42Organic Evolution

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INTRODUCTION
▢ Term: The term ‘evolution’ (L., evolvere = to unfold or unroll) was introduced by English philosopher, Herbert Spencer (1820-1903).
▢ Definition: Biological (organic) evolution is the change in the properties of groups of organisms over the course of generations.
▢ Study: Evolutionary Biology is the study of history of life forms on Earth.
▢ Central Theme: ‘Descent with modification’ is the central theme of evolution.
▢ Scope: Organic evolution deals with changes in the properties of population of organisms from time to time.
▢ Hypothesis: Evolution is an excellent working hypothesis to approach the problem of diversity of organisms.
▢ Process: The process of evolution is continuous, taking place even now.
▢ Quote: Theodosius Dobzhansky: 'Nothing in biology makes sense except in the light of evolution'.
▢ Postulates:
  1. Organisms that appeared earlier were simpler
  2. Earlier simpler organisms have gradually changed into existing complex forms
  3. All organisms are interrelated because of common origin
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EVIDENCES
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Taxonomy
▢ Definition: Taxonomy is the science of classification of organisms
▢ Common Characteristics: Members of each taxonomic group posses some common characteristics due to common ancestry
▢ Complexity: Categorization of animals in increasing complex form provides obvious evidence of evolution under taxonomy
▢ Phylogenetic Tree: Scheme of classification provides a proof of descent from a common ancestor
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Biogeography
▢ Definition: Study of geographic distribution of plants and animals
▢ Biogeographical Realm: Region characterized by a distinct biota
▢ Regions:
❖ Palaeartic: Europe and Asia north of the tropics, north-western corners of Africa
❖ Nearctic: North America exclusive of the tropics
❖ Neotropical: Central America including low lands of Mexico, Islands of the Caribbean and all of South America
❖ Ethiopian: Africa (with exception of the Atlas Mountains), Madagascar and adjacent islands
❖ Oriental: Tropical part of Asia, south of the Himalaya Mountains
❖ Australian: Australia, Tasmania, New Guinea and islands east of Borneo
▢ Separated Regions: Palaearctic and Oriental regions separated by high mountain ranges
▢ Prototherians: Most primitive mammals found in Australia
▢ Adaptive Radiation: Production of ecologically diverse species from a common ancestral stock (e.g., marsupials in Australia)
▢ Parallel Evolution: Evolutionary change where marsupials resemble equivalent placental mammals
▢ Galapagos Islands:
❖ Description: 'A living laboratory of evolution', named after giant tortoises
❖ Darwin's Finches: 13 species showing adaptive radiation in beak shapes and sizes
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Comparative anatomy
▢ Tectology: Study of functional anatomy
▢ Types:
  1. Homology and Homologous organs
  2. Analogy and Analogous organs (e.g., Sting gland of Honey bee and Scorpion)
  3. Vestigial organs
  4. Connecting Links
  5. Atavism
▢ Atavism Examples:
  1. Large canines
  2. Thick body hairs ('Lion's boy' of Russia)
  3. Monstral face
  4. Short temporary tails
  5. Gill slits
  6. Multiple nipples
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Comparative embryology
▢ Principle: Common patterns of development provide evidence of evolution
▢ Von Baer: Basic rules of embryonic development
▢ Biogenetic Law: Ernst Haeckel: 'Ontogeny recapitulates phylogeny'
▢ Examples:
  1. Tadpole larva resembles fishes
  2. Gill clefts in vertebrate embryos
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Physiology and biochemistry
▢ Molecular Evidence: Comparisons of DNA, RNA or proteins evaluate evolutionary relationships
▢ Examples:
  1. Uniform occurrence of enzymes (trypsin, amylase)
  2. Thyroxine effectiveness across vertebrates
  3. Amino acid configuration of cytochrome C (Dickerson, 1972)
  4. Precipitation test (Nuttall, 1904)
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Palaeontology
▢ Definition: Study of fossils (direct evidence of evolution)
▢ Types:
  1. Palaeobotany (fossil plants)
  2. Palaeozoology (fossil animals)
▢ Fossil Types:
  1. Petrifaction (bones, shells, teeth)
  2. Moulds
  3. Casts
  4. Compressions
  5. Coprolites (preserved intestinal contents)
  6. Palynofossils (spores, pollen)
  7. Pseudofossils (mineral patterns)
▢ Notable Finds:
  1. 20 million year old fossil forest (Birbal Sahni Institute)
  2. 25,000 year old frozen mammoths in Siberia
▢ Pioneers:
  1. Leonardo da Vinci (Father of Palaeontology)
  2. Georges Cuvier (Father of Modern Palaeontology)
▢ Dating Methods:
