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List the five conditions that
can disturb genetic equilibrium
in a population.(10)
The five conditions are non-random
mating, small population size,
immigration or emigration, mutations,
and natural selection.
What are three mechanisms for
reproductive isolation?(6)
behavioral isolation,
geographic isolation, and
temporal isolation.
According to the
_________________________
principle, allele frequencies in
a population can be disturbed
by one or more of five
conditions.
Hardy-Weinberg
After a forest fire, a moose population
is reduced to one tenth of its original
number. By chance, the average moose
that remain are larger than the average
moose in the original population. This
change in the population’s gene pool is
known as
the bottleneck effect
The genes carried by all
members of a particular
population make up the
population’s
gene pool
Natural selection acts directly
on
phenotypes
A(an) ____________________
uses mutation rates in DNA to
estimate the time that two
species have been evolving
independently.
molecular clock
In a rabbit population, the
allele frequency of a gene for
brown fur changes from 20
percent to 30 percent. What
can you say about that
population of rabbit?
it is evolving
A change in the genetic
material of a cell is called a
mutation
In organisms that reproduce
sexually, most variation that
can be inherited is due to
genetic recombination
Two populations that have
overlapping ranges can remain
reproductively isolated through
temporal isolation or
___________ isolation.
behavioral
Genetic recombination
includes the independent
movement of chromosomes
during meiosis as well as
crossing-over
A ____________ trait that has
two alleles and that shows a
simple dominant-recessive
pattern will result in two
phenotypes.
single-gene
A __________ trait can have
many possible genotypes,
producing many possible
phenotypes.
polygenic
When individuals at only one end of a bell
curve of phenotype frequencies have high
fitness, the result is
directional selection
When individuals with an average form of
a trait have the highest fitness, the result is
stabilizing selection
One group of birds has a short, parrotlike beak
and another group has a long, narrow beak.
What process has probably occurred?
disruptive selection
Genetic drift tends to occur in
populations that
are small
The type of genetic drift that
follows the colonization of a
new habitat by a small group
of individuals is called
the founder effect
The situation in which allele
frequencies in the gene pool of
a population remain constant is
called
genetic equilibrium
In a certain population of 100 individuals,
one fourth of the individuals have the
genotype BB, half have the genotype Bb,
and one fourth have the genotype aa. One
day, 10 individuals with the genotype bb
leave the area and cross a river into a new
habitat. Which of these processes has
changed the population’s gene pool?
emigration
The separation of populations
by barriers such as rivers,
mountains, or bodies of water
is called
geographic isolation
A factor that is necessary for
the formation of a new species
is___________ isolation.
reproductive
They mate and produce
offspring defines the members
of a _________.
species
What situation might develop
in a population having some
plants whose flowers open at
midday and other plants whose
flowers open late in the day?
temporal isolation
Which is the first step that
occurred in the speciation of
the Galápagos finches?
founders arrived
The Galápagos finch species
are an excellent example of
speciation
The frequency of phenotypes
for a typical _________ trait is
most often illustrated as a bellshaped curve.
polygenic
What did the Grants learn
about mate choice from the
Galápagos finches?
Finches prefer mates with beaks similar
in size to their own.
An example of a
____________ trait is sickle
cell anemia in humans.
single-gene
What do Hox genes control?
patterns of embryological development
A ________ mutation is a
change in an organism’s
genetic material that does not
affect its overall fitness
neutral
A dramatic reduction in the
size of a population following
a natural disaster can lead to
change in the population’s
gene pool known as the
bottleneck effect.
In the type of reproductive
isolation called _________
isolation, two populations are
separated by barriers such as
rivers or mountains.
geographic
A(an) ____________________
is all of the genes that are
present in a particular
population.
gene pool
When a population is NOT
evolving, it is in a situation
called
genetic equilibrium
If two populations have been
reproductively isolated and can
no longer breed and produce
fertile offspring, the process of
_________________________
has occurred.
speciation
In humans, skin color varies
from very light to very dark,
and many different phenotypes
exist in between these
extremes. Therefore, skin color
is probably a __________ trait.
polygenic