THEORIES OR OCCURRENCE OF EVOLUTION .pptx

MELC: Explain the occurrence of evolution
Ms. Jeraldel Encepto
Science 10 Teacher

Theories of Evolution

Why is it that fossil is the one most
important sources of evolution?

3 PICS 1 Word
You have 10 seconds to guess the word like
the 3 pictures shown.

1
R _ _ O_ D
3 PICS 1 WORD
RECORD

2
V_R_ _ T_ON
3 PICS 1 WORD
VARIATION

3
A_AP_ATI_N
3 PICS 1 WORD
ADAPTATION

5
E_OL_T_O_
3 PICS 1 WORD
EVOLUTION

Evolution
- considered as a gradual change of
organisms over time.
Theory
- an idea about how something in nature works that
has gone through rigorous testing through
observations and experiments designed to prove the
idea right or wrong.

Jean-Baptiste Lamarck (1744-1829)
Developed one of the first
theories on how species
changed
Concluded that organisms of
higher complexity had
evolved from pre-existing,
less complex organisms.
Lamarck’s Theories on Evolution

Jean-Baptiste Lamarck (1744-1829)
 Lamarckism, a theory of evolution
based on the principle
that physical changes in
organisms during their lifetime—
such as greater development of
an organ or a part through
increased use—could be
transmitted to their offspring.

Theory of Need Theory of Use
and Disuse
Theory of
Acquired
Characteristics

Organisms change
in response to
their environment
Theory of Need

Organisms change because they need to

Their ability to survive helped them develop characteristics
necessary for them to adapt in a given environment

Organs not in use will
disappear while organs
in use will develop and
gets stronger.
If you don’t use it, you
lose it!
Theory of Use and Disuse

If parent acquires a
body structure during
its lifetime, it could
pass on that
characteristic structure
to its offspring.
Theory of Acquired Characteristics

1. Petals on flowers
2. Corset
3. Frequent exercise
4. Tails of mice
5. Ear pinna
Disproving Lamarck

Charles Darwin (1809-1882)
Proposed an entirely different
mechanism to account for the
evolution of species
His theory of evolution by
natural selection became the
foundation of modern
evolutionary studies
Father of Modern Evolution

A long time ago, a small flock of sparrow-like birds
called finches were blown out to sea by a fierce storm.
They lost their bearings but flew on in search of the
mainland, going further and further out to sea. At the
point of exhaustion, 600 miles from home, they spotted
a speck of land - an island in the middle of the sea. They
were saved and could rest, drink and feed before
returning home. But this island was perfect: it had
abundant seeds and other food, plenty of shelter,
nesting sites and (amazingly) no predators or other birds
to compete with.

Life was much harder on the mainland. There
was no need for the birds to move on. Their
numbers grew - until they became just a bit too
numerous for the little island. Some found it hard
to find enough food for themselves or their
offspring, and young birds were driven away from
areas where food was available. Some birds were
forced to fly across the sea to nearby islands.
There, they found new territories, also with no
predators or other birds to compete with.

As the plants and their seeds were just a little
different on each island, some birds were better
than others at finding and eating the new food
sources. Birds which could break open fruits and
eat the seeds survived well enough to produce lots
of babies. Eventually, after a very long time, all
the islands became occupied by these birds but
the finches on each island were slightly different.

1. Explain why it is questionable that more than one
flock of birds would find the islands in this way at
the same time.
2. Suggest two possible reasons why there were no
predators on the island.
3. Why were there no other birds to compete with?
4. Why might some finches survive better than
others on the same food sources?
5. Why were the finches slightly different on each
island?
Guide Questions:

Theory of Natural Selection
HMS Beagle

 Darwin was able to see 13
varieties of finches, which
varied in size & shape,
from island to island.
 It took him 20 years to
organize the data.
Darwin’s finches

 Darwin presented his
theory of evolution
based on natural
selection
The Origin of Species

Alfred Russel Wallace (1823-1913)

 states that environmental
factors promote the
survival of the fittest and
eliminates the less fit.

Follow the Track
Explain the Theory of Natural Selection.

 Individuals within a
population with the
most favorable traits
for an environment
survive and pass on
those traits.
Natural Selection
SURVIVAL OF THE FITTEST!

 Organisms tend to
over reproduce
Species Overproduction

 There is a struggle
of existence and
the survival of the
fittest
 Living space and
food are limited
Competition

 No two individuals
are the same
 Plants and animals
of the same species
differ in size,
strength and
adaptive structures
Variation

 It is a process of
becoming better
suited to the
environment.
 It improves an
organism’s chance
of survival
Adaptation

 Environment
selects organisms
that survived to
be the parents of
succeeding
generations
Natural Selection

 Favorable
adaptations
gradually
accumulate in the
species and
unfavorable ones
disappear
Speciation

Lamarck’s Giraffes VS Darwin’s Giraffes

Why do you think it is important
to know the theories or
occurrences in evolution?

 Before the industrial
revolution in Britain,
most peppered moths
were of the pale
variety & were well
camouflaged against
the pale birch trees
that they like to sit on.
Peppered Moths

 Airborne pollution
mottled the birch tree
bark with soot, and now
the mutant black-
peppered moths
blended better against
the darkened bark,
while the white variety
became much more
vulnerable to predators.
Peppered Moths

Using the figure below, explain the Lamarckian Evolution. How
does it differ from Charles’s Theory of Natural Selection?

Assessment:
1.What is the correct definition of evolution?
A. Changes in a population of organisms over a period
of time.
B. Changes in individual organisms during their lifetime
C. Organisms coming into existence at a defined
moment in time and not changing

Assessment:
2. How did Lamarck’s theory of evolution differ
from that of Darwin’s?
A. Lamarck believed that characteristics acquired during
organism’s lifetime could be passed on to the next
generation.
B. Lamarck believed that Earth was old enough to provide
a sufficient time scale for the process of evolution.
C. Lamarck believed that the environment played a
significant role.

Assessment:
3. Which of the following best explains the mechanism of
natural selection?
A. Individuals in a population change to best suit their environment;
those that survive reproduce and pass on their traits.
B. Populations evolve in response to the individuals who compromise
the population of the environment.
C. There is variation among individuals in a population; those born
with traits best suited for the environment survive and reproduce.

Assessment:
4. Which of the following is the best example of natural
selection?
A. A population of arctic foxes undergoes a seasonal coat color
change from brown to white as soon as snow covers their habitat.
B. Field mice born during a year with excess wheat will gain muscle
mass and thus have offspring that have an increased muscle mass.
C. Trout that are born with darker scales are better able to survive in
the shadows among the river rocks.

Assessment:
5. Chameleon and salamander changes its color to
camouflage themselves from their predators. What do
you call a variation that can help a species survive in its
environment?
A. A characteristic
B. An adaptation
C. competition

Index of Mastery
5-
4-
3
2-
1-
0-

THEORIES OR OCCURRENCE OF EVOLUTION .pptx

THEORIES OR OCCURRENCE OF EVOLUTION .pptx

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