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Note Taking Guide – Evolution
Development of Evolutionary Thought
Isn’t evolution “just” a theory?
Scientific theories are explanations that are based on
__________________________________, enable __________ predictions, and
have been ______________________ in many ways.
What is Evolution?
Paleontology & Evolution
 Older layers of sedimentary rock (the layers on the bottom) contain
__________ species very dissimilar from modern life.
 Each layer (stratum) is characterized by a unique group of fossil species.
 As you move upward through the layers, you find species more and more
______________ to modern life.
James Hutton – 1795
 A Scottish geologist
 proposed that it was possible to explain the various landforms by looking
at mechanisms currently operating in the world
 Proposed that the earth was much more than a few thousand years old
Jean Baptiste Lamarck
 Theory of evolution in __________
 mechanism:
– ________ and _________ - the idea that the parts used the most
grow stronger; the parts that don’t get used deteriorate
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– inheritance of acquired characteristics - the modifications that an
organism acquires during its lifetime can be passed along to its
offspring
 recognized adaptation to environment as a primary product of evolution
Charles Darwin (1809-1882)
 Father of modern evolutionary theory
 Born in England
 HMS ___________________
 ____________________ Islands
Darwin’s Observations
 Darwin noticed that every bird on the Galapagos Islands was a modified
finch.
 The only differences in the birds were their ________ and what they ate.
 These finches looked very similar to one type on South American
continent, but none of these were found in S.A.
“How did one species change into a different species?”
He wrote On The Origin of Species (1859) after _______ years of study.
Darwin’s Four Postulates
 Individuals within a population _____ in their _________.
 Some of these traits are heritable.
 _______ offspring are produced than can survive because of
___________ resources. (remember competition!)
 Individuals with advantageous traits will _______ and reproduce.
What is natural selection?
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 Natural selection - a population of organisms can ________ over
generations if individuals having certain heritable traits leave more
offspring than others
 Natural selection is the ___________________by which evolution is
proposed to occur
What is “artificial selection”?
 Nature provides the variation among different organisms, and ________
select variations that they find useful.
 Example: _____________________________________
 Darwin used this to help _________________ his case for natural
selection.
Descent with modification
 the history of life is like a ________ , with multiple branching and
re-branching from a common trunk all the way to the tips of the
youngest twigs
 most branches of evolution are dead ends; about ______of all
species that have ever lived are ___________
Survival of the Fittest
• Another name for Darwin’s theory of natural selection.
• Biologists use the word fitness to describe how good a particular genotype
is at leaving offspring in the next generation relative to how good other
genotypes are at it.
Mechanisms of Evolution
1. ___________ ____________ & Survival of the _____________
(see notes above regarding Darwin)
(Modern Ideas)
 Darwin + Mendel’s work and the work of others, have lead to modern
ideas about evolution.
2. Another mechanism of evolution is ____________ ___________
(random changes in genes) which occurs through natural selection.
3. Speciation – formation of new species is due to _________ genetic
changes, and that large scale evolution is the result of a lot of
small scale evolution. (Variation)
___________________ – process responsible for the variations that exist
within a species, or a change in the allele frequency.
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4. _______________________ – evolution that occurs between species.
Examples: the separation of a species to form two distinct species
or the development of a new species from many small changes
within an existing species
5. Gene Flow -The change in occurrence of genes in a population.
This occurs when an individual leaves a population
(___________) or new individual joins a population
(__________).
6. Genetic Drift
______________changes in the occurrence of genes through chance events.
-Examples: can occur when a few individuals of a population break off from
the original group and start their own population (founder effect).
-Large number of population is killed due to disease, starvation, natural
disaster, etc. (bottle necking)
Punctuated Equilibrium
 Darwin felt that biological change was slow and steady as indicated in
the____________ __________________.
 Modern scientists see that this pattern does not always hold. (Darwin’s
finches)
 The term _______________ _________________________ is used to
describe a pattern of long, stable periods interrupted by brief periods of
more rapid change. This is still controversial today.
Evidence of Evolution
Fossil Evidence
 Fossils provided a ____________ ____________ of evolution.
 Fossils formed in different layers of rock were evidence of gradual change
over time.
__________________ Body Structures
 Structures in different species that may perform different functions but
are similar because of their common ancestry
 ______________ organs - structures of no apparent function to an
organism; leftover from ancestry; ex - snakes have leg & pelvis bones
More homology…
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 Molecular homology - similarity in _______ ____________ between an
ancestor and its progeny
 Embryological homology - similarities only apparent in
_________________ development
– ex: all vertebrate embryos have “pharyngeal pouches” which later
become gills or Eustachian tubes
Patterns of Evolution
_______________ Radiation
 When a ___________ species or a small group of species has evolved into
several different forms that live in different ways.
 Example: Darwin’s_________________ (more than a dozen evolved from
a single species)
______________ Evolution
 Explains how unrelated species can develop similar characteristics
 Porpoise (mammal) & Shark (fish)
 Unrelated animals, but share similar characteristics to suit their
environment
Analogous Structures
 Show similarity in structure based on adaptation for the _______
_____________, not common descent.
_______________ Evolution
 Suggests that many species develop from a _______________
__________________
 Penguins (wings for swimming) & vultures (wings for flying)
 Both are birds, diverged from a common ancestor
Co-evolution
 When two or more organisms in an ecosystem evolve in
_________________ to each other.
 Example: Flowers and their pollinators
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