Chapter 15 Part 1 Pg. 91 Evolution Introduction Definitions to Know Scientific Theory = a well-supported, testable explanation of phenomena that have occurred in the natural world. Evolution = change over time, the process by which modern organisms descended from ancient organisms Is Evolution Fact or Fiction? Scientists believe its Fact. Proof? Fossils Speciation Geological evidence DNA evidence Charles Darwin ( ) British naturalist famous for his theories of evolution and natural selection. Like several scientists before him, Darwin believed all the life on earth evolved (developed gradually) over millions of years from a few common ancestors. In 1831, Darwin took a trip around the world on the ship, the M.S. Beagle, where he collected evidence that led him to propose his famous Theory of Evolution. Charles Darwin Fossils Fossils = preserved remains of ancient organisms
Darwin didnt just observe and collect living animals, he also collectedfossils. Fossils = preserved remains of ancient organisms This led to questions like. Where did all these organisms go?Why arent they still here?Why do they resemble organisms we have living today? Armadillo= alive Glyptodon = dead The Galapagos Islands The most important, influential stop on Darwins trip was the Galapagos Islands 1000 km west of S. America, a clusterof islands isolated by miles of sea The islands had different climates, and therefore, had different varieties of animals and plants Animals Darwin studied: Box 7 3. Finches Giant Tortoises 2.Iguanas Galapagos Turtles Each turtle lives on a certain island, and their shells are different, island-dependent! Pinta Tower Marchena Pinta Island Intermediate shell Hood Island Saddle-backed shell Fernandina James Santa Cruz Isabela Santa Fe Floreana Hood The shape of each turtles shell is different and the different shapes depend on the turtles habitat. Isabela Island Dome-shaped shell Darwins Finches Darwin also collected finches, birds, matching their beak and body shapes with different islands- just like the tortoises. Adaptive Radiation the evolutionary process through which a single lineage gives rise to species occupying diverse environmental niches. Tree Finch Ground finch In other words, if you get separated from your own species, you evolve or change in response to your environment. Darwins Finches Leaves Seeds and Fruit Seeds Insects Grubs Tool using What took him so long? 25 years later.
In 1858, Alfred Wallace sent Darwin an essay with the same ideas about evolution! They presented their work together at a conference, but. This pushed Darwin to publishhis work, before Wallace The Origin of the Species Proposed a mechanism for evolution, called Natural Selection Presented evidence that evolution hasbeen happening for millions of years