Download Patterns of Evolution

Do Now:
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Open your books to page 308-309. Read
through section and answer the following
questions:
What is the relationship between allele
frequencies and a gene pool?
Why aren’t mutations in nonreproductive cells
sources of genetic variation?
Write down the following
statements in your notes.
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Important to Understand:
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The frequency of a phenotype depends on the
frequency of the genotype that codes for the
trait.
Genetic variation is the basis for the evolution
of populations
Phenotypic Variation
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Hitchhiker’s Thumb
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Tongue Rolling Ability
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What would happen to the genetic
variation of the population if, for example,
all of the tongue-rolling students left the
class or if 10 hitchhiker-thumbed students
were added to the class?
Looking at the picture answer the following questions:
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What traits of penguins are adaptive to the
Antarctic environment?
What factors would result in changes to the
genetic variation of penguins in a colony?
Remember: Only those penguins that
successfully reproduce and raise, live, healthy
chicks will pass on their genes and the
phenotypes that they code for. INDIVIDUALS
DO NOT EVOLVE; POPULATIONS DO!
Patterns of Evolution
Chapter 11
Species adapt to their environment in several
ways.
The speed and pattern of evolution depend on
the changes occurring in the environment.
The 3 main patterns of evolution are:
 Coevolution
 Convergent evolution
 Divergent evolution
Coevolution
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Coevolution is the process of change in 2
or more species that are dependent on
each other.
An evolutionary change in one organism
may also be followed by a change in
another organism.
Examples:
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Birds and flowers
Bees and flowers
Coevolution Example
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Hummingbirds and the
flowers they pollinate.
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The longer the beak of
the hummingbird, the
more food it will get.
The farther away the
food in the flower, the
better the flower gets
pollinated.
Convergent Evolution
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What does Convergent mean?
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to bring together
Convergent evolution is when organisms with
different ancestry have similar phenotypes
This occurs because of the environment the
organisms live in causes similar characteristics to
be fit, therefore leading to similar characteristics
being passed on.
Structures are usually analogous to one another
Convergent Evolution Examples
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Sharks and dolphins
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Sharks are fish, while
dolphins are mammals.
However, both sharks
and dolphins are similar
in their body structures:
fins, smooth body, etc.
Divergent
Evolution
 What does divergent mean?
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To move apart
Divergent Evolution occurs when organisms
that are similar become different.
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Usually caused by different habitats
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Can result in new species formation
Examples of Divergent Evolution
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Polar bears and brown
bears
 Polar bears and brown
bears have common
ancestors
 The differing
environments selected
different fitness
characteristics
Adaptive Radiation is a type of
divergent evolution
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Adaptive radiation occurs when a number
of different species evolve from a single
common ancestor.
Ex: Galapagos Finches – Each evolved
from the same mainland species, but
because the islands had different food,
their beaks shapes changed over time.
Artificial Selection
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Artificial Selection is
the breeding of
organisms for certain
traits. It is a type of
divergent evolution,
but sped up.
In artificial selection,
nature provided the
variation, and
humans selected
those variations that
they found useful.
Ex: Peas
Peas have 2 variations
yellow and green
(recessive). All peas
we eat are green
because farmers bred
the green peas to
produce a pure strain.
Artificial Selection cont’d
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Ex: Domesticated
dogs
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All dogs are the
same species Canis
familiaris but they
have been bred by
humans for certain
characteristics.