ppt evolution presentation sciences evolution

Evolution

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2. EVOLUTION
•Evolutionary biology is the study of history of life forms
on earth.
•To understand this we must understand origin of life,
i.e.,
•evolution of earth,
•of stars and
•the universe itself.
•
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3. •Universe is 20 billion yrs. old
•Universe expanded-temp came down.
•Gases condensed and formed galaxies.
•Earth is part of solar system of milky way galaxy,
formed about 4.5 billion yrs. ago.
•Primitive atm.Water vapour, methane, Co2 and NH3.
•UV rays broke up water into H2 and O2.
•O2 formed water and Co2 with NH3 and CH4.
•Life appeared 500 million yrs. After the formation of
earth.
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ORIGIN OF LIFEORIGIN OF LIFE

4. Big bang theory
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7. Panspermia
According to it life came from out side
Early Greek scientists thought that units of life called spores were transferred
to different planets including earth
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8. Theory of spontaneous generations
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Life came out of the decaying & rotting matter like
straw,mud

9. Lowis pasteur experiment
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Life comes only from pre existing life,but it
did not answer how the first life form came
on earth.

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11. Oparin of Russia and Haldane of England
proposed that the first form of life coud have come
from pre-existing non-living organic molecules.
Formation of life was preceded by chemical
evolution.
First non-cellularforms o life could have
originated 3 billion yrs. Back.
2000 yrs. Back the first cellular forms could have
originated.
1. High temperature
2. volcanic storms
3. reducing atmosphere containing CH
4
, NH
3.
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13. Evolution of life forms
Conventional religious literature tells the theory of
special creation
There are three connotations
1. All living organisms that we see today were
created as such
2. The diversity was the same since creation& will be
the same in future also
3. The earth is about 4000 years old
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14. Evidences for organic evolution
1. Evidences from fossils
2. Evidences from comparative anatomy
 & morphology
3.Evidences from biochemistry
4.Evidences from plant & animal
 breeding
5.Evidences from natural selection
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15. Fossil evidences
Fossils are remaines of hard parts of life forms
found in rock
Rocks form sediments & a cross section of earth
crust indicates the arrangements of sediments
one over the other during the life history of the
earth
Different aged rock sediments contain fossils of
different life forms who died during the formation
of the particular sediment
They represent the extinct forms
A study of fossils in different layers indicates the
geological period in which they existed.
All these evidences are called palaentological
evidences.
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16. Different strata shows different fossils
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18. Fossil evidence
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19. Homologous organs
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In these animals the same structure developed along the
different directions due to the adaptations to different
needs . This is divergent evolution
Homology indicates common ancestry

20. Homologous organs
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Homologous organs have same structural plan the fore
limb has humerus, radius, ulna, carpals ,metacarpals,
phalanges

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HOMOLOGOUS ORGANS

23. Analogous organs
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They are not anatomically similar structures though they
perform similar function. hence, analogous organs are a
result of a convergent evolution .
Different structures evolving for the same function and
hence having similarity- this is said to be convergent
evolution

24. EXAMPLES FOR ANALOGOUS ORGANS
I. POTATO (Stem Modification) & SWEET POTATO( Root
Modiication)
2. OCTOPUS EYE &HUMAN EYE
3. FLIPPERS OF WHALE & PENGUIN

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ANALOGOUS ORGANS

26. Analogous organs
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HUMAN EYE

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Dolphin flipper & penguin flipper

28. Biochemical evidences
Similarities in proteins & genes performing a
given function among diverse organisms give
clues to common ancestory
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29. TYPES OF MOTHS
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There are two
types of moths
1 light winged
moth
2 Dark winged
moth

30. Tree trunks before industrialisation
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Before industrialization set in, it was observed that there are more white –
winged moths on trees than dark winged or melanised moths
Before industrialization set in the tree trunks were covered by thick growth
of the lichens. In that background the white winged moth survived , but
the dark coloured moths were picked out by predators

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32. TREE TRUNKS AFTER INDUSTRIALISATION
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After industrialization there were more dark winged moths on the tree trunks
During this period the tree trunks became dark due to the industrial smoke &
soots
Under this condition the white winged moth did not survive due to the
predators, because their body colour was not matched with the surrounding
colour
The dark winged moths were survived because their body colour was
matched with the surrounding colour

