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6 Animals That Are Rapidly Evolving

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We sometimes think of evolution as a thing of the past, but it continues today, especially as environmental pressures force humans and animals to adapt to survive. Here, a few examples of animals evolving in real-time.

1. The lizard with extra sticky feet

The native green lizards that occupy the lower branches and trunks of Florida’s trees got a rude awakening when their invasive cousins, the brown lizards, moved in. Faced with limited resources and double the competition, the green lizards made a move: they abandoned the lower branches for the treetops. Up there, the limbs are thinner and smoother, so the green lizards’ bodies had to adapt to the environmental shift. To better cling to the smooth branches, their toepads grew bigger and their scales got stickier—in just 15 years and about 20 generations. “The degree and quickness with which they evolved was surprising," said Yoel Stuart, a postdoctoral researcher in the College of Natural Sciences at The University of Texas at Austin and lead author of the study. "If human height were evolving as fast as these lizards' toes, the height of an average American man would increase from about 5 foot 9 inches today to about 6 foot 4 inches within 20 generations." 

2. The shrimp that lost its eyes

In the process of evolutionary change, you either use it or you lose it—and this is certainly true for a group of cave-dwelling crustaceans. These crabs and shrimp live underground where there is no light, and the sense of sight doesn’t do much good. As a result, they’ve gone blind, relying on smell and touch to navigate the cavernous depths. When researchers compared the brains of these spelunkers to their land-dwelling relatives, they found that not only are these creatures sightless, they’re actually losing the parts of their brains associated with vision. Meanwhile, the areas that control touch and smell are getting bigger. "It's a nice example of life conditions changing the neuroanatomy," the study’s lead author, Dr. Martin Stegner, from the University of Rostock in Germany, told the BBC. It’s taken about 200 million years for the brain changes to occur, which may not seem “rapid,” but as the Washington Post’s Rachel Feltman says, it’s “a relatively short time, in the evolutionary scheme of things.”

3. The owls that are changing color

Climate change is forcing many animals to adapt to survive. The tawny owl in Finland is a good example. These creatures come in two colors, brown or pale grey. The cold white winters have traditionally favored the grey owls, which can hide from predators by blending into a snowy color scheme. But as the winters have become more mild over the last 50 years, researchers noticed a shift: grey owls are on the decline and the brown birds are thriving, better suited to blending into the bare brown branches of the forest. As more brown owls survive, more brown genes get passed down through generations. Until now, the researchers say, “an evolutionary response to a quantified selection pressure driven by climate change has not been empirically demonstrated in a wild population.”

4. The fish that’s migrating earlier

Climate change is also the driving force behind a recent behavioral shift in pink salmon. As water temperatures rise, the fish are migrating from the ocean to the river to spawn about two weeks earlier than they did 40 years ago. And this isn’t just a new behavior—it’s actually a change at the genetic level. Between the 1980s and 2011, the number of late-migrating salmon declined by 20 percent, according to Ryan Kovach, a population ecologist at the University of Alaska in Fairbanks. The change happened over just one or two generations, which suggests organisms can adapt to climate change very quickly. “We show that there has been a genetic shift towards earlier migration timing through what appears to be natural selection against the late-migrating individuals in the population,” Kovach says

5. The bedbugs with super-strength

Unfortunately, our long-running battle with these bed-hopping pests has backfired, producing bedbugs with thicker shells and nerve cells of steel to resist the harsh chemicals we lob at them. Bedbugs in New York City are now 250 times more resistant to pesticides than the bedbugs in Florida, according to researchers at the University of Massachusetts in Amherst. "Insect resistance is nothing more than sped-up evolution," says insect toxicologist John Clark. 

6. The mouse that’s immune to poison

Bad news for anyone with a fear of mice: researchers have discovered a house mouse with an immunity to Warfarin, a type of poison typically deployed to fight infestations. The super mice were discovered in Germany, where the lowly house mouse bred with its poison-resistant distant cousin the Algerian mouse. The result? A hybrid mouse with a very useful genetic mutation that gives it a leg up over its rodent relatives. Usually hybrid animals can’t reproduce, but "sometimes there is the occasional odd hybrid that has just about the right novel combination of genomes from two species that renders them, at least temporarily, superior over the pure species," says the study’s lead author Michael Kohn. “We’ve caught evolution in the act.” 

All images courtesy of iStock unless otherwise noted.

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Animals
Where Do Birds Get Their Songs?
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iStock

Birds display some of the most impressive vocal abilities in the animal kingdom. They can be heard across great distances, mimic human speech, and even sing using distinct dialects and syntax. The most complex songs take some practice to learn, but as TED-Ed explains, the urge to sing is woven into songbirds' DNA.

Like humans, baby birds learn to communicate from their parents. Adult zebra finches will even speak in the equivalent of "baby talk" when teaching chicks their songs. After hearing the same expressions repeated so many times and trying them out firsthand, the offspring are able to use the same songs as adults.

But nurture isn't the only factor driving this behavior. Even when they grow up without any parents teaching them how to vocalize, birds will start singing on their own. These innate songs are less refined than the ones that are taught, but when they're passed down through multiple generations and shaped over time, they start to sound similar to the learned songs sung by other members of their species.

This suggests that the drive to sing as well as the specific structures of the songs themselves have been ingrained in the animals' genetic code by evolution. You can watch the full story from TED-Ed below, then head over here for a sample of the diverse songs produced by birds.

[h/t TED-Ed]

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NOAA, Wikimedia Commons // Public Domain
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Animals
Watch the First-Ever Footage of a Baby Dumbo Octopus
NOAA, Wikimedia Commons // Public Domain
NOAA, Wikimedia Commons // Public Domain

Dumbo octopuses are named for the elephant-ear-like fins they use to navigate the deep sea, but until recently, when and how they developed those floppy appendages were a mystery. Now, for the first time, researchers have caught a newborn Dumbo octopus on tape. As reported in the journal Current Biology, they discovered that the creatures are equipped with the fins from the moment they hatch.

Study co-author Tim Shank, a researcher at the Woods Hole Oceanographic Institution in Massachusetts, spotted the octopus in 2005. During a research expedition in the North Atlantic, one of the remotely operated vehicles he was working with collected several coral branches with something strange attached to them. It looked like a bunch of sandy-colored golf balls at first, but then he realized it was an egg sac.

He and his fellow researchers eventually classified the hatchling that emerged as a member of the genus Grimpoteuthis. In other words, it was a Dumbo octopus, though they couldn't determine the exact species. But you wouldn't need a biology degree to spot its resemblance to Disney's famous elephant, as you can see in the video below.

The octopus hatched with a set of functional fins that allowed it to swim around and hunt right away, and an MRI scan revealed fully-developed internal organs and a complex nervous system. As the researchers wrote in their study, Dumbo octopuses enter the world as "competent juveniles" ready to jump straight into adult life.

Grimpoteuthis spends its life in the deep ocean, which makes it difficult to study. Scientists hope the newly-reported findings will make it easier to identify Grimpoteuthis eggs and hatchlings for future research.

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