Download Struggle to Survive

Chapter 5:
The Evolution of
Living Things
Evolution
Evolution – change of species over time.
Evidence for Evolution #1
Fossils
• Fossil –a remain or imprint of once living organisms
• Fossil Record- A historical sequence of life through
fossils.
Proof of Evolution: Fossil record shows how the
characteristics of
some species have
changed over time.
• Ex.  dog to a horse
Evidence for Evolution #1
Fossils (Continued)
•One of the few animals for which we
have a fairly complete evolutionary
record is the horse.
•This is because all the main stages of
the evolution of the horse have been
preserved in fossil form.
•Over 60 million years, the horse evolved
from a dog-sized creature that lived in
rainforests into an animal adapted to
living on the plains & standing up to 2
meters high.
Evidence for Evolution #2
Homologous Structures
• Homologous Structures - Body parts that are
similar in related animals.
Proof of Evolution: The similar structures show that
we must have a common ancestor!
Evidence for Evolution #3
Vestigial Structures
•
Vestigial structures- structures present in
modern day organisms but are not even used.
Proof of Evolution: They are remnants of once useful
structures, so they may have been useful to our ancestors.
Evidence for Evolution #3
Vestigial Structures
Example: The pelvic bones in the baleen whale show
structural changes over time.
Video Clip
“Whale Evolution”
http://www.youtube.com/watch?v=8cn0kf8mhS4
Evidence for Evolution #4
Molecular Biology
• Molecular Biology – The more closely related the species are
to each other, the more similar the DNA is!
• Proof of Evolution: If 2 species have DNA in common,
then they must have a common ancestor!
•Similar species of
organisms have more
common DNA than
do organisms that are
more different
gorilla
siamang
gibbon
human
chimpanzee
orangutan
Can you tell which of these is human?
Evidence for Evolution #5
Fetal Similarities
• Fetal Similarities:
The unborn offspring of
many species resemble
each other.
• Proof of Evolution:
There must have
been a common
ancestor.
Evidence for Evolution Video Clip
Time 11:22
Recap Questions
What is the change of species overtime?
Evolution
What is the remains or imprints of once living
organisms called?
Fossil
What is it called when body parts are similar
in related animals?
Homologous Structures
What is a historical sequence of life through
fossils called?
Fossil Record
Recap Questions
The unborn offspring of many species resemble
each other.
Fetal Similarities
The more closely related the species are to
each other, the more similar the DNA is what
type of evidence for evolution?
Molecular Biology
What are structures that are present in modern
day organisms but are not even used.
Vestigial Structures
Recap Questions
Identify the piece of evidence for evolution for
each example:
• Humans have an appendix, tonsils, eyebrows and
wisdom teeth which is not needed for survival
Vestigial Structures
• The unborn offspring of the hog and calf are very
similar to each other.
Fetal Similarities
• A horse evolved from a dog-sized creature into an
animal adapted to standing up to 2 meters high.
Fossil
Recap Questions
Identify the piece of evidence for evolution for
each example:
• Humans have similar structures to whales, cats,
bats, horses and birds.
Homologous Structures
• The baleen whale has a pelvic bone
Vestigial Structures
• Chimpanzees and humans have similar DNA to
each other. Molecular Biology
Chapter 5 Section 2:
How Does Evolution Happen?
Charles Darwin’s Theory
Charles Darwin
• 1831- Charles Darwin took the British naval ship called
The HMS Beagle, which sailed to the Galapagos
Islands.
• He collected thousands of plants and animal samples and
kept detailed notes of his observations.
Charles Darwin Observed Finches
• Probing bill
He made careful notes about
the Finches on different
islands…
• Insect eater
• Feeds in trees
• Probing bill
• Insect eater
• Differences in their beak shapes.
• What they ate.
• How they differed from each
other as well as from Finches in
the surrounding areas!
• Uses twig to probe insects
from cactus
• Grasping bill
• Insect eater
• Feeds in trees
• Crushing Bill
• Cactus seed eater
Population
Galapagos Finches 1970-1990
19
90
19
88
19
86
19
84
19
82
19
80
19
78
19
76
19
74
19
72
19
70
big, strong beaks
soft, small beaks
Darwin Studied Fossils
• Darwin studied fossils of animals he had never seen
before.
• He observed differences between modern day
species and extinct species.
Darwin Observed Tortoises
• The tortoises on each of the Galapagos Islands
had different characteristics.
• Examples: Color, Size, Shape, Beak shape
Darwin Interviewed Farmers
• Darwin talked to farmers who used selective breeding.
• Selective Breeding: occurs when desirable traits are
chosen by farmers to make sure that these traits are
passed down to the next generation.
• Example: Juicy fruits, meatier chickens, higher milk
producing cows, etc.
Darwin’s Questions
Darwin was puzzled by:
• Why are the animals and
plants that live or lived in
one area different from the
ones that live or lived in
other areas?
