Darwin’s Theory of Evolution by Natural Selection Galapagos Islands Darwin arrived at the Galapagos Islands in 1835. Collected birds and other animals on the 4 islands. He noticed that different islands had their own slightly different varieties of animals. Charles Darwin Darwin was a naturalist (collected biological and geological specimens for study) Developed a widely accepted theory of evolution through the process of natural selection. Other theories were in place before Darwin developed his theory What two ways did people think change occurred? (think back to our Earth unit) Years later, Darwin determined that the finches didn’t live anywhere else. He suspected that populations of the birds from the mainland changed after reaching the Galapagos. Darwin thought that perhaps artificial selection (process of breeding to produce desired traits in offspring) could work in nature. Natural Selection Natural selection- The process whereby organisms better adapted to their environment tend to survive and produce more offspring. If you don’t adapt, you’ll die. Nature “selects” traits for organisms to aid in survival. What is natural selection This explains Darwin’s observations of different finch birds and their beaks. Darwin thought the different species of finches evolved from the same original species in response to adaptation to their environment. The overall goal for natural selection and evolution is so that animals will be more likely to survive and reproduce in the future. More about natural selection and adaptation Variation is a difference in a physical trait. Galápagos tortoises that live in areas with tall plants have long necks and legs. Why would that be an advantage? Galápagos finches that live in areas with hardshelled seeds have strong beaks. Why would that be an advantage? Types of adaptations Structural adaptation Protective coloration (Camoflauge) Mimicry Behavior adaptations (Herds) Hibernation Structural adaptation A structural adaptation involves some part of an animal's body. Teeth Body coverings Movement Protective Coloration Also called camouflage Their camouflage makes it hard for enemies to single out individuals. Mimicry Mimicry allows one animal to look, sound, or act like another animal to fool predators into thinking it is poisonous or dangerous. Behavior Adaptations Behavior adaptations include activities that help an animal survive. Behaviour adaptations can be learned or instinctive. Social behaviour Behavior for protection Hibernation This is deep sleep in which animal’s body temp droops, body activities are slowed to conserve energy. E.g. Bats, woodchucks & bears. Origin of Species In 1859, Darwin published On the Origin of Species by Means of Natural Selection. Used the term evolution only on the last page. Evolution- Cumulative changes in groups of organisms through time. Natural Selection is the mechanism evolution can occur.