AP Environmental Science Focus on Evolution

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AP Environmental ScienceFocus on Evolution

• Nothing in biology makes senseexcept in the
  light of evolution.
• Theodosius Dobzhansky (1973)

2
Biology during the 1800s

• Late 18th-early 19th c. was an age of discovery
  and natural history
• Natural Theology
• All plants animals were created as is 6,000
  to 10,000 years ago
• William Paley---a watch demands a watchmaker
  ---a design demands a designer!

3
Great Geological Debate1810-1840

• Catastrophism
• Cuvier, Buffon
• All changes to animals and geology are due to
  sudden cataclysmic events

• Uniformitarianism
• Hutton Lyell
• The earth was shaped by slow, gradual processes
  the we see today.

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Charles Darwin (1809-1882)

• Born February 12, 1809 in Shrewsbury, England
• Education
• Entered the University of Edinburgh at age 16 to
  study medicine
• Entered Cambridge Universitys Christ College in
  1828 to study for the ministry

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Darwins Parents

• Dr. Robert Darwin

• Susannah Wedgwood Darwin

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Darwins Famous Grandfathers

• Erasmus Darwin

• Josiah Wedgwood

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Wedgwood China
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J.S. Henslow (1796-1861)

• Darwins favorite botany professor
• Recommends Darwin to the British Admiralty to
  serve as ships naturalist on the H.M.S. Beagle

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H.M.S. Beagle

• Captain Robert FitzRoy
• Mission was to map the western coast of South
  America for the British Navy
• Darwin serves as ships naturalist and companion
  to the captain.

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Voyage of H.M.S. Beagle (1831-1836)
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Galapagos Islands
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Galapagos Unique Animals
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Return to England
H.M.S. Beagle by Conrad Martens

• Publishes what came to be known as the Voyage of
  the Beagle
• Begins notebook on Transmutation of Species

Title page 1905 edition
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Settling Down

• Marries his first cousin Emma Wedgwood on January
  29, 1839
• Moves into an 18 acre estate in Down, England

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Darwins Scientific Subjects
Barnacles
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Establishes a Theory of Atoll Formation
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Keeping Quiet on Evolution

• Despite working on transmutation since 1837
  Darwin publicly says nothing.
• Writes two private essays in 1842 1844.
• Robert Chambers publishes Vestiges of the Natural
  History of Creation in 1844.
• Contains evolutionary ideas but is severely
  ridiculed.

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Alfred Russel Wallace (1823-1913)

• June 18, 1858
• Darwin receives a manuscript from Wallace, a
  young naturalist working in the Malay
  Archipelago.
• On the Tendency of Varieties to Depart
  Indefinitely from the Original Type

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Joint Presentation

• On July 1, 1858 Charles Lyell and Joseph Hooker
  present both Darwins 1844 and Wallaces
  manuscripts before the Linnaean Society of
  London.
• Darwin does not attend due to his sons death
  from scarlet fever three days before.

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Publication of The Origin

• Darwin finally publishes his big book, On the
  Origin of Species by Means of Natural Selection,
  or the Preservation of Favoured Races in the
  Struggle for Life on November 24, 1859.
• Its 1250 copies sold out on the first day.

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Defending Darwin

• Thomas Henry Huxley - Darwins Bulldog

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Darwins Five Theories of Evolution

• 1) Evolution as Such
• 2) Common Descent
• 3) Variation Natural Selection
• 4) Population Thinking and Allopatric
  Speciation
• 5) Gradualness

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1) Evolution as Such

• Change happens!
• This theory was not new with Darwin.
• Others like Lamarck had said that change
  happens over 50 years before!
• However, the majority of scientists in 1859 did
  not believe in evolutionary change.
• The massive evidence that Darwin presents was so
  overwhelming that within a few years virtually
  every biologist was convinced.

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What we know now

• 1 billion years of chemical change to form the
  first cells, followed by about 3.7 billion years
  of biological change.

Figure 4-2
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Biological Evolution

• This has led to the variety of species we find on
  the earth today.

Figure 4-2
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2) Common Descent

• All organisms have descended from common
  ancestors by a continuous process of branching.
• Common descent explains so much about comparative
  anatomy, embryology, biogeography,
  systematicsand behavior.
• Putting humans into this branching tree of common
  descent takes humans away from their privileged
  positionand causes many people to reject the
  idea.
• What Darwin Doesnt Do
• Darwin stops short of publishing mans place in
  this evolutionary tree and he never speculates on
  the origins of the first organisms

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I think

• Sketch from Darwins 1838 notebook on
  transmutation
• First clue that Darwin had embraced the idea of
  common descent

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Common Descent Diagram in The Origin of Species
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Tetrapod Limb Homologies
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Comparative EmbryologyOntogeny recapitulates
phylogeny
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3) Variation Natural Selection

• 1) Individual variation in organisms within a
  population is the norm not the exception.
• 2) Populations reproduce at a geometric rate that
  is faster than the environment can support.
• Thomas Malthus, Essay on Population
• 3) Some organisms will survivemost will die.
• 4) Which organisms will live and which will die?
• Does each individual have an equal chance of
  survival? Darwin says---NO!
• Those individuals with the best adaptations will
  survive---Natural Selection!