• Were they once related?
• How did they change?
Darwin’s Conclusions
• This led him to
publish his book
called:
• On the Origin of
Species
by Natural
Selection
Darwin’s Book
• Darwin wrote about his theory on how species change
over time called: “The Theory of Natural Selection”
• This is a 4 part theory that states the organisms that are
better adapted to their environment survive and reproduce
more successfully than less well adapted organisms do.
Darwin’s theory part 1
Overproduction
•Organisms
have more
offspring than
can possibly
survive.
Darwin’s theory part 2
Inherited Variation
• Variations are caused by mutations.
• Mutation - random changes in our DNA that cause
changes. Some of these changes are bad, some are neutral,
& some are good.
• If it is bad  organism is less likely to mate & pass down the
gene. The organism dies along with the mutation that made it
less fit.
• If it is neutral,  nothing happens. This is what most
mutations are.
• If it is good  organism is more likely to survive and pass
down the gene to their offspring.
Darwin’s theory part 3
Struggle to Survive (Competition)
•
A natural environment does not have enough resources
to keep all offspring alive.
•
Offspring have to compete for the following: Food,
water, shelter, mates, land, etc.
•
Some variations give them an advantage and makes
them more likely to survive.
•
A variation that makes an organism more likely to
survive and reproduce is called: adaptation.
•
Examples: physical structures, behaviors for
finding food, mating, migrating.
Darwin’s theory part 4
Successful Reproduction
•
Individuals who survive are more likely to successfully
reproduce and pass on the variations that made them
more successful.
• Also known as: “Survival of the Fittest”
PRACTICE:
Look at each of these
organisms. Determine how
Darwin would explain how
they got their
characteristics.
How did the giraffe get a long neck?
How did the giraffe get a long neck?
1. Overproduction – lots of giraffes are born
2. Inherited Variation - Some giraffes are born
with long necks, some are born with short necks.
3. Struggle to Survive - The giraffes with long
necks can reach leaves on trees better. The
giraffes with short necks can’t reach leaves, so
they will die.
4. Successful Reproduction - The giraffes with
longer necks survive and reproduce and pass the
long necks on to their offspring.
How did the polar bear get white?
How did the polar bear get white?
1. Overproduction – Many polar bears are born.
2. Inherited Variation - Some polar bears are
whiter than others.
3. Struggle to Survive - The bears that are more
white can be camouflaged (protected from
predators, hidden from prey) better in the snow.
The bears that aren’t as white will die from
predators or starvation.
4. Successful Reproduction - The bears that are
whiter survive, reproduce, and pass the white fur
on to their offspring.
How did the cheetah get fast?
How did the cheetah get fast?
1. Overproduction – many cheetahs are born.
2. Inherited Variations - Some cheetahs are
faster than others.
3. Struggle to Survive - The faster cheetahs are
better at getting prey and escaping predators.
The slower cheetahs die.
4. Successful Reproduction -The faster cheetahs
survive, reproduce, and pass their speed on to
their offspring.
How did cacti get spines?
How did cacti get spines?
1. Overproduction – Many cacti are produced.
2. Inherited Variation - Some cacti have
spines and some do not.
3. Struggle to Survive - The cacti with spines
are protected from animals that want to eat
them. The cacti without spines get eaten by
animals and die.
4. Successful Reproduction - The cacti that
survive reproduce and pass the spines on to
their offspring.
How did elks get antlers?
How did elks get antlers?
1. Overproduction – lots of baby elk are born.
2. Inherited Variation - Some elk have antlers and
some do not.
3. Struggle to Survive - The elk without antlers
can’t defend themselves and don’t impress
female elks. The elk that don’t defend themselves
or mate die and they do not reproduce.
4. Successful Reproduction - The elks with antlers
survive and impress females, so they reproduce,
passing antlers on to their offspring.
How did flowers get bright colors?
How did flowers get bright colors?
1. Overproduction – lots of flowers are produced
2. Inherited Variation - Some flowers have brighter
colors than others.
3. Struggle to Survive - The flowers with bright
colors are attractive to birds and bees and get
pollinated. The flowers that are not bright are
attractive and do not get pollinated. They won’t
reproduce.
4. Successful Reproduction - The bright flowers
survive and pass their bright colors on to their
offspring.
How did sharks get sharp teeth?
How did sharks get sharp teeth?
1. Overproduction – lots of sharks are born.
2. Inherited Variation - Some sharks have
sharp teeth, and some have dull teeth.
3. Struggle to Survive - The sharks with dull
teeth can’t attack pray and eat as well as
sharks with sharp teeth. They will die.
4. Successful Reproduction - The sharks with
sharp teeth will survive, reproduce, and pass
their sharp teeth on to their offspring.
Recap Questions
What was the name of the ship that Charles
Darwin sailed on?
The HMS Beagle
What islands did Charles Darwin sail to?
