly The Worst Idea, Ever.”

“You’ll Do”: Lack of Choosiness in Female Strawberry Poison Dart Frogs

The “blue jeans” color morph of the strawberry poison dart frog, Oophaga pumilio, from Costa Rica.
Image from Wikimedia Commons user Pstevendactylus

Mate choice is one of the most well-studied aspects of evolution. To prove that they’re worth the effort, animals will do just about anything. They dance, prance, sing, bellow, and fight for attention. When you look around the animal kingdom, the wild results of mate choice boldly stand out, from the impractically beautiful tails of peacocks to the ostentatious antlers of elk and deer. With so much focus placed on quality, you might assume that every species has their own complex way of conveying their worth, and that all of the females of the world are finicky creatures.

But not so for the female strawberry poison dart frog — when she’s ready to mate, she doesn’t pick the strongest or the brightest guy around. She just goes for the closest. Continue reading ““You’ll Do”: Lack of Choosiness in Female Strawberry Poison Dart Frogs”

Eau de Manipulation: Malarial Mosquitoes More Attracted To Human Scent

An Anopheles gambiae mosquito gorging herself on blood. Photo by Jim Gathany, from the CDC’s Public Health Image Library

By the time you realize what has happened, it’s too late. An Anopheles gambiae mosquito can land on your skin completely unnoticed. While you continue unaware, she stealthily walks over your exposed flesh, searching, probing the surface of your skin with her proboscis until she finds a blood vessel. She then situates her body perfectly at just the right angle, hunches down, and plunges her needle-like mouthparts into your skin. Tiny pumps pull the warm, protein-rich blood into her mouth.

With every millisecond increasing her chances of exposure, she drinks as quickly as she can. Your hand isn’t the only obstacle she faces: even as she sucks, your body senses the wound and attempts to plug the hole by forming a clot. She needs your warm, nutritious blood for her eggs, so she’s not about to let your protective mechanisms interfere. To ensure her meal keeps flowing, she pumps saliva laden with anti-coagulants and vasodilators  into the wound — and that’s when it happens. That’s when the Plasmodium falciprum sporozoites that have been waiting patiently in her salivary glands enter your bloodstream. Dozens can hitch a ride in her saliva, but it only takes one to cause malaria. One single, microscopic protozoan is enough to kill you. Continue reading “Eau de Manipulation: Malarial Mosquitoes More Attracted To Human Scent”

Am I Sexy Now? Vocal Cues To Body Size Sound Attractive

What does your voice say about you?

Our voices communicate information far beyond what we say with our words. Like most animals, the sounds we produce have the potential to convey how healthy we are, what mood we’re in, even our general size. Some of these traits are important cues for potential mates, so much so that the sound of your voice can actually affect how good looking you appear to others. Which, really, brings up one darn good question: what makes a voice sound sexy?

Continue reading “Am I Sexy Now? Vocal Cues To Body Size Sound Attractive”

Cheater Cheater Mucus Eater: Simple Mechanisms Drive Cleaner Wrasses To Cooperate

Labroides dimidiatus feeding off a plexiglas plate in the lab at the Lizard Island Research Station. Photo courtesy of Simon Gingins

On the surface, cleaner wrasses seem like real nice fish. They set up their little cleaning stations on patches of reef, offering to eat any external parasites that other fish might have picked up. It’s a pretty sweet deal for both sides — the cleaners get a tasty meal, while the other fish get rid of pests. But not all of these do-gooders deserve their squeaky clean reputation. Every once in a while, a cleaner wrasse will take advantage of the situation and take a bite out of the tasty mucus coating of its client instead of eating parasites like it’s supposed to. This cheating behavior has fascinated scientists, who want to uncover what drives the cleaners to cheat, and what keeps them in line.

“They are a very good system to study cooperation between unrelated individuals,” explains Simon Gingins, who is studying the cooperation between cleaners and their clients for his PhD. Cleaner fish are dependent on their clients to eat, as they’re not fast enough to take bites out of fish that don’t sit and wait. “Their cooperative behavior is central to their life: most of what they do everyday is to interact with other fish species to obtain their food.”

Continue reading “Cheater Cheater Mucus Eater: Simple Mechanisms Drive Cleaner Wrasses To Cooperate”

Pretty great tits make better mothers

The white cheeks & black chest bar of a great tit
[photo (c) David Jirovsky, provided by BioMed Central]

As anyone in Europe knows, pairs of great tits aren’t hard to find. They’re really everywhere, if you keep an eye out for them — great tits can be found from the northern coast of Africa all the way to western central Russia, and in between. Bouncing around without a care in the world, great tits are one of the most popular and well known birds in the world. Yes, I’m talking about the birds, guys. The pretty, charismatic, if not slightly murderous birds.

Great tits have become a wonderful research model for scientists, as their widespread distribution and general lack of fear of people makes them easy study subjects. There are literally thousands of published papers looking at their ecology, behavior, genetics, and evolution. But while scientists have been studying these colorful, engaging birds for about a century, there’s still a lot to discover. Just last month, scientists from Palacky University in the Czech Republic learned something new, and incredible, about female tits: the prettier the mother, the healthier the offspring. Continue reading “Pretty great tits make better mothers”

High-Speed Evolution: Cars Driving Change In Cliff Swallows

Cliff swallows in their nest

I imagine that adjusting to life around humans, with all our buildings and fast-moving transport mechanisms, is tough for a bird. It’s estimated that some 80 million birds are killed in motor vehicle collisions every year, and with an ever-growing population of people driving around and paving roads in more remote areas, things must be getting harder and harder for the animals we share our world with. But, the American Cliff Swallow (Petrochelidon pyrrhonota) isn’t one to let people ruin the neighborhood. More and more, their huge nesting populations can be found in man-made structures like bridges and overpasses, and have even become cultural fixtures in areas like California. Their new nesting sites allow them to survive even as their former habitat disappears, but it comes at a cost: by living near roadways, the birds are more at risk than ever of being on the wrong end of an oncoming vehicle.

Continue reading “High-Speed Evolution: Cars Driving Change In Cliff Swallows”