So much for high school biology.
Evolution, it turns out, isn’t the long, invisible process we once thought.
Instead, it’s happening all around us, all the time.
By shaping landscapes, dumping pollutants into rivers and lakes, and transforming wild areas into suburban ones, humans are spurning the creation of everything from wild animal hybrids to pests immune to poisons and superbugs that can’t be killed with bacteria.
All of this is taking place at an unprecedented scale.
While you might be familiar (a little too familiar, you might say), with bedbugs, they didn't always used to be the terrifying critters we know today.
Thousands of years ago, our cave-dwelling ancestors got along perfectly fine with bedbugs -- mainly because they were nearly an entirely different species back then. Unfortunately, as humans migrated out of caves and into cities over thousands of years, they brought bedbugs along for the ride. The insects with traits that made them better able to survive their new urban lifestyle -- such as being more active at night, when humans sleep, and having longer, thinner legs for hopping away from us quickly -- outlived their less-evolved bedbug friends.
In just the last few decades, these city-dwelling insects have become almost an entirely separate species from their cave-dwelling cousins. In addition to their new penchant for the nightlife, today's urban bedbugs have also evolved resistance to pesticides: They have thicker, waxier exoskeletons (to shield them from toxins) and faster metabolisms (to beef-up their natural chemical defenses).
Typically, members of two different species can't mate with one another -- and if they do, the offspring they produce are often infertile or so weak they die before they can produce any babies.
In mice, at least 50% of hybrids are sterile. But sometime in the past 50 years, when wandering Europeans brought together the Algerian mouse (Mus spretus) and the common house mouse (Mus musculus), the two species got to mating.
Miraculously, their mice pups were fertile. Although rare, this sort of thing can happen every so often with just the right combination of genes. In addition to their baby-making capabilities, the hybrid mice got another gift from their parents: a chunk of genes that makes them immune to the poison warfarin, meaning they can't be killed by pesticides.
Unlike the house mice, the Algerian mice had this poison-resistance gene naturally -- they likely evolved it as an adaptation to a vitamin-K diet (the same gene that's responsible for warfarin-immunity manages vitamin K in the body.)
How to adapt to survive for months on nothing but sunlight? Try taking a cue from plants. Better yet, steal a few of their genes.
When food in the chilly coastal waters where they live runs scarce, the bright green sea slug snatches chunks of DNA from the algae they eat. Coupled with tiny energy-producing powerhouses called chloroplasts (which the sneaky slugs also pilfer from their algeae meals), the stolen genes are enough to allow the slugs to survive on nothing but sunshine for days.
The best part? The algae genes get passed onto the next generation of slugs.
Although future slugs will then come pre-equipped with the algae genes in their DNA, they will still need to snatch up new chloroplasts to keep the process going. This gene-swapping process is called horizontal gene transfer. By doing it, the slugs are effectively bypassing traditional evolution, which typically happens over thousands or millions of years. So far, these sea slugs are one of the only known examples of this process occurring between multicellular organisms.
There's nothing 'natural' about the silky-smooth fur, distinctive colouring , or even the friendly personality we've come to associate with man's best friend.
Over the past 150 years or so, humans have been specifically mating dogs that look a certain way to create the animals we now keep as pets via a process known as breeding. This is artificial selection, where one species (humans) directs the traits that get passed down to future generations of another species (dogs).
It's important to keep in mind, though, that all our selective pressures still haven't resulted in any new dog species (cocker spaniels and poodles can still interbreed, for example) but merely a bunch of breeds. Nevertheless, our actions can be seen in the doggie genome, the collection of all of its genes. At least 155 different regions show evidence of strong recent selection favouring traits from skin wrinkling (like that seen in the Shar-Pei) to coat and size.
Plus, these changes are still happening, as breeders mix and match breeds to create pets like labradoodles (labrador retriever and poodle mixes), and cockapoos, (cocker spaniel and poodle mixes).
Although dogs separated from their wolf ancestor around 18,000 years ago, several new groups of pups that are more genetically similar to wolves have begun to show up around the world sometime within the past 150 years.
This is a good example of what happens when a strong evolutionary pressure, like humans' intensive practice of breeding dogs for favourable traits, is suddenly removed.
Stray dogs in Moscow, for example, who've been living largely separate from humans for the past several hundred years, have evolved to be expert beggars. Because the survival rate in the wild for these animals is so low, their evolution has happened at a superfast pace: the strays who have the traits that help them survive (they're unfriendly toward humans, feeding only on their trash, they have superior navigation skills, etc.) pass those traits onto their pups.
The peppered moth can most easily be spotted on a dark surface: its distinctive off-white wings, speckled with tiny dark spots, make it stand out.
