Download Natural Selection Notes

Natural Selection Notes
What is scientific theory?
 In science, theories are statements or models that have been tested and confirmed many times.
Theories do NOT express doubt. Theories
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explain a wide variety of data and observations
can be used to make predictions
are not absolute, can be changed as new evidence is found
Select the letters that apply to scientific theory:
A.
Theories include observations
B.
Theories are hunches scientists have
C.
Theories can include personal beliefs or opinions
D.
Theories have been tested many times
E.
Theories are incomplete, temporary ideas
F.
A theory never changes
G.
Theories are inferred explanations, strongly supported by evidence
H.
Theories are used to make predictions
I.
Laws are more important to science than theories
What do you think the difference between a scientific theory and a scientific hypothesis is?
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Darwin’s Theory:
1. Organisms differ; _________ is inherited
2. Organisms _________________________________ than survive
3. Organisms compete for ____________________________
4. Organisms with ____________________ survive to pass those advantages to their children
5. Species alive today are ________________________________________________ from common ancestors
In your own words, explain Darwin’s Theory in a sentence:
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Darwin’s main ideas can be summarized in three points:
1.
Natural selection is _______________________________ in reproduction
a. (unequal ability of individuals to survive and reproduce).
2.
Natural selection occurs through ________________________________________ and the variability inherent among the
individual organisms making up a population.
3.
The product of __________________ is the adaptation of populations of organisms to their environment.
Summarize these points in your own words:
1.
2.
3.
Natural Selection - The traits that help an organism survive in a particular environment are “selected” in natural selection
1. ________________________exists among individuals in a species.
2. Individuals will ______________________ for resources (food, mates, and space)
3. Competition would lead to the death of some individuals while others would ___________________
4. Individuals that had advantageous variations are more likely to survive and _______________________.
This process came to be known as Natural Selection. The favorable variations are called Adaptations
How do variations/adaptations play a role in an organism’s survival?
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Natural selection
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Acts on the phenotype, or the observable characteristics of an organism
o individuals with _________________________ are more likely to survive and reproduce than those with less
favorable phenotypes.
The phenotype's genetic basis, the genotype associated with the favorable phenotype, will
o ____________________________ over the following generations.
o Over time, this process may _________________________ that specialize organisms for particular ecological
niches
o may eventually result in the emergence of new species.
Populations
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While natural selection involves interactions between individual organisms and their environment, it is populations, not
individuals that evolve.
Populations are defined as a group of interbreeding individuals of a single species that share a common geographic area.
Why can’t natural selection provide a change in an individual (Why can it only change populations)?
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Fitness
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Overtime, natural selection results in changes in the inherited characteristics of a population.
These changes increase a species fitness (survival rate)
How is survival of an organism based on fitness?
What does it mean for an organism to be fit?