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Mechanisms of Microevolution – v3
Genetics Review
Chromosome – a segment of
__________________________
Homologous chromosomes – a matched
pair of chromosomes, __________
_______________
Gene - a section of DNA on a
chromosome that has instructions to
_________________________
Allele – a ____________________
For example the _______________ has
alleles for blue, grey, brown and green.
There are 5 mechanisms that affect real populations resulting in microevolution or
changes to allele frequencies within a population.
1. Mutations
2. Genetic Drift
a. Bottleneck Effect
b. Founder Effect
3. Gene Flow
4. Non-random Mating
a. In-breeding
b. Assortative mating
5. Natural Selection
a. Stabilizing selection
b. Directional selection
c. Disruptive selection
d. Sexual Selection
1. Mutations
Mutations are only important to evolution if the mutated DNA is in a gamete and passed
on to offspring.
The new mutation may provide an
advantage for natural selection.
Ex) Daphnia adapted to warmer water
with climate change are more likely to
survive.
2. Genetic Drift
Genetic drift is defined as chance changes in allele frequencies due to a small
population size. The smaller the population the less likely all of the alleles in the
parent gene pool will be reflected in the offspring gene pool.
a) The Bottleneck Effect
The bottleneck effect is a reduction in alleles in a population resulting from a disaster
that drastically reduces population size.
Example: earthquakes, volcanoes
b) The Founder Effect
The founder effect occurs when a few individuals separate from a large population and
establish a new one. Their allele ratios can be very different and some alleles can be
missing in the new population.
3. Gene Flow
Gene flow is the gain or loss of alleles from a
population by the movement of individuals or
gametes. This could result from immigration or
emigration.
4. Non-Random Mating
In-breeding or mating between closely related
partners results in fewer heterozygotes and more homozygotes. ex. Purebred dogs are
homozygous for many traits.
Assortative mating is where a similar partner is chosen like toads choosing a same
size partner, or dog breeding.
5. Natural Selection
Natural selection is the process by which individuals with favorable traits that make
them better suited for their environment are more likely to survive to reproductive age
and leave more offspring.
Mechanisms of Microevolution – v3
Chromosome – a segment of
__________________________
Homologous chromosomes – a matched
pair of chromosomes, __________
_______________
Gene - a section of DNA on a
chromosome that has instructions to
_________________________
Allele – a _________________________
For example the _______________ has
alleles for blue, grey, brown and green.
There are 5 mechanisms that affect real populations resulting in _________________
or changes to ______________________________________________
1. ______________________
2. Genetic Drift including
a. _______________________
b. _____________________
3. __________________
4. Non-Random Mating including
a. _____________________
b. _____________________
5. _______________________
a. Stabilizing selection
b. Directional selection
c. Disruptive selection
d. Sexual Selection
1. Mutations
Mutations are only important to evolution if the mutated DNA is in a _________
___________________________________________________
The new mutation ___________________________________ for natural selection.
Ex) Daphnia adapted to warmer water with climate change are more likely to survive.
2. Genetic Drift
Genetic drift is defined as ___________
_______________________________
_________________________________
The smaller the population the less likely
all of the alleles in the parent gene pool
will be reflected in the offspring gene pool.
2a) The Bottleneck Effect
The bottleneck effect is a reduction in
_________________ in a population
resulting from a _________________ that _______________________ population size.
Example: earthquakes, volcanoes
2b) The Founder Effect
The founder effect occurs when a ________________________________________
and establish a new one. Their allele ratios can be very different and some
____________________________________ in the new population.
3. Gene Flow
Gene flow is the _____________________
___________ from a population by the
movement of individuals or gametes. This
could result from _________________ or
__________________________.
4. Non-Random Mating
In-breeding or mating between closely related partners
__________________________________________.
ex. Purebred dogs are homozygous for many traits
Assortative mating is where a ____________
_________________________________ like toads
choosing a same size partner, or dog breeding.
5. Natural Selection
Natural selection is the process by which individuals with _______________________
,that make them better suited for their environment, are more likely to ______________
______________________.
Watch the video The Making of the Fittest and answer the following questions.
1.
Describe the habitat of the rock mouse.
2.
Who are rock mouse predators?
3.
In your own words describe what changes occurred in the rock mouse population
and why the changes occurred.
4.
Which mechanism of microevolution was most important?