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BEFORE
INDUSTRIALISATION
AFTER
INDUSTRIALISATION

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They will not grow where there is industrial pollution
That’ s why in the rural areas we can see the growth
of the lichens

35. Evidence from animal & plant breeding
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Man has domesticated many wild animals & crops
this intensive breeding programme has created
breeds that differ from other breeds. they belong to
the same group
It is argued that within hundred of years man could
create new breeds, could not the nature have done
the same over millions of years

37. Adoptive radiation
The process of evolution of different species
in a given geographical area starting from a
point and literally radiating to other areas of
geography is called adaptive radiation.
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38. Examples for adoptive radiation
1. Darwin finches
2 Australian marsupials
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41. Adoptive radiation in marsupials of
Australia41
Common ancestor

42. When more than one adoptive
radiation appeared to have
occurred in an isolated
geographical area, it is said to
be convergent evolution
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43. 43
Convergent
evolution of
Australian
Marsupials and
Placental
Mammals

44. BIOLOGICAL EVOLUTION
Natural selection44
Colony A
Colony B
A colony of bacterium growing (A
colony) has variation in terms of
ability to utilize a feed component.
When the medium
composition is changed,
B population will get the
selective advantage & its
population will be
increased.
In due course of time new
sps will be appeared.
Thus nature selects for
fitnes.
The rate of appearance of
new forms is linked to the
life span or life cycle

45. Natural selection
Microbes that divide fast have the ability to
multiply & become millions of individuals
within hours .for the same thing to happen in
a fish or a fowl takes millions of years
Branching descent and natural selection are
the two key concepts of Darwinian Theory of
Evolution.
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47. Natural selection
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There are three basic ways that
natural selection can affect a
trait (also called the three modes
of selection): directional,
stabilizing and disruptive

48. Directional selection
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Directional selection occurs when one extreme
form of the character is favored. This form of
selection is very common in changing
environments. Industrial melanism is an example
of a discretely varying character under directional
selection
More individuals acquire value other than the
mean charecter

49. Stabilizing selection
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Stabilizing (or balancing) selection
occurs when an intermediate form
of the character is favored,
In this more individuals acquire
mean charecter

50. Distruptive selection
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It occurs when both extremes are
favored over intermediates.
More individuals acquire peripheral
character value at both ends of the
distribution curve

51. Natural selection
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53. 53
Evening primrose
MECHNISM OF EVOLUTION

54. Mutations
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According to Devries Mutations are large differences
arising suddenly in a population
He believed that mutation causes evolution & not the
minor variations what Darwin talked about

55. EVOLUTION
•AS PER DARWIN
•Mutations cause
evolution not minor
variations Darwin talked
about.
•Mutations are random
and directionless.
•Mutation caused
speciation, hence called
saltation (single step
large mutation)
•AS PER DEVRIES
•Minor variations cause
evolution.
•Darwin variations are
small and directional.
•Evolution slow and
gradual.
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56. HARDY-WEINBERG LAW
It states that allele frequencies in a population
are stable & is constant from generation to
generation
The gene pool ( total genes & their alleles in a
population ) remains a constant. This is called
genetic equilibrium
Sum total of all the allelic frequencies is 1.
Change of frequency of alleles in a population
would then be interpreted as resulting in
evolution.
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57. Hardy- weinberg law
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HW law states --> 
           original percentage of a genotypes alleles remains
CONSTANT
   HW Equilibrium...  is defined algebraically, by the binomial
expansion
           any gene with 2 allelic forms...       A  and  a
                   let frequency of one allele                     
(A)    =     p
                     & frequency of other allele                  
(a)    =     q
the frequency of AA in a population is =p2
the frequency of aa in a population is = q2
the frequency of Aa in population is =2pq
          
           Hence   (p + q)
2 
  =   p
2
   +   2 pq   +   q2   =  1
                                                             

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In population of canes...   Orange is dominant (AA) to Green
(aa) 
                                                
   of 1000 canettes, we observe that...                  
            40 are Green (aa)     & thus      960 are Orange    (AA&Aa)
               q
2 
=  freq homozygous recessive (green aa) = 0.04 
                                 40/1000 = [0.04] x 1000 = 40
               q   =  freq of recessive allele sq.root of 0.04        =   0.20  
               p   =  freq dominant allele [A] = 1 - q = 1 - 0.2        =   0.80
           2pq   =  freq of heterozygote [Aa]
                              =  2  (0.2) (0.8)  = [0.32 x 1000]             =    320
           p
2
= freq of homozygous dominant 
                              =  (0.8)
2
= [0.64 x 1000]                         =     640

  p2+2pq + q2= 0.04+0.32+0.64= 1
 
 
 

