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Each is a crucible where evolution proceeds have extorted the speed
You
Each island contains its own unique community
The discovery of these creatures inspired an idea that change our understanding of life on Earth
Evolution
And today
Scientists something like this are continuing to make discoveries that
Shed light on that crucial process and have revealed that human beings can be just as powerful a driving force of change
as any other factor
Something here was the catalyst that produced the most spectacular
explosion of biological diversity in the world
It's not just the number of species that appeared
But the rate at which they did so and the result is so extraordinary it inspired the most important of all biological theories
Charles Darwin's
evolution by natural selection
and now
200 years later, we are beginning to understand the deep lying forces that produce this biological, Wonderland
One of those factors is isolation
a
part of Isabella Island the largest of the 16 in the archipelago
Is so difficult to get to it's hardly ever visit
Wolf volcano
It's John crater lives exactly on the equator and is encircled internally by steep cliffs
And on its Frank's
Evidence was discovered of a catastrophe than might and redock sadly
Eventually lead to the creation of a new species
This flow of
recently solidified lava
Has created an impassable barrier a hundred metres wide right through the vegetation
The fresh lava is razor sharp enormous impossible to cross
On it lie bones
Bleached white by the baking Sun there those of John tortoises
Some animals that got stuck here are still clinging to life
Tortoises are tough
They can survive for months without any food or water
And that worsened their fate
It will take the months to die
Why so many tortoises tried to cross the lava barrier nobody knows
What drove them to keep attempting this impossible journey?
Perhaps they were desperately trying to rejoin other members of their group
Their deaths however are significant
They illustrate a principle that applies to the whole of nature
It's not unique to the Galapagos, but it's because of the Galapagos that we first came to understand it
This tragic scene filmed for the first time
May provide a clue as to how a new species may start to evolve
The lava flow created an impossible physical barrier across the tortoises territory
Dividing it into two
So two tortoise populations that were once one must now live apart
If there is any significant difference now or in the future between their two territories
The tortoises may eventually become two different species
Animals and plants are evolving throughout the natural world
But it was the strange creatures of Galapagos that first revealed how that happens
Nearly 200 years ago the islands were visited by a young naturalist on
September the 16th
1835
HMS Beagle
Arrived in the Galapagos Islands and the 26 year-old Charles Darwin stepped ashore to explore
At the time very little was known about the natural history of the islands
Darwyn initially was fascinated by its geology
But it was the animals that gave him his historic insight
Darwin was only on these islands for five weeks
But in that short time there were things. He saw and conversations he had
Which stuck in his mind?
for example the British vice-governor of floreana island
Said that he could tell which island the giant tortoise came from simply by the shape of its shell
He pondered on the vice governor's castle remarked
Why were populations of tortoises on separate islands all slightly different from one another
He said about making a collection of animals and plants from all the islands he visited
Although it was the tortoises at first alerted Darwin that the differences between animals on different islands
It was his collection of these
Undramatic little birds the finches which provided him with the most substantial evidence for his great theory
We now know that the ancestral galapagos finches arrived in these islands about two million years ago
Since then. They have diversified into a number of different species
Today there are 13 of them distributed throughout the archipelago
Each has its own special talents
The woodpecker Finch has discovered how to use a tool to Winkle grubs out of their burrows in the branches of trees
The vampire finches learned how to extract blood from sitting birds
Darwyn when he returned to England brought back with him a wide variety of specimens of all kinds
And he spent years studying his collections
He had a range of finches from several of the islands, and he noticed one particular way in which they different
They had beaks of different sizes
Why
An idea grew in his mind
It could also apply to tortoises maybe to all animals and plants wherever they occurred
Painstakingly meticulously he started to accumulate evidence from all over the world to support his idea
And he called the process that produced new species
evolution by natural selection
And
Nowhere is its workings more vividly evident than here when it first occurred to him in the Galapagos
He realized why it was that the were several species of giant tortoises
That original species probably had a high dome shell like this one
And that's very useful and well watered Islands like this where you have to barge your way through the vegetation
But on other islands there are other problems
In the southeast corner of the archipelago lies espaƱola island
Here there is virtually no edible vegetation at all
Except that is for this prickly pear cactus opuntia
but this species of opuntia is very tall and
He has a tough *** trunk
The only parts worth eating other fleshy needs and flowers that pop
Any chant taught us that could reach them could get a meal
Tortoises with low round fronts to their shells couldn't do that
But those were the peak at the front of the shell and longnecks could just manage it
So they were the ones that survived and produced young
Over many thousands of generations
And millions of years the shell shape of the Espanola tortoise became more and more
exaggerated
Now the peak at the front of the shell is shaped like a saddle
Such a change didn't happen just on Espanola different islands had their own versions
Eventually there were 15 different species in the islands all descended from a single founder
But why should the environments of the islands be so different
Well a hint of that reason may come from looking at films. I shot right here back in 1978
in these programs we're going to survey the
unimaginable variety of animals that have been produced by natural selection and look at them not as
Isolated oddities that image of me shot 30 years ago indicates something extraordinary
In that time the rock on which I was sitting
Has moved its position by about a meter from where I was then to where I am now in
Fact the whole of this island is drifting across the surface of the globe at a rate of about
Three centimeters a year roughly the rate at which my fingernails grow
That may not sound much
