Chapter 15 Evolution

Section 1: Darwin’s Theory of Natural Selection

Section 2: Evidence of Evolution

Section 3: Shaping Evolutionary Theory

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15.1 Darwin’s Theory of Natural Selection

Darwin on the HMS Beagle

Evolution

• Darwin’s role on the ship was as naturalist and companion to the captain.

• His job was to collect biological and geological specimens during the ship’s travel.

Chapter 15

The Galápagos Islands

Evolution

• Darwin began to collect mockingbirds, finches, and other animals on the four islands.

• He noticed that the different islands seemed to have their own, slightly different varieties of animals.

15.1 Darwin’s Theory of Natural Selection

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• Almost every specimen that Darwin had collected on the islands was new to European scientists.

Evolution

• Populations from the mainland changed after reaching the Galápagos.

15.1 Darwin’s Theory of Natural Selection

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Darwin Continued His Studies

Evolution

• Darwin hypothesized that new species could appear gradually through small changes in ancestral species.

• Darwin inferred that if humans could change species by artificial selection, then perhaps the same process could work in nature.

15.1 Darwin’s Theory of Natural Selection

Chapter 15

Natural Selection

Evolution

• Individuals in a population show variations.

• Variations can be inherited.

• Organisms have more offspring than can survive on available resources.

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

15.1 Darwin’s Theory of Natural Selection

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Visualizing Natural Selection

Evolution

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Data Analysis Graph

• http://www.glencoe.com/ose/showbook.php

• Darwin’s theory of natural selection is not synonymous with evolution.

The Origin of Species

Evolution

• Darwin published On the Origin of Species by Means of Natural Selection in 1859.

• It is a means of explaining how evolution works.

15.1 Darwin’s Theory of Natural Selection

Chapter 15

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Vocab Review

Definition

1. Theory of evolution based on 4 ideas, excess reproduction, variations, inheritance, and advantages of specifics traits.
2. Organisms selected for certain traits in order to produce off spring having those traits.
3. Change in groups of living organisms over time.
4. Inherited characteristics of species that develop over time in response to an environmental factor allowing species to survive.

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Vocabulary Word

1. Evolution
2. Adaptation
3. Artificial Selection
4. Natural Selection

15.1 Check for understanding

1. Describe the evidence Charles Darwin gathered that led to his theory of evolution.
2. Explain how the idea of artificial selection contributed to Darwin’s ideas on Natural Selection.
3. Identify the 4 principals of natural selection and provide examples.
4. Infer the consequences for evolution if a species did not vary.

15.2 Evidence of Evolution

Support for Evolution

Evolution

• The fossil record

Glyptodont

• Fossils provide a record of species that lived long ago.

• Fossils show that ancient species share similarities with species that now live on Earth.

Armadillo

Chapter 15

Evolution

• Derived traits are newly evolved features, such as feathers, that do not appear in the fossils of common ancestors.

• Ancestral traits are more primitive features, such as teeth and tails, that do appear in ancestral forms.

• Anatomically similar structures inherited from a common ancestor are called homologous structures.

15.2 Evidence of Evolution

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Evolution

Vestigial Structures

• Structures that are the reduced forms of functional structures in other organisms.

15.2 Evidence of Evolution

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Evolution

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Evolution

• Show that functionally similar features can evolve independently in similar environments

15.2 Evidence of Evolution

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Evolution

• Vertebrate embryos exhibit homologous structures during certain phases of development but become totally different structures in the adult forms.

Comparative Embryology

15.2 Evidence of Evolution

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Evolution

• Common ancestry can be seen in the complex metabolic molecules that many different organisms share.

Comparative Biochemistry

15.2 Evidence of Evolution

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Evolution

• Comparisons of the similarities in these molecules across species reflect evolutionary patterns seen in comparative anatomy and in the fossil record.

• Organisms with closely related morphological features have more closely related molecular features.

15.2 Evidence of Evolution

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Geographic Distribution

Evolution

• The distribution of plants and animals that Darwin saw first suggested evolution to Darwin.

Rabbit

Mara

15.2 Evidence of Evolution

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Evolution

• Patterns of migration were critical to Darwin when he was developing his theory.

• Evolution is intimately linked with climate and geological forces.

15.2 Evidence of Evolution

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Evolution

Types of Adaptation

• An adaptation is a trait shaped by natural selection that increases an organism’s reproductive success.

• Fitness is a measure of the relative contribution an individual trait makes to the next generation.

15.2 Evidence of Evolution

Chapter 15

Evolution

Camouflage

• Allows organisms to become almost invisible to predators

Leafy sea dragon

15.2 Evidence of Evolution

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Evolution

Mimicry

• One species evolves to resemble another species.

Western coral snake

California kingsnake

15.2 Evidence of Evolution

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Bee Orchid

Evolution

Consequences of Adaptations

• Some features of an organism might be consequences of other evolved characteristics.

