OTHER MECHANISMS FOR EVOLUTION

1/23/20

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DO NOW▸ Identify what is wrong with the following

statement:

▸ “Polar bears evolved to become white because they needed to be camouflaged with the white snow to ensure successful hunting”

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GENETIC DRIFT ROLES▸ In your group decide who will do what.

1. Drift Picker (This Person will without looking pick 6 M&Ms out of the cup and put them on the paper towel.

2. One Person is the Counter (count the number of colored M&Ms.

3. One Person will work with the counter and Record the Data on to the lab data chart

4. One Person will Convert the data into a Percent (%) (Equation= # of colors divided by the total # of the population, Then Multiple by 100)

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GENETIC DRIFT ACTIVITY ▸ Step 1: DO NOT Eat M&M’s It will throw off your data.

▸ Step 2: WITHOUT LOOKING Drift Picker remove 6 M&M’s and place them on the paper towel; this represents the genetic drift population.

▸ Step 3: Data Recorder will Record all the necessary information for the genetic drift population.

▸ Step 4: Only after you have recorded all the info for the genetic drift population, empty the rest of the cup and record the necessary information for the original population. The 6 M&M's you removed are included in the original population data.

▸ Step 5: Together. Enjoy your M&M’s as you answer all post lab questions!

***(% Convert Equation= # of colors divided by the total # of the population (M&Ms), Then Multiple by 100)

AGENDA

▸ Pass back work/quizzes

▸ Gene flow and genetic drift

▸ Summary

GENE FLOW & GENETIC DRIFTCORNELL NOTES TITLE (PAGE 11)

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GENES▸ Determines the trait or characteristic of an

organism (DNA)

▸ Is passed down from parent to offspring

ALLELES▸ Different forms of a gene

▸ Example: gene - fur color; alleles - light fur, tan fur, dark fur

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ALLELE FREQUENCY▸ Incidence of an allele in a population

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GENETIC DIVERSITY▸ Variation of genes within a population

▸ The more genetically diverse a population is, the higher its chances of evolving with changing environments

▸ Low genetic variation puts a population at risk for extinction or population decline

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EVOLUTION CAN OCCUR THROUGH OTHER MEANS▸ Gene Flow

▸ Genetic Drift

▸ *Natural selection is not the only way evolution can occur

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GENE FLOW

GENE FLOW▸ Movement of genes from

one population to another population

▸ Changes the allele frequency of both populations

▸ Reduces differences between populations

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GENETIC DRIFT

GENETIC DRIFT

DRIFTMoving Slow

Aimless (without direction)

GENETIC DRIFT▸ Random changes in allele frequency in a

population

▸ This process is RANDOM, not influenced by adaptation

▸ 2 cases: Founder effect & Bottleneck effect

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FOUNDER EFFECT▸ Small population breaks off from the bigger

population and moves to a new habitat

▸ These individuals will become the “founders”

▸ Leads to DECREASED genetic diversityWHY?

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BOTTLENECK EFFECT▸ Drastic decrease in population size due to a

natural disaster or widespread disease

▸ Leads to DECREASED genetic diversityWHY?

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OVERVIEW

GENETIC DRIFT

▸ https://www.youtube.com/watch?v=W0TM4LQmoZY

ILLUSTRATIVE SUMMARYPAGE 10 (UNDER DO NOW)

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ILLUSTRATIVE SUMMARY

ALL TERMS must be included

If you do a flow chart, you must explain the connections

Use at least 4 colors

Label as necessary

HOMEWORK