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Evolution I.
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
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
GEORGES CUVIER
- 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)
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
Darwin´s finches
The fate of the Darwin's theory
Alfred Russel Wallace
(1823 – 1913)
- 1855 –published an article
concerning the succession
of species and their
mutability
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
MECHANISMS OF EVOLUTION
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.
http://www.pbs.org/wgbh/evolution/index.html
Public Broadcasting Service
- www section about evolution
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).
What happened during the prebiotic
evolution?
Urey-Miller
experiment
The Urey - Miller experiment