XX November 2013
Introduction
The Galapagos Island or the Galapagos archipelago is a group of volcanic islands off the coast of South America in the Pacific Ocean. They are about 973 km away from the coastline, and belong to the country Ecuador. There are 18 main islands, 3 smaller islands, and 107 rocks and islets. This group of islands contains a large number of endemic species which were studied by Charles Darwin during his voyage on the Beagle. His research led to the formation of Darwin’s theory of evolution and natural selection. Charles Darwin was an English geologist cum naturalist (Desmond 2004). Galapagos is home to a lot of unique creature like the Marine iguanas, Galapagos Land Iguanas, Galapagos Giant Tortoise, Flightless Cormorants, Waved Albatross, Great Frigate birds, 13 different species of Finches etc.
Climate
Charles Darwin in his treatise The Voyage of the Beagle says:
Considering that these islands are placed directly under the equator, the climate is far from being excessively hot; this seems chiefly cause by the singularly low temperature of the surrounding water, brought here by the great southern Polar current. Except during one short season, very little rain falls, and even then it is irregular; but the clouds generally hang low. (Darwin 300)
The climate of Galapagos is influenced by different ocean currents. Humboldt Current is responsible for cold, nutrient-rich waters from Antarctica and Chile, and the Cromwell current when it reaches the Galápagos it upwells, mainly off the coast of Fernandina and west Isabela, brings both cold and nutrient-rich, from deep beneath to the surface. There are mainly two seasons – garúa (or the cold dry season) and the wet season (also the hot season). Average temperature during garúa is about 22°C, while that during the hot season is about 25°C.
The phenomenon of El Niño, which is caused by the reversal of the equatorial atmospheric circulation and occurs on an average every four years, has a tremendous effect on the flora and fauna of the islands. It causes irregularity in the seasons, causing unexpected heavy rainfalls and prolonged dry seasons. Climate here also varies from island to island and even with elevation on a single island (Vinuza 111).
Adaptations
The Galapagos was first discovered by the bishop of Panama when suddenly they had to land on the island due to a few days of calm on the sea. They found a harsh and hostile place with strange creatures that they have never seen. Darwin’s research revealed that the strangeness of these creatures were actually adaptations by these animals to the unique conditions posed the islands like remoteness and resource crunch. Some fascinating adaptations are shown by the marine iguanas (Matthew 20) and Darwin’s finches (Grant 100).
The marine iguana (Amblyrhynchus cristatus) is the only lizard known to have the ability to dive under water. They are slow on land but are good swimmers. Their laterally flattened tail and spiny dorsal fins helps them swim under water. They have long sharp claws which help them to hold on to underwater rocks in strong currents. These marine iguanas feed on algae growing on under water rocks as deep as 30 ft. Since they are ectothermic they can dive for only about 10 minutes. Once they come out of water they need to bask in the sun to higher their body temperature before they can go in the water again. While basking they spit out excess salt water that they may have ingested while feeding underwater. They can vary their body size depending on food availability. During El Niño years due to reduced food supply they reduce their body size by 20% by shortening their bones and shrinking their connective tissue by secreting certain stress hormones (Wikelski 1985).
Another excellent example of adaptation and natural selection are Darwin’s finches, which are about fifteen species of passerine birds (Grant 50). Among them vegetarian finch is the largest and warbler finch is the smallest. The most important difference among them is the size and shape of their beaks, which are adapted specifically towards their selection of food resources. The Woodpecker Finch has a very short tongue, but they have developed an ability to use various tools that it makes out of twigs for cactus thorns. Using it they can pull out grubs from inside tree barks. They can even manipulate the size of the tool. Because of this ability they are also called the carpenter finch (Tebbich 656).
Symbiotic relationships
A lot of animals on the Galapagos islands have developed symbiotic relationships to survive the challenging environment that they face on the islands. One such relationship exist between the Marine Iguanas and the Sally Lightfoot Crab. These carbs would often crawl over swarms of basking Iguanas scrapping off dead skin, parasites and algae. The Galapagos Lava Lizard offers similar service to the Galapagos Sea Lions, when they eat flies which sit on the sea lions and irritate them. Similarly, the Galapagos Giant Tortoise lets certain species of Darwin’s finches rid them of ectoparasites (MacFarland 464).
Colonization of the Galapagos Islands and Threats
The first human came to Galapagos when pirates took pit stops during their plundering voyages. Later various explorers came and left. Later human settled in five islands - Baltra, Floreana, Isabela, San Cristobal and Santa Cruz. None of them are natives. They are mostly from mainland Ecuador who came and settled mainly in the last century. A 2006 population estimation of humans on the islands gave a figure of 25000 people. The annual population growth is about 8%.
Introduced flora and fauna, such as cattle, feral goats, cats, dogs etc. pose a grave threat to the native species. Initially these species were mostly introduced by pirates. The native animals who have never seen any animals were defenseless against introduced predators. There are also a large number of introduced plat species who have invaded the domain of native species, eradicating them. Dogs, pigs and rats attack nests of birds and giant tortoises. There is grave threat of diseases from the local poultry industry. The marine resources are under threat from illegal fishing off the coast (Carr 317).
Damage Control
In 1996 a 5 year long mission worth US$5 million was undertaken to eradicate introduced species such as goats, donkeys, deer, and rats. Various travel companies and conservation groups formed the IGTOA (International Galapagos Tour Operators Association) to protect the islands for the future generations (igtoa.org). Galapagos Islands were included in List of World Heritage in Danger in 2007 by UNESCO, because of danger posed by introduced species, illegal fishing and unchecked tourism (unesco.org). Later it was removed from the list due to improvement in prevailing conditions (unesco.org)
Works Cited
Carr, Lindsey A, et al. "Illegal Shark Fishing in the Galapagos Marine Reserve." Marine Policy 39 (2013): 317-21. Print.
Darwin, C. The Voyage of the Beagle. Cosimo, Incorporated, 2008. Print.
Grant, P.R., and B.R. Grant. How and Why Species Multiply: The Radiation of Darwin's Finches. Princeton University Press, 2011. Print.
International Galapagos Tour Operators Association (IGTOA). Web. 22 Nov. 2013.
MacFarland, Craig G, and WG Reeder. "Cleaning Symbiosis Involving Galápagos Tortoises and Two Species of Darwin's Finches1." Zeitschrift für tierpsychologie 34.5 (1974): 464-83. Print.
Matthew, Henry Colin Gray, Brian Harrison, and R James Long. "The Oxford Dictionary of National Biography." (2004). Print.
Nelson K., Snell H., and Wikelski M. "Amblyrhynchus cristatus". IUCN Red List of Threatened Species International Union for Conservation of Nature, 2004. Print.
Tebbich, Sabine, et al. "The Ecology of Tool‐Use in the Woodpecker Finch (Cactospiza Pallida)." Ecology Letters 5.5 (2002): 656-64. Print.
UNESCO. "List of World Heritage in Danger ". Web. 23 Nov. 2013.
Vinueza, LR, et al. "Top-Down Herbivory and Bottom-up El Niño Effects on Galápagos Rocky-Shore Communities." Ecological Monographs 76.1 (2006): 111-31. Print.
Wikelski, Martin. "Evolution of Body Size in Galapagos Marine Iguanas." Proceedings of the Royal Society B: Biological Sciences 272.1576 (2005): 1985-93. Print.
