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Evolution

Evolution. Ms. Siegel. What is Evolution?. Evolution is the process by which populations change slowly over a period of time. In order for evolution to occur, there must be a genetic variation. Genetic variation is what causes Evolution. Without it, there would not be evolution.

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Evolution

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  1. Evolution Ms. Siegel

  2. What is Evolution? • Evolution is the process by which populations change slowly over a period of time. • In order for evolution to occur, there must be a genetic variation. Genetic variation is what causes Evolution. Without it, there would not be evolution. • The benefit of having genetic variation in a population of organisms is that it increases the species’ chances of survival in a changing environment.

  3. NATURAL SELECTION: A DRIVING FORCE OF EVOLUTION NATURAL SELECTION: Organisms with more beneficial traits are more likely to reproduce successfully, which in turn will pass the beneficial traits on to their offspring. Only the most fit and best adapted organisms survive and reproduce. • For example, there are two giraffes. One giraffe has a longer neck then the other, making it easier for him to eat the leaves high up on the trees. They both eat the leaves at the bottom of the trees, but when those leaves are all gone, the giraffe with the longer neck can still reach food, while the giraffe with a shorter neck cannot. The giraffe with the shorter neck dies from starvation while the giraffe with the longer neck survives and reproduces, passing the long neck gene on to his offspring and so on until the majority of giraffes have this long neck gene.

  4. Natural Selection VS Selective Breeding • Natural Selection happens from natural environmental pressures while Selective Breeding requires human direction • Natural Selection Selective Breeding

  5. Adaptations • Adaptations can also affect evolution in different species. • Over time, animals may change behavior or physical appearance in response to changes in the environment. • EXAMPLES: • A moth’s camouflage • A porcupines quills

  6. Fossils help us learn about the past • Fossils are the preserved remains or traces of organisms that lived in the past. • A species is a group of similar organisms that can mate and produce fertile offspring. • If a species is no longer living, the species is known as extinct. • How can extinction occur? • One way is if the environment changes quickly and the species in that environment has no adaptations to survive in the new conditions.

  7. Fossils and Superposition • The Law of Superposition is a concept related to layers of soil and bedrock in the Earth’s crust that claims that in undisturbed Earth, the layer on the very bottom is the very oldest and the layer on the very top is the newest. By finding fossils in these layers, scientists can determine a relative age for that fossil and when that organism was alive!

  8. TEST YOUR KNOWLEDGE! • The fossil of a tiny mouse is found in a layer of rock above the fossil of a lizard. What can you tell me about the age of the mouse relative to the age of the lizard? • HINT: Is the mouse older or younger then the lizard?

  9. Gradualism VS Punctuated equilibria • GRADUALISM • Gradualism is a theory that suggests that Evolution occurred in steady tiny changes over a long period of time. • PUNCTUATED EQUILIBRIA • Punctuated Equilibria is a theory that suggests that species evolve during short periods of rapid change.

  10. Charles Darwin • Born February 1809 – Died April 1882 • He was a Naturalist, noted for being the father of the Theory of Evolution • His most famous expedition was a 5 year scientific expedition which included the Galapagos Islands from 1831-1835. He and the other scientists traveled on a ship called the HMS Beagle.

  11. DARWIN and the Galapagos • During Darwin's’ 5 year trip around the Galapagos Islands and South America, he inferred that the species of animals he saw on the Galapagos Islands came from the mainland. This is known as speciation. • He spent a lot of time observing a type of bird called a Finch on the Islands. He noted that on each Island, there were different types of Finches all with small differences in their beaks. • Darwin inferred that the Finch’s beaks were adapted to match the types of seeds that were available on the island they were on. Speciation is the process of a new species forming which begins by a portion of a population becoming physically or geographically separated.

  12. Evidence for Evolutionary relationships The following evidence, when combined, help scientists determine the evolutionary relationships among different species. • Fossils • Homologous Structures • Early Development • DNA Sequences • Homologous Structures: structures that are derived from a common ancestor or same evolutionary or developmental origin. • EXAMPLES: Crocodiles, birds, whales, bats, and humans all have forelimbs. They are all used differently, but their basic skeletal structure is the same.

  13. Overproduction • Certain species use overproduction to help ensure their species survives. • An organism has hundreds of offspring and only a few survive to maturity, ensuring survival of the organism. • EXAMPLE: A spider has hundreds of eggs, but only a few may survive to reproduce.

  14. Branching Tree Diagrams • A diagram that shows how scientists believe different groups of organisms are related. • Look at this diagram. • Which are more closely related, Sharks and Whales or Saurischians and Birds?

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