EVOLUTION

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Evolution

• In the broadest sense, it simply means

“CHANGE”

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EvolutionEvolution

• Change in what?

More specifically, biological evolution is a

“change in the genetic composition of a population of organisms from one generation to the next”.

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Evolution

• “Nothing in biology makes sense, except in the light of evolution”

………Theodosius Dobzhansky

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• Some things in biology seem a bit bizarre until examined in the light of evolution, ---- then it makes sense.

• Let’s examine a few instances and later we’ll see how the activity might be explained……….

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A pride of lions

Lion with dead cub

This male lion has just killed a lion cub

Why?

Ant/Fungus

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Peacocks and Peahens

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QUESTIONS ABOUT LIFE

Where to living things come from?

Why are there so many different kinds of organisms on earth? Why do so many of them resemble others?

How have these organisms become so good at finding food, mates, fighting disease and predators, producing offspring?

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Special Creation

• Has also been called:

• “Creation Science” or

“Intelligent Design Theory”

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SPECIAL CREATIONSPECIAL CREATION(“Intelligent Design Theory”)

1. All species (as well as this earth they

inhabit) were created recently (about 6000 yrs ago).

2. Species were created independently of one another.

3. Species do not change through time.

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What about the age of the earth?

Catastrophism -

Past geological upheaveals, like Noah’s Flood, are sufficient to explain existing geological features. The earth is roughly 6000 years old.

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Geological evidenceGradualists – like James Hutton andSir Charles Lyell (founder of Geology,pictured at the left) argued instead that….slow, cumulative action of everydayprocesses like sedimentation and erosionwere sufficient to explain geologicalfeatures. These processes came to beknown as uniformitarianism.

Their Conclusion:The earth was not created recently, it is very, very, very old!

1797 - 1875

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How old is the earth and has it really changed ?

Hutton and his followers put together the geologic time table using relative dating.

The actual dates were later determined using radiometric dating. The earth is approximately 4.5 billion years old!!

We now believe the earth has been changing ever since it was formed through processes such as continental drift.

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If the earth itself has changed, have living organisms changed?

Evidence:

Direct observation:

There have been many studies, such as those by Peter and Rosemary Grant who’ve studied Darwin’s finches now for more than 30 years, and have witnessed further evolution here.

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If the earth itself has changed, have living organisms changed?

Evidence: Direct observation Vestigial structures:

- human appendix, or

tailbone (coccyx)

- lungs and pelvis in

whales

- eye sockets in blind

fish (Mexican tetra)

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If the earth itself has changed, have living organisms changed?

Evidence: Direct Observation Vestigial Structures Fossil Record:

- extinction

It is estimated that 99% of all species that have ever existed on this earth are now extinct.

The most probable likely happenstance for the human race is extinction.

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If the earth itself has changed, have living organisms changed?

Evidence: Direct Observation Vestigial Structures Fossil Record

- extinction

- succession -

some of these are

transitional forms

(e.g., Archaeopteryx

a reptile with wings)

If the earth itself has changed, have living organisms changed?

Evidence: Direct Observation Vestigial Structures Fossil Record

- extinction

- succession Homologies:

-structural -

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If the earth itself has changed, have living organisms changed?

Evidence: Direct Observation Vestigial Structures Fossil Record

- extinction

- succession Homologies

- structural

- molecular- [see next slide]

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• Living things have, and continue to, change!

• This is EVOLUTION.

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--Materialism--

• A doctrine that states that observations are to be explained in relation to the action of observable processes….NOT spiritual forces.

- Galileo Galilei was one of the first to

employ this doctrine.

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What about Darwin?

Charles R. Darwincirca 1832

Darwin published “On The Origin of Species by Means of Natural Selection” in 1859.

…… outlining the fact that evolution was occurring.

….. proposing “Natural Selection” as the mechanism of evolution.

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“Evolution by Natural Selection”

• This is Darwin’s theory!

• Evolution has occurred by “descent with modification”. All living organisms have descended from a common ancestor.

• Darwins’s theory has 4 postulates:

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Evolution by Natural Selection

1. Individuals within populations vary.

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Evolution by Natural Selection

2. The variation among individuals is, at least in part,

…..inherited

(passed

on from parent to offspring).

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Evolution by Natural Selection

3. In every generation, some individuals are more successful at surviving and reproducing than others.

Reproductive Potential____________________________________________

Elephant 19 million in 750 years Starfish 1079 in 16 years

Housefly 191x1018 in 5 months Staph. aureus cells would cover the

earth 7 ft deep in 48 hours

Evolution by Natural Selection

4. Survival and reproduction are NOT random; individuals with variations that are better at surviving and reproducing are selected. These individuals, in turn, pass those inherited variations on to their offspring and so on.

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Darwin Claimed Fitness was

• The ability of an individual to survive and reproduce in its environment.

• Darwin emphasized ‘differential reproduction’.

• He did not use the phrase, “survival of the fittest”, which should probably be restated as, “survival of the fit enough”.

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What is fit enough?

• Old Serengeti proverb………..

Every morning in Africa a gazelle wakes up. It knows it must run faster than the fastest lion or it will be killed. Every morning a lion wakes up. It knows that it must outrun the slowest gazelle or it will starve to death. It doesn’t matter whether you are a lion or a gazelle, when the Sun comes up, you’d better be running.

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What is differential reproduction?

BirdMatestwice

HasSix eggs

One Lives

BirdMates4 times

NoneLive

HasFourEggs

BirdMatesOnce

Has Two Eggs

TwoLive

Differential Reproduction

Grow toadults

Growtoadult

Mate andProduce6 eggs

AllSurviveto adult

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How does differential reproduction result in evolution?

• It causes changes in the genetic composition of a population from one generation to the next.

• How does it do that?

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Suppose we have a small population (40) or rabbits in a field

and one (1) fox.Let’s assume these rabbits have different colored coats as

shown below:

Color: Black Brown WhiteNumber: 12 24 4Gene type: (BB) (Bb) (bb)

How many “B” genes are there? 12x2+24 = 48 (60%)

How many “b” genes are there? 4x2+24 = 32 (40%)

The fox kills all white rabbits and 25% of the brown and black rabbits

• Remaining are:

Color: Black Brown WhiteNumber: 9 18 0 Gene Type: BB Bb bb

How many “B” genes are left? 9x2+18 = 36 (66%)How many “b” genes are left? 0x2+18 = 18 (33%)

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Gene Frequencies Change

• The frequency of the “B” gene changed from 60% to 66%.

• The frequency of the “b” gene changed from 40% to 33%.

• Here we see a “change in the genetic composition of a population (of rabbits) from one generation to the next”.

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The Process of Natural Selection is NOT goal directed.

• The process of Natural Selection merely ensures that individuals become better adapted to their environment.

• Those that are better adapted live longer, producing more offspring than others. These offspring, because they are carrying the genes that improved their parents fitness, also live longer and have more offspring.

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What is the goal of individuals?

• While Natural Selection isn’t goal-directed, all living organisms behave as if they have an individual goal……

• TO GET AS MANY OF THEIR GENES AS POSSIBLE INTO INDIVIDUALS IN THE NEXT GENERATION…

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How to win the evolutionary race?

• Have as many offspring as possible that have offspring!

• in other words…..

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“The one with the most grandkids WINS!!”

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