Galápagos - Charles Darwin's natural selection

Do school children still get taught about Charles Darwin and the "Origin of Species"? I certainly was, and how the HMS Beagle arrived in 1835 for a five-week stay with Darwin on board as a science officer. His initial excitement was centred on the volcanic activity associated with the islands, but it was the land birds and tortoises which got him thinking about evolution. Although it would be another twenty-four years before he would dare publish the Origin of Species.

Medium Ground Finch

Today, the Galápagos is a real wildlife hot spot with the legendary tameness of the animals fully justified. Thankfully a tight reign is kept on visitor numbers with certain protocols followed when landing on the uninhabited islands. It's also possible to see for yourself the subtle differences at play between the islands and observe evolution in action.

Bartolome Island looking towards Pinnacle Rock

The Galápagos will always be synonymous with Darwin but how much it actually contributed to his thinking is under debate. For example, Darwin didn’t appreciate the differences in the finches until the skins were handed over to ornithologist John Gould on his return to the UK.

Although to be fair, I’m struggling to identify particular species with a photograph and guide book in front of me! What is certain, various facts would have been imprinted into his mind which all eventually added credence to his rationale.

The Large Cactus Ground finch

The Galápagos is made up of 21 islands spread over a distance of 137 miles with some of the finch species endemic to certain islands. The key here is the diet where the beak shape has evolved to allow the eating of certain food types which vary from island to island.

Being some 563 miles west of Ecuador, the remoteness really has allowed the islands to be nature's laboratory with the ancestral vagrants evolving over thousands of years into several species.

Small Ground Finch

The genus known as Camarhynchus is better known as the Darwin finches being split between thirteen species, twelve of which can be found on the Galápagos. Although it was Darwin’s initial examination of the Mockingbird skins which caught his eye. Research has shown all four species evolved from the same common ancestor.

The scruffy-looking Hood mockingbird, endemic to Española

The Galápagos mockingbird is found on most islands

The Chatham mockingbird is endemic to San Cristóbal Island with the best identifying feature being the colouring of the eye.

Another fact which Darwin observed was the different shapes of the tortoise shells which varied from island to island. To understand the reason for the variety you need a quick lesson in island formation. Being on a fault line, volcanic activity creates the Galápagos Islands which are then colonised over thousands of years by plants and animals. Eventually, the islands erode away, but new ones are always being formed.

Where you have islands with lush vegetation’s, the tortoises tend to graze looking downwards so have developed a domed shell, while more arid islands where they need to look up and eat vegetation from bushes and cacti, the saddleback shell has developed so they can stretch the neck upwards.

The domed shaped shell of the Santa Cruz tortoise

The saddleback shaped shell of the San Cristóbal tortoise

It's hard not to mention Lonesome George who was discovered on Pinta Island in 1971 and was the only living example of his species, effectively making him the rarest creature on the planet. Attempts to get him to mate so to pass on his genes were unsuccessful with George passing away in 2012. But will always be seen as an icon for Galápagos conversation.

Lonesome George

Lastly, we come to the Iguana's, although not noted for its variation in colours by Darwin, I couldn't help noticing a difference between the Islands myself.

So for example, in Santa Fe, the Land Iguana's had a sandy colour but in South Plaza, they were very much more yellow.

While the Marine Iguana's of Española Island had a distinctive red colouring which was very subtle in other Islands such as Bartolome.

Marine Iguana's of Española Island

Marine Iguana on Bartolome

There is no doubt that Galápagos is a very special place, a fact not lost on the scientists of today with research ongoing. What does amaze me is how tortoises got here in the first place? Presumably, a small number of individuals swept out to sea on some sort of raft of vegetation which eventually ran aground?

But as with everything on this earth, be it the extinction of the dinosaurs or the colonisation of the Galápagos, much of it is out of our control.

I guess it's what we call destiny?