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Transcript
Age of Earth “Isn’t Evolution Just A Theory? Clip How did the theory of Evolution come about? • James Hutton -1785-Earth is millions of years old. • Thomas Malthus -1798populations outgrew their food supplies, causing competition between organisms and a struggle for one species to survive against another • Jean-Baptiste Lamarck -1809believed that all life forms evolved and that the driving force of evolution was the inheritance of acquired characteristics. He believed that organisms changed due to the demands of their environment. •1831: Charles Darwin – voyage to the Galapagos Islands •Lyell -1833- plant and animal species had arisen, developed variations, and then became extinct over time. He also believed that the Earth’s physical landscape changed over a long period of time. •Alfred Russel Wallace -1858-competition for resources is the main force in natural selection •Charles Darwin -1859- Publishes “On the Origin of Species” Charles Darwin On the Galapagos Islands Darwin noticed many variations among plants and animals of the same general type as those in South America. clip Tortoises- noticed different shaped shells which allowed for different neck movement based on the environment Finches- noticed different shapes and sizes of beaks which fit the type of food each bird eats Natural Selection Video Clip If an organism reproduces, then the traits of that organism are passed to the next generation. Traits that are favorable for a certain environment become more prevalent within that population. What if the environment changes? The organisms must adapt to the environment. Those that don’t adapt-die. This is a very slow process….does not occur over night…many generations must past before any change in the population can be seen. Example: Peppered Moth When the trees were normal, the black moths were easily seen by the birds, so there were more peppered moths that survived. When the trees were black, the peppered moths were easily seen by the birds, so there were more black moths that survived. Decent with modifications These changes increase a species’ fitness in their environment. WOLF HUSKY Crab Clip Examples: The largest hog, the cow that gives the most milk, fastest horse, domesticated dogs. Evidence for Change Over Time 1. Fossil Record – Fossils that show how an organism looked millions of years ago. 2. Geographic Distribution 3. Comparative Anatomy and Embryology 4. Genetics & Molecular Biology How do we know evolution is happening? Clip Relative Dating of fossils helps us to know how old organisms are and when they lived… Embryologystudy of early stages of development This may show that organisms had a common ancestor. Vestigial organs –Organs or structures that are no longer used by an organism. –They are usually reduced in size. Vestigial Organs c Speciation •the evolution of a new species when the genes in a population changes Speciation Mechanisms • Behavioral Isolation – Populations are capable of interbreeding, but have different courtship rituals or other type of behavior. • Geographic Isolation – Separated by bodies of water or mountains. • Temporal Isolation – Reproduction takes place at different times of the year •Overtime they can change so much that they become unable to breed as they adapt to their environment. Changes in allele frequency with in a population Divergent Evolution Example…Adaptive Radiation Convergent Evolution Coevolution Evolution is the ______ in a species over _____. Structural Adaptation • Change in physical structure or anatomy • EX: wings of a seagull Physiological Adaptation • Change in internal function or chemistry • EX: having the proper enzyme to digest carbs Behavioral Adaptation • Change in behavior that responds to environment • EX: lay eggs in nests Rates of Evolution Gradualism • Very gradually change, over a long time... • Change is slow, constant, and consistent. • Small variations that fit an organism slightly better to its environment are selected for: a few more individuals with more of the helpful trait survive, and a few more with less of the helpful trait die. Punctuated Equilibrium •change comes in spurts. •There is a period of very little change, and then one or a few huge changes occur, often through mutations in the genes of a few individuals. 38 LABEL each as gradualism or punctuated equilibrium GRADUALISM PUNCTUATED EQ PUNCTUATED EQ GRADUALISM Resistance in Bacteria 39 Read page p403. 40