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Evidence for EVOLUTION Fossils A fossil is the naturally preserved remains or traces of animals or plants that lived in the geologic past. There are two main types of fossils; body and trace. Body fossils include the remains of organisms that were once living and trace fossils are the signs that organisms were present (i.e. footprints, tracks, trails, and burrows). http://imnh.isu.edu/digitalatlas/geo/basics/fossil.htm http://www.ucmp.berkeley.edu/science/trackways/trackways2.php http://www.amnh.org/exhibitions/permanent-exhibitions/fossil-halls/hall-of-ornithischian-dinosaurs/dinosaur-mummy Megalodon fossil record Megalodon lived 10 million years ago Megalodon’s bite force was 41,000lbs compared to TRex’s bite force of 13,000 lbs. http://www.fossilguy.com/gallery/vert/fish-shark/carcharocles/carcharocles.htm Evidence in layers of sediment Sediment is pieces of minerals, plants, animals and other organic matter. Sediment is deposited and compressed over time with the oldest layers being the deepest layers and the newest layers are the layers we see below our feet. Compressed sediment is called rock. Layers of sediment form strata which can be seen in cliffs Fossils have never been discovered in the “wrong” layer. http://www.prehistoricplanet.com/news/index.php?id=48 Homologous structures indicate a common ancestor Vestigial Structures - A feature that an organism inherited from its ancestor but that is now less elaborate and functional than in the ancestor. http://evolution.berkeley.edu/evolibrary/article/0_0_0/lines_05 Embryology – embryos of several different species share similarities. In an early stage of the human embryo a gill slit and a tail is present similar to fish and primates. Note: this image is a simplified artists rendition to convey a complex concept. Putting it all together https://www.youtube.com/watch?v=O21VOcLIb3M https://www.youtube.com/watch?v=lIEoO5KdPvg Charles Darwin Liked to collect and study beetles. Born 2/12/1809 In 1831, went on a 5 year journey on the HMS Beagle as their naturalist. The finch species Darwin studied on the Galapagos Islands were important in developing Darwin’s ideas of natural selection. Darwin’s Influences • Darwin’s ideas were influenced by an essay he read in 1838 that was written by Thomas Malthus titled, “Essay on the Principle of Population.” • Malthus said that in nature, plants, animals and even humans produce more offspring than can survive. He thought that human population growth would lead to an insufficient food supply and thus keep the population in check. • Darwin applied and extended Malthus’ theory to his own. He concluded that variations among offspring would produce some offspring who are better equipped to survive and reproduce in a competitive environment. Darwin’s Influences Cont’d. Darwin struggled with 2 social influences during his time in history. People believed: 1. The Earth was thousands of years old. 2. All species were created at one time and never changed over time. Darwin had, however, observed similarities among species all over the globe. Some of the changes were consistent with changes in locations. This lead him to believe that these species gradually evolved from a common ancestor. Species that developed adaptations that helped them survive in their habitat reproduced and passed the adaptive trait on. Those that did not have the favorable adaptation, failed to reproduce as often and eventually died off. This became know as the theory of NATURAL SELECTION. Darwin also read a book called “Principles of Geology” by Charles Lyell that provided evidence that the Earth was much older than anyone ever thought. This new understanding supported Darwin’s view that evolution is a very slow process in which small changes can accumulate over long periods of time. Alfred Russel Wallace In 1859 Alfred Russel Wallace had reached the same conclusion about evolution as Charles Darwin. Wallace had also gone on an expedition during which he studied many plant and animal species around the world. He wrote a scientific paper and sent it to Darwin for review. Darwin had been holding off on publishing his ideas because he wanted to stockpile an abundance of evidence. Also, he know his ideas may not be accepted due to the prevalent religious social setting of the time. He was astounded to read Wallace’s work and discover that it was almost identical to his own theories. He and Wallace published together, then Darwin published his famous and widely accepted book, “On the Origin of the Species by Means of Natural Selection.” Natural Selection I have called this principle, by which each slight variation, if useful, is preserved, by the term Natural Selection. - Charles Darwin, The Origin of Species Natural Selection is the process by which organisms that are better adapted to their environment survive and reproduce more successfully than less well adapted organisms do. 4 Parts of Natural Selection 1. Overproduction – The environment can’t support unlimited population growth. There will be competition for resources and not all offspring can survive to reproduce. 2. Variation – Each offspring is similar to, but not identical to its parent. Therefore there is variation among offspring. 3. Struggle to Survive - Organisms that are better suited to survive in their environment will live longer and reproduce more. The less well adapted will die off. 4. Heredity – Those organisms with traits that help them survive will reproduce more and pass on those traits through heredity. Eventually the favorable trait will take over the population and the less favorable trait will die off.