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EVOLUTION
Origin of life!!
Evolutionary biology is the study of history
of life forms on earth. To understand the
changes in flora n fauna…..we must have
an understanding of context of origin of
life.
Evolution, or change over time, is the
process by which modern organisms have
descended from ancient organisms.
ORigiN oF Life!!
BIG BANG THEORY: Acc. To this theory,about
15billion yrs ago all the matter & energy in the
visible universe was conc. In a small ,hot,dense
region,which flew apart in a gigantic
explosion(thermonuclear).The universe
expanded and hence the temp came
down.Hydrogen & helium formed sometime
later.the gases condensed under gravitation &
fomed the galaxies of the present day
universe…
Theory of spontaneous generation
Acc. To this theory, life originates
spontaneously from lifeless matterAbiogenisis. But this had been put to
rest when Louis Pasteur provided
proof that microorganisms come only
from other microorganisms i.e
Biogenesis.
Louis Pasteur’s experiment!!
Panspermiatic Theory!!
It was proposed by Richter & supported by
Arrhenius.It states that life forms came on
earth from some other planet in form of
seed or spore.
Oparin Halden theory!!
It states that primitive life originate in
the water bodies on the primitive
earth from inanimate matter by
chemical evolution through a series of
chemical reaction about 4 billion yrs
ago.
Stanley Miller’s experiment
Their apparatus produced a variety of
amino acids & other organism compounds
found in living organisms today .
Stanley Miller’s experiment
Charles Darwin and his theories
Voyage of the Beagle
Publication of Origin of Species
1844 Darwin wrote down
his ideas about evolution
& natural selection, but
didn’t publish his data
due to the controversy
that other scientist were
facing concerning this
topic- he wasn’t confident
enough.
Finally, he wrote the book
& it was published in Nov
1859.
Evidence of Evolution
The Fossil Record
Geographic Distribution of Living
Things
Homologous Body Structures
Similarities in Early Development
Evidence of Evolution
Fossils: offer the most direct evidence
that evolution takes place.
– A preserved/mineralized remain or
imprint of an organism that lived long
ago.
Provide an actual record of Earth’s past
life-forms.
Change over time can be seen in the fossil
record.
– ie. Fossilized species found in older rocks are
different from those found in newer rocks.
After observing the differences in fossils,
Darwin predicted that intermediate forms
between groups of organisms would
eventually be found.
– Some have been found.
– Some have not.
These intermediate forms are called
transitional fossils.
– Any fossil which gives us information about a
transition from one species to another.
Examples of transitional fossils
Anatomy & Development
Studying the anatomy of different types of
organisms often reveals basic similarities
in body structures even through the
structures function may differ between
organisms.
– Vestigial structures
– Homologous structures
– Embryonic development
Homologous Structures-structures that
have different mature forms in different
organisms, but develop from the same
embryonic tissue.
Vestigial organs-organs that serve
no useful function in an organism
i.e.appendix, miniature legs, arms
Similarities in Early Development
Adaptive Radiation
The process of evolution of different
species in a given geographical
areastarted from a point and literally
radiating to other areas of geography is
adaptive radiation.
Adaptive Radiation
Biological Evolution
Natural Selection
After gathering all of his information, Darwin
made a conclusion: “individuals that have
physical or behavioral traits that better suit their
environment are more likely to survive and will
reproduce more successfully than those that do
not have such traits”. Darwin called this natural
selection.
– Over time, the number of individuals that carry
favorable characteristics that are ALSO inherited will
increase in a population. Therefore, the population
will change. This changes = evolution.
Factors in Natural Selection
The process is driven by 4 important
points that are true for all real populations.
– All populations have genetic variation
– The environment presents challenges to
successful reproduction.
– Individuals tend to produce more offspring
than the environment can support.
– Individuals that are better able to cope with
the challenges tend to leave more offspring
than those who aren’t.
An example
Evolution of antibiotic resistant diseases.
– The bacteria needs to survive to reproduce.
– Eventually, a mutation will occur in its genome
that will allow even one bacteria cell to fight
off the antibiotics. As it reproduces, more
antibiotic resistant cells are made and the
antibiotic currently used becomes ineffective.
Hardy Weinberg Principle
Hardy Weinberg Principle
Evolution of plants!!
Evolution of Animals!!
Origin & Evolution of MAN!!
 Dryopithecus -15mya- hairy & walked like
Ramapithecus
gorillas & chimps
 Man like primates-3-4mya-they were not taller
than 4feet& walked
upright.
Autralopithecus-2mya-lived in east African
grasslands ate fruits.
Homo habilis-Brain capacities 650-800;didn’t
eat meat.
Origin & Evolution of MAN!!
 Homo eretus-1.5mya-had large brain with
(discovered in jawa)
900cc &ate meat
Neanderthal man-1,00,000-had brain of 1400
cc lived near
east central Asia.
Used hides to protect their bodies.
Homo Sapiens-arose in Africa & moved
across continents & developed into races.
Origin & Evolution of MAN!!
 Modern Homo Sapiens-75,000-10,000yrs
ago-pre historic cave art developed.
 10,000 yrs ago –Agriculture & human
settlement started.
Comparison of skulls!!