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Bellwork: Mon. Feb. 13, 2017 From – Video “Extinction” 1. What is a mass extinction? 2. There have been ____ mass extinctions on Earth? 3. Scientists think we are in the ____ mass extinction because__________________________ __________________________________________ occurs when more individuals are born than can survive. Those with the best traits pass them on. There is a struggle for existence – competition for resources http://www.youtube.com/watch?v=mPTf3DHmHe4 Darwin knew that individuals have natural Variations: differences among their heritable traits, and he hypothesized that some of those variants are better suited to life in their environment than others. Adaptation: Any heritable characteristic that increases an organism’s ability to survive and reproduce in its environment Pinta Pinta Island Tower Marchena Giant Tortoises of the Galápagos Islands Intermediate shell James Fernandina Santa Cruz Isabela Santa Fe Hood Island Floreana Isabela Island Hood Saddle-backed shell http://www.youtube.com/watch?v=uakRR7a2f3w Dome-shaped shell “The inhabitants...state that they can distinguish the tortoise from different islands; and that they differ not only in size, but in other characters. Captain Porter has described those from Charles and from the nearest island to it, namely Hood Island, as having their shells in front thick and turned up like a Spanish saddle, whilst the tortoises from James Island are rounder, blacker, and have a better taste when cooked.” Charles Darwin 1845 Adaptations can involve: 1. Body parts or structures: like a tiger’s claws; length of body… 2. Colors: Those that make camouflage or mimicry possible 3. Physiological functions, like the way a plant carries out photosynthesis. Fitness describes how well an organism can survive and reproduce in its environment. Individuals with adaptations well-suited to their environment can survive and reproduce = high fitness. Individuals with characteristics not well-suited to their environment either die without reproducing or leave few offspring = low fitness. This difference in rates of survival and reproduction is called survival of the fittest. Darwin named his mechanism for evolution natural selection because of its similarities to artificial selection. Natural selection is the process by which organisms with variations most suited to their local environment survive and leave more offspring. In natural selection, the environment—not a farmer or animal breeder—influences fitness – if that happens it is called artificial selection From generation to generation, populations change - they become better adapted as their environment changes. Natural selection acts on inherited traits - those are the only characteristics that parents can pass on to their offspring. This hypothetical population of grasshoppers changes over time as a result of natural selection. Grasshoppers can lay more than 200 eggs at a time, but only a small fraction of these offspring survive to reproduce. variations, called adaptations, increase an individual’s chances of surviving and reproducing. variation = yellow and green body color. Green color is an adaptation: The green grasshoppers blend into their environment and so are less visible to predators. Because their color serves as a camouflage adaptation, green grasshoppers have higher fitness and so survive and reproduce more often than yellow grasshoppers do. Green grasshoppers become more common than yellow grasshoppers in this population over time because more grasshoppers are born than can survive, individuals vary in color and color is a heritable trait, and green grasshoppers have higher fitness in this particular environment does not make organisms “better.” Adaptations don’t have to be perfect—just good enough to enable an organism to pass its genes to the next generation. doesn’t move in a fixed direction. There is no perfect way of doing something. Natural selection is just a process that enables organisms to survive and reproduce in a local environment. If local environmental conditions change, some traits that were once adaptive may no longer be useful, and different traits may become adaptive. If environmental conditions change faster than a species can adapt to those changes, the species may become extinct. http://www.youtube.com/watch?v=WbW8GgAWKi8&feature=fvst Darwin based his explanation for the diversity of life on the idea that species change over time. “A single ‘tree of life’ links all living things…” 1 on the chart represents a “Common Ancestor” an ancestor from which all the others descended Natural selection produces organisms that have different structures, establish different niches, or occupy different habitats. descent with modification: Darwin theorized that each living species has descended, with changes, from other species over time. http://www.youtube.com/watch?v=_ksdV9HPwBY Bellwork: Tues. Feb. 14, 2017 Name as many Evidences of Evolution you can think of (look in your notes): 1 2 3 4 5 6 Evidences of Evolution 1. Fossil Record 2. Geographical Distribution: Plate Tectonics (Biogeography) 3. Transitional Forms: Homologous Structures/ Analogous /Structures/Vestigial Structures 4. Embryology 5. Genetics and Molecular Biology – DNA: hox Genes - major control genes every organism has 6. Molecular Clock: constant mutation rates Pre-Registration info.: Freshmen < D in Algebra = Environmental Science > C in Algebra = Physics > C in Geometry = pre-AP Physics Sophomores < D in Algebra = Chemistry Essentials > C in Algebra (with intent to register in Algebra II) = Chemistry > C in Algebra (with intent to register in Intermediate Algebra) = Chemistry Essentials > C in Algebra II = pre-AP Chemistry Relative age: Law of Superposition in a sequence of undeformed sedimentary rocks the oldest beds are at the bottom and the youngest ones are at the top 1. layers were originally deposited horizontally 2. the beds are not overturned (sedimentary structures can be used to determine whether a sedimentary succession is overturned or not). Which layer is the oldest here? Other Scientists Many scientists recognize that Earth is millions of years old and things (like earthquakes and erosion) that changed Earth in the past are still doing so today. Like Hutton and Lyell Charles Lyell in “Principles of Geology” stressed that scientists explain past events in terms they can actually observe. James Hutton’s the idea of: uniformitarianism: that the earth was shaped by slow-moving forces still in operation today. think of Haiti living things have changed over time. all species were descended from other species. organisms were adapted to their environments. Lamark: (Giraffe Neck Theory) selective use or disuse of organs - organisms acquired or lost certain traits during their lifetime – which could then be passed on to their offspring. Lamarck’s hypotheses of evolution are incorrect in several ways: Lamarck did not know: how traits are inherited (DNA) that an organism’s behavior has no effect on its heritable characteristics. But he paved the way for discoveries of later biologists. As in the study of epigenetics today The idea that phenotype (or gene expression – remember protein synthesis?) can be caused by mechanisms other than changes in DNA sequence Copyright Pearson Prentice Hall http://news.nationalgeog raphic.com/news/2011/0 1/110118-oldestdomestic-dogs-northamerica-eaten-texascave-science-animals/ Darwin noted that plant and animal breeders would breed only the largest hogs, the fastest horses, or the cows that produced the most milk. He called this process: Artificial selection: selection by humans for breeding of useful traits from the natural variation among different organisms. Compare it to: Natural Selection: Process where individuals better suited to their environment survive and reproduce most successfully Copyright Pearson Prentice Hall Copyright Pearson Prentice Hall Cocoa Bean and Clyde Animal mutations and structural variations – one of the first to come up with the idea of Master (or hox) Genes Hint words: partial word bank (look for the rest of the terms in your notes) Relative dating Radiometric dating Half-Life Geologic Time Scale Cenozoic erz Precambriam Era Mesozoic Era Transitional forms: Fossils or organisms that show the intermediate states between an ancestral form and that of its descendants. Common Ancestor: Proposed ancestor from which other organisms evolved http://evolution.berkeley.edu/evolibrary/news/060501_tikt aalik Transitional forms: Fossils or organisms that show the intermediate states between an ancestral form and that of its descendants are referred to as transitional forms. Bellwork: Thurs. Feb. 14, 2013 1. A tetrapod is any 2. The “Cambrian Explosion” is when