Evolution POWERPOINT

Evolution

2

Definition

•

1. Evolution

is… the slow,

gradual

change in a

population of

organisms

• 2.

Populations evolve

over many

generations

,

not individuals

•Populations are groups of interbreeding

individuals that live in the same place at

the same time

Changes in Gene Frequency

3.

Evolution only happens when there is a change in the gene frequency within a population over time.

• When the frequency of

genes within the gene pool

change, so will the

population of organisms.

• This eventually leads to

Long-term change in the population

History of

Evolutionary

Lamarck’s Theory of

Evolution

 4. Jean-Baptiste

Lamarck, 1809, was one of the first scientists to understand that

Change

Occurs Over Time

 5. He believed that

changes were adaptations

to the environment that organism’s acquired in their lifetime

 He thought that acquired

What are “Acquired” Traits?

Lamarck’s Theory of

Evolution, continued…



Inheritance of Acquired

Characteristics



Lamarck proposed that by

selective “Use or Disuse” of

organs, organisms either

acquired or lost certain traits

during their lifetime

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Lamarck’s Theory of

Evolution



Use & Disuse -

Examples

– Blacksmith’s Arms

(muscular arms)

» Sons would have Muscular arms too

– 6. Giraffe’s Necks

(Longer from stretching)

» Offspring would

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Lamarck’s Theory of

Evolution



Inheritance Of Acquired Traits

– Traits Acquired During Ones Lifetime Would Be Passed To Offspring

Lamarck’s Mistakes



7. Lamarck Did NOT know

how traits were inherited

through genes

*Genes Are NOT

Changed By Activities

In Life

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Charles Darwin:

Voyage of the Beagle

8. Charles Darwin

 Born Feb. 12, 1809  In 1831 he joined the

crew of the HMS Beagle as the ship’s Naturalist

 This was a 5 Year voyage

around the world

 Avid Collector of Flora and

Fauna

 Darwin was astounded by

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Darwin Left England in 1831

The Galapagos Islands

 Volcanic islands off the

coast of South America with very different

climates

 Island species varied

from mainland species & from island-to-island

species

 Animals On Islands

Unique

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9. Darwin’s Observations

 A. Patterns of

Diversity were shown

 B. Unique

Adaptations in organisms

 C. Species Not

Evenly Distributed

» Australia has Kangaroos

Darwin’s Observations

 10. Left unchecked,

the number of

organisms of each species will increase exponentially,

generation to generation

 In nature, populations

tend to remain stable in size

 Environmental

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Darwin’s Conclusion

•

11. Production of

more individuals than

can be supported by

the environment leads

to a

struggle for

existence

among

individuals

•

Only a

fraction

of

offspring

survive

each

generation

Darwin’s Observations

• 12. Individuals of a population compare with each other by…

• varying extensively in their characteristics

• with no two individuals being exactly alike.

•

13. Much of this

variation

between

individuals in a

population is

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Darwin’s Conclusion

• 14. Which organisms in a population are most

likely to leave offspring to pass on their traits?

Individuals who inherited

characteristics most fit for their

environment

• 15. This process is

called Natural Selection

and was proposed by

•

The

unequal ability of individuals to

survive and reproduce

leads to a gradual

change in a population, with favorable

characteristics accumulating over

generations

(natural selection)

16.

Darwin’s

Theory

of

STOP HERE TODAY

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18. Mechanisms of Change



Mutation



Migration



Genetic Drift

19. Mutations

 Can occur during

DNA replication and/or

transcription

 If it benefits an

organism that trait will survive in the gene pool.

 Most mutations are

harmful and are eliminated.

 Everyone has 7-10

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20. Migration

 21. Migration is the

movement of

populations, groups or individuals.

