1. Presented By -
Upasana Kumari
(Enrollment no :
CUB1403122024)
M.Sc. Bioinformatics
r 1
CENTER FOR BIOLOGICAL SCIENCES
(BIOINFORMATICS)
CENTRAL UNIVERSITY OF SOUTH BIHAR, PATNA
EVOLUTION

2. CONTENTS
1.DEFINITION
2.EVOLUTION BY NATURAL SELECTION
3.PREVALENT IDEAS AT DARWIN’S TIME
4.DARWIN’S IDEA OF EVOLUTION
5.CHANGE MECHANISMS
6.FOUR STEPS OF NATURAL SELECTION
7.WEALTH OF EVIDENCES
8.PATTERNS OF EVOLUTION
9.REFERENCES

3. DEFINITION
“Evolution: The gradual process by which the present
diversity of plant and animal life arose from the earliest
and most primitive organisms, which is believed to have
been continuing for the past 3000 million years."
-Oxford Concise Science Dictionary

4. EVOLUTION
 The last shore-dwelling ancestor of modern whales was Sinonyx, top left,
a hyena-like animal. Over 60 million years, several transitional forms
evolved: from top to bottom, Indohyus, Ambulocetus, Rodhocetus,
Basilosaurus, Dorudon, and finally, the modern humpback whale.

5. EVOLUTION BY NATURAL
SELECTION
The theory of evolution by natural selection, first
formulated in Darwin's book “The Origin of Species" in
1859, is the process by which organisms change over
time as a result of changes in heritable physical or
behavioral traits.
Darwin wrote, "…Natural selection acts only by taking
advantage of slight successive variations; she can never
take a great and sudden leap, but must advance by
short and sure, though slow steps."

6. PREVALENT IDEAS AT
DARWIN’S TIME
NEW IDEAS PROPOSED
•
Fossils indicated the earth was very old.
•
Lyell, a Geologist argued that land forms changed
constantly.
•
Lamarck proposed that organisms changed and these
changes were passed to progeny.
 Species are fixed.
 Earth is about 6,000 years old.

7. DARWIN’S IDEA OF
EVOLUTION
 In 1831,Darwin went on a
round the world voyage while
he made observations of
organisms in South America
and the Galapagos Islands.
"I can see no difficulty in a race of
bears being rendered, by natural
selection, more aquatic in their
structure and habits, with larger
and larger mouths, till a creature
was produced as monstrous as a
whale," he speculated.
 The idea didn't go over very
well with the public. Fig. Coverpage of Darwin's Book.

8. Medium
ground finch
Cactus
ground finch
Small
tree finch
Large
ground finch
Small
ground finch
Large cactus
ground finch
Sharp-beaked
ground finch
Vegetarian
finch
Seed
eaters
Ground finches
Cactus flower
eaters
Bud
eaters
Tree finches
Insect
eaters
Medium
tree finch
Large
tree finch
Mangrove
finch
Woodpecker
finch
Green
warbler finch
Grey
warbler finch
Warbler finches
Common ancestor from
South America mainland
DARWIN’S FINCHES

9. CHANGE MECHANISMS
 Mutation
 Migration
 Genetic drift
 Natural selection

10. FOUR STEPS OF NATURAL
SELECTION
1. Overproduction
2. Variation
3. Competition
4. 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

11. WEALTH OF EVIDENCES
 Embryology
 Vestigial and Homologous structures
 Biogeography
 The Fossil Record
 Biochemical Evidence

12. Snake Chicken Possum Cat Bat Human
Embryology & Homologous
Structures

13. Fossil Record & Biochemical evidence
HOMINID SKULL & AMMONITE CASTE DNA-BIOCHEMICAL EVIDENCE

14. PATTERNS OF EVOLUTION
1. Macroevolution-
Large scale changes taking place over
long periods of time.
Lead to new species formation.
2. Microevolution-
Small scale changes within a species.
Produce new varieties or species in a
relatively short amount of time.
Macroevolution
v/s
Microevolution

15. REFERENCES
• Biology Book – Class 12th
NCERT
• Class lectures
• http://evolution.berkeley.edu/evolibrary/article/