Download 1 Chapters 16-17 Notes: Evolution Words to Know: evolution, fitness

Name _______________________
Chapters 16-17 Notes: Evolution
Words to Know: evolution, fitness, adaptation, natural selection, competition, descent with
modification, common descent, mimicry, camouflage, homologous structures, analogous structures,
vestigial organs, gene pool, relative frequency, genetic equilibrium, directional selection, stabilizing
selection, disruptive selection, speciation, convergent evolution, divergent evolution, genetic drift,
founder effect, bottleneck effect, species
Darwin’s Voyage
Evolution: Change over _________________
Charles Darwin
•
Developed a scientific theory that explains how modern organisms evolved over long periods of
time through __________________ from common ancestors.
Darwin’s Observations:
1.) Different, yet similar, animal species inhabited separated, but similar, habitats around the
__________________.
2.) Different, yet related, animal species occupied different habitats within a __________________area.
3.) Some __________________ of extinct animals were similar to living species.
Ideas that Shaped Darwin
Public Perception:
•
All life was only a few __________________ years old.
•
Since its creation, not much had __________________.
Scientists that Influenced Darwin:
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(1785) James Hutton: Using geological examples, concluded that the earth must be much
__________________than a few thousand years.
•
(1798) Thomas Malthus: Reasoned that if the human population grew unchecked, there
wouldn’t be enough _________________ and _________________ for everyone.
•
(1830) Charles Lyell: Argued for _________________, which holds that the geological processes
we see today must be the same ones that occurred long ago.
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Jean Baptiste Lamark
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(1809) Published a theory of evolution that suggested organisms could change during their
lifetimes by _________________ using or not using parts of their bodies. These
_________________ traits could then be passed onto their offspring.
Natural Selection
fitness: the ability to ____________________________________________________________
adaptation: an inherited characteristic that increases an organism’s _____________________________
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Adaptations __________ an organism’s fitness.
Natural selection
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AKA: _____________________________
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Selected traits __________ an organism’s __________.
•
No ____________________involvement. (Unlike selective breeding.)
In order for natural selection to occur:
1. The population must be __________ in size, which creates __________.
(Competition: when two organisms want the same __________ at the same __________.)
2. __________ __________ (of inherited traits) must exist.
3. This variation must affect the organism’s ______________________________.
Descent with modification: Species _________________ from other species over time.
ex: dogs descended from wolves.
Common descent: all things, living and extinct have ______________________________
Evidence of Evolution
1. Structural adaptations
a. Mimicry: one species _________________another species
b. Camouflage: species _________________in with surroundings
2. Behavioral adaptations
a. _________________
b. Courtship
c. Defending or claiming _________________
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d. Cooperation (Ex: hunting in packs)
e. Kin selection: helping a relative _________________ because they share the same genes
f. Communication (visual, chemical, sound, language)
3. _________________
4. Geographic Distribution of Species (similar, but _________________ species live in different parts
of the world)
5. ______________________________:
basic arrangement of bones in body
structures of different species is similar
ex: bird wing and whale flipper
• Note: Not to be confused with
analogous structures (have the same
function, but different structures)
6. ______________________________: body structures that serve no purpose in the present day
organism
ex: an ostrich’s wings
7. ____________________________________________________________________________
8. ______________________________________________________________________________
Evolution of Populations
•
_______________, NOT _______________ evolve!
Gene pool: all of the _______________ of a population’s genes
Relative frequency =
Genetic equilibrium: when the ______________________________remains the same over several
generations
•
If the relative frequencies in a gene pool change, _______________ has probably occurred!
Sexual vs. Asexual Reproduction
•
The two main sources of genetic variation in sexually reproducing organisms are through
_______________ and ______________________________.
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•
The main source of genetic variation in asexually reproducing organisms is through
_______________ .
Natural Selection on Single Gene Traits
Before
After
Natural Selection on Polygenic Traits
Three Types of Natural Selection for Polygenic
Traits:
1.) ______________________________
2.) ______________________________
3.) ______________________________
Regular Graph of a Polygenic Trait
Directional Selection: Natural selection favors one of the _______________ variations of the trait, so
the entire graph moves. Ex: height, beak lengths
Before
After
Stabilizing Selection: Natural selection that favors the _______________ individuals in a population. Ex:
birth weight
Before
After
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Disruptive Selection: Individuals with either _______________ variation are selected for. (The average
drops.)Ex: Light and dark colored limpets
Before
After
Speciation: Occurs when members of the same population can no longer _______________ to produce
_______________ offspring.
•
Can occur from _______________ , _______________ or _______________ isolation.
Divergent evolution: members of one species
become less and less _______________,
eventually resulting in _______________
species
Convergent evolution: members of
_______________ species evolve
_______________ traits because of their
environment
The Effect of Small Populations
Genetic drift: a _______________ in allele frequencies due to something _______________ than
natural selection
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Ex: Ashkenazi Jews, the Amish, the Holocaust
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Specific types of genetic drift are…
Founder effect: a small group starts a new
population elsewhere and their
_______________ genes become
Bottleneck effect: a _______________ disaster
drastically reduces the population
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