Chapter 15: Theory of Evolution

Chapter 15: Theory of Evolution

Objectives:Objectives:

Summarize the history of scientific ideas about evolution.

Describe Charles Darwin’s contributions to scientific thinking about evolution.

Analyze the reasoning in Darwin’s theory of evolution by natural selection.

The Idea of EvolutionThe Idea of Evolution

Evolution is the process of change in the inherited characteristics within populations over generations such that new types of organisms develop from preexisting types.

Old Theories of EvolutionOld Theories of EvolutionOld Theories of EvolutionOld Theories of Evolution

Jean Baptiste LamarckJean Baptiste Lamarck (early 1800’s) proposed:

““The inheritance of acquired characteristics”The inheritance of acquired characteristics”

He proposed that by using or not using its body parts, an individual tends to developdevelop certain characteristicscharacteristics, which it passespasses on to its offspringoffspring.

Darwin’s BackgroundDarwin’s Background

Born in England, 1809  Studied Medicine at

Edinburgh University Transferred to Cambridge

University Studied to be a Minister

Library of Congress, Prints and Photographs Division [reproduction number, e.g., LC-USZ61-104].

Charles DarwinCharles DarwinCharles DarwinCharles Darwin

Wrote in 1859Wrote in 1859: “On the Origin of Species by “On the Origin of Species by Means of Natural Selection”Means of Natural Selection”

Two main points:Two main points:

1.1. Species were not created in their present Species were not created in their present form, but evolved from ancestral species.form, but evolved from ancestral species.

2.2. Proposed a mechanism for evolution:Proposed a mechanism for evolution: NATURAL SELECTIONNATURAL SELECTION

Darwin’s Expedition - 1831 Darwin’s Expedition - 1831 Hired as Naturalist on H.M.S. Beagle Sailed on Five Year Scientific

Expedition

– Down East Coast of South America

– Up Pacific Coast to Galapagos Islands

– Made Stops on Mainland and Islands

– Observed Variety of Life and Habitats

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Darwin’s VoyageDarwin’s Voyage

Section 1 History of Evolutionary Thoughthttp://player.discoveryeducation.com/index.cfm?

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Darwin’s Work Darwin’s Work Outlined Theory in his Book in 1859:

– On the Origin of Species by Means of Natural Selection

Published Other Works on Biology Died in 1882 http://player.discoveryeducation.com/index.cfm?guidAssetId=56A5F7FE-FBBE-469B-

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Summary of Origin of SpeciesSummary of Origin of Species

Proposed Evolution Resulting from Natural Selection:

– Organisms Produce Many Offspring

– Competition for Food, Territory, Mates, etc.

– Those With Best Traits Survive

– Organisms Change Over Many Generations

Time Frame: Millions of Years

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Darwin’s Ideas, continuedDarwin’s Ideas, continued

Natural Selection

– Organisms in a population adapt to their environment as the proportion of individuals with genes for favorable traits increases.

– Those individuals that pass on more genes are considered to have greater fitness.

Section 1 History of Evolutionary Thought

Example of Natural SelectionExample of Natural Selection

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BiogeographyBiogeography Biogeography, the study of the

locations of organisms around the world, provides evidence of descent with modification.

Section 2 Evidence of Evolution

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Anatomy and PhysiologyAnatomy and Physiology In organisms, analogous structures

are similar in function but have different evolutionary origins.

Homologous structures have a common evolutionary origin.

Section 2 Evidence of Evolution

Analogous StructuresAnalogous Structures

Different structure design, same purpose.

Homologous StructuresHomologous Structures

Different uses, same design

Darwin’s Support for His TheoryDarwin’s Support for His Theory Characteristics of Organisms Coincide

With Habitats Changes Produced by Breeding of

Organisms Geologic Ages Suggested by Charles

Lyell Similarities of Various Organisms

What is natural Selection?What is natural Selection?

Species with the best traits survive to reproduce.

Over a period of time will develop into a separate species.

– Convergent Evolution

– Divergent Evolution http://player.discoveryeducation.com/index.cfm?

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What is Convergent Evolution?What is Convergent Evolution?

Different unrelated species demonstrate similar traits in response to environment.

What is divergent Evolution?What is divergent Evolution?

Common ancestor Develop different

traits

SummarySummary

Charles Darwin

– “Survival of the fittest”

– Species with the best traits will live to reproduce.

– The trait will adapt to the environment.

– Takes place over millions of years.– http://player.discoveryeducation.com/index.cfm?guidAssetId=EC3622D3-

6490-43D8-870D-098235A1E3F8&blnFromSearch=1&productcode=US