“This episode is supported by Prudential”
Here in Tambopata Peru, EO Wilson once found more species of ant in a single tree than
there are in all of the British Isles.
Scientists have seen this pattern all over the world.
More species exist near the tropics.
Why is that?
In one night here in the Peruvian rainforest, I saw more insects in an hour
than I’ve seen in my entire life, total.
It’s not just insects.
Birds, mammals, plants…
鸟类 哺乳动物 植物等等
Regions like this, tropical rainforests are some of the most biodiverse places on Earth.
It’s not just the abundance of it,
it’s how many different species we find in a given area.
But why is that?
It might seem obvious, or even like a silly question, but the more you think about it,
答案可能显而易见 这甚至是一个愚蠢的问题 但越深入思考
the weirder it gets, because life has shown it can succeed pretty much anywhere, from
the top of the highest mountains to the bottom of the ocean.
Yet Earth’s most biodiverse places
are always regions like this, tropical rainforests.
One reason why is maps lie to us.
Rectangular projections are distortions of a sphere that make the poles look bigger and
tropics look smaller than they really are.
When in reality, the tropics contain about 40% of area on Earth.
Unsurprisingly, larger areas usually have more species.
In less than half a square kilometer in the Amazon, we can find as many tree species as
we find in four million square kilometers of temperate forest.
Species here are at a higher density.
There must be something special about tropical ecosystems.
Climate is one factor.
When we look at plant fossils and when and where we can find them
in this climate history, tropical forests are older than temperate forests,
they’ve had more time to get rich.
But just because the tropics don’t have cold winters.
then they survive at ice age doesn’t mean that’s easy to survive here
There are dry and wet seasons, they have to competition for resources,
no matter what kind of organism you are, there’s a lot of stuff that wants to eat you.
On average the tropics are warm and they get plenty of water.
总的来说 热带地区气候温暖 水量充足
This part of the planet gets more average solar radiation throughout the year.
Which means that plants and the animals they support get more energy,
they are more productive.
But this still only explains why there’s *more* life,
not why so many *different* kinds of life.
If you have a pie, more people can get a slice
if you cut it up into a thousand tiny ones vs just a few.
And in ecosystem we call these slices niches
It’s the conditions, the habitat that one organism needs to flourish,
and here in the rainforest, there’s a lot of slices.
Organisms that live at higher latitudes have to be little more adaptable,
be able to handle more different conditions.
One week it might be snowing.
The next, flowers and fish are everywhere.
Specialization is too risky, you’ve gotta be adaptable.
Life is more stable in the tropics.
One thing I noticed here in Peru is the sun sets a lot earlier here this time of year
我注意到 在秘鲁 每年这个时候的日落时间
than what I’m used to back at home.
Here near the equator there’s essentially the same number of hours
in day and night no matter what month it is.
Let’s say you’re a bird that eats insects, and maybe these bats over here
You’ve got the same number of hours to do your feeding.
The birds get the day shift, the bats get the night shift.
You get to split that niche evenly.
That wouldn’t work at higher latitudes and more temperate climates.
There’s simply just too much change, too much disruption for these species to keep track of.
And this might explain a reason why more species coexist near the equator.
The tropics are crowded, so the competition for resources is extreme.
That competition drives organisms to specialize, like how we see ants or caterpillars that
might be able to live on just one single type of plant.
But because climate and seasons are more stable, that specialization isn’t as risky.
More species, less area.
These theories are really good at explaining
why there’s so many species in the tropics NOW, we’re still missing the beginning
where those species came from.
It’s possible that evolution is actually working on overdrive here near the equator, speciation,
the creation of new species by various natural forces,
actually happens FASTER near the equator.
Each generation of living things gathers changes, mutations, some are good,
每一代生物都在积累变化 突变 其中一些是好的
some are bad, some are neither, but it isn’t until those changes are passed on to the next generation
that natural selection and time can do their thing .
The reason that bacteria are so good at adapting is because they reproduce quickly,
they have more generations in less time.
The same thing happens here in the rainforest. Plants and animals
grow up faster, they can have more generations.
This drives competition, this is what forces plants and animals to specialize
in all of the amazing ways that we’ve seen.
This theory, that evolution happens faster near the equator, finally ties together the
ideas of time, area, and energy to explain the origin of biodiversity.
将时间 面积 能量的概念联系在一起来解释生物多样性的起源
There’s an idea that says the tropics are so well suited to the creation of new species…
that it’s like an engine for biodiversity
Another idea says the tropics are so rich and productive, and the climate’s so stable,
另一个观点是 热带地区肥沃富饶 气候稳定
that species don’t go extinct as fast.
More species are born here and species live longer here
在热带地区 生物繁衍更多 生存时间更长
The tropics are like a cradle AND a museum.
Scientists even think that over many many years, species from places like this
科学家甚至认为 多年后 这些地方的物种会
go and seed biodiversity throughout the rest of the world.
This is why it’s so important to protect the rainforest
to preserve life’s cradle and museum.
To keep it from being cut up,
because more area means more species.
To keep the climate from changing, to keep this place stable and rich.
Chemists know all the elements on the periodic table
Physicists probably know all the subatomic particles that make up matter.
But biology still hasn’t answered one of its most basic questions:
how much life IS there?
EO Wilson once wrote that “unlike the rest of science,
the study of biodiversity has a time limit”.
If species begin to go extinct faster than we can describe them
then we might never know how much life Earth has to offer.
And after seen something like THIS, I don’t want to see that happen.
Thanks to prudential for sponsoring this episode.
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I hope you enjoy the first video from our trip to the Peru Amozon.
I should add that when it comes to explaining
why there is more species near the equator,
scientist aren’t totally sure what the right answer is yet,
but these are the best theories we have right know.
Remember, that how science works.
We gotta keep studying them,
which means we gonna make sure these species that you want study are still around.
I have lots more video from Peru in the coming months.
So stay tuned.
A special thank you to rainforest expeditions for hosting us in Peru
It was incredible experience,
and we cannot wait to share with you
the rest of our peru adventure.
“This episode is supported by Prudential”