43Theories of Evolution

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LAMARCKISM
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Founder
β–’ Name: Jean Baptiste de Lamarck
β–’ Details:
  1. French naturalist
  2. First to suggest complete theory of organic evolution
  3. Published in 'Philosophie Zoologique'
  4. Severely criticized by Cuvier
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Postulates
  1. Internal forces increase body size
    2. β—ˆ Formation of New Organs: Result of continuous needs (Doctrine of Appetency)
  2. Organ development proportional to use (Use and Disuse)
    3. β—ˆ Inheritance of Acquired Characters:
    1. Most controversial postulate
    2. Known as Lamarckian Doctrine
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Key concepts
  1. Direct influence of environment on individuals
  2. Weismann's disproval (tail-cutting experiment in mice for 80 generations)
  3. Weismann's 'Theory of Continuity of Germplasm'
  4. Neo-Lamarckism: Only germplasm-affected characters are heritable
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Examples
  1. Webbed feet in aquatic birds
  2. Long-necked giraffes
  3. Limbless snakes
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DARWINISM
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Founders
β–’ Charles Darwin:
  1. British naturalist
  2. Voyage on HMS Beagle (1831)
  3. Influenced by 'Malthus Principle of Population'
β–’ Alfred Russel Wallace:
  1. Developed similar ideas independently
  2. Joint paper 'Origin of Species' with Darwin
  3. Darwin's detailed book: 'On the Origin of Species by Means of Natural Selection'
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Postulates
  1. Overproduction
    2. β—ˆ Struggle for Existence:
    1. Intra-specific (high competition)
    2. Inter-specific
    3. With environment
  2. Heredity and Variation
  3. Natural Selection (Survival of the Fittest - Spencer)
  4. Structural modifications for changing environment
  5. Origin of Species
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Drawbacks
  1. Focused only on minute fluctuating variations
  2. Didn't distinguish somatic vs germinal variations
  3. Pangenesis theory (discarded explanation for inheritance)
  4. No satisfactory explanation for variations
  5. Didn't account variation with heredity
  6. Neo-Darwinism incorporates mutations + natural selection
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Examples
    β—ˆ Overproduction:
    1. Fast reproducers: Paramecium, Housefly, Oyster, Salmon
    2. Slow breeder: Elephant
  1. Variations in Galapagos tortoises and finches
  2. Long-necked giraffes
  3. Industrial melanism in peppered moth (Biston betularia)
  4. Dinosaur extinction
  5. Sickle-cell anemia
  6. Mosquito DDT resistance
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NEO-DARWINISM
β–’ Basis: Variation
β–’ Chief Contributors:
  1. Weismann
  2. Mendel
  3. De Vries
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MUTATIONTHEORY
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Founder
β–’ Name: Hugo de Vries
β–’ Details:
  1. Dutch botanist
  2. Experimental plant: Oenothera lamarckiana (Evening primrose)
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Keyconcepts
  1. Mutations = Discontinuous variations ('Sports' - Darwin, 'Saltatory variations' - Bateson)
  2. Generally harmful and recessive
  3. Source of genetic variations in evolution
  4. May or may not be inherited
  5. Germinal mutations are inheritable
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Explanatorypower
  1. Progressive/retrogressive evolution
  2. Persistence of vestigial and overspecialized organs
  3. Struggle for existence + Survival of fittest with useful mutations
  4. Speciation
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Additionalpoints
  1. X-rays induce hereditary variations in plants
  2. Selected mutations increase in population frequency
  3. Greater evolutionary potential in sexually reproducing species
  4. Evolution impossible without genetic variations
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MODERNSYNTHETICTHEORY
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Components
  1. Genetic variations (mutations, recombination)
  2. Natural selection
  3. Reproductive isolation
  4. Genetic drift
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Example
Human evolution
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COMPARATIVETABLE
Theory
Key Mechanism
Inheritance Mechanism
Strengths
Weaknesses
Lamarckism
Use/Disuse + Acquired Characters
Inheritance of acquired traits
Explains adaptation to needs
No germplasm concept
Darwinism
Natural Selection
Pangenesis (discarded)
Explains survival adaptations
No genetic basis for variations
Mutation Theory
Saltatory variations
Germinal mutations
Explains sudden changes
Most mutations harmful
Neo-Darwinism
Natural Selection + Mutations
Mendelian inheritance
Combines genetics & selection
Complex mechanisms
Q1.
According to neo-Darwinism, evolution is due to
πŸ“…IE 2009
Q2.
Two sets of muscles responsible for ear movement are
πŸ“…IE 2002
Q3.
During vertebrate brain evolution, the part showing greatest evolution by acquiring large size is
πŸ“…IE 2002
Q4.
The morphological study based on phylogenetic characters and homologous development is
πŸ“…IE 2002
Q5.
The study of evidence of origin of evolution and its branches according to phylogenetic tree is called
πŸ“…IE 2002
Q6.
Fossils are mostly found in
πŸ“…IE 2003
Q7.
Natural selection acts directly on
πŸ“…IE 2004
Q8.
Evolution of photosynthetic ability resulted in division of living world into
πŸ“…IE 2008
Q9.
Allopatric speciation is caused by
Q10.
Connecting link between arthropoda and annelida is
πŸ“…BPKIHS 2014
Q11.
Who gave the principle of biogenetic law?
πŸ“…BPKIHS 2014
Q12.
During evolution of earth, the first compound formed was
πŸ“…BPKIHS 2014
Q13.
Which gas was most abundant during earth formation?
πŸ“…BPKIHS 2014
Q14.
Sudden appearance of tail in a small baby is an example of
πŸ“…BPKIHS 2015
Q15.
Connecting link between animal and plant is
πŸ“…BPKIHS 2016
Q16.
Which of the following is closest to man?
πŸ“…BPKIHS 2014
Q17.
The main strong evidence for evolution is
πŸ“…BPKIHS 2014
Q18.
The most basic substance of origin of life is
πŸ“…BPKIHS 2014
Q19.
Harold C. Urey's laboratory experiment found large number of complex organic compounds, among which the essentials of life were
πŸ“…MOE 2014β€’MOE 2013
Q20.
Stout-running forelegs of horse and forearms of human used for catching are
πŸ“…MOE 2014
Q21.
Canine teeth in man are
πŸ“…MOE 2014
Q22.
Gill slits present in embryonic stage of vertebrates represent
πŸ“…MOE 2014
Q23.
The word coacervate was first used by
πŸ“…MOE 2012
Q24.
Modern human beings were originated from
πŸ“…MOE 2012
Q25.
Origin of species was postulated by
πŸ“…MOE 2062
Q26.
Which of the following were first formed?
πŸ“…KU 2015
Q27.
The concept of survival of the fittest was advanced by
πŸ“…KU 2015
Q28.
The term Homo sapiens was coined by
πŸ“…KU 2015
Q29.
Recapitulation theory means that
πŸ“…KU 2014
Q30.
Darwin's statement 'survival of the fittest' means that
πŸ“…KU 2012
Q31.
The process of inheritance of character in living beings is called
πŸ“…KU 2011
Q32.
The principle of inheritance of acquired characters was given by
πŸ“…KU 2011