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Transcript
Chapter 6 Evolution (p. 154) I can: • Understand the concept of evolution (change) by natural selection. • Describe Charles Darwin’s contribution to the foundation of biology. • Explain the relationship of artificial selection to natural selection. • Know the key points of evolution. Species - is a group of organisms that share similar characteristics and can reproduce among themselves and produce “viable” offspring. Evolution – the change of inherited characteristics in an organism over time. EVOLUTION OF HORSES 55 MILLION YEARS AGO TO TODAY Horse Legs The habitat is changing from moist forest to arid grassland. The fastest horses survive. All organisms evolve as climate and habitat changes. Those best suited to the conditions, survive and pass those traits to their offspring. Jean Baptiste de Lamarck’s hypothesis on the inheritance of aquired traits. (1809) - said that the offspring keep the traits that their parents developed during their lives and lost the traits that were not used. Dad - the theory was rejected Son Evolution by Natural Selection. Charles Darwin: 1850’s - organisms with traits best suited to their environment are more likely to survive and reproduce. Darwin was the naturalist aboard the HMS Beagle -surveying the east and west coasts of South America. Darwin’s voyage in 1831 to 1836 Darwin: was gone for 5 years, he spent 5 weeks in the Galapagos Islands. The Galapagos Islands are 600 miles off the coast of Ecuador. Galopogos Islands. The species of animals that Darwin found on the Islands bore similarities to those found on South America and to each other. Darwin saw huge tortoises, similar to: but different from tortoises on the mainland. He could tell what island a tortoise was from by its shell pattern. Ecuador Galapagos Darwin really noticed the differences between the finches.was the variety of Finches. -there are 13 species. What is different about them? Their beaks were shaped differently. They adapted to the available food on each island. - Seed eaters (thick beak) - Insect eaters (long beak) - Bud eaters It’s all about the beak. They are of different shapes, and they feed on different foods. One even uses a tool to pick insects out of cracks. Ancestor:Grassquit Adaptation and Variation Variation: - is an inherited trait that makes an individual different from other members of the same species. (variety) It gives nature something to pick from! Variation Some variations could be harmful. Albino – no pigments. - easily seen by predators – their trait is not passed on to offspring. Adaptation - is any variation that makes an organism better suited to it’s environment -more likely to survive and reproduce and pass on these traits. Ex. color, shape, behavior Ex. Peppered moth in England The coal from the Industrial Revolution turned the tree trunks darker - the dark moth became more common as it could ‘hide’ from predators. (great example of natural selection) Modern coal plants are much cleaner. Camouflaged Scorpion Fish Questions Page 161 1/3/5 Page 169 1 Page 178 8/12 Sources of Variations in Populations p. 159 1. Mutations of the genetic code. 2. Movement of new individuals into a population. - they can have different traits. 3. Geographic Isolation (p. 159) - when a population is separated from other populations. - by mountains, rivers, etc -eventually the populations become so different they can no longer reproduce with each other. In 1856 Darwin published his book: “On the Origin of Species by Means of Natural Selection” It has become one of the most influential and controversial books ever written Darwin’s Principles of Natural Selection • Organisms must produce more offspring than can survive. • Variation must occur in the population. • The variations must be inheritable. • The variation must make the individual more able to survive and pass this trait to offspring. • The variation must become common in the population What if a hare was born with an allele that caused it’s fur to not change color with the change of seasons? How would would it’s survival be affected? What if the climate changed?…and it did not snow? Artificial Selection - people select the traits they want in an organism through breeding. The Speed of Evolution - some scientists say it takes millions of years. - some say it happens quickly. - some say it is both. 1. Gradualism - the slow change of a species to another new species Ex. horses - evidence in the fossil record.. Ex. camels Worksheet “Natural Selection” 2. Punctuated Equilibrium: - the rapid evolution of a species, usually due to a huge change in the environment ex. bacteria becoming antibiotic resistant. ex. peppered moths. gradualism Punctuated Equilibrium EVIDENCE FOR EVOLUTION 1. Fossils - the remains of life from an earlier time. Insect in amber - 45 million years old Clam – 400 million years old Most fossils are found in sedimentary rock Ex. limestone / sandstone - sand / silt / clay are compacted and cemented together. Archaeopteryx: a transitional fossil, the link between dinosaurs and birds. Determining a Fossil’s Age A) Relative Dating -the oldest fossils are at the bottom layer B) Radiometric Dating • Rocks contain a small amount of radioactive elements that decay at a certain rate • By finding how much of it remains can date the rock Worksheet “Evolution” 2. Embryology - the study of embryos and their development. - mammals, birds, fish and reptiles share similar traits. 3. Homologous Structures - body parts that are similar in structure and origin. - can indicate the species share a common ancestor. 4. Vestigial Structures - organs that seem to not have a function. Ex. appendix -but once functioned in their ancestors. Ex. whale – pelvic bones for legs. ex. ear muscles to rotate ears 5. DNA - by studying DNA sequences, scientists can determine how closely organisms are related. Chapter 6 Evolution (p. 154) I can: • Understand the concept of evolution (change) by natural selection. • Describe Charles Darwin’s contribution to the foundation of biology. • Explain the relationship of artificial selection to natural selection. • Know the key points of evolution. Geologic Time Scale p.164 Scientist’s divide the earth’s history into eras and periods. Cenozoic: present to 65 million Mesozoic: 65 million to 250 million Paleozoic: 250 million to 400 million Precambrian: 400 million to 4 billion 225m. 65m 125m present The amazing thing is not that we don’t have more fossils, but that we have any at all. It requires a unique series of events to cause a life form to be preserved… 6.3 Primate Evolution Some Traits all primates share: • Opposable thumbs • Binocular vision • Rotating forelimbs and shoulders • Increasing brain size • Flat finger nails. Primates are divided into 2 major groups: Prosimians Higher Primates Lemurs Tarsier Monkeys Apes Hominids Hominids: • ate both meat and vegetables •Primates: Walked upright on 2 feet. •They had a larger brain. Australopithicus: (Lucy) = Southern ape • hominid •3 million yrs old. •Small brain •Human-like jaws and teeth. •From Africa Homo habilis = handyman •2 million yrs old •Used stone tools •Direct human ancestor. Homo erectus: •Larger brain •About 1.5 million years old. •Migrated out of Africa 1 million years ago. Homo sapiens = wise human 250,000 years ago. By 125,000 years ago 2 groups of Homo sapiens lived in Africa and Europe. Modern humans left Africa 60,000 years ago in several migrations. Neanderthal Short heavy body Massive bones Cro Magnon In Europe 40,000+ yrs Cave art Cared for the elderly Family groups in caves Buried their dead Well made tools They are Us Adapted to cold weather. Extinct 35,000 yrs. neanderthal Cro magnon Direct Ancestor To humans 6.4 Extinction: the dying out of species. Extinction occurs naturally because the environment is always changing. Those individuals unable to survive are naturally removed. There have been 5+ mass extinctions in the earths history, each followed by an explosion of new species that evolved rapidly to fill the empty environment. Endangered species: organisms with so few individuals left they are in danger of extinction. Since the 1500s over 500 species have become extinct in the U.S. alone. There are now 1090 animals 1838+ plants worldwide on the endangered species list. In the States alone there are: 398 animals and 599 plants in immediate danger of becoming extinct. All but 3 are considered to be the result of human action. Based on past rates of extinction, most life scientists agree that we are now in another age of mass extinction. We are changing the environment by our actions.