* * Speciation & Patterns of Evolution. * Explain how the isolation (physical or genetic) of populations can lead to speciation. * Objectives.

**

Speciation &

Patterns of

Evolution

*

•Explain how the isolation (physical or genetic) of populations can lead to speciation.

*

Objectives

Vocabualry

•Species•Speciation•Geographic isolation•Allopatric Speciation•Reproductive Isolation

•Sympatric Speciation•Gradualism•Punctuated equilibrium•Adaptive Radiation/Divergent Evolution•Convergent Evolution

*

*

•Species: a group of organisms that look alike and can interbreed to produce fertile offspring in nature.

•SPECIATION: when members of Similar populations can no longer interbreed to produce fertile offspring.

What is speciation?

*

What can cause speciation?

1. GEOGRAPHIC ISOLATION•Physical barrier separates a population

•Allopatric Speciation: New species arise as a result of geographic isolation

*

What can cause speciation?2. REPRODUCTIVE ISOLATION•Organisms can no longer mate to produce offspring•Timing•Behavior•Habitat•Infertile Hybrid offspring

•Sympatric Speciation•New species arise as a result of reproductive isolation

*

•Gradualism•species originate through a gradual change of adaptations

•Punctuated equilibrium•speciation occurs relatively quickly, in rapid bursts, with long periods of genetic equilibrium in between.

How fast does speciation occur?

*

Comparing Gradualism vs. Punctuated Equilibrium

*

How does environment affect speciation?

•Divergent evolution/Adaptive Radiation:•when populations change as they adapt to different environmental conditions, eventually resulting in new species.

•Convergent evolution:•distantly related organisms evolve similar traits•occurs when unrelated species occupy similar environments in different parts of the world

*

ADAPTIVE RADIATION – AN EXAMPLE OF DIVERGENT EVOLUTION

*

CONVERGENT EVOLUTION EXAMPLE

Psst: this is an example of Analogous Structures

*

Natural processes such as speciation and gradualism provide the genetic basis for _____.

A.evolutionB.biogenesisC.spontaneous generationD.sexual reproduction

Question #1

*

Natural processes such as speciation and gradualism provide the genetic basis for _____.

A.evolutionB.biogenesisC. spontaneous generationD.sexual reproduction

Question #1

*

A pattern of evolution that results when two unrelated species begin to appear similar because of environmental conditions is _____.

A.disruptive selectionB.directional selectionC.convergent evolutionD.divergent evolution

Question #2

*

A pattern of evolution that results when two unrelated species begin to appear similar because of environmental conditions is _____.

A.disruptive selectionB.directional selectionC.convergent evolutionD.divergent evolution

Question #2