How can animals living thousands of mile apart evolve to be so similar? It's called convergent evolution: animals filling the same "roles" in similar ecosystems have evolved with similar characteristics. (It's also sometimes called parallel evolution; scientist can't exactly agree on the distinction.) It's a remarkable process. And thanks to Australia's "isolation" as an island for the last 100 million years, we have plenty of examples of parallel or convergent evolution to observe.
Parallel evolution examples from "down under" include marsupial versions of, well, just about every mammal on the planet. That's an exaggeration, but it's not too far off. Marsupials are some of the clearest examples of convergent evolution animals out there: two different animals with remarkable similar traits... but one's got a pouch! There are plenty of non-marsupial (and non-mammalian) examples, too. Read on to learn more about some of the most weirdly similar animals on the plant... that just so happen to live thousands of miles apart.
These two adorable little critters developed the whole "body-as-parachute" thing independently, believe it or not. On the left is the flying squirrel, commonly found in North America or Northern Europe. The other dude is a sugar glider, commonly found in Australia, New Guinea, and adorable YouTube videos. Their similar "wings" and big eyes are independent adaptations that evolved because they have similar lifestyles: they both leap from the tops of trees and forage at night. There's one big difference between the two: the flying squirrel is a placental mammal (like humans) while the sugar glider is a marsupial mammal (like a kangaroo).
These two are actually technically unrelated, despite their obvious similarities. The toucan on the left is found in the American tropics. Toucans get all the press and love, but hornbills aren't too shabby, either. They are native to tropical Africa and Asia and also evolved a large-yet-light bill "to reach fruits from leafy branches that will not support their weight." This is a classic case of convergent evolution: their environments exerted the same "pressure" on the evolution that eventually formed those big bills.
The familiar hummingbird on the left is a New World (Americas) bird, while the similar sunbird is from the Old World (Africa, Europe, and Asia). They belong to different orders but have similar lifestyles. Encyclopedia Britannicanotes that they both "dart among tropical flowers, feeding upon nectar" and have a similar appearance because of how their feeding habits evolved (check out those bills). Some sunbirds also hover like hummingbirds when they feed. Their metabolic behavior is similar in certain species, too: both sunbirds and hummingbirds living at high altitudes have been known to enter a state of torpor at night, just like stoners in Denver.
These guys look remarkably similar, eh? On the left is an antelope (gazelle to be exact) and on the right is a pronghorn. Pronghorns are native to North America, while antelopes call Africa and Asia home. You know that classic American song "Home on the Range"? The one that goes, "Oh, give me a home where the buffalo roam/Where the deer and the antelope play"? There are no antelope in America. You've been lied to! Despite appearances to the contrary, the pronghorn's closest "relative" is actually the giraffe. They are, however, found in the same biomes as antelope, which likely led to their similar behavioral traits.
Yes, the little fella on the left is a small species of kangaroo, which helps to better illustrate the point, but even big 'roos share similarities with cavies (also known as a dillaby or mara). The cavy is typically found in Argentina, while the kangaroo is, as everyone knows, synonymous with Australia. The Lincoln Park Zoo's page on cavies sums it up nicely. Like kangaroos, their "rear legs are long...They are brown with white undersides, with hindquarters marked with a white patch. A large snout and large eyes are prominent on the face." The kangaroo, however, is a marsupial, unlike the cavy.
The chevrotain on the left is native to Africa and Asia, while the paca is from South America. Convergent evolution, scientists say, led to them both have similar markings on their torsos. Despite their remarkably similar appearance, the chevrotain is an ungulate (hoofed animal) while the paca is a rodent. Their "similar environmental demands" made them analogous creatures of a sort, despite being separated by the Atlantic Ocean, fulfilling the same "roles" in their respective ecosystems.
