Unit 1: Evolution 1 Summary - Mon and Wed 1. Wrap up red tape 2. - - PowerPoint PPT Presentation

Unit 1: Evolution

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Summary - Mon and Wed

• 1. Wrap up red tape
• 2. Short answers - the tautology
• 3. Recap scientific method/inference to the best explanation
• 4. The natural sciences before Darwin
• 5. Influences on Darwin's theory of evolution by natural selection
• 6. Darwin's theory
• 7. Opposition to Darwin

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Short answer questions and science writing

Instructions (will also be on the test and creason.co) Answer each question in less than three sentences. Do's Simplicity Jump right in Do not's Plagiarize or quote (use own words) Go over three sentences (unless specified)

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Natural Selection - Initial requirements

Individuals with favorable variations --> survive and reproduce at higher rates

• 1. Populations grow faster than the growth of available resources.
• 2. Populations have differential variation among members
• 3. More offspring are produced than survive due to competition for resources.
• 4. Individuals with favorable traits (speed, disease resistance, size) are more likely to survive* than

individuals without those traits.

Fitness - A relative measure of reproductive success. *Not who can live the longest but who can survive long enough to reproduce.

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Natural Selection

• 5. Favorable traits determined by environmental context
• 6. Offspring resemble their parents

Reproductive success - favorable traits are inherited and become more common.

• 7. This favorable variations accumulates in a population over many generations so newer generations are

distinct from ancestral generations. New species emerge

• 8. Geographical isolation - populations become geographically isolated and over time they respond to

selective pressures - different ecological contexts - to become distinct species.

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Natural Selection in Action

Reproductive success - favorable traits are passed on with a higher frequency compared to less advantageous traits which decrease in frequency over time. Selective pressures - Environmental forces influencing the reproductive success of individuals in a population. Fitness - A relative measure of reproductive success. Adaptations - The evolutionary shifts in the variation of traits in a population in response to environmental changes.

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Natural Selection in Action

Peppered Moths Industrial melanism in populations of peppered moths documented. Shifts of pigment pattern frequencies in response to the change in the environment caused by the industrial revolution.

Such responses are called adaptations.

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Natural Selection in Action - Finches

WHAT: Galapagos island finch population

• Beak thickness changed over time in the

population of medium ground finches.

• a favorable trait (thicker beaks) confers a

selective advantage in a population over time. Thicker-beaks had greater reproductive success during droughts. (Resources were limited)

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Natural Selection in Action - Finches

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Finches competed for limited resources

• Thomas Malthus inspired

Members of finch population varied in beak size

• Ex. 13 species among the Galapagos Islands

Natural Selection - Insights Gained from examples

• 1. Traits are inherited - otherwise natural selection cannot act
• styling your hair with lots of product are not hereditary.
• 2. Populations of individuals exhibit biological variation of characteristics
• Selection also only works on existing variation!
• 3. Fitness is relative - it changes relative to environmental change
• Finch beak size correlated with extended periods of drought on the islands
• 4. Natural selection only acts on traits that affect reproduction
• Traits expressed after an organism reproduces are not influenced by natural selection
• Not who can live the longest but who can survive and reproduce.

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Natural Selection - Main Points

*Darwin was able to recognize that it was variation among the individuals of a population that contributed to the change in a species over time. Think about clones. Natural selection operates on individuals but it is the population that evolves

Unit of Natural Selection - Individual Unit of Evolution - Population Individuals don't change genetically but overtime populations do.

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Common Ancestry - Finches

Evolution demonstrated in the finch populations found on the Galapagos islands

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Common Ancestry - Finches

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Issues with Darwin's Evolutionary Theory

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???

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John Ray (1627-1705)

• Identified reproductive isolation of species
• First to use "species" and "Genus"

Carolus Linnaeus (1707-1778)

• Binomial Nomenclature
• Taxonomic classification of biological
• rganisms

Comte de Buffon (1707-1788)

• Plants and animals interacted with the

environment

• Changes in the environment correlated with

changes in plants and animals Jean-Baptiste Lamarck (1744-1829)

• Species change influenced by environmental

change

• First to really attempt and explain evolutionary

process James Hutton (1726-1797)

• First to use Uniformitarianism
• the processes we see today to explain the geological history
• f our planet

Georges Cuvier (1769-1832)

• Extinction
• Catastrophism

Charles Lyell (1797-1875)

• Father of modern geology
• The processes happening today were the same in the past:

Uniformitarianism Alfred Wallace (1823-1913)

• Independently generated the concept of Natural Selection
• Father of Biogeography

Thomas Malthus (1766-1834)

• Populations grow exponentially while food

supplies/production grow arithmetically

• Populations outgrow food supply - survival of individuals

dependent on access to food supply or resources

Precursors Recap