1. the environment and
change over time

2. who was the main person to put evolution on the table?
charles darwin What book did Darwin
write explaining his theory
of evolution?
On The Origin of Species

3. darwin’s travels england
HMS Beagle

4. darwin’s theory
Darwin thought the
varieties of plants and
animals could be best
explained by descent from
a common ancestor.
He used the plants and
animals of the Galapagos
Islands as an example.

6. Darwin studied 13
species of finches.
They were all similar,
except for their:
body size
beak shape
eating habits
darwin’s theory

8. • Darwin saw that the giant
tortoises on each island looked
different.
• On one island, tortoises had
shells that came close to their
necks. They could eat only short
plants.
• On other islands, tortoises had
more space between the shell
and neck. They could eat taller
plants.
darwin’s theory

9. • Tortoises with long necks lived
on islands that had tall cacti.
Their long necks made it
possible for them to reach high
to eat the cacti.
• The tortoises with short necks
lived on islands that had plenty of
short grass.
darwin’s theory

10. darwin’s theory

11. • He suggested that millions of
years before, a storm had carried
a group of tortoises to one of the
islands from South America.
• In time, the tortoises spread to
the other islands. Their neck
lengths and shell shapes
changed to match their islands’
food sources.
• Darwin became convinced that all the tortoise
species were related. He thought they all
shared a common ancestor.
darwin’s theory

12. A variation is an inherited trait that makes an
individual different from other members of its species.
Variations result from mutations.
Some gene changes produce small variations, such
as differences in the shape of human hairlines.
Mutations can lead to changes in phenotype.
Genetic changes to phenotype can be passed on to
future generations.
variations

13. variations

14. variations

15. The mechanism Darwin thought that was responsible
for evolution was Natural Selection.
He argued that it had the power to make new forms of
life.
Darwin’s idea became known as the “Theory of
Evolution by Natural Selection”.
Natural Selection means that organisms with traits best
suited to their environment are more likely to survive
and reproduce.
darwin’s theory:
evolution through natural selection

16. natural selection

17. principles of natural selection

18. principles of natural selection

19. principles of natural selection

20. principles of natural selection

21. The buildup of many similar variations can lead to an
adaptation.
adaptation
An adaptation is a
characteristic of a species
that enables the species
to survive in its
environment.
The long neck of certain
species of tortoises is an
adaptation to an
environment with tall cacti.

22. adaptation

24. Structural Adaptations
These adaptations involve color, shape, and other
physical characteristics. The shape of a tortoise’s
neck is a structural adaptation.
types of adaptations

25. Behavioral Adaptations
The way an organism behaves or acts is a behavioral
adaptation. Hunting at night and moving in herds are
behavioral adaptations.
types of adaptations

26. Functional Adaptations
These adaptations involve chemical changes in body
systems. A drop in body temperature during
hibernation is a functional adaptation.
types of adaptations

27. Many species have adaptations that make them
nearly invisible.
For example, a seahorse may be the same color as
and similar in texture to the coral it rests on.
This is a structural adaptation called camouflage.
Camouflage is an adaptation that enables species to
blend in with their environments.
environmental interactions

30. Some species have adaptations that draw attention
to them or make them more visible. A caterpillar may
resemble a snake. Predators see it and are scared
away.
The resemblance of one species to another species is
mimicry.
Camouflage and mimicry are adaptations that help
species avoid being eaten. Many other adaptations
help species eat.
environmental interactions