byJerzy Barchanski

Galapagos Islands - an inspiration for the Theory of Evolution

Location of the Galapagos Islands

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Galapagos Islands

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Galapagos Islands

• The Galapagos Islands are located in the eastern Pacific Ocean approximately 600 miles (1000 km) off the west coast of South America. The closest land mass is the mainland of Ecuador to the east (the country to which they belong), to the North are the Cocos Islands 432 miles (720 km) and to the South is Easter Island and San Felix Island at 1920 miles (3200 km).

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Charles Darwin1809 - 1882

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Darwin’s Journeys

In 1831 Darwin accepted the offer of Commander Robert FitzRoy of travelling on a survey ship, HMS Beagle, as a "scientific person" or naturalist. The round-the-world journey lasted five years

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Darwin’s Journeys

Darwin spent most of these years investigating the geology and zoology of the lands he visited, especially South America, Pacific Oceanic islands and the Galapagos islands .

Darwin was exploring the Galapagos archipelago from 16 September to 20 October of 1835.

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HMS Beagle

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Most important works

• In 1859 On the Origin of Species by means of Natural Selection, or the Preservation of Favoured Races in the Struggle for Life was published in London on 24 November by John Murray.

• 1871 The Descent of Man, and Selection in relation to Sex.

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Charles Darwin

• Darwin's most famous book, was published in 1859. Within 20 years it convinced most of the international scientific community that evolution was a fact

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Richard Dawkins

• Ethologist and Evolutionary Biologist

• Emeritus fellow of New College, Oxford University

• Oxford University Professor for Public Understanding of Science from 1995 until 2008

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Richard Dawkins Books

• The Selfish Gene, 1976 and 2006 • The Extended Phenotype. 1982• The Blind Watchmaker 1986• The God Delusion, 2006• The Greatest Show on Earth: The Evidence for Evolution, 2009 ……and many more

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Odyssey

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Panga boat

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In front of the Charles Darwin research station,Santa Cruz, Galapagos

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Posters at the CDS

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History of evolutionary thought

• Aristotle - 4th century BC- Natural History• Pliny the Elder- 1st century AD – Natural History• Linnaeus- 18th century – Classification• Erasmus Darwin – 18th century – common ancestors• Lamarck – 19th century - common ancestors• Cuvier – 19th century - fossils• Charles Darwin - 1859 - natural selection• Alfred Russell Wallace – 1859 – similar ideas as

Darwin

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Age of the Earth Controversy

• According to literary Bible interpretation - 4600 years• Using modern scientific methods (accepted by

most scientists) - 4.5 bln years

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The basic timeline is a 4.5 billion year old Earth, with (very approximate) dates:3.8 billion years of simple cells (prokaryotes),3 billion years of photosynthesis,2 billion years of complex cells (eukaryotes),1 billion years of multicellular life,600 million years of simple animals,570 million years of arthropods (ancestors of insects, arachnids and crustaceans),550 million years of complex animals,500 million years of fish and proto-amphibians,475 million years of land plants,400 million years of insects and seeds,360 million years of amphibians,300 million years of reptiles,200 million years of mammals,150 million years of birds,130 million years of flowers,65 million years since the non-avian dinosaurs died out,2.5 million years since the appearance of the genus Homo,200,000 years since humans started looking like they do today,25,000 years since Neanderthals died out.

Darwin vs modern Evolutionists

• Much of the Darwin’s theory of evolution was an inspired guesswork

• Darwin’s greatest idea was that of natural selection

• Darwin was wrong on the mechanism of inheritance

• Modern evolutionists need not to guess - they can consult genetic scripture – DNA code

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Summary of modern theory of evolution

Life on Earth evolved gradually beginning with one primitive species – perhaps a self replicating molecule – that lived more than 3.5 billion years ago; it then branched out over time, throwing off many new and diverse species; and the mechanism for most (but not all) of evolutionary change is natural selection.

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Components of the evolution theory

• Evolution• Gradualism• Speciation• Common ancestry• Natural selection• Nonselective mechanisms of evolutionary

change

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THE EVIDENCE FOR EVOLUTION: Biogeography

• Biogeography is the science that seeks to explain the distribution of living things through space and time on Earth. Biogeography looks at current species of animals and plants as well as the evidence of past life (fossils) in order to determine how species arose.

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THE EVIDENCE FOR EVOLUTION: Biogeography

• If species were created as perfectly adapted to their environment, we might assume similar environments to have similar plant and animal life. This is NOT the case. Instead, the animals and plants of a region are most closely related to those of nearby regions and reflect the history of the region. Biogeography states that the range and dispersal (basically, where an organisms lives) is dependent upon the barriers in moving from one area to another.

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Galapagos Mockingbird

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Galapagos Mockingbird

• The Galapagos Mockingbirds descended from the Ecuadorian Long-tailed Mockingbird. They were the first that were found in Darwin’s trip to the islands in 1835. They had a greater influence than any other animal on Darwin’s theory of evolution when he arrived there because it was the first species that Darwin noticed distinct differences among when he looked from island to island.

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Galapagos finches

• The Galapagos Archipelago is home to 13 species of finch, belonging to 4 genera. These finches all evolved from a single species similar to the blue-black grassquit finch (volatina jacarina) commonly found along the Pacific Coast of South America. Once in the Galapagos Islands the finches adapted to their habitat and the size and shape of their bills reflect their specializations. Vegetarian finch and ground finch all have crushing bills while tree finch have a grasping bill and cactus finch, warbler finch and woodpecker finch have probing bills.

