Hons Zoology Panjab University Chandigarh ORIGIN OF UNIVERSE BIG BANG THEORY Thermonuclear explosion Origin of universe occurred 20 bya ORIGIN OF EARTH NEBULAR HYPOTHESIS Condensation of gases under Gravitational force ID: 929524
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EVOLUTION
TINA CHOPRA
M.Sc
(Hons), Zoology
Panjab University, Chandigarh
Slide2ORIGIN OF UNIVERSE
BIG BANG THEORY
Thermonuclear explosion
Origin of universe occurred 20 bya.
Slide3ORIGIN OF EARTH
NEBULAR HYPOTHESIS
Condensation of gases under Gravitational force
Origin of Solar system occurred 4.5 bya.
Slide4ORIGIN OF LIFE
THEORIES ON ORIGIN OF LIFE
Theory of special creation
Theory of catastrophismCosmozoic TheoryTheory of Spontaneous Creation/ AbiogenesisTheory of Biogenesis
Theory of Chemical Evolution
Slide5Theory of Chemical Evolution of Life
Given by Oparin and Haldane
Oparin’s book- Origin of Life
“Abiogenesis first and Biogenesis ever since”
3 phases of chemical evolution
Chemogeny
Biogeny
Cognogeny
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SEQUENCE
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EXPERIMENTAL EVIDENCE OF CHEMICAL EVOLUTION
Slide9CHANGES AFTER OXYGEN EVOLUTION
Oxidising
EnvironmentOzone formationOrigin of Aerobic forms of life
Slide10EVIDENCES OF EVOLUTION
Morphological and Anatomical evidences
Biogeographical Evidences
Paleontological EvidencesEmbryological EvidencesBiochemical Evidences
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MORPHOLOGICAL & ANATOMICAL EVIDENCES
Slide12HOMOLOGOUS ORGANS
Arm of a human, the wing of a bird or a bat, the leg of a dog and the flipper of a dolphin or whale
2. Forelimbs of a frog, a bird, a rabbit and a lizard
3. Pelvis of a dog, of a cat and of a human and of a snake4. Tailbone of a human being and the tail of a monkey
5. leaves of a pitcher plant, a Venus fly trap, a cactus
6. mouthparts and the antennae of different insects
Slide13ANALOGOUS ORGANS
1. Potato is a stem while sweet potato is a root
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ADAPTIVE RADIATION IN MARSUPIALS
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Adaptive convergence in placental mammals and Australian marsupials
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VESTIGIAL ORGANS
Vermiform appendix.
Hind limbs is a
vestigeal
organ of python.
Muscles of ear pinna
Wisdom teeth
Caecum
Body hair
Mammary glands in males
Nictitating membrane
Coccyx
Splint bones in horse
z
ATAVISM
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CONNECTING LINKS
Slide19EMBRYOLOGICAL EVIDENCES
The development from zygote to adult shows many similarities in various organisms
Slide20PALEONTOLOGICAL EVIDENCES
FOSSILS
Father of
PaleontologyFather of modern PaleontologyFather of Indian Paleontology
Slide21Fossil Dating methods
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BIOCHEMICAL EVIDENCES
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BIOGEOGRAPHICAL EVIDENCES
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GEOLOGICAL TIME SCALE
Slide26THEORIES OF EVOLUTION
LAMARCKISM
DARWINISM
MUTATION THEORYMODERN THEORY
Slide27LAMARCKISM
Theory of Inheritance of Acquired characters
Book “
Philosphic Zoologique”1. New needs:So according to Lamarck, an existing individual is the sum total of the characters acquired by a number of previous generations and the speciation is a gradual process.
2. Living organisms or their component parts tend to increase in size.
3. Production of new organ is resulted from a new need.
4. Continued use of an organ makes it more developed, while disuse of an organ results in degeneration.
5. Acquired characters (or modifications) developed by individuals during their own lifetime are inheritable and accumulate over a period of time resulting a new species.
