Evolution Among Populations

Evolution Among Populations PowerPoint PPT Presentation

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Evolution occurs on the Genetic Level. Scientists combined Mendel's work with Darwin'sFocused on how populations change (evolve). . Because Members of a Population Interbreed They Share a Common Gene Pool. The combined genetic information of an entire population.. Genetic Evolution. Populations ev

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Evolution Among Populations

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1. Evolution Among Populations Chapter 16

2. Evolution occurs on the Genetic Level Scientists combined Mendel’s work with Darwin’s Focused on how populations change (evolve)

3. Because Members of a Population Interbreed They Share a Common Gene Pool The combined genetic information of an entire population.

4. Genetic Evolution Populations evolve (change) as gene pools change.

6. Variety is key to a population’s ability to adapt Phenotypic variation (looks) is the result of genetic variation. So a bigger gene pool = healthier population

7. Two Main Sources of Genetic Variation: Mutations- newly formed genes made by random changes in DNA Genetic Shuffling from sexual reproduction

8. Natural Selection works to Change a Population’s Gene Pool Genes that produce adaptations become more common. This is known as directional selection.

10. Genetic Drift can lead to loss of Variation in Small Populations Rare genes that can be preserved in large populations are lost in small ones

12. When populations get smaller, the gene pool gets smaller Some genes are completely lost. This is known as the bottleneck effect.

13. Bottleneck Effect Results is a loss in genetic variation. Ex. cheetahs

14. Bottleneck Effect Even if a population recovers (increases in size) it will never be as healthy, because its genetic variation is lost Has less ability to adapt.

16. If a population becomes segregated, it can evolve into two separate species

17. Speciation process by which a new species comes about Requires a portion of the population to become isolated.

18. Isolating Mechanisms Geographic Isolation- population becomes seperated by geographic barriers

19. Isolating Mechanisms Behavioral isolation – groups develop different habits, mating rituals, etc.

20. Isolating Mechanisms Temporal Isolation – groups reproduce at different times

21. Geographic Isolation

23. Speciation Occurs when the two Groups can No Longer Interbreed Isolation means the two groups don’t share genes As a result traits become increasingly different

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