Causes of Diversity and Evolution of Life on EarthCauses of Diversity and

Evolution of Life on Earth

Charles Darwin Alfred Russell Wallace

Causes for Diversity of LifeCauses for Diversity of Life

1. All populations have the potential to increase in size2. Many populations retain a constant size

• Many individuals die young3. Individuals in a population differ in their abilities

• Some of these abilities affect survival4. Best adapted individuals are most likely to survive and

produce offspring (Natural Selection)• “Abilities” are passed on to offspring (Genetics)

5. Over time the “abilities” of the population shift to include advantageous traits (Evolution)

1. All populations have the potential to increase in size2. Many populations retain a constant size

• Many individuals die young3. Individuals in a population differ in their abilities

• Some of these abilities affect survival4. Best adapted individuals are most likely to survive and

produce offspring (Natural Selection)• “Abilities” are passed on to offspring (Genetics)

5. Over time the “abilities” of the population shift to include advantageous traits (Evolution)

Note:

Natural Selection Affects Individuals

Evolution Affects Populations

Note:

Natural Selection Affects Individuals

Evolution Affects Populations

Net Result:

Populations change with time to become better

adapted to their environment (Evolution)

Net Result:

Populations change with time to become better

adapted to their environment (Evolution)

Example: Microbe Resistance

Example: Microbe Resistance

Apply Antibiotic

Survivor’s with Resistance Reproduce

Why is there Genetic Variation?Why is there Genetic Variation?(How do will fill the Gene Pool?)

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How does it Work?How does it Work?Variation is a result of (1) Mutations and (2) Sex

Errors occur in DNA Replication

On average 1:10,000-100,000genes per individual per generation

Errors increased by exposure to radiation, etc.

Most Mutations are bad or at least neutral

What is “good” depends on environmental conditions

Evidence for EvolutionEvidence for Evolution

Evidence for Evolution: Fossils

Evidence for Evolution: Fossils

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Evidence for Evolution: Analogous Structures

Evidence for Evolution: Analogous Structures

Evidence for Evolution:Homologous StructuresEvidence for Evolution:Homologous Structures

Evidence for Evolution:Embryology

Evidence for Evolution:Embryology

Evidence for Evolution:

Biochemistry of Life

Evidence for Evolution:

Biochemistry of Life

Evidence for Evolution:

Gene Sequencing

Evidence for Evolution:

Gene Sequencing

Evidence for Evolution:Artificial Selection

Evidence for Evolution:Artificial Selection

Evidence for Evolution:Artificial Selection

Evidence for Evolution:Artificial Selection

Evidence for Evolution:Modern Examples

Evidence for Evolution:Modern Examples

Some InterestingEffects of EvolutionSome Interesting

Effects of Evolution

Evolution & PsuedoextinctionEvolution & Psuedoextinction

Species A Species B

Through time Species A evolves into Species B

In effect, Species A goes extinct

ExtinctionExtinction

Species A

Sometimes a species cannot adapt fast enough to environmental change or competition

“Background Extinction”:Species Lifespan

“Background Extinction”:Species Lifespan

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Mass ExtinctionMass Extinction

Evolution & SpeciationEvolution & Speciation

Species A

Species B

Species C

Species A is separated into 2 isolated populations, each affected by different environmental conditions

In effect, Species A goes Extinct

Speciation ofKaibab & Abert Squirrels

Speciation ofKaibab & Abert Squirrels

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Speciation of Hawaiian

Honeycreepers

Speciation of Hawaiian

Honeycreepers

Diversity IncreasesDiversity Increases

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Classification:Based on

Evolutionary Relationships

Classification:Based on

Evolutionary Relationships

Species

Genus

Family

Convergent EvolutionConvergent Evolution

Coevolution:Plants and Pollinators

Coevolution:Plants and Pollinators

Coevolution:Predator/PreyCoevolution:Predator/Prey

Conclusions:

Biodiversity, genetic diversity, and community complexity are all the result of 100’s million of

years of evolution

Conclusions:

Biodiversity, genetic diversity, and community complexity are all the result of 100’s million of

years of evolution