LIFESCI 1 Lecture Notes - Lecture 1: Spermophilus, Null Hypothesis
Chae Won Park
UID: 704407988
Section 1C
Introduction
When observing animals in their natural habitats, we can document behavior patterns specific to
the animal. In this laboratory, we studied two different species of squirrels, Beecheyi and
Variegatus, and compared their behaviors in snake scent application (SSA). Many researchers
have observed that ground squirrels, Beecheyi, and rock squirrels, Variegatus, chew up
rattlesnake skin and apply it to themselves by licking their fur. The reasons for doing this can be
tested with a couple testable hypotheses. Squirrels may use SSA as a defense mechanism to mask
their scent from predators, to attract another squirrel of the opposite sex for mating, or to ward
off other animals from taking up their resources or territory.(Clucas) For this laboratory, we
addressed the question, is SSA applied randomly over the squirrels’ bodies? Based on this
question, we made the null hypothesis that the squirrels apply the snake scent randomly on their
bodies. Thus, the hypothesis that we tested was that SSA is non-random. A logical prediction
that arises from this hypothesis would be that the squirrels apply snake scent on certain regions
of their bodies more than other regions of their bodies. For example, we can predict that the
squirrels apply more frequently to their tails and lower parts of the body because the movement
of the tail and hind legs will allow for more dissemination of the scent.
Methods
In this laboratory, we observed SSA behavior of two different species of squirrels, Beecheyi and
Variegatus, by watching videos of them chewing and applying the snake scent to their bodies.
After watching four videos of Beecheyi and four videos of Variegatus, we tallied how many
times the squirrels applied the scent on the following body regions: flank, head, front leg, hind
leg, and tail. (Life Science Core, UCLA. 2008-11)
Results
Species
Ind
Head
Tail
Flank
H.Leg
F.Leg
Total
S. beecheyi
1
0
2
0
0
0
2
2
0
3
0
2
0
5
3
0
2
1
1
0
4
4
0
1
1
1
0
3
Total
0
8
2
4
0
14
S. variegatus
1
0
4
0
0
0
4
2
0
2
6
3
0
11
3
0
7
5
0
0
12
4
0
2
0
0
0
2
Total
0
15
11
3
0
29
After observing the two species in multiple videos, we were able to see that the frequency of
SSA in both species was highest in the tail and flank area.
S. beecheyi
Head
Tail
Flank
H.Leg
F.Leg
Total
Expected
2.8
2.8
2.8
2.8
2.8
14
Observed
0
8
2
4
0
14
o-e
-2.8
5.2
-0.8
1.2
-2.8
(o-e)^2
7.84
27.04
0.64
1.44
7.84
(o-e)^2/e
2.8
9.66
0.229
0.514
2.8
16.0
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