Slide 1 of 40 + 16-3 Process of Speciation HORSE DONKEY MULE.

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+ 16-3 Process of Speciation

HORSE DONKEY

MULE

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+ What is a species?Species: group

of organisms that can interbreed and produce fertile offspring

x

Hippogriff *not real

Horse and Eagle DNA are too different to create viable offspring

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+Same species?

If organisms can produce fertile offspring = same species

If organisms cannot produce fertile offspring = different species

Can a cat and dog interbreed and produce fertile offspring?

Can a lion and a tiger interbreed and produce fertile offspring?

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+What is a species?

HORSE DONKEY

MULE

Are they the same species?

X

What do you need to know?

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+Speciation

Speciation: the formation of new species.

Natural selection and sex selection, along with random/chance events can change the relative frequencies of alleles in a population and lead to speciation.

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+Categories of Speciation

Copyright Pearson Prentice Hall

Allopatric Sympatric

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+Factors involved in speciation

The gene pools of two populations must become separated for them to become “new” species

As new species evolve, populations become reproductively isolated from each other

Reproductive isolation: when the members of two populations cannot interbreed and produce fertile offspring

The basics of reproductive isolation video

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+Isolating mechanisms

Reproductive isolation can develop in a variety of ways, including:

behavioral isolation geographic isolation temporal isolation

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+Behavioral Isolation

When two populations are capable of interbreeding but have differences in courtship rituals or other reproductive strategies that involve behavior.

Albatross courtship ritual

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+Behavioral Isolation

EXAMPLE: eastern and western meadowlarks are very similar birds and their habitats overlap. However, these two species will not mate, partly because they use different songs to attract mates.

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+Geographic Isolation

Geographic isolation occurs when two populations are separated by geographic barriers such as rivers or mountains.

Allopatric speciation example

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+Geographic isolation

Geographic barriers do not guarantee the formation of new species.

If two formerly separated populations can still interbreed and produce fertile offspring, they remain a single species.

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+Geographic Isolation

Potential geographic barriers may separate certain types of organisms but not others. Example: a large river will keep squirrels and other small rodents apart, but it does not necessarily isolate bird populations

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+Temporal Isolation

Temporal isolation occurs when two or more species share the same habitats, but reproduce at different times.

Example: 3 similar species of orchid all live in the same rainforest. They each release pollen only on a single day. Because they release pollen on different days, they cannot pollinate each other.

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+Group Activity

Place the 14 example scenarios into one of three catagories:1) Behavioral Isolation2) Geographic Isolation3) Temporal Isolation

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+

What does this graph tell us?

Individuals with large beaks survive better during times of drought (when food is scarce).

During times of drought

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+The Grants provided evidence of the process of evolution.

Beak size can be changed by natural selection.

Natural Selection will favor ???

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+Speciation in Darwin's Finches

Speciation in the Galápagos finches occurred by:

founding of a new populationgeographic isolationchanges in new population's gene pool

reproductive isolationcompetition

End Show

16-2 Evolution as Genetic Change

Slide 19 of 40

CH. 16 Quiz

Copyright Pearson Prentice Hall

16-1

Which of the following statements is TRUE?

The relative frequency of an allele is not related to whether the allele is dominant or recessive.

Mutations always affect an organism's phenotype.

Crossing over decreases the number of different genotypes that appear in an offspring.

Evolution does not affect the frequency of genes in a gene pool.

16-1

Most inheritable differences are a result of

gene shuffling.

frequency of alleles.

mutations.

DNA replication.

16-1

The main sources of inherited variation are

gene shuffling and mutations.

gene pools and frequencies.

single-gene and polygenic traits.

genotypes and phenotypes.

16-1

A widow's peak in humans is an example of a(an)

invariable trait.

single-gene trait.

polygenic trait.

mutation.

16-1

A graph of the length of the little finger on the left hand versus the number of people having fingers of a particular length is a bell-shaped curve. This indicates that finger length is a

single-gene trait.

polygenic trait.

randomly inherited trait.

strongly selected trait.

16-2

Which of the following patterns of natural selection on polygenic traits favors both extremes of a bell curve?

a. stabilizing selection

b. disruptive selection

c. directional selection

d. genetic drift

16-2

Which of the following events could lead to genetic drift?

a. A few new individuals move into a large, diverse population.

b. A few individuals from a large, diverse population leave and establish a new population.

c. Two large populations come back together after a few years of separation.

d. The mutation rate in a large population increases due to pollution.

16-2

The situation in which allele frequencies remain constant in a population is known as

a. genetic drift.

b. the founder effect.

c. genetic equilibrium.

d. natural selection.

16-2

Which of the following conditions is required to maintain genetic equilibrium in a population?

a. movement in or out of the population

b. random mating

c. natural selection

d. small population

16-2

According to the Hardy-Weinberg principle, no evolution will take place if

a. all five of the Hardy-Weinberg conditions are met.

b. any one of the Hardy-Weinberg conditions is met.

c. at least three of the Hardy-Weinberg conditions are met.

d. none of the Hardy-Weinberg conditions are met.

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.

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.

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.

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.

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.

END OF SECTION

Slide 1 of 40 + 16-3 Process of Speciation HORSE DONKEY MULE.

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