– Immigration = coming in – Emigration = going out

 22. In genetic terms,

migration enables gene flow: the movement of genes from one

23. Genetic Drift

 An allele or change

in DNA can become more or less

common simply by

chance

 Entirely random

process

 Genetic drift =

– a change in the allele frequencies in small

populations that cause a certain

phenotype (look) to become most

Example = Big cats in Asian forests

24. Natural Selection

 The driving force of

evolution

 During the struggle for

resources, only the “strongest” individuals

survive & reproduce

 some of the

differences between individuals, which

impact their survival

and fertility, are

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25. Natural Selection

 4 simple

components 1) Variation 2) Environmental Challenge 3) Differential Reproduction

» More offspring produced than

Processes Continued

4) Heredity



Final Result

Brown beetles pass on their genetic info

Brown colored beetle survived and

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Survival of the Fittest?



26. What does “fitness” mean?

– Doesn’t necessarily mean the

strongest, fastest, or biggest!

– It means…

» Ability to survive

» Find a mate

» Produce offspring



27. Adaptation-

has become common in a population because

Survival of the Fittest



28. Three types of

adaptations can be:

1. Physical

» Speed, Camouflage, Claws, Quills, etc.

Types of Adaptations,

continued

2. Behavioral

» Grouping: Solitary, Herds, Packs, etc…

» Social and Courtship Activity

Types of Adaptations,

continued

3. Physiological

“adjustments” within an organism in response to an environmental stimulus

» http://www.pbslearningmedia.org/resource/vtl07.l a.ws.style.peacock/peacocks/

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29. Some EXAMPLES…



Natural selection

is probably the most

well documented principle in biology

a.) Darwin’s Finches

b.) Pesticide

resistance

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Survival of the Fittest

30. What happens to organisms

with LOW fitness?

They die off and their “un-fit”

genes die off with them

Natural Variation and

Artificial Selection

VARIATION

Nature always provides

some variation among different organisms

ARTIFICIAL SELECTION

(a.k.a selective breeding) involves humans selecting

those variations that they find useful. Desired traits in stock or crops are

HOW SPECIATION OCCURS

&

3 TYPES OF SELECTION

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32. Speciation

 Sample Cladograms  Define Speciation:

– Events that split the lineage and produce two or more separate species

 33. How is this

shown?

The process of speciation







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34. There are 3 general ways

that new species are created:

 1. Geographic

Isolation

 2. Behavioral Isolation

 3. Temporal /

1. Geographic Isolation

 When 2 groups are

separated by

physical (usually geographic)

barriers

– EX: rivers,

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2. Behavioral Isolation

 When 2 groups have

different behaviors or courtship rituals

 EX: bird songs, dances

3. Temporal Isolation

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 Occurs when 2 species reproduce at different times (different mating seasons)

 EX: spawning of fish,

Evolutionary

Time Scales

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36. Microevolution:

Short time scale events (generation-to-generation) that change the

genotypes and phenotypes of populations

Effects on phenotypes:

3 Types of Selection

 Directional selection- when individuals on one end

of the curve have a higher fitness than on the other end or middle.

Types of Selection,

continued…

 Stabilizing selection – when individuals in the center of the curve have a higher fitness than at either end.

Types of Selection,

continued…

 Disruptive selection – when individuals on

either end have a higher fitness than in the middle.

Part 4:

Theory of Evolution

Today

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37. Evidence of Evolution

Darwin Argued That Living Things Have

Been Evolving On Earth For Millions of

Years. Evidence For This Process Could

Be Found In:

A. The Fossil Record

B. The Geographical Distribution of living species

C. Homologous Structures of living organisms D. Similarities In Embryology (early

development)

A. The Fossil Record

 The Earth is Billions of Years Old

 Fossils (preserved remains of organisms)

B. Geographic Distribution

of Living Species

 Different animals on

different continents, but similar

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C. Homologous Body

Structures

 Scientists Noticed Animals With

Backbones (Vertebrates) all had similar bone structure – these are known as

homologous structures

 Among different species, they may

differ in Form or Function

 Limb bones develop in similar patterns

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Homologous Body

Homologous Body

Structures



Not all serve important (or

seemingly any) functions

– These are called Vestigial Organs » Appendix In Man

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D. Similarities In

Embryology (Early

Development)



Embryonic Structures Of Different

Species

Show Significant

Similarities



Differentiation

occurs as

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E. Molecular Biology (DNA)



Compare

similarities in DNA

 Biochemistry:

– Proteins within us and apes are very

similar.

 Remember what

codes for proteins?

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