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