59. Factors which effect hardy –weinberg
principle
1.Gene migration or gene flow
2. Genetic drift
3. Mutation
4. Genetic recombination
5. Natural selection
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60. Gene migration or gene flow
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Migration (or gene flow): Some beetles with
brown genes immigrated from another
population, or some beetles carrying green
genes emigrated

61. Mutation
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62. Genetic drift
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Genetic drift: When the beetles reproduced, just by
random luck more brown genes than green genes ended
up in the offspring. In the diagram at right, brown genes
occur slightly more frequently in the offspring (29%) than
in the parent generation (25%).

63. Natural selection
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Natural selection: Beetles with brown genes escaped predation and
survived to reproduce more frequently than beetles with green
genes, so that more brown genes got into the next generation.

64. Founder effect
Some times the change
in the allele frequency is
so different in the new
sample of population that
they become a different
species.
The original drifted
population becomes the
founders for the formation
of new species & the
effect is called Founders
effect
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65. Brief account of evolution
About 2000 million years ago( mya) the first cellular forms of life
appeared on earth
Some of these cells had the ability to release O2. The reaction could
have been similar to the light reaction in photosynthesis where water
is split with the help of solar energy
Slowly single celled organisms became multicellular
By the time of 500 mya, invertebrates were formed & active
Jawless fish evolved around 350 mya
Sea weeds & & few plants existed probably around 320 mya
The first organisms that invaded land were plants they were wide
spread on land when animals invaded land
Fish with stout & strong fins could move on land & go back to water .
This was about 350 mya
 in 1938 a fish caught in South Africa was a Coelacanth which was
thought to be extinct
 these animals called lobefins evolved into the first Amphibians that
lived in both land & water
Lobefins are the ancestors of the modern day frogs & salamanders
The amphibians evolved into reptiles they lay thick shelled eggs
which do not dry up in sun unlike those of amphibians
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68. •In the next 200 million years , reptiles of different sizes &
shapes dominated the earth
•Some of the land reptiles went back into water to evolve
into fish like reptiles probably 200 mya ( Echthyosauras )
•The land reptiles were Dinosaurs
•About 65 mya dinosaurs suddenly disappeared from the
earth
•Most of the dinosaurs are evolved into birds
• the first mammals are like shrews their fossils are small
•Mammals are viviparous & protected their young inside
the mother womb
•When reptiles came down mammals took over the earth
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Tyrannosaurus Rex is the biggest Dinosaur
It was about 20 feet
It had huge fearsome dagger like teeth

74. Reasons for the disappearance of the
dinosaurs
We do not know the true reason
1. Some say climatic changes killed them
2. Some say most of them evolved into reptiles
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75. Evolution of man
Dryopithecus &
ramapithecus were existing
about 15 mya
They were hairy & walked
like gorillas
Ramapithecus was more
man like
Dryopithecus was more ape
like
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Dryopithecus
Ramapithecus

76. Ramapithecus
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77. Australopithecines
Few fossils of man like bones discovered in Ethiopia
&Tanzania
These revealed homonid features leading to the belief
that about 3-4 mya man like primates walked on earth
They were probably not taller than 4 feet but walked
upright
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78. Australopithecines
About 2 mya
australopithecines
probably lived in east
Africa grassland
They hunted with stone
weapons
They were fruit eaters
This creature was first
human being like
homonid & was called
Homo habilis
The brain capacities are
between 650-800cc
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79. Homo erectus
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About 1.5 mya
Homo erectus
were existed
They had a
large brain
around 900 cc
They probably
ate meat

80. Neanderthal man
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Neanderthal man was lived in near east& central asia
between 1,00,000-40,000 years back
They used hides to protect their bodies
Their brain size was 1400cc

81. Homo sapiens
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Homo sapiens arose in India
during ice age between
75,000-10,000 years ago
Agriculture came around
10,000 years back

82. Human evolution
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83. Human evolution
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84. Brain sizes
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85. Evolution of plants
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