But in the three million odd years since this island emerged above the surface of the ocean
It has drifted in a southeasterly direction by about 60 miles
Movements in the Earth's crust are the key to understanding the archipelago's extraordinary evolutionary history a
Giant hot spot rising from the Earth's molten core began to build the Galapagos 4 million years ago
But as the island different away from it other volcanoes replaced it one after the other
Each was built from an accumulation of ash and lava
But then as each moved away
eruptions ceased
So a group of items appeared one after the other
The islands are separated from one another by water so their populations can't for the most part mix
But they're just close enough for an occasional animal to float across and so seed a newly emerging Island
Because the islands are of different ages they contain between them a great variety of environments
And each has mode in its inhabitants in its own way
That is why their animals are so diverse
Each is a separate evolutionary community
Darwin had noticed some of the clearest differences
But there are many others with a less obvious an
Isolated population of animals can change not only in their Anatomy, but in their behavior
Little missiles like this are found throughout the archipelago
Each island has its own distinct species
And they differ not so much in the way, they'd look as the way they behave
This is a lava lizard
There are lots of them on the rocks around here
And in the breeding season which is now the male's are competing with one another
both for territory and for females and
the way they do say
It's with press-ups
watch
Actually, this is a model that he sings for scientists to investigate
The way in which these lizards communicate with one another
Let's see how it gets on
And there's a response
These press ups vary both in the number and the intensity the speed
There from species to species in other words each species
There are slight physical differences between the species of lava lizard on different islands
But now because they have developed different gestures they can't interbreed even if they meet
They're separated by a language barrier
New
technology now enables
Scientists to investigate the workings of evolution in ways that Darwin could hardly have ever imagined
X-rays are being used to work out
What's happening to one of the least impressive animals on the island a tiny land snail?
It's been known for a long time that there are many different snail species all closely related
But a recent study of their shells using x-rays has demonstrated just how diverse they have become
The length of the shell compared to the diameter of the tube inside is marginally different in different populations
It's certainly different enough to define them as different species and
There is an extraordinary large number of them throughout the islands without seem to be very complex into relationships
In fact there are more species of them than any other kind of animal on the islands
Even one small island may contain several different species
But why
It's all to do with the different microclimates that occur even within a single small island
Black lava rock has one species and Sandy Beach is close by a very different one
The dark cave has one sort and a leafy forest growing around its mouth yet another kind
And it seems to be connected with humidity at the one extreme there are these with a wide mouth
They come from relatively well watered islands and the wide mouth like that has a body which produces a
roughly
globular shell
But on dry islands the mouth has to be very small
to prevent evaporation and that produces a long
conical shape
So Galapagos is new species range from the subtly different like snails to the obvious like the marine iguanas
In other parts of the world evolution usually proceeds in a slow gradual way
It can take millions of years for new species to appear
But in Galapagos, it's been happening in an evolutionary blink for now
Galapagos for its size has more unique species than anywhere else on earth and
All have appeared in the islands comparatively short history
That raises another intriguing question
Why did such a great number appear so quickly
The answer is to do with the absence of some animals
Predators the few that are here are all very small
This is one of the most lethal scholar pendra a centipede
It roams the undergrowth searching for prey which it kills by injecting venom from the sharp claws on its front legs
But it's only 30 centimeters long so its victims are mr. Tiny
Bigger animals like mockingbirds can easily subdue one
They even feed centipedes to their chicks
The greatest concentration of predators in the whole archipelago is found on the rocky island of Fernandina
But they two of their kind are rather small and comparatively ineffectual
Snakes
The Galapagos racer
They search for prey in the colonies of marine iguanas
But all they can manage to do is to pick off the young the weak of the dying and even that they find quite difficult
They hunt in the rocks around the fringes of the colony
They have to use a combination of both venom and constriction to make a kill
And even then because they're small snakes it may take more than one to overcome a victim
And then there's a tug of war between the winners to settle who has surprised
There are other predators that prey on the iguanas from the air
The galapagos hawk
But even this hunter is seldom powerful enough to subdue a big man
It usually waits until it finds one that is weak or encumbered
a pregnant female tried to find a place to make eggs
And there are not many Hawks here
Only a hundred and fifty mated pairs because there's only a limited number of nesting sites
There are so few birds that they make very little impact on the iguana population
So why are there no larger predators on collab occurs
Most of the Galapagos animals came from the rainforests of South America 600 miles away
There are plenty of big predators in these forests
Reptiles got to Galapagos by floating across the ocean on rafts of vegetation
Only Hardy animals like the iguanas and tortoises could make that 600 mile voyage
The great predators of the junglers however are mammals big fast and warm-blooded like Jaguars
If any of them had ever been carried away on a raft of vegetation
They would have perished out on the open ocean within a few days
So now while there are many kinds of herbivorous reptiles in the capitis
there are no large predatory mammals of any kind and
This has had a profound effect on the animals that did get here
It's something noticed by every visitor who comes to the island
All the animals here are amazingly tame
Even the little finches are happy to bathe within inches of a stranger
The lack of predators may have a surprisingly widespread effect
It's not just that animals are not frightened of strangers the so-called
Island tameless, but that time that would be spent
hiding from attackers
Can now be used to find food by mate and raise young and so produced more young
Which hastens the progress of evolution?
