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What is gradualism and
punctuated evolution?
Agenda for Monday Nov 15th
1. Finish Fossil Lab
2. Theories of Evolution Notes: Lamarck
1. Lamarck’s Giraffes
Theories of Evolution
• Evolution – change in the inherited traits of a
population of organisms over time
• 2 Main contributors
– Lamarck and Darwin
Jean Baptiste de Lamarck
• Proposed similar species descended from a
common ancestor
• Living species were descended from similar
extinct species
Lamarck
• Use and disuse of organs
– developing/changing structure and function of old
organs
• Inheritance of acquired traits
– Acquired trait – a trait that arises during the
lifetime of an organism
– acquired traits were passed on to the organism's
offspring
Lamarck
• Organisms acquire traits and then pass these
traits on to their offspring
Lamarck Right and Wrong
Incorrect
• Not all traits acquired get passed on
Important
• Introduced Evolution/change
• Realized organisms are changing
What was Lamarck’s Theory of
Evolution?
Agenda for Tuesday Nov 16th
1. Theories of Evolution: Darwin
1. Lamarck’s Giraffes
2. Darwin’s Postulates
Darwin
Darwin
• Quit Medical School and became a naturalist
• H.M.S. Beagle – 5 year journey to survey
• Wrote The Origin of Species
Charles Lyell
• Wrote Principle of Geology
• Uniformitarianism
• Darwin
– Habitats change slowly = requires organisms to adapt
to these changes in order to survive
Galapagos Islands
• Darwin landed in the Galapagos Islands and
noticed differences in animal species
• Drew and made observations while in the
Galapagos
• Back in England he looked at his findings
– Tortoises and Finches
Galapagos Islands
• Finches – collected 13 similar but separate
species of finches
– Each had a distinct bill (beak)
• Finches implied a shared recent common
ancestor
– Adapting to different environments
• Darwin reasoned over millions of years =
many large differences
Darwin’s Theory
• Natural selection – organisms best suited for
their environment reproduce more
successfully than other organisms
• Over several generations organisms with
favorable traits increase
Darwin’s Theories
Descent with Modification
• Newer forms in the fossil record are modified
forms of older species
• All species descended from one or a few
original types of life
Darwin’s Theories
Modification by Natural Selection
• Influenced by Thomas Malthus
– Populations have the potential of doubling and
redoubling their numbers
– Human pop. have been limited by war, disease, etc.
– Darwin noted most pop. have limited growth
Modification by Natural Selection
• Env’t affect individual organisms in different
ways – natural selection
• Adaption
– traits that enhance the survival and reproductive
success
– Resulting change in the genetic makeup of a
population is evolution
2 types of Adaptations
• Camouflage and mimicry
Modification by Natural Selection
• An organism’s genetic contribution to the next
generation is fitness
– Greater fitness = better adapted to env’t =
reproduces more successfully
• Favorable traits give organisms an adaptive
advantage
• Environment “selects” traits
– Favorable traits depend on demands of env’t
Postulate 1
• Postulate 1 – Variation within a population
Postulate 2
• Traits are inherited/passed on
Postulate 3
• More offspring are produced than can survive
Postulate 4
• Individuals with advantages traits survive
Summary of Darwin
• Inherit traits
• Natural Selection – organisms best suited/best
adapted to the environment survive and
reproduce
– Adaptations
What is Natural Selection?
Agenda for Wednesday Nov 17th
1. Lamarck’s Giraffes Coloring
2. Darwin’s Postulates
What are Darwin’s Postulates of
Evolution?
Agenda for Thursday Nov 18th
1. Go over Postulates Worksheet
2. Lab
3. Rat Island Evolution
Agenda for Friday Nov 19th
1. Quiz
2. Galapagos Islands Video