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To be successful today…

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Presentation on theme: "To be successful today…"— Presentation transcript:

1 To be successful today…
Pick up graded work from blue table in lab Pull out Biology notebook BYOD Color of the day is Phones are in put away in backpacks

2 Is this population evolving?
What do you think? Is this population evolving?

3 This population IS evolving
Allele frequency changes from one generation to the next

4 Mechanisms of Evolution

5 Evolution is the change in allele frequency
Remember…evolution occurs Over time In populations…NOT individuals On phenotypes

6 Two Main Sources of Genetic Variation
1) Mutations 2) Gene Shuffling

7 1) Mutations Caused by mistakes during replication
Any change in a sequence of DNA. Caused by mistakes during replication

8 2) Gene Shuffling ~ Mixing of genes during the production of gametes in meiosis

9 How Does Variety Arise? Video
2) Gene Shuffling Recombination as homologous chromosomes move independently during meiosis Crossing over: the exchange of genetic material during prophase I How Does Variety Arise? Video

10 Gene Pool & Allelic Frequency
Gene Pool: Entire collection of all the alleles in a population Allelic Frequency: The number of times an allele appears in the gene pool

11 Gene Pool & Allelic Frequency
Gene Pool: 12 green alleles and 8 brown alleles Allelic Frequency of green: 12/20 Allelic Frequency of brown: 8/20

12 Evolution is the change in allele frequency
Occurs in one of three ways: Gene Flow Genetic Drift Natural Selection

13 1) Gene Flow ~ The movement of alleles into or out of a population
Can increase or decrease genetic variation

14 2. Genetic Drift Random change in allelic frequencies due to chance.
Decreases genetic variation

15 Types of Genetic Drift Founder Effect ~ A small group of individuals colonize a new habitat

16 Types of Genetic Drift Bottleneck ~ a sharp reduction in the size of a population due to environmental events (flooding, earthquake, etc.)

17 3) Natural Selection Decreases genetic variation
~ Most common source of evolutionary change Decreases genetic variation

18 Main Mechanisms of Evolution Video


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