NOTES: GENETIC DRIFT
Objective: What is genetic drift and how does
it affect the diversity of a population?
Title Box 1: What is genetic drift?


Changes in a small
population’s allele frequency
due to random chance
Not based on fitness its about
luck
Title Box 2: What are the types of genetic drift?


Founder’s effect: part of
the population
immigrates to and
colonizes a new area
Bottleneck effect: a
disaster happens leaving
few survivors from an
original population
Title Box 3: Quick Write
Talk it Over and Write it Down: Look at the
population of cats before and after.
1)What do you notice happen to the phenotypes?
2)What happened to genetic diversity?
3)What type of genetic drift happened?
DIE in flood
Title Box 4: What does genetic drift do to
a population?


Decreases
diversity within
a population
Affects small
populations
Title Box 5: What is genetic equilibrium?
When allele frequencies
remain the same
 Conditions for genetic
equilibrium:
1. Random mating
2. Large population
3. No immigration/ emigration
4. No mutations
5. No natural selection

Genetic Drift WS
1. Roll dice put dot
next to that #
worm
2. Example roll 3 put
dot next to worm
3
3. Roll 5 more times
(total 6 times)
4. Color the next
generation worms
those colors with
dots
5. Repeat until you
get to generation
4
Title Box 6: Exit Ticket
At the bottom of today’s notes answer the
following questions in complete sentences:
Explain how genetic drift affects the diversity
of a population. How does this affect the
fitness of the population?