The Galapagos Islands were to Charles Darwin what the legendary falling apple was to Isaac Newton, experts say.
The volcanic archipelago in the east Pacific Ocean, 970km west of Ecuador, did no less than inspire Darwin's theories on biological evolution that revolutionised humanity's understanding of Planet Earth.
A 26-year-old Darwin, whose birth bicentennial is celebrated on February 12, visited the islands in 1835 during his historic voyage aboard the British Beagle vessel, and copiously studied its myriad endemic species.
The young biologist's stay was to consume his life's work. Darwin's 1859 scientific masterpiece "On the Origin of Species" grew almost entirely out of the fledgling evolutionary theories he began constructing on Galapagos' plants and animals.
"If true that Newton was inspired by the falling apple to develop the principle of gravity, it could also be said that the islands were decisive for Darwin's evolutionary theory," said Carlos Valle, who heads the biology department at Quito's San Francisco University and is a renowned expert on Galapagos animal life.
On the unique islands, Valle told AFP, the young Darwin "found the best evidence" to develop the theories of natural selection as he studied how species had adapted to their environment over million of years.
On the archipelago, comprised of 13 larger islands and 17 islets, Darwin "noted that environmental conditions vary little from one island to another, but that these differences influenced the size of beaks in birds from the same species, depending on the type of seed found in their surroundings," Valle said.
Therefore, Darwin discovered that "in a relatively small area there could 14 types of the same bird species, and its variations were related to the environment where it was raised," he added.
"Darwin travelled to many places around the world, but in Galapagos he found a unique situation: the islands' birds appeared identical, but he realised the differences between them depended on where they were," confirmed Matthias Wolff, a director at Charles Darwin Foundation for the Galapagos Islands (CDF).
The islands "are not the main theme in 'Origin of Species', but his trip here was very important -- you could say they were the key to his understanding of evolution" said Wolff.
Galapagos was declared a UNESCO World Heritage Site three decades ago, but has been identified as a site where invasive species and tourism are taking a toll on preservation.
In 2006 the CDF launched a ten year strategic plan that identifies "major hurdles that must be overcome" for Galapagos, which it calls "a global icon of conservation and evolutionary history."
The plan to conserve the site involves attempts to rid the site of invasive species and manage the burgeoning tourist trade.