Biology 1108

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Lecture 2

• Biology 1108
• Chapter 22
• Descent with Modification

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Learning Objectives (p. 1 of 2)

• List
• Evolutionary adaptations of the Blue-footed booby
• Examples of artificial selection, natural
  selection
• Recite
• 4 lines of evidence supporting evolution
• Contrast
• Artificial vs. natural selection

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Learning Objectives (p. 2 of 2)

• Attribute concepts to scientists
• Example Cuvier developed catastrophism
• Discuss
• How Charles Darwin developed evolutionary theory
• A strategy to combat insecticide resistance

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What is an Evolutionary Adaptation?

• An inherited trait
• Increases likelihood of survival

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Adaptations of the Blue-footed Booby

• Lives on Galapagos Islands
• Big feet
• Yes, they look silly
• But good for swimming
• Nostrils close during diving
• Prevents water from getting into lungs
• Oil gland in tail for waterproofing feathers
• Salt gland excretes excess salt

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Western Thought

• Dominated by classical Greek philosophers
• Influenced biological thought greatly until Darwin

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Plato (427 to 347 B.C.)

• 2 world concept
• Real world eternal, perfect
• Illusory world imperfect, perceived by people
• Problem with concept Organisms are already
  perfect for their environment
• A change from perfect would only be imperfection

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Aristotle (384 to 322 B.C.)

• Scala naturae (scale of nature) held that life
  could be classified like rungs on a ladder of
  increasing complexity
• Problems with concept
• Every rung was always occupied (not always
  trueexinct sp. like dinos?)
• Like steps on a ladder, no intermediate species
  possible, no branches

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Georges Cuvier (1769 to 1832)

• Great French paleontologist during French
  monarchy, Revolution, Napoleonic eras
• Major contribution to evolutionary theory
  established extinction
• Noticed that some fossil organisms in Paris Basin
  no longer existed

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More About Cuvier

• Ironically, did not believe organisms changed
  over time
• See UC Berkeley website look for
• Work with mummies
• Belief in change to perfect anatomy would result
  in death of organism
• Felt that catastrophism (sudden floods, or
  droughts) caused most extinctions
• Felt immigration, rather than evolution gave rise
  to new species in fossil record

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James Hutton (1726 to 1797)

• Formulated gradualism
• Ideas that competed against Cuviers
  catastrophism
• Looked to present geological process to explain
  how Earth was formed
• A canyon formed by the river flowing through it
• Grand Canyon Movie

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Charles Lyell (1797 to 1875)

• Developed uniformitarianism
• Incorporated Huttons work
• Postulated that geological principles work the
  same throughout time
• Mountains are built eroded at same overall rate
  throughout Earths history

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Jean Baptiste Lamarck

• Published his evolutionary theory in 1809 (year
  Charles Darwin born)
• Incorporated two popular ideas of time
• Use disuse
• Giraffes neck got larger through stretching, as
  a blacksmiths arm gets bigger through hammering
• Inheritance of characteristics
• Acquired characteristics are passed on to
  offspring
• Giraffe necks evolved larger through generations
  of effort
• Managed invertebrate collection of Natural
  History Museum in Paris

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More on Lamarck

• Often seen as wrong, but in fact, a visionary
• The first biologist to propose that the
  environment affected the traits of an organism
• Most people, including Cuvier, still felt that
  organisms never changed!

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Voyage of the Beagle

• A ship of the British Royal Navy
• Mission to map parts of the Southern Hemisphere
• Charles Darwin aboard as naturalist

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Things Darwin Saw

• In Andes, marine snail fossils high in mountains!
• Clearly, mountains were once under ocean
• On Galapagos Islands, marine iguanas
• Resembled South American iguanas, but different
  species
• Had unique salt gland

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Things Darwin Read

• Charles Lyells Principles of Geology
• Concept of Earth changing over millions of years
• Darwin reasoned life could change too
• Thomas Malthus essay
• Concerned with human population increase, with
  limited natural resources
• Darwin felt this could apply to other species too

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Major Darwininan Concepts

• Environment can support limited individuals
• In nature, more are born than can survive
• Survival and reproduction differ among
  individuals
• Traits, inherited from parents, affect survival
  reproduction

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After the Voyage

• 1840s Darwin had written long essay on
  revolutionary concepts
• Did not publish feared social backlash
• Most people thought Earth only 6 thousand years
  old
• Platos and Aristotles ideas dominated western
  thinking
• 1850s Alfred Russell Wallace communicates
  similar ideas
• Darwin felt scooped
• Happy ending mutual friends presented Darwin and
  Wallaces works to scientific community

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7th Inning Stretch
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Evolution Defined

• Evolution is inherited change in organisms over
  time
• A population and species level process
• Does not occur within an individual
• Key concepts
• Survival AND reproduction of the fittest
• Form follows function
• Fitness of a trait depends upon environment

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4 lines of Evidence for Evolution

• Biogeography
• Comparative anatomy
• Comparative embryology
• Molecular biology

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Biogeography

• Literally, the study of where things live
• Ex Galapagos iguanas resemble those in South
  America
• Suggests common ancestors

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Comparative Anatomy

• Studies body structure of closely-related
  organisms
• Especially vertebrates

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Comparative Embryology

• Studies early development of closely-related
  organisms
• Ex all vertebrate embryos have gill slits
• In fish, become gills
• In humans, become bones supporting voicebox

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Molecular Biology

• Nucleotides can be sequenced in RNA, DNA
• Amino acids sequenced in proteins or polypeptides
• Sequences more similar if
• Individuals related
• Species are more closely related
• Ex human-monkey hemoglobin 8 amino acids
  different

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Whales are Related to Cows!

• Fossil whales have leg bones!
• DNA evidence supports

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Artificial Selection

• Done by humans to many organisms
• The many breeds of dogs all just modified wolves
• Many veggies from single species of wild mustard

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Natural Selection Defined

• Done by nature, rather than people
• Can lead to
• Variation in species
• New species (ex many species in dog family)

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Examples of Natural Selection Observed

• Individuals with certain traits may be favored
• Depends upon the environment
• Examples
• Peppered Moth in England
• Beak size of Galapagos finches
• Insecticide resistance

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Beak Size Galapagos Finches

• Larger beaks
• Stronger, can break larger seeds
• During dry spells
• Small seeds rare
• birds with larger beaks have higher reproductive
  success
• Smaller beaks
• More efficient for eating many small seeds

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Insecticide Resistance
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Evolution of HIV

• 3TC
• An antiviral which blocks reverse transcriptase
• Mimics cytosine
• Eventually, whole virus population is resistant