section 10.1 key concept there were theories of...

Section 10.1

KEY CONCEPT

There were theories of biological and geologic

change before Darwin.

Early scientists proposed ideas about evolution.

Evolution is the biological change process by which

descendants come to differ from their ancestors.

Early scientists proposed ideas about evolution.

A species is a group of organisms that can reproduce and

have fertile offspring.

There were many important naturalists in the 18th century.

Carolus Linnaeus: classification system from kingdom to

species

There were many important naturalists in the 18th century.

Jean-Baptiste Lamarck: environmental change leads to use

or disuse of a structure

Theories of geologic change set the stage for Darwin’s

theory.

Catastrophism: natural disasters such as floods and

volcanic eruptions have happened often during Earth’s

long history

Can lead to mass extinctions

Theories of geologic change set the stage for Darwin’s

theory.

Gradualism: the changes observed in landforms

resulted from slow changes over a long period of time

Section 10.2

KEY CONCEPT

Darwin’s voyage provided insight on evolution.

I. Darwin observed differences among island species.

1. Variation is a difference in a physical trait.



2. Galápagos tortoises that live in areas with tall plants have

long necks and legs.



2. Galápagos tortoises that live in areas with tall plants have

long necks and legs.

3. Galápagos finches that live in areas with hard-shelled nuts

have strong beaks.

1. An adaptation is a feature that allow an organism to better

survive in its environment.

– Species are able to adapt to their

environment.

– Adaptations can lead to genetic

change in a population.

II. Darwin realized species could adapt to their environment.

1. Fossil evidence included:

- Found fossils of extinct animals that resemble modern

animals.

- Found fossil shells high up in the Andes mountains.

III. Darwin observed fossil and geologic evidence supporting

an ancient Earth.

2. Geological evidence included:

- Saw land move from underwater to above sea level due to

an earthquake.

III. Darwin observed fossil and geologic evidence supporting

an ancient Earth.

Section 10.3

KEY CONCEPT

Darwin proposed natural selection as a mechanism for

evolution.

Several key insights led to Darwin’s idea for natural

selection.

• Artificial selection is the process by which humans

select traits through breeding.

• Darwin noticed a lot of variation in domesticated plants

and animals.

neck feathers

crop

tail feathers

• Heritability is the ability of a trait to be passed down.


selection.

• There is a struggle for survival due to overpopulation

and limited resources.


selection.

Natural selection is a mechanism by which individuals that

have inherited beneficial adaptations produce more offspring on

average than do other individuals.


selection.

Darwin proposed that adaptations arose over many generations.

Variation

The differences among individuals that result from

differences in the genetic material of the organisms

Can be inherited from a parent or occur from a mutation

There are four main principles to the theory of natural

selection.

VARIATION

Overproduction

While having many offspring raises the chance that some

will survive, it also results in competition between offspring

for resources.


selection.

OVERPRODUCTION

Adaption

Allows an individual to survive better than other individuals

it competes against in its environment.


selection.

ADAPTATION

Descent with Modification

More individuals will have the trait in every following

generation, as long as the environmental conditions

continue to remain beneficial for that trait.


selection.

The measure of survival ability and ability to produce more

offspring.

Fitness

• Natural selection can act only on traits that already exist.

• Structures take on new functions in addition to their

original function.

Natural selection acts on existing variation.

wrist bone

five digits

Section 10.4

KEY CONCEPT

Evidence of common ancestry among species comes

from many sources.

Evidence for evolution in Darwin’s time came from several

sources.

• Fossils provide evidence of evolution.

• Fossils in older layers are more primitive than

those in upper layers.

• The study of geography provides evidence of evolution.

– island species most closely resemble the nearest

mainland species

– populations can show variation from one island to

another


sources.

• The study of anatomy provides evidence of evolution.

Human hand Bat wing Mole foot

– Homologous structures are similar in structure but

different in function.

– Homologous structures are evidence of a common

ancestor.


sources.

Human hand

Bat wing

Mole foot

Fly wing

– Analogous structures are not evidence of a common

ancestor.

• The study of anatomy provides evidence of evolution.

– Analogous structures have a similar function.


sources.

• Vestigial structures are remnants of organs or structures

that had a function in an early ancestor.

• Ostrich wings are examples of vestigial structures.

Structural patterns are clues to the history of a species.

• Embryology studies the embryo of different species

– Developmental similarities provide evidence of evolution.


sources.

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