1.
Evolution
Presented by: Sehar Mangi(B.Ed VII)

2.
Content
• Cause of Diversity
• Evolution
• Lamarck’s Theory of Evolution
• Darwin’s Theory of Evolution
• Natural Selection
• Evidence of Evolution
• Misconceptions
• References

3.
3
“Nothing in
biology makes
sense EXCEPT in
the light of
evolution.”
Theodosius
Dobzhansky

4.
Lets think for a while about planet Earth
and Diversity of Living Organism

5.
Cause Of Diversity
1. Theory of Special Creation
o All living things came into existence in their present forms
especially and specifically created by nature.
o Carolus Linnaeuos.

6.
Cause of Diversity
2. Theory Of Natural Selection
o Organisms might EVOLVE through time , with one type of
organisms giving rise to another type of organisms.

7.
Cause of Diversity
2. Theory Of Natural Selection
o Aristotle
o Jean Baptiste Lamarck
o Charles Darwin

8.
What is Evolution?
…

9.
Evolution
• It refers to the
process that have
transformed or
changed life on earth
from its earliest
forms to the vast
diversity that we
observed today.
• Any Change in the
heritable traits with in
a population across
generation.

10.
Evolution
• Evolutionary Change
is based mainly on
the interactions
between population
of organisms and
their environment.

11.
Lamarck’s Theory of Evolution
• Organisms constantly strive to improve themselves
by changing.
• Changes are adaptations to environment acquired in
an organism’s lifetime.
• A structure is modified or changed by use or disuse
• The modification is inherited to the offspring.
• Inheritance of acquired characteristics.

12.
Darwin’s Theory of Evolution
• Check the video:
https://www.youtube.com/watch?v=yGV82kE4IEc

13.
Darwin’s Theory of Evolution

14.
Common descent with modification
• All organisms are
related through
descent from some
unknown ancestor
that lived in the
distant past.

15.
Natural selection and Adaptation
• He suggested that population of individual species
become better adapted to their environment through
natural selection.
“I have called this principle, by which
each slight variation, if useful, is preserved,
by the term Natural Selection.”
—Charles Darwin from "The Origin of Species“, 1859

16.
Lets Discover what is
Natural selection ?
Activity : A Paper plan
Instructions:
• Construct paper planes.
• Fly your plane 10 feet. If your plane survives, it will go on
to the next test. If it does not survive you will create an
offspring of one of the survivors.
• The survivors and offspring face a second trial of 15 feet.
The survivors will go on to the final round and those that
did not survive will create offspring of survivors to go to the
final round.
• The final test will be at 20 feet. Survivors will be judged for
a prize based on beauty, distance and uniqueness.

17.
Theory OF Natural Selection
• The Struggle for Existence -members of each
species have to compete for food, shelter, other life
necessities to reproduce in a specific environment.
• Survival of the Fittest-Some individuals better
suited for the environment.
• Natural Selection-The unequal ability of individuals
to survive and reproduce leads to a gradual change in
a population, with favorable characteristics
accumulating over generations new species evolve .

18.
Natural Selection & Artificial Selection
• Natural selection results in
changes in inherited
characteristics of a
population. These changes
increase a species fitness
in its environment.
• Artificial selection- nature
provides the variation
among different organisms,
and humans select those
variations they find useful.

19.
Evidence of Evolution
1. Fossils Record
• Remains or imprints of past life.
• Preserved in sediments.
• Occur in layers (strata).
• Fossils in different layers of rock (sedimentary
Rock Strata) showed evidence of gradual change
over time.

20.
Strata layers in Rocks

21.
Fossilized remains of a bird like dinosaur Archeopteryx

22.
Fossil Jellyfish

23.
Fossil Evidence for Evolution
• Fossils distributed consistently throughout strata of same
age.
• Order of fossil appearance shows more complex forms
appearing after simpler forms.
• Recent fossils (new strata) most closely resemble modern
organisms.

24.
Evidence of Evolution
2. Taxonomy
• Hierarchical classification structure developed by
Linnaeus
• Implies that species can be grouped together based
on their relatedness
• Bears with bears, bees with other bees
• A family tree can be made implying descent

25.
Related species of Ursus

26.
Evidence of Evolution
3. Comparative Anatomy
• Compares anatomical structures from different
organisms.
• Similar structures in two or more species are called
homologous structures.
• Homologous structures may perform different tasks
in different organisms.

27.
Comparative Anatomy Structure
Evidence of Evolution
• Scientists noticed animals with backbones
(Vertebrates) had similar bone structure.
• May differ in form or function.
• Limb bones develop in similar patterns.
Arms, Wings, Legs, Flippers

28.
Comparative Anatomy Structure Evidence
of Evolution
• Structures that have different mature forms but
develop from the same embryonic tissues
• Strong evidence that all four-limbed animals with
backbones descended, with modification, from a
common ancestor
• Help scientist group animals

29.
Homologous forelimbs

30.
Evidence of Evolution
4. Comparative Embryology
• Embryos (young stage of organisms are compared)
• Embryonic Structures Of Different Species Show
Significant Similarities.
• Similar features due to shared ancestry.

31.
Human Fetus – 5 weeks

32.
39
Chicken Turtle
Rat

33.
Evidence of Evolution
5. Biogeography
• Distribution of species
• Many related species occur across the
earth
• Isolated areas (islands, Australia)
often have unique species
• Biogeography explained by
continental drift of plates and
speciation

34.
Evidence of Evolution
6. Molecular Biology
• Includes comparisons of
• protein sequences
• DNA sequences
• chloroplast genomes (plants only)
• Used to developed phylogenetic trees (hypothesized
relationships)

35.
Evidence of Evolution
Lets Explore More
http://www2.edc.org/weblabs/exploringevolution
/evolution.swf

36.
Misconception about Evolution
• Evolution is “just a theory” or the “best guess”, so it
is not supported by scientific evidence.
• Organisms change and evolve because they have a
desire to do so.
• We can’t see evolution happening.
• Evolution leads to more advanced organisms that are
“climbing the evolutionary ladder”.
• Evolution occurs in individual organisms.

37.
Lets conclude the session through Mind
Map…

38.
Group Activity
• Watch the Video.
https://www.youtube.com/watch?v=GhHOjC4oxh8
• Make a list of ideas.
• Write down ideas on the Chart.
• Present it , in front of the Class

39.
Any Question?

40.
References
• http://www.southgateschools.com/web/userfiles/garrityd/15.pp
t
• http://www.biologyjunction.com/darwin%20evolution%20revi
sed.ppt
• http://www.slideshare.net/imlovestruck/theory-of-
evolution?qid=9f48c386-d204-40ad-b387-
3876e335f45f&v=&b=&from_search=6
• http://www.sas.upenn.edu/~dewees/Site/Assessment_files/Evo
lutionUnitPlan.pdf
• https://www.youtube.com/watch?v=GhHOjC4oxh8
• http://www2.edc.org/weblabs/exploringevolution/evolution.sw
f
• https://www.youtube.com/watch?v=yGV82kE4IEc
• Biology Textbook Of Class 12 Of Punjab Board