biology ii - evolution and natural selection review

8/10/2019 Biology II - Evolution and Natural Selection Review

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Darwins Dangerous IdeasAnother Review

Evolution & Natural Selection


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Basic Definitions

Evolution: the process of change over time

evolution is a change in the genetic makeup of apopulation of interbreeding individuals within aspecies.

Natural Selection: survival of the fittest

the process whereby some organisms in aspecies have certain inherited variations thatgive them an advantage over others.


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Species have changed through

time and are related by descent

from a common ancestor

The primary mechanism ofEvolutionary Change is Natural

Selection

Darwins Theory of Evolution

by Natural Selection


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1. Individualswithin apopulation orspecies show

variation insome features

2. There ishereditary

similaritybetweenparents andtheir offspring

Darwin provided a mechanism for

evolutionary changeNatural Selection


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3. In every

generation, more

offspring will be

produced thancan survive

4. Each variant has

a characteristicsurvival and/or

reproductive

success

An individuals abilityto survive and

reproduce

is called fitness

1 starfish has 1079offspring

in 16 years

Darwin provided a mechanism for

evolutionary change --> Natural Selection


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If the above four things are met, and

the environment remains constant, thecomposition of the species will tend

towards an increase of the variant with

the highest reproductive success.


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Can selection produce evolutionary change?

Hypothesis: Natural selection is the primarymechanism through which organisms have

evolved over long periods of time

Prediction: selection can lead to small

evolutionary changes in short periods of time

-example - artificial selection

-direct observations:Biston moths,

antibiotic resistance in bacteria,

herbicide resistance in weeds


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Artificial Selectionan example


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Biston Moths: a Classic ExampleSelection in peppered moths in

England by Kettlewell

2 genetically determined types:

black & mottled white

Prior to 1700 (industrial revolution)

black form approximately 1%

white form approximately 99%

After 1700 (widespread pollution, smoke and soot)

black form approximately 90%

white form approximately 10%

Now (local pollution from smokestacks)

Near Pollution Away

black form 50% 10%

white form 50% 90%


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Implications of Natural Selection

Natural selection acts on individuals, but itsconsequences occur in populations

Natural Selection Acts on Individuals, butEvolution consists of changes in gene

frequencies

Natural Selection is backward-looking,

not forward looking


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Implications of Natural Selection

Natural Selection acts on existing traits

Natural Selection does not have a goal

nor is it "progressive

Natural Selection acts on individuals,

not groups


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The idea of evolution was developed from many

observations of life over the centuries.

It has been tested and challenged many times and

in many ways, and has survived in great shape.

There is NO observed evidence against evolution.

Evolution therefore holds the high status of near

certainty.


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Discussion Question:

Are humans still evolving?


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CommonMisperception:

And now there go the Wilsons!... Seems

Like everyones evolving except us!

Individualsevolve


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Acquired characteristicsare not inherited!

Common Misperception:


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Timmy & Gobbles


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Classroom Assignment:

Building a More Perfect HumanI want you to think about how the human

body has evolved over time, and how it

might have evolved better.

- Today you are in charge of the world,and you have to think about ways to

make the human species better.


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Building a More Perfect Human

Address Six Characteristics of Humansthat you think should be improved

Design a new human, describing your siximprovements in detail, writing a shortparagraph for each improvement

Draw me a picture of your perfect beast


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OK, Any Questions So Far?

If not, get to work on your perfect human

biology ii - evolution and natural selection review

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