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Chapter 16: Evolution
16-1 Darwin’s Voyage of Discovery
Voyage of the Beagle
• 1831, Darwin set sail on ____________________
• Ship’s naturalist -observer/collector of plants, animals, & fossils
• Left from England, sailed around South America, across Pacific, around
Africa, and back to England
• _________________________________________________________
• ____________________ – change of populations of organisms over
time
• Darwin noted 3 patterns of biodiversity:
 ______________________ – different, yet ecologically similar
animal species inhabited separate, but ecologically similar, habitats
around the globe (rheas, ostriches and emus)
 _______________________ – different, yet related animal species
occupied different habitats within a local area (tortoise shell shape Galapagos)
 _______________________ – fossils of extinct animals were similar
to living species
16-2 Ideas That Shaped Darwin’s Thinking
Darwin was influenced by:
• James Hutton - proposed that layers of rock form very ___________
– Some rocks move up, while others are buried to create _________
_________________________________
– Natural forces such as _____________________________ shaped
the landscape
– These processes happen very slowly over millions of years
• Charles Lyell – said earth was _________________________________
- Earth changed over time due to geologic forces (volcanoes,
earthquakes, wind, erosion, etc.)
- Darwin reasoned that if Earth changed, those who lived on it
_________________________________________.
• Jean-Baptiste de Lamarck suggested that organisms acquired traits
__________________________ to adapt to their environment and
passed those acquired traits onto their offspring.
• WRONG – ___________________________________________
______________________________________________________
• Thomas Malthus – an economist that said the human population was
limited by the ___________________________.
- Darwin reasoned that the same limits could apply to
organisms in nature.
Natural Variation and Artificial Selection
• Natural Variation – ____________________________________________.
• Farmers depend on natural variation for ____________________________.
– Only the largest hogs would be bred.
• Artificial Selection – ___________________________________________.
16-3 Darwin Presents His Case
• Darwin published his findings in 1859 in a book entitled ___________
____________________________________________________.
• He was motivated to publish his book in 1859 because Alfred Wallace
had independently come up with the same conclusions
Adaptations vs. Variations
• Variations – differences that exist within a population ____________
____________________________________________
• Ex: length of your thumb
• Adaptations –_____________________________________________
________________________because that trait improves fitness
• Ex: an opposable thumbs
• Sources of variation:
•
– individual genes change
• Ex: ATC  AGC
•
– during meiosis, chromosomes get mixed
up (crossing over) in making eggs & sperm
•
– which sperm fertilizes which egg –
determined by chance
• Three types of adaptations:
•
– ____________________ of an organism
• Ex: long tongue to get food, sharp teeth
•
– ____________ an organism takes
• Ex: migration, tracking prey, storing nuts, growing toward
light
•
– _________________________________
• Ex: venom, ink of octopus, protein in web, respiration rate,
digestive enzyme, blood clotting
Camouflage
Migration
Snake Venom
• __________________________________________________________
• Natural selection - the process by which environment acts on a
population, determining which organisms are most “fit.” Those
organisms who are most “fit” survive and reproduce more often than
those who are not.
• Fitness – reproductive success (“survival of the fittest”)
Common Descent
• Darwin noticed similarities between species seen on mainland and island
chains
• Thought similarities could be explained by
–
species came to ________________________________________ as the
species adapted to its new environment.
Page from Darwin’s notebook
showing the first evolutionary tree
ever drawn.
16.4 Evidence of Evolution
• ____________
• Anatomy
• ________________ structures
• ________________ structures
• _______________ structures
• ___________________
• ___________________
• ___________________
Fossil Evidence
• Fossils - the remains of past life
• Ex: shells, bones, teeth, imprints
• Tell us ________________________________________
• Record is incomplete – many organisms leave no fossils behind
Anatomical Evidence
• All vertebrate forelimbs contain _______________________ –suggests
they evolved from a common ancestor.
• Homologous structures - structures that are similar because they ______
__________________________________________________________
• Ex: frog, lizard, bird, whale, cat, bat, and human forelimbs
• Analogous structures - _______________________________________
______________________________________________
• Ex: bird wing & insect wing
• Vestigial structures – ________________________________________
________________but may have been used by its ancestors.
• Ex: human appendix, python leg bone
Embryology –___________________________________at certain stages of
development, __________________________ they are thought to be.
Biochemical Evidence
• Universal genetic code – ___________________________________
__________________________________in proteins
• All organisms have certain organic molecules in common.
1.Hemoglobin - carries oxygen in blood
2. ____________________ - protein for cell respiration found in almost
all living cells
3. _______________ – control development
Direct observation – We’ve seen evolution occur in cases like:
• The Grant’s studies of finches on Daphne Major in the Galapagos
• Bacteria becoming resistant to antibiotics
• Insects that become resistant to pesticides