Key Points: Evolution Part 3

	Supports to Natural Selection: Anthropogenic Selection Artificial Breeding Industrial Melanism Insecticide/Pesticide Resistance Resistance to antibiotics
	Adaptive Radiation: process of evolution of different species from a geographical area, by moving into different geographical area (habitat). E.g Australian Marsupial More than one adaptive radiation in an area – Convergent evolution e.g. Australian Marsupial & Placental mammals
	Vestigial organs: Organs present in non-functional forms. e.g. Vermiform appendix, Nictitating Membrane, hair on body
	Connecting Links: organisms possessing characters of two different groups of organisms, e.g. Connecting Links Organism Groups Euglena Plants & Animals Peripatus Annelida & Arthropoda Balanoglossus Non-chordates & Chordates Chimaera Cartilaginous & Bony Fish
	Missing Links: Fossil evidence showing combined forms of two groups. E.g Archaeopteryx (reptiles & Birds)
	Atavism: reappearance of ancestral characters. E.g. short tail in human babies, winged petiole in citrus
	Lamarck’s Theory: Use & Disuse of organs Characters are acquired due to new needs in changing environment.
	Mutation Theory: Hugo de Vries (Evening Primrose) New species originate due to mutations or discontinuous variations Mutations subjected to natural selection If unfavourable; destroyed
	Synthetic Theory: synthesis of Darwin’s & Hugo de Vries theories Five basic factors of evolution: 1.       Mutations 2.       Gene Recombinations 3.       Gene Migration / Gene Flow 4.       Genetic Drift              Founder Effect 5.       Hybridisation
	Types of Natural Selection: 1.       Stabilising Selection: favours average characteristics & eliminates extremes 2.       Directional/Progressive Selection: favors non-average or extreme for of trait & pushes population in one direction 3.       Disruptive Selection: favours both extremes and eliminates individuals with average traits. Forms two peaks in population. Two different populations formed. Disruptive section leading to formation of two new species – adaptive radiation
	Hardy Weinberg Principle: Describes theoretical situation where no evolution is occurring in a population i.e. frequency of alleles in a population is constant – genetic equilibrium uses algebraic equation: For a gene A with 2 alleles A & a Genotypes        Frequency AA                         p aa                          q Aa                         2pq Where, p frequency of dominant allele in population                q frequency of recessive allele in population              p2 Probability of occurrence of homozygous dominant              q2 Probability of occurrence of homozygous recessive             2pq Probability of occurrence of hetrozygous Allele frequency: p+q=1 So genotype Frequency: p2+q2=2pq=1
	Conditions/Absence of Genetic Equilibrium: Absence of Mutation, Gene Flow, Genetic Drift, genetic recombination, natural selection Founder Effect: Drifted population forming a new species (founder species) in the new area.
Lobefins (Coelacanth): fish capable of traversing between land & water Difference in eggs of amphibians & reptiles?	Evolution chronology: 3 eras: Paleozoic, Mesozoic & Cenozoic Age of Ferns & Amphibians: carboniferous Origin of Angiosperms & Age of Dinosaurs: Jurassic Current Age: Quaternary
	Evolution of Man: Dryopithecus: 15mya, knuckle walker Ramapithecus: 14-15 mya, walked like gorilla Australopithecus: 5mys, erect walker, omnivorous Cranial capacity 500cc Homo habilis: 2 mya, fully erect, vegetarian (no meat), tool maker Cranial capacity 650 – 800 cc Homo erectus: 1.5mya, meat eaters, used fire, Cranial capacity 900cc Neanderthals: 40,000 to 100,000 yrs ago, Omnivorous, Cranial capacity 1400cc Homo sapiens: 25,000 yrs ago, Omnivorous, Cranial capacity 1300-1600cc

Key Points: Evolution (Big Bang & Origin) Part 1

XII	EVOLUTION
QUESTIONS	NOTES
	Age of universe: 20 bn yrs ago Age of Earth: 4.5 bn yrs ago Life appeared: 4 bn yrs ago
	Universe m/o clusters of galaxy. Galaxy m/o clusters of stars, clouds of gases & dust. BIG BANG THEORY: explains origin of universe.
	Composition of Earth: Water vapour, methane, CO2, NH3 (frm molten mass on Earth’s surface) No atmosphere
	Processes on Earth post big bang led to formation of CO2, water etc.
	Theories of Origin of Life: ·       Panspermia: Life came from outer space as ‘spores’ ·       Spontaneous generation: Life originated from decaying matter ·       Life comes from pre-existing life – Louis Pasteur ·       Abiological Origin of life: Oparin & Haldane ·       Exp demo of above: Miller
Define Biogenesis	Biogenesis/ Chemical Evolution: Inorganic molecules            Non-living organic molecules s/a proteins, RNA etc.                                                   Life Conditions required: High temp, Volcanic storms, reducing atmosphere containing CH4, NH3 etc
	Miller’s exp: Flask with: CH4, NH3, H2 (red. Atm)                      Water vapour                      Electric Spark (high temp – 800°C) Result: Amino acids formed Further Proof: ·       Others obtained sugars, pigments, fats, N bases in similar exp ·       Meteorite content reveals similar material from other places in space