Natural Selection& Evolution

Answer these questions as we go…1. What island did Charles Darwin research while on the HMS Beagle? 2. What is natural selection? 3. What did he collect on his journey? 4. What did he observe about the islands (climate)? 5. What did he notice about the animals on the islands? 6. What is the difference between natural selection and evolution? 7. What 5 pieces of evidence do we have for evolution?8. How does evolution work?9. What 3 mechanisms allow for change in a population? 10. Give 2 examples of environmental pressures that lead to adaptations.11. Define Adaptation. 12. List the two types of adaptations.13. Define physical adaptations. (Give an example of one) 14. What is the difference between camouflage and mimicry. 15. Define Behavioral adaptations. 16. Distinguish between instinctive and learned behavior.

• TSW investigate and understand how populations change through time, including:– How variation of traits, reproductive strategies,

and environmental pressures impact on the survival of populations

– Recognizing how adaptations lead to natural selection

– How new species emerge

Charles Darwin

• On the Origin of Species • Sailed with the HMS Beagle• Observations made in the Galapogos

Islands• These observations helped him form the

theory of how species change over time called natural selection

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Voyage of the BeagleDuring his travels, Darwin made numerous observations and collected evidence that led him to propose a hypothesis about the way life changes over time.

That hypothesis has become the theory of evolution (aka theory of natural selection).

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Living Organisms and Fossils

•Darwin collected the preserved remains of ancient organisms, called fossils. •Some of those fossils resembled organisms that were still alive. •Others looked completely unlike any creature he had ever seen.

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Darwin's Observations

The Galápagos IslandsDarwin observed that the Galápagos Islands were close together but had very different climates.

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The Journey HomeDarwin observed that the characteristics of many animals and plants varied noticeably among the different islands of the Galápagos.

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The Journey HomeDarwin wondered if animals living on different islands had once been members of the same species. These separate species would have evolved from an original South American ancestor species.

Fact: Evolution- process by

which modern organisms have

descended from ancient organisms.

Theory- Natural Selection- based

on the principles of genetics.

*Note-A scientific theory is a well-supported testable explanation of phenomena that have occurred in the natural world.

Natural selection vs Evolution?

Evidence for Evolution

• Fossil record• Anatomy– Homologous structures– Analagous structures

• Vestigial structures• Embryology• Molecular biology (DNA differences)

What is a Population?

• Populations are groups of interbreeding individuals that live in the same place at the same time

• Individuals in a population compete for resources with each other.

• Populations evolve over many generations, individuals don’t.

How Does Evolution Work?

• Populations produce more offspring than the environment can support

• The unequal ability of individuals to survive and reproduce leads to the gradual change in a population over many generations.

Mechanism for change in a population of organisms.

• Animals who have greater fitness survive in environment and live to reproduce

• Random changes (mutations) can lead to greater or less fitness

• Adaptations allow an organism to survive better in their environment

Adaptations

• Can arise in response to environmental pressures– Temperature– Antibiotic resistance in

bacteria– Pesticide resistance– Morphological changes

in peppered moths

What is an Adaptation?

Evolutionary process by which an animal becomes better suited for its environment.

Physical Behavioral

Physical Adaptations

• are body structures that allow an animal to find and consume food, defend itself, and to reproduce its species.

toad

Physical adaptation

Camouflage (use of color in a surrounding)

The chameleon can change its color to match its surroundings. Can you do that?

Mimicry (looking or sounding like another living

organism)The Viceroy butterfly uses mimicry to look like

the Monarch butterfly. Can you tell them apart?

Poisonous

Not poisonous

Physical adaptation

I’m the Monarch!

I’m the Viceroy!

Chemical defenses (like venom, ink, sprays)

Physical adaptation

Body coverings & parts (claws, beaks, feet, armor plates, skulls, teeth)

Physical adaptations

The elephant’s trunk is a physical adaptation that helps it to clean itself, eat, drink, and to pick

things up.

Behavioral

Adaptations…

Behavioral Adaptations allow animals to respond to life needs. They

are the animals’ actions.

Behavioral Adaptations

InstinctiveThese behaviors happen naturally & don’t have to

be learned.

Learned These behaviors

must be taught.

Methods of gathering & storing food

Finding shelter

Defending oneself

Raising young

Hibernating

Darwin Video • Show Darwin Video

http://www.pbs.org/wgbh/evolution/educators/teachstuds/unit2.html

• Answer Questions: – Who is Darwin? – What college did he attend? What did he study? – What book did most people read that explained creation? – How many years was he on the Beagle? How old was he? – What was the name of his book? – What was his Mechanism of change called?