During the industrial revolution in Britain and the US, when humans started pumping their air full of pollutants, that dark soot fell on trees, darkening their bark and endangering the moth, who'd easily be picked out by predators on a shadowy tree. Over several generations, as the lightest moths were eaten and the darker moths tended to survive, the majority of moths in the region became dark via a process called natural selection.
But when pollution control laws in both countries started to scale back the amount of soot in the air in the 1970s, dark moths again became more prone to getting eaten. Today, most moths have returned to their original light colour.
And you thought coyotes were terrifying.
A new hybrid of the coyote and the wolf, or coywolf, that first emerged in the last few decades is now coming out in droves in the Northeastern US. About 2/3 of the coywolves' DNA is from wolves, while another 1/4 is from coyotes. The remainder is from domesticated dogs.
But nothing about these animals is domestic. They're even bigger than either their wolf or coyote ancestors, weighing in at as much as 140 pounds. They're also social, like wolves, meaning they tend to hunt in packs.
Coyotes and wolves would likely have never come together in the first place if not for human farming and hunting practices, which drove the wolf north and coyotes east. But they're definitely here to stay -- the coywolf's unique genetic makeup appears to be particularly appropriate for its northern habitat -- moreso, even, than either of its parent species, meaning the hybrid genes will likely keep getting passed down to future generations. While the DNA from the wolf appears to allow the coywolf to hunt larger prey, the coyote DNA helps it adapt rapidly to urban areas.
Bacteria have evolved to outsmart our antibiotics -- and we're on the cusp of an 'apocalyptic scenario.'
Doctors commonly treat bacterial infections with antibiotics. When one drug doesn't work, they try another. But now, physicians are finding that some of our infections are resistant to even our strongest drugs. The bacteria have, genetically speaking, outsmarted us. Those with traits that allow them to survive in antibiotic-rich environments pass them onto future generations, making each successive strain more resistant to our drugs than the last.
Last year, 23,000 Americans died from bacterial infections that didn't respond to antibiotics. Certain strains of 'nightmare bacteria' kill up to half of the patients they infect, and cases are becoming increasingly common across 42 states.
The problem isn't exclusive to the US, though. Because of our global overuse of these drugs -- and our increasing reliance on them -- antibiotic-resistant bacteria could kill up to 10 million people worldwide each year by 2050, according to a recent report from the Healthcare Infection Society.
When New Yorkers started dumping PCBs (a type of industrial toxin) in the Hudson River in 1929, they wiped out a large majority of its wildlife.
But at least one species survived -- and thrived. Over the span of a few decades (PCBs were banned in 1979) a fish called the tomcod evolved to resist the poison via natural selection.
Fish with a special set of genes that make a key poison-shielding protein were the only critters to survive the toxic onslaught. They, in turn, passed their protective genes onto their offspring.
About 75 years ago, the Australian sugar bureau decided to lug a handful of cane toads from Hawaii to Australia with the idea that they'd rid the country of the sugar-cane-devouring cane beetle. On their new continent, where they lacked the predators of their native Hawaii, the toad population immediately exploded.
Typically when an invasive species is first introduced to a new continent, its population levels stay low for a few decades before growing exponentially.
But these toads expanded rapidly, likely because of several adaptive traits that allowed them to travel faster and farther. Compared with their pioneering ancestors, the toads in Australia today have longer legs and hop much quicker, since they were able to move faster and were always at the forefront of an invasion into a new area. When they mate, they pass their longer legs onto their offspring.
A pest that thrives on one of our favourite foods is developing immunity to the toxins we use to keep it at bay.
Corn is one of the staples of American cuisine. It's derivatives are in everything from candy and soda to hamburger patties and fast-food taco meat. To soothe our corn sweet tooth, we've begun growing the crop in massive quantities, making powerful pesticides necessary to kill of pests that feed on the increasingly vulnerable plant.
Unfortunately, our overuse of pesticides have, in turn, spurned genetically stronger pests.
When the western corn rootworm, for example, developed a resistance to the chief pesticide in Monsanto's GMO corn (a gene designed to produce a special protein to destroy the worm's digestive tract), the company responded by switching up the pesticide in its corn to another type of protein. The worms evolved to resist it that as well.
This South African flower, whose gorgeous red tubular flowers blossom close to the ground, looks upside down.
In a sense, it is. The type of birds that typically polinate the plant are relatively scarce in the western portion of the country, and they avoid the ground, where they make easy prey for predators.
As a result, natural selection favoured the versions of this low-lying plant that featured stems shooting upwards from the ground -- skittish, ground-shy birds would perch on those plants to feed, and the pollinated upside-down plants outlived the non-pollinated stemless plants.
How do scientists know this is evolution at work and not simply some weird-looking plant?
In the East, where there's a bigger variety of birds looking for potential sources of food, the stalk has receded over many generations, a process scientists call relaxed selection. As a result of this process, traits that were once useful gradually fade away in subsequent generations as they lose their utility.
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