Transcript EVOLUTION
WHAT EVIDENCE DO WE HAVE TO SUPPORT THE IDEA OF EVOLUTION BY NATURAL SELECTION? FOSSILS any remains of life from an earlier time and the most abundant evidence for evolution Sedimentary rock contains the most fossils and is formed from mud, sand, and other fine particles How do scientists figure out how old something is? Relative Dating — looking at where the rock is located. Older layers are deeper than the layers above. This method only provides an estimated age of a fossil. How do scientists figure out how old something is? Radioactive Dating —measuring how a radioactive element in the fossil (like Carbon or Uranium) has decayed. They compare the amount of stable rock to amount of radioactive element still present. Not the same kind of dating… http://www.pbs.org/wgbh/evolution/library/03/4/l_034_05.html Fossils document how organisms changed over time, but much of the fossil record is missing or incomplete (like a book with pages ripped out)! Fossil Hunting on the Galapagos THERE ARE DIFFERENT KINDS OF FOSSILS…AND DIFFERENT WAYS THAT FOSSILS CAN FORM… Amber Fossils Fossils that are hardened in tree sap… Prehistoric termites trapped in amber Lizard in Amber Frog in Amber Bones… Frozen in ice or permafrost… Woolly Mammoths When do humans “show up” on the planet? Additional Video Clips Geologic Time by Brainpop Fossils by Brainpop Fossils Adv. by Brainpop HOMOLOGOUS STRUCTURES body parts that are similar in origin and structure. Example: arms, dolphin fin, bat wing, bird wing VESTIGIAL STRUCTURES A body part that is reduced in size and does not seem to have a function. Examples: human appendix, wisdom teeth and muscles that are for moving the ears. EMBRYOLOGY study of the development of embryos (an organism in its earliest stages of development). Examples: gills and tailbones in humans What similarities do you see between these embryos? COMPARING DNA CODES the closer the DNA sequences are in organisms, the more closely related they are. Example: DNA has shown that dogs are the closest relatives of bears. Human’s closest relatives are from the ape family. Cousins? Example: Humans are most closely related (99.9%) to chimpanzees. http://www.pbs.org/wgbh/evolution/library/03/4/l_034_05.html Other Video Clips Woolly Mammoths Elephant Evolution WHAT CONCLUSIONS CAN BE DRAWN FROM THESE CONCEPTS? DIVERSITY over millions of years, the process of natural selection has created all the different life forms on Earth. Scientists estimate anywhere from 5 million to 100 million species on the planet, but have only identified about 2 million. DIVERSITY CLICK HERE FOR A BIODIVERSITY INTERACTIVE MAP: http://www.biodiversityho tspots.org/xp/Hotspots/p ages/map.aspx RELATEDNESS since species evolve from one to the other, there is always a degree of similarity between them. Generally, the more closely related they are, the more recently they evolved or separated into distinct species. All species are connected on earth because they all share some level of DNA. RELATEDNESS RELATEDNESS TREE OF LIFE WEB PROJECT: http://tolweb.org/tree/ EXTINCTION occurs when an entire species dies out Due to a change in the environment without time to adapt/evolve to survive in it EXTINCTION BY BRAINPOP