Name: 7 Animals That Evolved at Hyperspeed — Because of Us
Uploaded: 2020-03-30T03:29:18.000Z
Duration: 14 min 10 s
Description: Thousands of YouTube videos with English-Chinese subtitles! Now you can learn to understand native speakers, expand your vocabulary, and improve your pronunciation...

A lot of people think evolution on Earth happens a little something like this:

a slimy creature crawls out of the ocean, and hundreds of millions of years later

its descendants peel themselves off the sofa,

wondering how they managed to binge-watch all five seasons of Breaking Bad in less than three days.

Some species can rapidly adapt to cope with fast changing environmental conditions like:

you know-- things that are 100% our fault.

Biologists call this high-speed adaptation

Though that kind of makes it sound awesome--

it's how some species are able to respond in times of severe population stress.

that's a species of swallow that builds nests on cliffs.

Except, lots of them don't do that anymore.

Today, many cliff swallows make their nests on bridge supports.

That, of course, means there are large populations of cliff swallows living next to roads.

Birds that live next to roads  face a strange new enemy.

It seems like cliff swallows are quickly adapting to this threat.

the number of road-killed swallows has declined-

-even though there are more birds than ever nesting next to roads.

That's probably because populations near roads

Biologists studying the birds have found  that road-killed cliff swallows

tend to have longer wings than the not road-killed variety,

and they think that's because shorter wings give the  swallows an advantage against vehicles.

Longer wings are better for air speed and gliding,  but shorter wings make the birds more maneuverable-

-so they can quickly take off vertically and evade oncoming cars.

What's really impressive is that the change in wing length

Also, shorter wings may help the swallows cope with climate change.

In 1996, half of a cliff swallow population that scientists were studying starved to death during a cold snap -

probably because the freezing temperatures killed a lot of the insects they normally eat.

was that the birds that survived had shorter wings.

Researchers think the birds with shorter wings were much more maneuverable,

and that made them better at catching the few insects that didn't freeze.

So it's possible the short wings they evolved for dodging cars

will help them survive the more frequent and severe cold snaps brought on by a changing climate.

Commercial fishing operations catch a lot -A LOT - of fish every year.

that species -like Salmon, Cod, and Herring- have all evolved quickly to avoid extinction.

Basically, they're now living fast and dying young.

You see, human fishing tends to favor larger specimens;

so many species evolved to be smaller overall,

or are becoming sexually mature at a younger age,

In some populations the change is really dramatic,

like: the average adult fish is 20% smaller than the species used to be,

The advantage of this is pretty obvious -

smaller fish are less likely to be harvested by humans.

So--fish that stay small -or reach sexual maturity sooner,

can pass their genes on before they end up someone's dinner.

For example: after they were over-harvested in the 1920s,

Chinook Salmon took only about 30 to 40 years to get roughly 25% smaller;

unless we start letting people catch smaller fish to keep up with the demand.

When the London Underground was built in 1863,

workers inadvertently created a tidy isolated habitat for the world's favorite bug--

Standing water would collect in the tunnels,

which made a perfect breeding ground for the bloodsuckers.

Humans discovered this the hard way during World War Two,

when the tunnels were used as overnight bomb shelters

and the mosquitoes took to feasting on those people.

It's bad enough when you're underground trying to avoid getting exploded,

without being covered in blood-sucking bugs.

What's actually weird about this is that they were biting people at all.

Because the mosquitoes that live in the London Underground are a subspecies of Culex pipiens -

a species that -above-ground- usually feeds on birds.

So in the eight decades or so it had spent apart from its kin,

the London Underground mosquito has switched to preferring the blood of mammals.

Probably because rats are a bit more common than pigeons in the new habitat.

And that's not the only difference between the underground mosquito and the species it evolved from--

the London Underground mosquito doesn't hibernate in the Winter,

and the females don't need blood in order to lay their eggs.

In fact, the two types are now so genetically distinct

that they can't mate and produce offspring.

So the metro mosquitoes are arguably a new species -

researchers think it only took a few hundred mosquito generations for this new pest to evolve.

Okay, all sorts of garbage and pollution get dumped into the sea,

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7 Animals That Evolved at Hyperspeed — Because of Us

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