Download Speciation - Trimble County Schools

Biology
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Copyright Pearson Prentice Hall
16-3 The Process of
Speciation
16-3 The Process of Speciation
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Copyright Pearson Prentice Hall
16-3 The Process of Speciation 16-3 The Process of Speciation
Speciation is the formation of new
species.
•Chance
•Natural selection
A species is a group of organisms that
breed with one another and produce
fertile offspring.
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Copyright Pearson Prentice Hall
16-3 The Process of Speciation
Isolating Mechanisms
Isolating Mechanisms
As new species evolve, populations
become reproductively isolated from each
other (gene pools must be separated)
When the members of two populations cannot
interbreed and produce fertile offspring,
reproductive isolation has occurred.
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Copyright Pearson Prentice Hall
16-3 The Process of Speciation
1. Behavioral
Isolating Mechanisms
Isolation (sympatric)
Behavioral isolation occurs when two
populations are capable of
interbreeding but have differences in
courtship rituals or other reproductive
strategies that involve behavior.
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Copyright Pearson Prentice Hall
16-3 The Process of Speciation
Isolating Mechanisms
2. Geographic Isolation (allopatric)
Geographic isolation occurs when
two populations are separated by
geographic barriers such as rivers or
mountains.
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Copyright Pearson Prentice Hall
16-3 The Process of Speciation
3.
Isolating Mechanisms
Temporal Isolation (sympatric)
Temporal isolation occurs when two
or more species reproduce at different
times.
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16-3 The Process of Speciation
Testing Natural Selection
in Nature
Testing Natural Selection in Nature
Finches in the Galapagos Islands
Honey Creepers in Hawaii
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Copyright Pearson Prentice Hall
16-3 The Process of Speciation
Testing Natural Selection
in Nature
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Copyright Pearson Prentice Hall
16-3 The Process of Speciation
Testing Natural Selection
in Nature
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Copyright Pearson Prentice Hall
16-3 The Process of Speciation
Testing Natural Selection
in Nature
Peter and Rosemary Grant tested Darwin’s
hypothesis, which relied on two testable
assumptions:
• For beak size and shape to evolve, there must be
enough heritable variation in those traits to
provide raw material for natural selection.
• Differences in beak size and shape must produce
differences in fitness, causing natural selection to
occur.
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Copyright Pearson Prentice Hall
16-3 The Process of Speciation
Testing Natural Selection
in Nature
When food was scarce, individuals with large beaks
were more likely to survive.
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Copyright Pearson Prentice Hall
16-3
When two species do not reproduce because of
differences in mating rituals, the situation is
referred to as
a. temporal isolation.
b. geographic isolation.
c. behavioral isolation.
d. reproductive isolation.
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Copyright Pearson Prentice Hall
16-3
The most important factor involved in the
evolution of the Kaibab and Abert squirrels of
the American Southwest appears to be
a. temporal isolation.
b. geographic isolation.
c. behavioral isolation.
d. different food sources.
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Copyright Pearson Prentice Hall
16-3
One finding of the Grants' research on
generations of Galápagos finches was that
a. natural selection did not occur in the finches.
b. natural selection can take place often and
very rapidly.
c. beak size had no effect on survival rate of
the finches.
d. natural selection was slow and permanent.
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16-3
All of the following played a role in speciation of
Galápagos finches EXCEPT
a. no changes in the gene pool.
b. separation of populations.
c. reproductive isolation.
d. natural selection.
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Copyright Pearson Prentice Hall
16-3
Beak size in the various groups of Galápagos
finches changed primarily in response to
a. climate.
b. mating preference.
c. food source.
d. availability of water.
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Copyright Pearson Prentice Hall
END OF SECTION