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Genetic Variation & Natural Selection

Genetic Variation & Natural Selection. Brain Pop VIDEO: Natural Selection http://www.brainpop.com/science/ecologyandbehavior/naturalselection/ Brain Pop VIDEO: Charles Darwin http://www.brainpop.com/science/famousscientists/charlesdarwin/ Brain POP VIDEO: Genetic Mutation

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Genetic Variation & Natural Selection

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  1. Genetic Variation & Natural Selection Brain Pop VIDEO: Natural Selection http://www.brainpop.com/science/ecologyandbehavior/naturalselection/ Brain Pop VIDEO: Charles Darwin http://www.brainpop.com/science/famousscientists/charlesdarwin/ Brain POP VIDEO: Genetic Mutation http://www.brainpop.com/health/geneticsgrowthanddevelopment/geneticmutations/

  2. Organisms thrive in the environments for which they are best suited. • All bears belong to the same species, but you wouldn’t find a polar bear in Georgia or a black bear in Alaska.

  3. Genetic Variation • A population is the number of a specific species of organisms in a specific place. • The assortment of genes in a population is its genetic variation.

  4. Genetic Variation • Genetic variation in a population can increase in different ways. • One way is through mutation. • A mutation is a change in a gene or a chromosome.

  5. Genetic Variation • Since a mutation changes an organism’s DNA, that mutation can be passed on to the next generation. • A beneficial mutation helps an organism thrive and reproduce (leading to the passing of desirable traits). • A harmful mutation keeps an organism from thriving and reproducing (causes undesirable traits to not be passed on).

  6. Natural Selection • Most organisms produce more offspring than are able to survive. • This results in competition for resources, such as food and living space.

  7. Natural Selection • Although the offspring are similar, some will have variations that help them to survive in a particular environment. Those that are unsuccessful at competition die. Those with favorable variations produce favorable variations on to their offspring. • Over time, favorable variations are found in more and more organisms.

  8. Natural Selection • Adaptations are inherited traits that increase an organisms chances of survival. • They include structures, functions, and behaviors. • Sometimes changes in the environment may cause adaptations (changes) in organisms over time.

  9. Natural Selection • Natural selection can result in small changes over time. • It can also result in very large changes and in the formation of new species from existing species.

  10. Extinction • Extinction is the death of all members of a species. • Species may become extinct when they cannot survive changing conditions or can’t compete with new or different species.

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