State Standard

SB5D. Relate natural selection to changes in organisms

Natural Selection (15.3)

Evolution

Natural Selection Nature acts to

select the individuals that are best adapted for survival and reproduction in a particular environment

15.3 Natural Selection-Speciation-Resistance

Chapter 15

Principles of Natural Selection

Evolution

Individuals in the population show variations.

The variations are inheritable.

Members of the population have more offspring than can survive on available resources (overproduction).

Variations that increase reproductive success have a greater chance of being passed on.

Chapter 15

Natural selection takes place when…

15.3 Natural Selection-Speciation-Resistance

• Industrialization & the peppered moths

Evolution

Stabilizing selection operates to eliminate extreme expressions of a trait when the average expression leads to higher fitness.

15.3 Natural Selection-Speciation-Resistance

Chapter 15

Ex: Peppered Moths before the Industrial Revolution

Evolution

Directional selection makes an organism more fit by selecting against one extreme.

15.3 Natural Selection-Speciation-Resistance

Chapter 15

Ex: Pollution from the Industrial Revolution caused directional selection in the peppered moths.

Evolution

Disruptive selection is a process that splits a population into two groups.

15.3 Natural Selection-Speciation-Resistance

Chapter 15

Ex: Different rock types in the same biome will favor different coat varieties of these mice

Evolution

Sexual selection operates in populations where males and females differ significantly in appearance.

Qualities of sexual attractiveness appear to be the opposite of qualities that might enhance survival.

15.3 Natural Selection-Speciation-Resistance

Chapter 15

Evolution

Adaptive Radiation – AKA Divergent Evolution/Speciation

Can occur in a relatively short time when one speciesgives rise to many different species in response to the creation of new habitat or some other ecological opportunity

15.3 Natural Selection-Speciation-Resistance

Chapter 15

Evolution

Coevolution

The relationship between two species might be so close that the evolution of one species affects the evolution of the other species.

Associated with mutualism

15.3 Natural Selection-Speciation-Resistance

Chapter 15

Evolution

Unrelated species evolve similar traits because of similar environmental pressures.

Convergent Evolution

15.3 Natural Selection-Speciation-Resistance

Chapter 15

Evolution

Rate of Speciation Evolution proceeds in small, gradual steps

according to a theory called gradualism.

Punctuated equilibrium explains rapid spurts of genetic change causing species to diverge quickly.

15.3 Natural Selection-Speciation-Resistance

Chapter 15

Evolution

15.3 Natural Selection-Speciation-Resistance

Chapter 15

1. A2. B3. C4. D

FQ 14

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EvolutionChapter 15

15.3 Formative Questions

A. coevolution

B. convergent evolution

C. directional evolution

D. divergent evolution

Which evolutionary pattern is represented by the similarities between these two organisms that live on separate continents?

1. A2. B3. C4. D

CAQ 2

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EvolutionChapter 15

Chapter Assessment Questions

A. coevolution

B. mutation

C. adaptive radiation

D. convergent evolution

The divergent evolution of these cichlid fish is an example of what type of speciation?

1. A2. B3. C4. D

CAQ 3

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EvolutionChapter 15

Chapter Assessment Questions

A. gradual

B. elevated

C. sequential

D. punctuated

What tempo of evolution does this model represent?

1. A2. B3. C

STP 5

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EvolutionChapter 15

Standardized Test Practice

Within a population of squirrels, those that live higher in the mountains where it is cooler have long fur. Squirrels that live in the foothills where it is warmer have short fur. The original population is believed to have had intermediate fur length. Which graph represents this type of natural selection?

A. B.

C.