The Galapagos Islands
On the Galapagos Islands, what did Charles
Darwin collect and keep samples of?
Plants & Animals
Recap Questions
What organism did Charles Darwin specifically
look at including their beak shape, what they
ate, and how they differed from each other?
Finches
This occurs when desirable traits are chosen by
farmers to make sure that these traits are
passed down to the next generation.
Selective Breeding
What is the name of the book that Charles
Darwin published?
On the Origin of Species by Natural Selection
Recap Questions
Darwin’s Theory states the organisms that are
better adapted to their
, will survive
and reproduce more successfully than less well
adapted organisms.
Environment
What are the 4 parts of Darwin’s Theory of Natural
Selection called?
Overproduction, Inherited Variation, Struggle to
Survive (Competition), Successful Reproduction
What part of Darwin’s Theory is also called
Survival of the Fittest?
Successful Reproduction
Recap Questions
What part of Darwin’s Theory states that mutations
cause variations among organisms?
Inherited Variation
What part of Darwin’s Theory states that there are
not enough resources to keep all organism alive so
the ones better suited for the environment will
survive? Struggle to Survive (Competition)
What part of Darwin’s Theory that that organisms
have more offspring than can possibly survive?
Overproduction
Recap Questions
What are random changes in the DNA that could
be good, bad, or neutral?
Mutations
What are some things that animals compete for?
Food, water, shelter, mates
A variation that makes an animal more likely to
survive and reproduce is called?
Adaptation
Individuals who survive are more likely to
successfully reproduce and pass on the variations
that made them more successful is what part of
Darwin’s Theory? Successful Reproduction
Chapter 5 Section 3:
Natural Selection In Action
Generation Time
• Populations change due to the environment
• Generation Time - the period between the birth of one
generation and the birth of the next one.
• Species with short generation times adapt quickly.
• Species - a group of organisms that can mate with one
other to produce fertile offspring.
– EX: red eyed tree frogs mate with red eyed tree frogs to make
more red eyed tree frogs
http://www.zo.utexas.edu/faculty/a
ntisense/tree.pdf
Formation of New Species
• Speciation- the
formation of a new
species as a result
of natural selection.
3 Steps to Speciation
1. Separation
2. Adaptation
3. Division
Separation
1. Separation- portion of the
population becomes isolated.
• Example: canyon forms, mountain range,
volcano, tsunami
Example - Separation
• A population of wild fruit flies minding its
own business on several bunches of rotting
bananas, cheerfully laying their eggs in the
mushy fruit…
Example – Separation (Continued)
• Disaster strikes: A hurricane washes some of the
bananas and the immature fruit flies they contain out to
sea. The banana bunch eventually washes up on an island
off the coast of the mainland.
• The fruit flies mature and emerge from their slimy nursery
onto the lonely island. The two portions of the population,
mainland and island, are now too far apart to reproduce
with each other.
• At this point, speciation has not occurred—any fruit flies
that got back to the mainland could mate and produce
healthy offspring with the mainland flies.
Adaptation
2. Adaptation- the part of the
population that got separated has a
different environment to adapt to.
Example - Adaptation
• The populations diverge: Ecological conditions are
slightly different on the island, and the island
population evolves under different selective
pressures and experiences different random events
than the mainland population does.
• Morphology, food preferences, and courtship
displays change over the course of any generations
of natural selection.
Division
3. Division– over hundreds to
thousands of generations, the 2
groups became so different that they
are no longer the same species and
can no longer interbreed.
Example - Division
• So we meet again: When another storm reintroduces
the island flies to the mainland, they will not readily
mate with the mainland flies since they’ve evolved
different courtship behaviors.
• The few that do mate with the mainland flies, produce
eggs that can’t hatch because of other genetic
differences between the two populations.
• The lineage has split now that genes cannot flow
between the populations.
Speciation of Squirrels
• The Kaibab squirrel (left) became isolated in the
Grand Canyon approx. 10,000 years ago.
Features have gradually evolved that separate it
from close relative, the Abert squirrel (right) .
Croatian Lizards
• Experiment: Scientists placed 5 pairs of insectivorous
species in a new island habitat.
• Old island habitat very little plants but plenty of insects
– (Lizards diet was 93% insects, 7% plants)
• New island habitat  had an abundance of plants, but limited
insects.
• After 80 generations, the lizards diet was 36% insect & 64% plant
In a few decades the
lizards have developed:
• New digestive structure
• Larger heads
• Harder bite
Galapagos tortoise
• All subspecies of Galapagos tortoise
evolved from a common ancestor that
arrived from mainland South America
about 6-12 million years ago.
• A volcano formed the oldest Galapagos
Island. Tortoises that arrived there
colonized the island.
• The distance between the islands
prohibited much inter-breeding and
resulted in independent evolution of the
populations.
Video Clip
“A small basic Journey of how
Evolution Happens”
Time 5:48