• They do not increase reproductive success.

• Features likely arose as an unavoidable consequence of prior evolutionary change.

15.2 Evidence of Evolution

Chapter 15

15.3 Shaping Evolutionary Theory

Mechanisms of Evolution

Evolution

• Population genetics

• Hardy-Weinberg principle states that when allelic frequencies remain constant, a population is in genetic equilibrium.

Chapter 15

Evolution

• This equation allows us to determine the equilibrium frequency of each genotype in the population.

• Homozygous dominant (p²)

• Heterozygous (2pq)

• Homozygous recessive (q²)

15.3 Shaping Evolutionary Theory

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Evolution

15.3 Shaping Evolutionary Theory

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Evolution

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Evolution

Genetic Drift

• A change in the allelic frequencies in a population that is due to chance

• In smaller populations, the effects of genetic drift become more pronounced, and the chance of losing an allele becomes greater.

15.3 Shaping Evolutionary Theory

Chapter 15

Evolution

Founder Effect

• Occurs when a small sample of a population settles in a location separated from the rest of the population

• Alleles that were uncommon in the original population might be common in the new population.

15.3 Shaping Evolutionary Theory

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Evolution

Bottleneck

• Occurs when a population declines to a very low number and then rebounds

15.3 Shaping Evolutionary Theory

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Evolution

Gene Flow

• Increases genetic variation within a population and reduces differences between populations

Nonrandom Mating

• Promotes inbreeding and could lead to a change in allelic proportions favoring individuals that are homozygous for particular traits

15.3 Shaping Evolutionary Theory

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Evolution

Natural Selection

• Acts to select the individuals that are best adapted for survival and reproduction

15.3 Shaping Evolutionary Theory

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Evolution

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

15.3 Shaping Evolutionary Theory

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Evolution

• Directional selection makes an organism more fit.

15.3 Shaping Evolutionary Theory

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Evolution

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

15.3 Shaping Evolutionary Theory

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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 Shaping Evolutionary Theory

Chapter 15

Natural Selection

Evolution

• Prezygotic isolation prevents reproduction by making fertilization unlikely.

• Prevents genotypes from entering a population’s gene pool through geographic, ecological, behavioral, or other differences

Eastern meadowlark and Western meadowlark

15.3 Shaping Evolutionary Theory

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Evolution

• Prevents offspring survival or reproduction

Liger

15.3 Shaping Evolutionary Theory

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Evolution

Allopatric Speciation

• A physical barrier divides one population into two or more populations.

Abert squirrel

Kaibab squirrel

15.3 Shaping Evolutionary Theory

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Evolution

Sympatric Speciation

• A species evolves into a new species without a physical barrier.

• The ancestor species and the new species live side by side during the speciation process.

15.3 Shaping Evolutionary Theory

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Evolution

Adaptive Radiation

• Follows large-scale extinction events

15.3 Shaping Evolutionary Theory

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South American Cichlids

Evolution

Coevolution

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

• Mutualism

• Coevolutionary arms race

15.3 Shaping Evolutionary Theory

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Evolution

• Unrelated species evolve similar traits even though they live in different parts of the world.

Convergent Evolution

15.3 Shaping Evolutionary Theory

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Evolution

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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 Shaping Evolutionary Theory

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Evolution

15.3 Shaping Evolutionary Theory

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Evolution

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Evolution

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Chapter Diagnostic Questions

Formative Test Questions

Chapter Assessment Questions

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1. Individuals show variations.
2. Variations can be inherited.

Which is not a principle of Darwin’s theory about

the origin of species?

Evolution

4. Offspring always inherit the best traits.

Chapter 15

Chapter Diagnostic Questions

1. ancestral traits
2. analogous structures
3. homologous structures
4. vestigial structures

Identify the term that is used to describe

anatomically similar structures inherited from

a common ancestor.

Evolution

Chapter 15

Chapter Diagnostic Questions

1. snake pelvis
2. Kiwi wings
3. porpoise flipper
4. human appendix

Which is not a vestigial structure?

Evolution

Chapter 15

Chapter Diagnostic Questions

1. a degree in theology
2. an interest in science
3. a knowledge of biology
4. an understanding of geology

Which was Charles Darwin’s only qualification

for his position as naturalist on the Beagle?

Evolution

Chapter 15

15.1 Formative Questions

1. evolution
2. speciation
3. artificial selection
4. natural selection

What was Darwin’s term for selective breeding?

Evolution

Chapter 15

15.1 Formative Questions

1. Animal breeders could create new species.
2. A similar process could work in nature.
3. Reproductive success could be increased.
4. Variation in a species could be produced.

What did Darwin infer from his observations of

artificial selection?

Evolution

Chapter 15

15.1 Formative Questions

1. They mean the same thing.
2. Evolution works against natural selection.

What is the relationship between the terms

natural selection and evolution?