There is no more impressive example of that than fernandinho xiguan economy
With no significant predators around these herbivores produce lots of young
So many that their problem is not how to defend themselves, but how to find enough food to support their great numbers
so they ventured into the sea itself to graze seaweed on the sea floor and
Although swimming in the cold sea cools them uncomfortably
With no predators around they can soon put that right by stretching out in the Sun
The lack of big predators has had an effect on all the animals of the Galapagos
they reproduce freely so populations increase rapidly and
So consequently does evolutionary change
But island tameness has dangers
If a major predator does appear then wildlife will be ill-equipped to defend itself
And one did in the year of
1535 the most successful predatory animal of all arrived
Man
By the beginning of the 17th century the islands had become a haven for pirates
by the 19th century
whalers and Burton men were calling here regularly and
All these ships had a disastrous effect
There is little or no freshwater on these islands, but they have a much rarer resource
Jan thought is's can survive without food or water for very long periods
So ships could come here collect the tortoises stow them in the hold and then after weeks at sea bring one out
Butcher it and have a meal of fresh meat
Slow lumbering and with no way of defending themselves the tortoises were easy victims
The population was decimated
Between the 16th and 20th centuries more than a hundred thousand were taken away and slaughtered
and
the ships brought other dangerous
Rats
They feasted on the tortoises eggs
On the island of pins on rats consumed nearly every single egg
Leaving the tortoise population on the brink of extinction
But another island lost its tortoise population altogether
Pinter located on the shipping route around the north and fringe of the archipelago was a favorite stopover for ships
And they're hungry crews and the unique winter tortoise was presumed extinct by the early 20th century
But in
1972 an amazing discovery was made and filmed a
Living male Pinta tortoise was discovered in the undergrowth
He was taken off to a protected enclosure on the main island to live out his days in comfort and safety
Here he became an international celebrity, and he was given a name to reflect his state
Lonesome George
He's about 18 years old
And he's getting at mr.. Creaky in his joints I
was indeed
am I
He is arguably the
rarest animal in the world
Certainly there can be none rarer
For he is the last of his kind
his female
Died a long long time ago
When he dies the Pinta species of Galapagos tortoise will be extinct
But he is a very important animal
Probably more than any other single creature
he's
Focused the attention of the world on the fragility of our environment
And he stimulated science
To look into whole new areas of research
here on the Galapagos
Just 14 days after we filmed lonesome he died in his sleep
But he's not forgotten
And some George's story like Darwin's fleeting
But famous visit 200 years ago has attracted many visitors to the islands
Today the archipelago is the basis of a multi-million dollar tourist industry
30,000 people live here in three small towns and
fleets of small boats take visitors on carefully planned trips to see the islands main sights
It took animals and plants millions of years to find and colonize the Galapagos
Now new species of animals and plants from the world's continents can get here in a matter of hours
And having got here, they're often inadvertently spread almost immediately through the islands
Seeds of foreign plants hitch a ride on the air currents generated by passing traffic
And the Galapagos is network of roads is now lined by foreign invaders
Among them the common European blackberry a plant that can grow a centimeter a day and create
impenetrable thickets four metres thick
They not only choke and kill native plants. They even blocked the paths of large animals such as the tortoises
Scientists are now trying to analyze the impact of human beings on the course of evolution in the islands
And surprisingly perhaps the finches that Darwin made famous are still providing new insights
Biologist Andrew Hendry is looking at how the finches evolution may have been affected by human settlements
When humans come into a new location essentially what they do is they change the environment?
