Why is biodiversity so important? - Kim Preshoff

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Our planet’s diverse, thriving ecosystems may seem like permanent fixtures, but they’re actually vulnerable to collapse. Jungles can become deserts, and reefs can become lifeless rocks. What makes one ecosystem strong and another weak in the face of change? Kim Preshoff details why the answer, to a large extent, is biodiversity.

Lesson by Kim Preshoff, animation by TED-Ed.

Our planet's diverse thriving ecosystems
may seem like permanent fixtures,

but they're actually
vulnerable to collapse.

Jungles can become deserts,

and reefs can become lifeless rocks,

even without cataclysmic events,
like volcanoes and asteroids.

What makes one ecosystem strong
and another weak in the face of change?

The answer, to a large extent,
is biodiversity.

Biodiversity is built out
of three intertwined features:

ecosystem diversity,

species diversity,

and genetic diversity.

The more intertwining
there is between these features,

the denser and more resilient
the weave becomes.

Take the Amazon rainforest,

one of the most biodiverse
regions on Earth

due to its complex ecosystems,

huge mix of species,

and the genetic variety
within those species.

Here are tangled liana vines,

which crawl up from the forest floor
to the canopy,

intertwining with treetops

and growing thick wooden stems
that support these towering trees.

Helped along by the vines,

trees provide the seeds, fruits
and leaves to herbivores,

such as the tapir and the agouti,

which disperse their seeds
throughout the forest so they can grow.

Leftovers are consumed
by the millions of insects

that decompose and recycle nutrients
to create rich soil.

The rainforest is a huge system filled
with many smaller systems, like this,

each packed with interconnected species.

Every link provides stability to the next,

strengthening biodiversity's weave.

That weave is further reinforced

by the genetic diversity
within individual species,

which allows them to cope with changes.

Species that lack genetic diversity
due to isolation

or low population numbers,

are much more vulnerable
to fluctuations

caused by climate change, disease
or habitat fragmentation.

Whenever a species disappears
because of its weakened gene pool,

a knot is untied
and parts of the net disintegrate.

So, what if we were to remove one species
from the rainforest?

Would the system fall apart?

Probably not.

The volume of species,

their genetic diversity,

and the complexity of the ecosystems

form such rich biodiversity in this forest

that one species gap in the weave
won't cause it to unravel.

The forest can stay resilient
and recover from change.

But that's not true in every case.

In some environments, taking away
just one important component

can undermine the entire system.

Take coral reefs, for instance.

Many organisms in a reef
are dependent on the coral.

It provides key microhabitats,
shelter and breeding grounds

for thousand of species of fish,
crustaceans and mollusks.

Corals also form interdependent
relationships with fungi and bacteria.

The coral itself is a loom

that allows the tangled net
of biodiversity to be woven.

That makes coral a keystone organism,

one that many others depend on
for their suvival.

So what happens when destructive
fishing practices,

pollution and ocean acidification

weaken coral
or even kill it altogether?

Exactly what you might think.

The loss of this keystone species
leaves its dependents at a loss, too,

threatening the entire fabric of the reef.

Ecosystem, species
and genetic diversity

together form the complex tangled weave
of biodiversity

that is vital for the survival
of organisms on Earth.

We humans are woven
into this biodiversity, too.

When just a few strands are lost,

our own well-being is threatened.

Cut too many links,
and we risk unraveling it all.

What the future brings is unpredictable,

but biodiversity can give
us an insurance policy,

Earth's own safety net
to safeguard our survival.