Evolution - International Baccalaureate Biology - Lecture Slides, Slides of Biology

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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

• 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.

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