Insect eaters Bud eater Seed eaters Cactus eater Warbler finch Tree finches Ground finches Darwin & Evolution by Natural Selection

Charles Darwin Proposed a way how evolution works – How did creatures change over time? – by natural selection Collected a lot of evidence to support his ideas – – British naturalist

Darwin’s Life Darwin took a convoluted path on his way to developing his theory. His first career was to be a doctor, but he could not stand being around blood He then studied to be a pastor- his plan was to preach and study nature as a hobby After completing school, he was invited to serve as a doctor/naturalist on an incredible voyage

Introducing… the trip that changed it all… In 1831, Darwin set sail on the Beagle for a voyage around the world During his travel, Darwin made numerous observations and collected evidence that led him to propose a revolutionary hypothesis about the way life changes over time = The Theory of Evolution Darwin was interested in the diversity of organisms in specific areas and the specific locations species inhabited – How are there so many different organisms and why do they live in specific areas? Darwin used these observations to scientifically explain the diversity of life on this planet.

Robert Fitzroy Voyage of the HMS Beagle Invited to travel around the world – (22 years old!) – makes many observations of nature main mission of the Beagle was to chart South American coastline

present day Armadillos During his trip, Darwin found: that creatures have changed over time Evidence that creatures have changed over time ancient Armadillo Darwin asked: Why should extinct armadillos & modern armadillos be found on same continent? Darwin found…clues in the fossils

Voyage of the HMS Beagle Stopped in Galapagos Islands – 500 miles off coast of Ecuador

Galapagos Recently formed volcanic islands. Most of animals on the Galápagos live nowhere else in world, but they look like species living on South American mainland. 800 km west of Ecuador

Darwin asked: Why were these creatures found only on the Galapagos Islands? Darwin found…many unique species

The Galapagos Islands Darwin observed that the characteristics of many animals and plants varied noticeably among the different islands. – Why were these close islands inhabited by similar organisms that appeared slightly different? – Did these species evolve from a common ancestor after being isolated to different islands needing different survival skills? Pinta Island Intermediate shell Isabela Island Dome-shaped shell Hood Island Saddle- backed shell

Darwin found… birds Darwin found: Many different birds on the Galapagos Islands. He thought he found very different kinds…

Darwin was amazed to find out: All 14 species of birds were finches… But Darwin found… a lot of finches But there is only one species of finch on the mainland! Darwin asked: If the Galapagos finches came from the mainland, why are they so different now?

Upon closer examination, Darwin found: The differences between species of finches were associated with the different food they ate.

Simplified version of what happened Original Group of finches migrated to islands with some variation in beak characteristics. different beaks are inherited variations The beaks serve as adaptations that help birds compete (or reduce competition) for food Best suited birds survive & reproduce pass on the genes for those more fit beaks over time nature selected for different species with different beaks Original Species separated into many new species

Relationship between species (beaks) & food

Warbler finch Woodpecker finch Small insectivorous tree finch Large insectivorous tree finch Vegetarian tree finch Cactus finch Sharp-beaked finch Small ground finch Medium ground finch Large ground finch Insect eaters Bud eater Seed eaters Cactus eater Warbler finch Tree finches Ground finches variation natural selection for best survival & reproduction From 1 species to 14 species…

Not Just Finches Original

The rest of the trip Darwin continued noticing the specializations of certain organisms, as well as evidence of extinctions and geologic processes through the end of his voyage. He struggled to explain how these variations and apparent extinctions had occurred.