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What's the awesomest place in the world? Scientists can think of at least 137, the newly released list of the most biologically important places on Earth. Hank explains how ecologists arrived at this list, and takes you on a tour of four of them, from the mountains of Tanzania to the flattened hilltops of Venezuela.
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Hank Green: What is the most awesome place in the world? Seems like that would be pretty much the most subjective question ever, but this week, scientists used a set of objective criteria to come up with a list of the world's most biologically important places. There might be one near you. I'm Hank Green and this is SciShow News.


Hank: It's official! Dave's basement is not an important place, at least as far as ecologists are concerned. As described in Thursday's edition of the journal Science, a team of researchers led by the Centre for Functional & Evolutionary Ecology put together a list of the most biologically irreplaceable places on Earth, which seems like a tough call, because the world is a diverse place, right? Well, working through a list of almost 200,000 areas known for their biological importance, the researchers ranked each one based on its importance to rare and threatened species. They calculated the fraction of every species on the IUCN Red List, that's the official list of the world's threatened and endangered species, that lived in each place, and then gauged how dependent each species was on that particular area. They ended up with 137 sites that were deemed the most irreplaceable. And while I wish we had time to talk about all 137 of them together, a sample of only four might be enough to give you a sense of how amazing, mind-blowing, beautiful the diversity of life is that's hiding out there.

Let's start with the Udzungwa Mountains National Park in Tanzania. This isolated mountain park contains the whole Earth's worth of habitats in one place: tropical rainforests, woodlands, grasslands, and steppes. It's home to more than 400 birds species and six primate species, five of which can only be found there, for example, the highly endangered Sanje Mangabey monkeys that have been vulnerable to poaching because they live mostly on the ground. And there's the extremely weird Grey-Faced Sengi, an elephant shrew that was only discovered in 2008, and most of which live entirely inside the park.

While Udzungwa is rich in threatened animals, it's got nothing on number three, the Palawan Game Refuge in the Philippines. Composed of island mangroves and grasslands, Palawan has the greatest mammal diversity of any site on the list, but it's most famous for its birds, twelve species of which are endemic, including the beautiful Palawan Peacock-Pheasant. Despite the park's small size, only 7600 square kilometers, it's home to more than 200 bird species and 600 butterfly species. Thankfully, since it's isolated on a chain of islands, Palawan has been well preserved.

Number two on our list is more endangered though, due to grazing and plantations encroaching upon it: The Western Ghats in Western India are the last hope for animals like the Lion-Tailed Macaque, which lives in the region's dwindling rainforests. And with competition from domestic livestock and the spread of invasive plants, fewer than 2000 Nilgiri tahr, a rather lovely kind of ibex, survive. Western Ghats is also full of endangered frogs, like this species, which was only discovered in 2001.

But if you're really looking for endangered species, you have to head to number one: Canaima National Park in Venezuela, ranked as the most irreplaceable site for overall animal diversity in the world. Canaima owes its one-of-a-kind biodiversity to an equally unique geological feature, steep, flat-topped mountains in the park called tepuis. They've managed to isolate its many different habitats for thousands of years, thousands of meters above the valley floor. As a result, each tepui is a unique evolutionary microcosm, many are home to species found nowhere else, like the Roraima Black Frog, restricted to the summit of only two mountaintops in the world. Although the frog is well-protected for now, its tiny range makes it vulnerable to pretty much any disturbance, which is like the whole point of the list. 

Having identified the most irreplaceable places, the researchers are calling for more protection of these sites. I think that we've all got a special place in our hearts that we want to see preserved or that maybe we wish had been preserved, and that'd be a cool thing to talk about in the comments below.

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