And and that's that's changing selection is acting on the populations
Hendrie is studying one particular species
the medium ground free, okay, yeah
Remarkably he's found that this Finch in its natural setting is on the verge of dividing into two separate species
The two are defined by the size of their beaks one is small the other large
The difference between them has been caused by the types of food they eat
so if you feed on some small seed then you
Tend to have a small beak, and if you feed on a large seed
Then you tend to have a really big beak, and you tend to have a hard bite
Remarkably Henry has found that among medium ground finches that live near human beings the distinct big and small
Beak forms are getting fewer
It's as if the two variants are here merging back into one
The presence of human beings has stopped this Finch from revolving
We found that they feed a lot on human foods ranging from
rice to fruit to grains to potato chips and
feeding on those types of different foods doesn't really seem to
Matter what your beak size is anymore
So there isn't that pressure to have a small beak version and a large beak version
And there's no selection against those intermediate Birds anymore. There's plenty of foods for them to eat, so it seems like
Humans have caused the speciation reversal there. They're fusing back together again as a result of human influences
So human beings can be just as much a part of nature as the forces that first shaped these islands and the
Organisms that live on them
But human beings can not only destroy they can conserve
In the 1970s the tortoise population reached an all-time low there were only a few thousand of them left
But now there's a major breeding program for them
The tortoise population today is increasing
Once threatened species have been brought back from the brink
And scientists are discovering just how important and influential this reintroduction program might be?
on
our seder volcano home for the largest population of free roaming jar tortoises a
Study has shown that they're crucial to the health of all the surrounding wildlife
Today there are some 15,000 tortoises on the collab occurs, and they're an essential element in the islands ecosystem
One study in particular has shown just how important they are
Biologist Steve Blake uses satellite tags to track their movements
They reveal to most people's great surprise that the tortoises migrate over huge distances
From the depths of the crater right up to the rim
It's just phenomenal. Why would a?
600-pound reptile migrate from sea level to up to a thousand meters on some Islands
From the air the roots the tortoises take are clearly visible
And they use the same highways year after year
One of the fundamental drivers of the migration seems to be food
Tortoises tend to come to the highlands at the coolest time of year up in the highlands they can feed on a year-round
low quality food source
But then when the rains kick in the lowlands tend to green up and the tortoises go down there probably to fatten up
But Blake's studies reveal much more about the tortoises than just where they go they
Demonstrate the extraordinary effect that tortoises have on their surrounding environment
They create special conditions that suit all kinds of other animals
They shape and prune the landscape they disperse seeds
travel down the undergrowth and trim the lowest branches of the bushes and
All that allows seeds to germinate
It disturbs insects so that they can be gathered by hungry predators
Their dung is also crucial to the survival of many other creatures
Beetles lay their eggs in it and their larvae grow fat on the nutriment that it still contains
Tortoises are definitely the megafauna of the islands, they're like the elephants of Galapagos
They're out there in large numbers. They've got big bodies. They're creating myriad
micro habitats for other species
They truly are gardeners of Galapagos. That's probably the best way to sum up their
ecological role
The implications are very important they suggest that the
Reintroduction of tortoises to islands where their numbers have been seriously reduced could restore the richness of the whole environment
We have the chance to bring back the full glory of these fragile ecosystems
Today unlike many other tropical islands elsewhere
95% of Galapagus
biodiversity still survives
Just
And amazingly new species are still being discovered
One was found just 35 miles north of El Sayed Oh on the giant little visited volcano
wolf
To get the wolf you really need a helicopter it's one of the most hostile and least explored parts of the whole archipelago
There had been rumors of something strange living up on these remote high slopes
Something that lived in burrows and only emerged every now and then to feed
The scientific team went out to investigate
What they discovered astonished everybody a
Completely new and unknown species of reptile
a pink iguana
Until now it was thought that the Galapagus possessed only three species of ikana
The black marine iguana that lives on the seashore and
Two species of yellow iguana that live inland feeding on cacti and other vegetation
This land iguana is certainly the most closely related to the newly discovered
Genetic studies of the hundred or so individuals that make up this tiny
Population have shown that it diverged from its land iguana cousins more than 5 million years ago
So amazingly it has been here. Just as long as the other two, but has remained unknown to science until now
The discovery also means that it is even older than wolf volcano where it now lives
And of course there is another great mystery that no one has yet explained
Nobody knows why it's pink
Could it be that to be pink up here brings something good. We don't know
maybe this
Was once spread widely over the island, and this is just the relic population. That's left
Again, we don't know
for by
But there's one thing that is quite certain and that
Is that there's a lot we have yet to learn about?
the enchanted Islands and about the animals that have evolved here and
One thing I have no doubt
Charles Darwin would be delighted
In just a few million years this empty expanse of ocean was transformed a
Series of volcanoes broke the surface and built the islands
Against heavy odds a few species managed to reach them
They adapted to what they found
And so evolved into a multitude of new species
Each new discovery we make gives Darwin's theory a greater relevance
But beyond the strange grants and reserve anna-news there is a greater significance
What we've learned here has given us a greater understanding of our planet
This small group of islands has revealed in microcosm the processes that have shaped all life