SBI3U
Genetic Drift
Name: _____________________
Natural Selection

Nature “selects” some traits over others to survive

Selection is NOT random

BUT evolutionary change doesn’t always happen this way
Change without Selection (background)

Allele: ____________________________

Ex: if there is a gene responsible for ____________________________
o Allele A gives you ____________________________
o Allele B gives you ____________________________
o Allele C gives you ____________________________
Genetic Drift

Genetic drift:
____________________________________________________________________________

Due to ____________________________

Some generations may see ________________________________________________________,
and others may see ________________________________________________________
Genetic Drift

Two different types of genetic drift:
o ____________________________
o ____________________________
Genetic Bottlenecks

________________________________________________________ in population size
o Ex: a population of ____________________________ that
_________________________________
o Caused by:
The Founder Effect

A small number of individuals ________________________________________________________
and ________________________________________________________
SBI3U
Genetic Drift
Name: _____________________
Genetic Drift and Population

Genetic drift affects ____________________________ differently from
____________________________

In large populations, we expect to see ______________________________________________________
o Overall, genetic variability remains ____________________________ from
________________________________________________________
o Large populations are ____________________________ by genetic drift

If genetic drift happens to ____________________________, alleles are
________________________________________________________
In-class assignment:
So far, you have learned about the following mechanisms of evolution:
 Natural selection
o Gathering resources
o Avoiding predators
o Adapting to an unique environment
 Sexual selection
o Intersexual selection
o Intrasexual selection
 Genetic drift
o Bottleneck effect
o Founder effect
To show your understanding of these concepts, you will create a comic strip for each of these 3 types of
evolutionary change (3 in total). Pick one of the sub categories (e.g. gathering resources) for each comic
strip.
Your comic strip should meet the following criteria:
 Have at least 4 panes
 Demonstrate a thorough understanding of the concept in question
 Be understandable to fellow classmates
 Humour and creativity is a plus
Due tomorrow (Tuesday, Oct 26) at the end of class