Evolution

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15.1 Formative Questions

True or False

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The Archaeopteryx seems to have evolved from

reptiles and is a direct ancestor of modern birds.

Evolution

Chapter 15

15.2 Formative Questions

1. a tail
2. bones
3. feathers
4. teeth

Which is an example of a derived trait?

Evolution

Chapter 15

15.2 Formative Questions

1. analogous structures
2. embryological structures
3. homologous structures
4. vestigial structures

Which features are similar in use and evolve in

similar environments, but do not evolve from a

common ancestor?

Evolution

Chapter 15

15.2 Formative Questions

True or False

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Organisms with similar anatomy share

similar DNA sequences.

Evolution

Chapter 15

15.2 Formative Questions

1. adaptation
2. biogeography
3. gradualism
4. speciation

At the heart of the theory of evolution by natural

selection lies the concept of __________.

Evolution

Chapter 15

15.2 Formative Questions

1. genes
2. traits
3. adaptation
4. competition

The development of the evolutionary theory has

led to the understanding that the raw material

for evolution is _________.

Evolution

Chapter 15

15.3 Formative Questions

Why does the ratio of gray to red owls remain

the same after the population has doubled?

Evolution

Chapter 15

15.3 Formative Questions

Evolution

2. They compete with one another for resources.

1. They each have different predators.

Chapter 15

15.3 Formative Questions

1. mutations
2. natural selection
3. nonrandom mating
4. small population size

Which of these conditions can act on

phenotypes to provide adaptive advantages

to a population?

Evolution

Chapter 15

15.3 Formative Questions

Evolution

Which description is evidence that a

speciation has taken place?

Chapter 15

15.3 Formative Questions

Evolution

Chapter 15

15.3 Formative Questions

1. coevolution
2. convergent evolution
3. directional evolution
4. divergent evolution

Which evolutionary pattern is represented by

the similarities between these two organisms

that live on separate continents?

Evolution

Chapter 15

15.3 Formative Questions

1. camouflage
2. mimicry
3. embryological adaptation
4. vestigial structure

Determine which morphological adaptation the

monarch butterfly exhibits.

Evolution

Chapter 15

Chapter Assessment Questions

1. coevolution
2. mutation
3. adaptive radiation
4. convergent evolution

The divergent evolution of these cichlid fish is

an example of what type of speciation?

Evolution

Chapter 15

Chapter Assessment Questions

1. gradual
2. elevated
3. sequential
4. punctuated

What tempo of evolution does this model

represent?

Evolution

Chapter 15

Chapter Assessment Questions

1. The different tortoises were different species.
2. The environment on each island was different.

Which explains why the tortoises on the different

islands of the Galápagos had slightly different

variations in their shells?

Evolution

Chapter 15

Standardized Test Practice

Evolution

Which is the best explanation for the similarities in

the construction of these forelimbs?

Chapter 15

Standardized Test Practice

Evolution

Chapter 15

Standardized Test Practice

Which is the best explanation for the similarities in

the construction of these forelimbs?

1. camouflage
2. fitness
3. mimicry
4. resemblance

Predators learn to avoid monarch butterflies

because they contain a poison that is distasteful

and can cause the predator to get sick. The viceroy

butterfly finds protection by closely resembling the

monarch. What is this adaptation in the viceroy

called?

Evolution

Chapter 15

Standardized Test Practice

Evolution

Why are cheetahs so genetically similar that they

appear inbred?

Chapter 15

Standardized Test Practice

Evolution

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?

Chapter 15

Standardized Test Practice

Evolution

Chapter 15

Standardized Test Practice

1. adaptive radiation
2. allopatric speciation
3. convergent evolution
4. disruptive coevolution

These cichlid fish are believed to have diverged

from a single ancestor. What type of speciation

is represented by this divergence?

Evolution

Chapter 15

Standardized Test Practice

Evolution

Chapter 15

Glencoe Biology Transparencies

Evolution

Chapter 15

Image Bank

Evolution

Chapter 15

Image Bank

artificial selection

natural selection

evolution

Evolution

Vocabulary

Section 1

Chapter 15

derived trait

ancestral trait

homologous structure

vestigial structure

analogous structure

embryo

biogeography

fitness

mimicry

camouflage

Evolution

Vocabulary

Section 2

Chapter 15

Hardy-Weinberg principle

genetic drift

founder effect

bottleneck

stabilizing selection

directional selection

disruptive selection

sexual selection

prezygotic isolating mechanism

Evolution

Vocabulary

Section 3

Chapter 15

allopatric speciation

postzygotic isolation mechanism

sympatric speciation

adaptive radiation

gradualism

punctuated equilibrium

Evolution

Vocabulary

Section 3 (cont.)

Chapter 15

Chapter 15

Evolution

Animation

• Visualizing Natural Selection
• Punctuated Equilibrium