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Chapter 5
The Evolution of Living Things
Objectives
Differences Among Organisms
● Adaptation is a characteristic that helps an
organism survive and reproduce in its
environment
Adaptations Video
Differences Among Organisms
● Species are living things that share the same
characteristics and adaptations. They can
mate with one another to produce fertile
offspring.
Do species change over time?
● Scientists estimate Earth as 4.6 billion years
old
● Fossil evidence shows that many species
have died out and been replaced by newer
species
● Evolution is the process by which
populations accumulate inherited changes
over time
Evidence of Evolution
● Fossils
○ formed when a dead organism is covered in
sediment and then minerals replace the organism
with stone, or a mold is created when a hole is left
behind
○ older fossils are found in deeper layers of the Earth
Fossil Record
Fossil Record
● Fossils found in upper (newer) layers of
Earth resemble modern day organisms
Gap in the Fossil Record
● Not every dead organism leaves a fossil
● Fossils are rare and often difficult to find
● Gaps remain in the fossil record
Vestigial Structures
● vestigial structures-remains of
once useful structures inside of a
body
Case Study: Evolution of Whale
Hypothesis:
● Whales evolved from a land
mammal based on fossil evidence
Dispute:
Dispute of the theory of whale
evolution from land mammals
Comparing Skeletal Structures
● The bones in the
front limbs of
multiple animals are
similar
● They have evolved
different functions
over time
Comparing DNA
● all organisms have
DNA
● the more similar an
organism is the
more similar their
DNA is
Comparing Embryonic Structures
● all vertebrate
embryos are similar
in the early
development stages
Section 2 How Does Evolution Happen?
● Charles Darwin
○ served as a naturalist on board the HMS Beagle
Darwin’s Adventure
● collected thousands
of species
● visited the
Galapagos Islands,
near Ecuador and
observed many
organisms
Darwin’s Finches
● Darwin noticed that the
organisms were similar,
but not identical to
mainland organisms
● He noticed that the
finches were different
from each other
● Finches had adapted
different ways to find
food
Darwin’s Observations
● he learned from farmers about selective
breeding
● he realized that big changes could take place
in a short period
● he decided that this could happen in nature,
but would take longer because it would be by
chance
Darwin’s Observations
● he learned from geologist Charles Lyell that
the Earth was very old and these changes
could take place over long periods of time
● Because of Malthus’ theory on population,
Darwin decided that species that survive
starvation, disease & predators were better
equipped to survive
Natural Selection
● A four part process of evolution:
○ 1. overproduction- species produces too many
offspring
○ 2. genetic variation- unique traits increase or
decrease survivability
○ 3. struggle to survive- only some individuals make
it to adulthood
○ successful reproduction- well adapted individuals
more likely to survive and reproduce
More Evidence
● genetic inheritance- variations can be
caused by mutations
● most scientists believe that the theory of
evolution by natural selection explains the
diversity of organisms on Earth
Review
Why are some animals more likely to survive to
adulthood than others?
1/29/14
Objectives:
● Observe two examples of natural selection
● Outline the process of speciation
Section 3 Natural Selection in Action
● Natural selection continually takes place
● populations change over time in response to
their environment
Insecticide Resistance
● in 50 years of insecticide use >500 insects
have developed resistance
● insects produce many offspring & short
generation time
● generation time is the period between
generations
Peppered Moth
White moths
eaten
● pollution
trees darken
Dark moths survive
● moths adapted and the population changed from mostly
white moths to mostly dark moths
Peppered Moth Video
Formation of a New Species
● Speciation- if a portion of a species is
separated from the original population, they
can become so different that they can no
longer interbreed
Speciation
1. Population becomes separated & isolated
2. Separated group adapts to new environment
and evolves
3. Separated group and original group can no
longer interbreed
4. The two groups are now two different
species