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Evolution CHANGE OVER TIME Evolution Refers to the process through which species change over time This change results from a change in the genetic material of an organism and is passed from one generation to another Influential Scientists JEAN BAPTISTE DE LAMARCK C H A R L E S DA RW IN Jean Baptiste de Lamarck (1744-1829) Believed that the fossil record showed that the species had changed over time Around 1800, he proposed that an organism could ACQUIRE a new trait during its lifetime and then pass that trait on to its offspring Unfortunately he was unable to provide evidence to support this theory Jean Baptiste de Lamarck Inheritance of Acquired Characteristics Charles Darwin (1809 - 1882) W H O WA S C H A R L E S D A R W I N ? H T T P : / / W W W. Y O U T U B E . C O M / WAT C H ? V = W V 9 O L U E R YM0 Schooling Shrewsbury Grammar School Studied medicine at Christ's College, Cambridge University Witnessed surgery on a child…quit medicine Edinburgh Studies botany with Professor Henslow Wants to become a clergyman/naturalist like Henslow The Voyage Reverend John Henslow and George Peacock invite him to be the Naturalist aboard the H.M.S. Beagle Would survey South America Charles Darwin After the trip, he came up with the modern theory of evolution, using his research from the 18 different Galapagos Islands He found that plants and animals not only differed from those he saw on the mainland, but some differed from island to island On The Origin of Species Collected massive amounts of data while on his trip (3 volumes of 1,000 pages a piece) Did not publish his book for 20 years For fear of how people would react Answer the following question Why is Charles Darwin important? Restate the question in your answer. Darwin’s Tortoises Darwin’s Tortoises Tortoises: Darwin noticed that tortoises with short necks were living in damp areas with abundant plant life that grew close to the ground. Longer necked tortoises were living in dry areas with cacti. He considered whether the lengths of their necks made it possible for the tortoises to live in different environments. Darwin’s Finches Darwin’s Finches Among the different islands he noticed a variety of beak shapes and sizes. Some finches had heavy, short beaks useful for pecking trees or seeds, while others had small, thin beaks that could be used for capturing insects. These observations cause Darwin to wonder if the birds had evolved from similar species. Bird's Beaks How did tortoises and birds differ among the islands of the Galapagos? • competitive exclusion = adaptation = speciation Each island had its own type of tortoises and birds that were clearly different from other islands SPECIATION The Formation of A New Species: portion of gene pool becomes isolated; process of generating new species the accumulation of changes may separate a population into distinct groups Speciation These squirrels live on opposite sides of the Grand Canyon. This is an example of geographic speciation. Speciation in Darwin’s Finches Speciation in the Galapagos occurred by: - Geographic Isolation which led to - Reproductive Isolation and - Changes in the gene pool driven by - Competition. Natural Selection Natural Selection Natural Selection: This is a process by which members of a species that are best suited to their environment survive and reproduce at a higher rate than other members of species “Survival of the fittest.” Natural Selection Darwin came up with this theory of Natural Selection based on 4 key principles: 1. 2. 3. 4. overproduction variation adaptation selection Principles of Natural Selection Overproduction: When a plant or animal reproduces, it usually makes more offspring than the environment can support Principles of Natural Selection Variation: Within a species there are natural differences in traits among individuals Principles of Natural Selection Mutation: • a change in genetic material causing a new variation to come about which can be passed to the next generation BrainPOP - Genetic Mutations Principles of Natural Selection Adaptation: any inherited trait that gives an organism an advantage in its particular environment Principles of Natural Selection Selection: Individual organisms with a particular adaptation that are most likely to survive long enough to reproduce will pass this adaptation to the next generation. As this process repeats from generation to generation, more members of a species show the adaptation; the species is evolving over time Artificial Selection Outside forces guiding selection of desired traits. Nature provides variation then humans select upon specific variations. Ex: A farmer breeds only his best livestock Evidence Supporting the Theory of Evolution Theory: A widely accepted statement based on scientific evidence that helps explain a group of facts Evidence Supporting the Theory of Evolution 1. B I O LO G I C A L E VO LU T I O N Genetic Evidence 2. G EO LO G I C A L E VO LU T I O N Fossil Record Evidence Supporting the Theory of Evolution Biological (Organic)Evolution: genetic change in a population of organisms the change over time in the proportion of individual organisms differing in one or more inherited traits Biological Evidence Similarities in Structure: Vestigial Structures: physical structures that were fully developed and functional in an ancestral group of organisms but are reduced and unused in the later species. Ex: Snakes have traces of leg-like structures, whales also have small leg-like structures that are not used Biological Evidence Similar Structure, Different Function: Many species share similar structures but the structures have different functions Ex: lizards, bats, and manatees have forelimbs that have a similar bone structure but they are all used in different ways Biological Evidence Biological Evidence Similarities in Development Various animals look similar in their earliest stages of life Biological Evidence Genetic Evidence DNA is the genetic material found in all organisms DNA contains the information all organisms need to grow and to maintain themselves When an organism reproduces they pass their DNA on to their offspring Genetic Evidence Scientists are able to tell how closely organisms are related by comparing their DNA