❖ Radioactive Clock: Introduced by Boltwood (1907)
❖ Radiometric Dating:
  1. William F. Libby (Nobel 1960 for Carbon-14 dating)
  2. Half-life: 5568 years for C-14 → N-14 (useful up to 70,000 years)
  3. Potassium-Argon method (for hominid fossils)
  4. Electron-Spin Resonance (ESR, Zeller 1967 - most accurate)
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GEOLOGICAL TIME SCALE
Era
Period
Epoch
Years Ago
Major Biological Events
Precambrian
4.6 billion
Origin of Earth
3.5 billion
First prokaryotes appear
2.5 billion
Oxygen accumulates in atmosphere
1.5 billion
First Eukaryotes appear
0.7 billion
Origin of first animals
Palaeozoic
Cambrian
0.57 billion
Origin of most invertebrate phyla
Ordovician
0.52 billion
First fish (Ostracoderm)
Silurian
0.45 billion
First jawed fish; land colonization
Devonian
0.42 billion
Age of fishes; Origin of Amphibians
Carboniferous
0.375 billion
Age of Amphibians; Origin of Reptiles
Permian
0.285 billion
Radiation of reptiles
Mesozoic
Triassic
0.240 billion
First dinosaurs and mammals
Jurassic
0.195 billion
First bird (Archaeopteryx)
Cretaceous
0.135 billion
Extinction of Dinosaurs
Coenozoic
Palaeogene
Palaeocene
65 million
Primitive primates appear
Eocene
57 million
Origin of horse
Oligocene
34 million
Monkey-like primates appear
Neogene
Miocene
23 million
Radiation of Mammals
Pliocene
5 million
First hominids appear
Pleistocene
1.8 million
Man evolved
Holocene
0.01 million
Age of Man
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CONTENT
▢ Extinct Reptiles:
  1. Ichthyosaurs (fish-like)
  2. Pterosaurs (bird-like flying)
▢ Best Fossil Record: Horse
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AGES
▢ Stone Age:
  1. Paleolithic
  2. Mesolithic
  3. Neolithic
▢ Bronze Age:
▢ Iron Age:
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KEY TERMS
Term
Coined/Used by
Evolution
Spencer
Organic evolution
Charles Darwin (theory by Lamarck)
Founder of Evolution concept
Empedocles
Father of Evolutionary concept
Buffon
Prebiotic soup
Oparin
Coacervates
Oparin
Hot dilute soup
Haldane
Protenoid microspheres
Sydney Fox
Natural selection
Darwin
Survival of the fittest
Spencer
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Concepts
  1. Nucleic acids - Most important for Origin of Life
  2. Protobiont components: Amino acids + Sugar + Glycerol + Fatty acid
  3. Microsphere - Protobiont made of Polypeptides
  4. Liposomes - Protobiont made of Lipids
  5. Coacervates - Protobiont made of Polypeptide + Nucleic acid + Polysaccharide
  6. Pre-cell - Coacervate with nucleoprotein and surface membrane
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Laws
▢ Dollo's Law: Evolution is irreversible
▢ Parallelism: Adaptive convergence of closely related groups
▢ Discontinuous Distribution: Organisms present at different places without traces in between
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Miscellaneous
  1. Process of evolution is continuous
  2. Darwin's finches evidence from Biogeography
  3. Cladistics - Study of evolutionary branches
  4. Phylogeny - Study based on homologous development
Q1.
Heredity and variation was postulated by
📅MOE 2008
Q2.
Charles Darwin's theory of evolution is based on
📅MOE 2064
Q3.
Most accepted theory for origin of life is
📅MOE 2063
Q4.
Organs which have same basic structure and origin but differ in function are called
📅MOE 2062•MOE 2055
Q5.
Wings of birds and insects are
📅MOE 2061
Q6.
Fins of fishes and flipper of whale are
📅MOE 2003
Q7.
Inheritance of acquired character is given by the concept of
📅MOE 2005•MOE 2054
Q8.
Theory of continuity of germ plasm was proposed by
📅MOE 2033
Q9.
Postulation of the theory of natural selection published in 1858 was given by
📅MOE 2054
Q10.
Organs having similar function but different structure or origin are called
📅IOM 2007
Q11.
The mutation theory of evolution was proposed by
📅IOM 2004
Q12.
Which of the following is a living fossil?
📅IOM 2024
Q13.
Which of the following is a connecting link between animal and plant kingdom?
📅IOM 2003
Q14.
Founder of palaeontology is
📅IOM 2003
Q15.
The main drawback of Darwin's theory is
📅IOM 1995
Q16.
Earlier organisms were
📅BPKIHS 2002
Q17.
Three stages of evolution was given by
📅BPKIHS 2002
Q18.
The sun, earth and stars are reformed from
📅BPKIHS
Q19.
Correct sequence among the following is
📅BPKIHS 2004
Q20.
Coacervates are clusters of
📅BPKIHS 2005
Q21.
The organisms which depended on organic molecules present in primitive ocean were referred as
📅BPKIHS 2005
Q22.
The study of fossils is called
📅MOE 2062
Q23.
Wings of mosquito, bat and sparrow exhibit the phenomenon called
📅MOE 2062
Q24.
Phylogeny represents
📅MOE 2062
Q25.
Which is not a universal character of protoplasm?
📅MOE 2003
Q26.
Protoplasm is
📅MOE 2003
Q27.
Peripatus is a connecting link between
📅MOE 2002