Download - Evolution I 2007
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Evolution I.Evolution I.
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EVOLUTION• gradual unfolding of new varieties of life from
previous forms over long periods of time (Darwin)
• from the genetic perspective : a change in allele frequency from one generation to the next
• TWO KINDS OF EVOLUTION– microevolution – short term effects occuring over
just a few generations– macroevolution – long-term effects through fossil
history, large changes produced only after many generations
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Evolutional theories
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JEAN BAPTISTE LAMARCK (1744 – 1829)
• Popularised the idea of evolution
• First scientific evolution theory
• Basic concepts of the Lamarck’s theory:– emphasis on the dynamic interaction of organic
forms with the environment
– environment affects and induce change in organic forms
– acquired characteristic is passed through heredity to the next generations
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GEORGES CUVIER(1769 – 1832)
• the „father“ of zoology, palaeontology, and comparative anatomy
• criticised Lamarck’s views on evolution• proposed theory of catastrophism:
– series of violent and sudden catastrophes– all of creatures were destroyed during the
catastrophe– after things settled down, areas were restocked
with new organisms different from those previously living there)
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CHARLES DARWIN(1809 – 1882)
• 1828 – 1831 theology studies (Christ’s College, Cambridge)
• (Reverend John Stevens Henslow – lectures in botany)
• 1831 – 1836 naturalist on a scientific expedition around the globe (H.M.S. Beagle) – recommended by Professor Henslow
• 1842 – short summary of Darwin’s views on natural selection
• 1859 – Darwin completed and published his work “On the Origin of Species by means of Natural Selection, or the Preservation of Favoured Races in the Struggle for Life”
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Charles Darwin
stopover at the Galápagos Islands – Darwin described 13 species of finches resembled one another in the structure of their beaks, body
forms, and plumage
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Darwin´s finches
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DARWIN’S CONCEPT OF EVOLUTION
• All species are capable of producing offspring faster than the food supply increases.
• All living things show variation; no two individuals of a species are exactly alike.
• Because there are more individuals than can possibly survive, there is a fierce struggle for existence and those with a favourable variation in characteristics are necessary for survival will possess an advantage over others.
• These favourable variations are inherited and passed on to the next variation.
• Over long periods of geologic time, these successful variations produce great differences that result in new species.
• The background of the process is natural selection.
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The fate of the Darwin's theory
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Alfred Russel Wallace
(1823 – 1913)
• 1855 –published an article concerning the succession of species and their mutability
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NEODARWINISM - THE MODERN SYNTHESIS
• Evolution is defined as a two stage
process:
– Production and redistribution of variation
(inherited differences between individuals)
– Natural selection acts on this variation
(inherited differences, or variation, among
individuals differentially affect their ability
to reproduce successfully
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RECENT CHALLENGES TO THE MODERN SYNTHESIS
• neutral mutations– Much of variation in natural population is due to neutral
mutations and chance factors (i.e. genetic drift).
– Neutral mutations are not controlled by natural selection.
– “Natural selection is the editor, rather than composer of genetic message” (King and Jukes 1969)
• gradualism X punctuationalism– gradualism – evolution changes accumulate gradually in
evolving lineages
– punctuationalism (punctuated equilibrium) – evolution is nongradual process, evolutionary rates are not constant, the evolution is a process of long stasis and sudden quick spurts
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MECHANISMS OF EVOLUTION
• Factors that produce and redistribute variation– mutation– migration– genetic drift– recombination
• Natural selection– differential net reproductive success– Some of genetic variations among
individual within a population may influence reproductive success. Therefore some individuals contribute more offspring to succeeding generations.
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Theodosius Dobzhansky (1900 – 1975)
"Nothing in
biology makes
sense except in
the light of
evolution."
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http://www.pbs.org/wgbh/evolution/index.html
Public Broadcasting Service
– www section about evolution
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EARLY EVOLUTIONARY HISTORY
• The origin of Earth
– 4,5 – 4,6 thousands million years ago
• The oldest fossils were found in
3,8 thousands million years old
sedimentary rocks from Greenland (the
oldest terrestrial rocks).
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Prebiotic evolution
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What happened during the prebiotic evolution?
Urey-Miller experiment
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The Urey - Miller experiment
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The theory of RNA world
nucleotides
RNAaminoacids,
proteins
DNA
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GEOLOGIC PERIODS
Origin of life
PREKAMBRIANARCHAEAN
PROTEROZOIC
PALEOZOIC
MESOZOIC
CENOZOIC ERATERTIARY
QUARTERNARY
Recent
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Geologic periods
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The Precambrian's lower limit is not defined, but ended about 542 (570?) million years ago.
The Precambrian encompasses about 90% of Earth's history.
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EARLY EVOLUTIONARY HISTORY II.
• Earliest known structurally preserved organisms are stromatolites found near the North Pole, Australia.
• They have been dated at 3,5 thousands million years.
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Ediacara Hills - Australia
Tribrachidium
CharniodiscusMawsonites
Dickinsonia
Fossils of precambrian soft-bodied organisms
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Ediacaran (Vendian) organisms – possible reconstruction
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Riddle of Ediacara
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Cambrian – beginning of Paleozoic
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Pikaia – a fossil of the first chordate
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Pikaia – reconstruction
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Cambrian explosion(cambrian radiation)
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At the end of Paleozoic first land vertebrates appeared
reptile Dimetrodon
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Mass extinction at the end of Permian
90% of species extinct
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http://www.pbs.org/wgbh/evolution/change/deeptime/index.html
Evolution of life
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http://www.pbs.org/wgbh/evolution/extinction/dinosaurs/index.html
What happened before 65 millions
of years?K/T border (= cretaceous / tertiary) – extinction
of dinosaurs and a lot of other species (approximately 75 % of species)