Slide28Evidences in
favour
of Lamarckism
Increase in their evolution from simple to complex forms.2. Development of present day long-necked and long fore-necked giraffe from deer-like ancestor3. limbless snakes with long slender body from the limbed ancestors due to continued disuse of limbs
4. Development of webs between their toes for wading purposes in aquatic insects.
5. Development of flightless birds like ostrich from flying ancestors due to continued disuse of wings
Slide29Evidences against Lamarckism
August Weismann who proposed the “Theory of continuity of germplasm”
Boring of pinna of external ear and nose in Indian women;
Tight waist, of European ladies small sized feet of Chinese women etc are not transmitted from one generation to another generator.Eyes which are being used continuously and constantly develop defects instead of being improved. Similarly, heart size does not increase generation after generation though it is used continuously.Presence of weak muscles in the son of a wrestler Reduction in the size of organs e.g. among Angiosperms, shrubs and herbs have evolved from the trees.So, Lamarckism was rejected.
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DARWINISM
Theory of Natural Selection
Main postulates of Darwinism are:
1. Geometric increase.
2. Limited food and space.
3. Struggle for existence.
4. Variations.
5. Natural selection or Survival of the fittest.
6. Inheritance of useful variations.
7. Speciation.
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EXAMPLES OF DARWINISM
Evidences in
favour
Slide33Darwinism is not able to explain:
The inheritance of small variations in those organs which can be of use only when fully formed e.g. wing of a bird. Such organs will be of no use in incipient or underdeveloped stage.
2. Inheritance of vestigial organs.
3. Inheritance of over-specialised organs e.g. antlers in deer and tusks in elephants.4. Presence of neuter flowers and sterility of hybrids.5. Did not differentiate between somatic and germinal variations.6. He did not explain the causes of the variations and the mode of transmission of variations.7. It was also refuted by Mendel’s laws of inheritance which state that inheritance is particulate.
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MUTATION THEORY
1. The evolution is a discontinuous process and occurs by mutations.
2. Elementary species are produced in large number to increase chances of selection by nature.
3. Mutations are recurring so that the same mutants appear again and again. This increases the chances of their selection by nature.
4. Mutations occur in all directions so may cause gain or loss of any character.
5. Mutability is fundamentally different from fluctuations (small and directional changes).
He worked on evening primrose
(
Oenothera
lamarckiana
).
Evolution is a discontinuous and jerky process ,so that new species arises from pre-existing species in a single generation (
macrogenesis
or saltation) and not a gradual process as proposed by Lamarck and Darwin.
“Mutations are the fountain head
of evolution.”
Slide36Evidences in
favour
of Mutation theory
1. Appearance of a short-legged sheep variety, Ancon sheep from long-legged parents in a single generation2. It can explain the inheritance of vestigial and over-specialized organs.3. It can explain progressive as well as retrogressive evolution.
Slide37Evidences against Mutation theory:
It is not able to explain the phenomena of mimicry and protective
colouration
.2. Rate of mutation is very low, i.e. one per million or one per several million genes.3. Oenothera lamarckiana is a hybrid plant and contains anamolous type of chromosome behaviour.
4. Chromosomal numerical changes as reported by de Vries are unstable.
5. Mutations are incapable of introducing new genes and alleles into a gene pool.
Slide38Slide39Slide40THE MODERN SYNTHETIC THEORY
FACTORS RESPONSIBLE FOR EVOLUTION ARE :
NATURAL SELECTION
MUTATION
HYBRIDISATION
ARTIFICIAL SELECTION
CROSSING OVER
GENETIC DRIFT
MIGRATION
Slide41HARDY WEINBERG PRINCIPLE
allele
and genotype frequencies in a population will remain constant from generation to generation in the absence of other evolutionary influences.
Slide42FACTORS WHICH DISTURB HWE
NATURAL SELECTION
CROSSING OVER
MIGRATION
GENETIC DRIFT
RECOMBINATION
Slide43Slide44Slide45Slide46Slide47FOUNDER’S EFFECT
Slide48BOTTLE NECK EFFECT
Slide49TYPES OF NATURAL SELECTION
Slide50HORSE EVOLUTION
Slide51Slide52HUMAN EVOLUTION
Slide53Slide54Slide55PREVIOUS YEAR QUESTIONS
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