Comprehensive and detailed Exam 1 Learning Objective based Summary for Biol 141.
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Evolution by Natural Selection
o Describe the transition in philosophy of considering variation of traits within a species as
being unimportant to being the key to understanding the nature of species
Plato: claimed variation was unimportant
Because every organism must deviate from the perfect type, and these
types are unchanging
TYPOLOGICAL
Aristotle: “The great chain of being” with organization from complexity and size
TYPOLOGICAL
Lamarck: claimed species change with their environment and pass it on to
offspring
Ex. Giraffes
o Describe how Darwin and Wallace came up with their theory
Darwin
Galapagos Mockingbirds
o Different islands had slightly different birds, yet they were like a
species that he saw on the mainland
o Must have evolved
Wallace
Malay Archipelago
o Saw adaptations in flying frogs and birds of paradise
o Must have evolved
Evidence for Evolution of Natural Selection
o Describe how Darwin and Wallace’s theories were different from existing theories
Common belief in their time:
Earth was young (4004 BC)
Species were created perfect by God (they don’t vary or change)
Darwin and Wallace’s theories
Gradualism (species change over time)
Multiplication of species
Evolution as such (species change)
Common descent
Natural Selection (sexual selection)
o Describe the lines of evidence for the theory of evolution by natural selection
The Earth must be OLD
~4.5 Billion years old
South American Rhea
2 species of flightless bird; different flightless birds elsewhere, but
similar in many aspects
Common rhea and lesser rhea
o List the following 8 lines of evidence and explain how they provide evidence for
evolution by natural selection
Biogeography
Similar species are found in the same geographic area
, Study Guide for Exam #1 Biology 141 Cafferty
Artificial breeding
Descent with modification through artificial breeding
HUMANS do this, NOT nature
Intermediate forms
Gradual stages between simple and complex forms
o Ex. Eyes
Imperfections
Octopus do not have a blind spot while humans do
Does being more complex always mean being more perfect?
o NO
Transitional fossils
Intermediate forms in fossil records
Used to be known as the missing link
o Inaccurate as these fossils are not necessarily direct
descendants of previous organisms OR direct ancestors of later
organisms
Hierarchical Organization
Life is organized in nested groups of organisms
o EX. Animals
Insects
Beetles
butterflies
birds
ducks
eagles
Homology
Definition
o Characteristics in different organisms have similar underlying
molecular and anatomical structures, or are based on similar
developmental processes
Similarities
o Humerus, radius, ulna, carpals, metacarpals, phalanges
IN
o Humans, moles, horses, dolphins, bats
Vestigial traits
Definition
o A useless of rudimentary version of a structure that has an
important function in other organisms, sometimes used for a
new function
Ex. Whales
o Vestigial pelvis/femur
Phylogenetic Trees
o Analyze phylogenetic trees
Phylogeny: evolutionary tree
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