Transcript Evolution Power Point

What is Evolution?
EVOLUTION:
the process of change over time
Evolution is the idea that new species
develop from earlier species by
accumulated changes. This is also
referred to as “descent with
modification”.
Evolution is NOT…
It is NOT a fact...it's a theory:
a well supported testable explanation
of something that occurred in the
natural world.
FAMOUS SCIENTISTS in
Evolution:
- Hutton and Lyell: Earth is many millions of
years old and that the same geologic
processes that changed Earth then are still
occurring.
Lamarck's Hypothesis:
Inheritance of Acquired Characteristics
1. “Acquired Characteristics”: Through use and/or
non-use, those features needed for survival are
developed in each individual.
2. Inheritance: Those characteristics
developed (“acquired”) by individuals are
passed on to their offspring, who can
continue that development.
 Thomas Malthus- Birth rates are higher
than death rates in plant and animal
species.
What consequences might this have on a
population?
Darwin's Hypothesis:
Natural Selection
1. Overproduction: There are more offspring
produced than will survive and reproduce
2. “Survival of the fittest” (not necessarily the
strongest): Those with more adaptive traits tend
to survive longer and/or produce the most
offspring; these are the “naturally selected”.
Darwin’s Travels
 He sailed from
England in the
Beagle
 Galapagos Islands
near South America
were most
influential
Fitness
 How well an organism is adapted to its
environment
 Who has a greater fitness for the North
Pole? A human or a polar bear?
Natural selection is based on 4 facts:
1.Organisms produce more
offspring than can survive.
2.There is variation among offspring.
3.There are limited resources
(not enough food, water, space,
etc. for everyone).
4.The organisms best fit to their environment
will survive and the others will not.
Organisms produce more
offspring than can survive.
 Example: A frog can lay 200
eggs, yet not all eggs
will survive to become
adult frogs.
Results of Evolution -- Speciation!!
 Speciation is the process that creates new species!
 A species is a group of organisms that can naturally
interbreed and produce fertile offspring.
 The Liger--the offspring of a tiger and a lion.
 Tigers and lions are still considered separate species, because
although they can produce
offspring, the offspring
is not fertile.
Evidence of Evolution -Fossils!!
 Fossils are
preserved remnants
or impressions left
by an organism that
lived in the past.
 Usually, the deeper
down
the fossil is, the
older it is.
Evidence of Evolution -Embryology!
 It is believed that all vertebrates evolved from a
common ancestor. The genetic
information that guides their
development is nearly the same.
 That's why scientists can learn about human
development by studying other organisms-including zebrafish.
Evidence of Evolution -Anatomical/Physiological Similarities
 Notice how there are similar bones and similar
structures in humans, birds and whales!

Can you tell which is the bird and
which is the whale?
Analogous Structures
 Serve the same function but are
anatomically different. Serve as evidence
that the organisms evolved independently
Vestigial Organs
organ that serves no useful function
over generations, they reduce in size
Adaptations!
Inherited characteristic that increase
an organism’s chance of survival
 Why are most animals in the artic white?

So they blend in with the snow and avoid being seen!
 Why do sharks have such sharp
teeth?

It allows them to catch their prey!
 Why do elephants have such big ears?


To let heat escape their bodies so they can
stay cool!
Extinction!
 Extinction occurs
when there
are no members
of a species
left alive.
BIG HONKIN’ TICKET OUT
1. What do these pictures represent?
ANSWERS ONLY!!!
2. What is a vestigial structure?
3. How do vestigial structures support the
theory of evolution?
4. Give an example of a vestigial structure.
5. How do fossils serve as evidence of
evolution?
6. What can we learn about evolution by
looking at amino acid sequences (DNA)?
Ticket Out
7. Copy the table below
and fill in.
Definition
Homologous
structures
Analogous
structures
Vestigial
structures
Examples
8. FIRST WORD
EVOLUTION-
H/Pre-AP Homework:
Evaluate the theory of evolution
Strengths
Use your notes and Ch 15
to help you. You should
also look at outside
resources (internet,
encyclopedia, etc)
Weaknesses