WEBVTT

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

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but they're actually 
vulnerable to collapse.

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Jungles can become deserts,

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and reefs can become lifeless rocks,

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even without cataclysmic events, 
like volcanoes and asteroids.

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

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The answer, to a large extent,
is biodiversity.

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Biodiversity is built out 
of three intertwined features:

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ecosystem diversity,

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species diversity,

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and genetic diversity.

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The more intertwining 
there is between these features,

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the denser and more resilient 
the weave becomes.

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Take the Amazon rainforest,

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one of the most biodiverse 
regions on Earth

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due to its complex ecosystems,

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huge mix of species,

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and the genetic variety 
within those species.

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Here are tangled liana vines,

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which crawl up from the forest floor 
to the canopy,

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intertwining with treetops

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and growing thick wooden stems
that support these towering trees.

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Helped along by the vines,

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trees provide the seeds, fruits
and leaves to herbivores,

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such as the tapir and the agouti,

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

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Leftovers are consumed 
by the millions of insects

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that decompose and recycle nutrients
to create rich soil.

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

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each packed with interconnected species.

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Every link provides stability to the next,

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strengthening biodiversity's weave.

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That weave is further reinforced

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by the genetic diversity 
within individual species,

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which allows them to cope with changes.

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Species that lack genetic diversity
due to isolation

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or low population numbers,

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are much more vulnerable 
to fluctuations

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caused by climate change, disease
or habitat fragmentation.

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Whenever a species disappears
because of its weakened gene pool,

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a knot is untied 
and parts of the net disintegrate.

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

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Would the system fall apart?

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Probably not.

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The volume of species,

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their genetic diversity,

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and the complexity of the ecosystems

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form such rich biodiversity in this forest

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

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The forest can stay resilient
and recover from change.

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But that's not true in every case.

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In some environments, taking away
just one important component

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can undermine the entire system.

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Take coral reefs, for instance.

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Many organisms in a reef
are dependent on the coral.

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It provides key microhabitats,
shelter and breeding grounds

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for thousand of species of fish,
crustaceans and mollusks.

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Corals also form interdependent 
relationships with fungi and bacteria.

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The coral itself is a loom

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that allows the tangled net 
of biodiversity to be woven.

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That makes coral a keystone organism,

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one that many others depend on
for their suvival.

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So what happens when destructive
fishing practices,

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pollution and ocean acidification

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weaken coral 
or even kill it altogether?

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Exactly what you might think.

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

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threatening the entire fabric of the reef.

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Ecosystem, species
and genetic diversity

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together form the complex tangled weave
of biodiversity

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that is vital for the survival 
of organisms on Earth.

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We humans are woven 
into this biodiversity, too.

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When just a few strands are lost,

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our own well-being is threatened.

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

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What the future brings is unpredictable,

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but biodiversity can give 
us an insurance policy,

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Earth's own safety net 
to safeguard our survival.