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Natural Selection and Adaptation Leaving More
Offspring With Beneficial Traits

• Three conditions are necessary for biological
  evolution
• Genetic variability,
• Traits must be heritable,
• Trait must lead to differential reproduction.
• An adaptive trait is any heritable trait that
  enables an organism to survive through natural
  selection and reproduce better under prevailing
  environmental conditions.

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Coevolution A Biological Arms Race

• Interacting species can engage in a back and
  forth genetic contest in which each gains a
  temporary genetic advantage over the other.
• This often happens between predators and prey
  species.
• Or results in symbioses

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Hybridization and Gene Swapping other Ways to
Exchange Genes

• New species can arise through hybridization.
• Occurs when individuals to two distinct species
  crossbreed to produce a fertile offspring.
• Some species (mostly microorganisms) can exchange
  genes without sexual reproduction.
• Horizontal gene transfer

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Limits on Adaptation through Natural Selection

• A populations ability to adapt to new
  environmental conditions through natural
  selection is limited by its gene pool and how
  fast it can reproduce.
• Humans have a relatively slow generation time
  (decades) and output ( of young) versus some
  other species.

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4) Population Thinking Allopatric
Speciation

• Darwin recognizes that it is populations that
  change, not individuals.
• Gives rise to population thinking
• Darwin realizes that varieties are no more than
  incipient species.

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Geographic Isolation
Figure 4-10

• Darwin realizes that when a population becomes
  split by geographic barriers that these separate
  populations change in their own unique
  ways---Geographic Isolation.

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Allopatric Speciation
After a long period of time these changes become
so great that the individuals from the different
populations can no longer reproduce with one
another---Reproductive Isolation
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5) Gradualness
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GEOLOGIC PROCESSES, CLIMATE CHANGE, CATASTROPHES,
AND EVOLUTION

• The movement of solid (tectonic) plates making up
  the earths surface, volcanic eruptions, and
  earthquakes can wipe out existing species and
  help form new ones.
• The locations of continents and oceanic basins
  influence climate.
• The movement of continents have allowed species
  to move.

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Extinction Lights Out

• Extinction occurs when the population cannot
  adapt to changing environmental conditions.

• The golden toad of Costa Ricas Monteverde cloud
  forest has become extinct because of changes in
  climate.

Figure 4-11
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Species and families experiencing mass
extinction
Bar width represents relative number of living
species
Millions of years ago
Era
Period
Current extinction crisis caused by human
activities. Many species are expected to become
extinct within the next 50100 years.
Extinction
Quaternary
Today
Cenozoic
Tertiary
Extinction
65
Cretaceous up to 80 of ruling reptiles
(dinosaurs) many marine species including
many foraminiferans and mollusks.
Cretaceous
Mesozoic
Jurassic
Triassic 35 of animal families, including many
reptiles and marine mollusks.
Extinction
180
Triassic
Permian 90 of animal families, including over
95 of marine species many trees, amphibians,
most bryozoans and brachiopods, all trilobites.
Extinction
250
Permian
Carboniferous
Extinction
345
Devonian 30 of animal families, including
agnathan and placoderm fishes and many trilobites.
Devonian
Paleozoic
Silurian
Ordovician
Extinction
Ordovician 50 of animal families, including
many trilobites.
500
Cambrian
Fig. 4-12, p. 93
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Effects of Humans on Biodiversity

• The scientific consensus is that human activities
  are decreasing the earths biodiversity.

Figure 4-13
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Darwins Later Life

• Becomes even more reclusive in later life.
• Publishes extensively, including The Descent of
  Man (1871) and Expressions of the Emotions in Man
  and Animals (1872).
• Dies of a heart attack on April 19, 1882 and is
  buried in Westminster Abbey near Sir Isaac Newton.

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Darwins Legacy

• Darwin moved intellectual thought from a paradigm
  of untestable wonder at special creation to an
  ability to examine the workings of the natural
  world, however ultimately formed, in terms of
  natural mechanisms and historical patternshe in
  effect creates the modern science of biology.

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Work Cited

• ""gradualism vs. punctuated equilibrium"." 18
  October 2009 ltlhs2.lps.org/.../U6Evolution/gradual
  ism.gifgt.
• Biello, David. "Gene Swapping Helps Bacteria."
  Scientific American 21 November 2005.
• "Cool Bug 9 Acacia ants." 2 October 2007.
  Bioblog Music and Biology in the News . 18
  October 2009 lthttp//bioblog.biotunes.org/bioblog/
  2007/10/02/cool-bug-9-acacia-ants/gt.
• "Hand in hand saving the coral reef." 13 August
  2008. 18 October 2009 ltcoralreeftoday.com/wp-admin
  /acropodia/1b.jpggt.
• Martens, Conrad. ""HMS Beagle"." The Voyage of
  the Beagle by Charles Darwin. 18 October 2009
  ltwww.sacred-texts.com/aor/darwin/beagle/beagle.jpg
  gt.
• Siegel, Robert David. ""Darwin's Finches"." 31
  October 2008. Darwin Safari 2007. 18 October 2009
  lthttp//stanford.edu/siegelr/england/darwinsafari
  2007.htmlgt.
• Speciation. 30 March 2009. 18 October 2009
  lthttp//users.rcn.com/jkimball.ma.ultranet/Biology
  Pages/S/Speciation.htmlgt.
• Wyhe, John van. The Complete Works of Charles
  Darwin online. 6 October 2009. 18 October 2009
  ltdarwin-online.org.uk/life14.htmlgt.
•