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Evolution of bird’s beaks as tools

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Galapagos finches

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Galapagos finches

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GALAPAGOS TORTOISES

Naturalists believe tortoises arrived in the islands clinging to a piece of driftwood from a river mouth along the Pacific Coast. A relatively large tortoise, related to the Galapagos tortoise lives on the South American mainland. The tortoises arrived in San Cristobal then spread throughout the archipelago. Those on individual islands or in isolated parts of the larger islands developed into its own sub-species.

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GALAPAGOS TORTOISES

• The Galapagos was once home to 15 sub-species of which 11 sub-species still exists. The smallest tortoises like those on Española and Pinta have "saddle backs”.

• The largest of the tortoises, those on Santa Cruz and from the Alcedo Volcano on Isabela have "dome backs". In this isolated habitat these giant tortoises fill the niche occupied by larger vegetarian mammals in continental regions.

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Giant tortoise

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Tortoise at the CDS

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GALAPAGOS IGUANAS

• The Galapagos Islands are home to Marine Iguanas, Land Iguanas, and a hybrid mix whose father's are marine iguanas and mother's are land iguanas as well as the newly discovered pink iguanas.

• Land iguanas grow to a bulky girth and 3 ft (1 m) in length. Their yellowish-orange belly and brownish red back make them more colorfull then their cousins, the marine iguana. The land iguana lives in the arid portion of the islands.

• The cactus provides both food and water for the land iguana, who can go without fresh water for a year. Part of the adaptation to the drier environment includes a conservation of energy by slow movement

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Land iguana

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Land iguana on Santa Cruz

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Marine iguanas

• Marine iguanas exist only in the Galapagos Islands. Living on the black lava shore rocks they have developed into efficient swimmers feeding off shore mostly on marine algae and seaweed.

• The cold waters of the Galapagos provide both the necessary food for the marine iguanas and its most deadly threats. Until the arrival of man, marine iguanas only threats were that of larger fish and sharks encountered while swimming.

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Marine iguanas on Espanola

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Marine iguanas on Isabela

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THE EVIDENCE FOR EVOLUTION VESTIGES

• A vestigial organ is something that had an important function a long time ago, but over time has lost it

• The vestiges are important because they provide evidence for evolution

• They are little clues to what could have been billions of years ago

• Gives a stable foundation that some organisms share a common ancestor

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Evolution of wings

• The appearance of wings on flightless birds is considered a strong proof for evolution

• Wings that are incapable of flight are now used for;– Absolutely nothing at all (cormorant, kakapo)– One time flight (queen ants)– Swimming (penguins)– Sexual displays– Insulation– Balance

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WHY GIVE UP FLIGHT?

• Species families with shorter wings may be predisposed to flightlessness due to the higher cost associated with flight

• There is a trade off between stability and maneuverability

• Dominant pressures may keep wings short such as;– Predation– Foraging ( taking over for mammals)– Nesting– Habitat

• Many flightless birds are found on islands, like Galapagos

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The Galapagos Penguin

• The only penguin living exclusively in equatorial region• Second smallest of all penguins,• Nest mainly inside lava tubes, underneath big boulders or in

crevices offering a cool environment• 95% occurs around Fernandina• Lives in small colonies of 2 to 12 birds• Feed mainly in inshore waters

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The Galapagos Pinguin

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The Galapagos Pinguin

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THE GALAPAGOS CORMORANT

• The only flightless cormorant;• Unique mating behaviour – female initiate and play

more active role in courtship than male;• Male choses from the competing females;• Female deserts its mate and offspring and goes off to

find a new mate, while the male alone raises the young until they attend full independence.

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THE FLIGHTLESS CORMORANT

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Sexual selection

• Supported by sexual dimorphism – traits that differ between males and females of a species (tails, color)

• Reduces chances of male survival by wasting a lot of energy and exposure to predators

• Exists in two forms – direct competition between males for access to females and female chooseness among possible males

• Support natural selection by increasing rate of reproduction of winning or chosen males

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Sea lions of Galapagos

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Sea lions of Galapagos

Sea lions form colonies at their hauling-out areas. Adult males known as bulls are the head of the colony, growing up to 7 ft (2 m) long and weighing up to 800 lb (363 kg). As males grow larger, they fight to win dominance of a harem of between 5 and 25 cows and the surrounding territory. Swimming from border to border of his colony, the dominant bull jealously defends his coastline against all other adult males. While patrolling his area, he frequently rears his head out of the water and barks, as an indication of his territorial ownership

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Frigate Birds of Galapagos

• Frigate birds are large seabirds, about the size of a hen and have extremely long, slender wings.

• They are large (almost 6 feet/1.8 m. wingspan), lightweight and have a long, hooked beak to catch fish without getting wet.

• Male frigates have shiny green or purple plumage (depending on the species) and a resplendent scarlet pouch, which is displayed in courtship.

• There are two species of frigates in Galapagos: the Magnificent Frigate Bird and the Great Frigate Bird.

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Frigate Birds of Galapagos

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Courtship of Frigate birds

• During courtship display, the male forces air into the pouch, causing it to inflate over a period of 20 minutes into a startling red balloon.

• As males tend to display in groups, the effect is magnified. Then the males sit quietly in the low shrubs watching for a female to fly overhead.

• At this, the males waggle their heads from side to side, shake their wings and call. If the display is attractive enough, then the female will land and sit beside her amour

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Conclusion

• The Galapagos Islands provided Charles Darwin an inspiration to creation of the theory of evolution.

• Many of Darwin’s ideas were just good guesses, he did not explain some

aspects of evolution, like e.g. speciation.

However the following research by others

made the theory of evolution a proven fact. 58