The Moths and the Trees
The Forest Ecosystem diagram shows part of a forest ecosystem. Tussock moths are
native to the forest ecosystem. In the fall, tussock moths lay eggs on Douglas fir trees.
In the spring, tussock moth larvae eat the needles of the Douglas fir trees.
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2. There are different types of tussock moths in the forest ecosystem. Charcoal-brown
tussock moths and white-marked tussock moths can be found in the same area.
a) Describe one type of evidence that could lead scientists to conclude that there is a
close evolutionary relationship between the charcoal-brown tussock moth and the
white-marked tussock moth.
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Task Title: The Moths and the Trees
Item number: 2
Performance Description
A 4-point response demonstrates the student understands:
Content Standard LS3E: Biological classifications are based on how organisms are related, reflecting
their evolutionary history. Scientists infer relationships from physiological traits, genetic information,
and the ability of two organisms to produce fertile offspring.
Item Specifications 1: Describe that scientists infer the degree of evolutionary relationship among
organisms using physiological traits, genetic information, and/or the ability of two organisms to
produce fertile offspring.
Item and example response
Points
LS3E(1)
a) The response describes one type of evidence that could lead scientists to conclude that
there is a close evolutionary relationship between the charcoal-brown tussock moth and
the white-marked tussock moth.
Examples:
 The two moths have similar genes/patterns in the DNA.
 The same proteins are made in both moths.
 When a brown moth and white-marked moth are mated, fertile offspring are produced.
 Charcoal brown moths and white-marked moths have similarly shaped wings.
 The pattern of development from egg to larvae to moth is the same time/stages.
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Response A
You could do a DNA test between the charcoal-brown tussock moth and the white-marked
tussock moth and if the DNA is the same that would mean they are the same species.
Response B
Scientists could mate the two moths and if they produce fertile offspring then the moths
are related.
Response C
Observe the bodies and wing shapes. If these are alike that would show a relationship
between the moths.
Response D
See if the two moths look the same. They are related if the moths look alike.
Response E
Use a DNA test on the moths.
Response F
Could test by looking at the habitat. If both moths live on the same tree then they must
have the same gene.
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Response G
So if their not the same species the moths baby wont be able to reproduce more babies.
Response H
The genes of the parents of the moths. The mother or father may have charcoal-brown or
white-marked bodies or may be a different moth species.
Response I
DNA test. If the DNA is alike, then they are close. If the DNA is different, then they are not.
Response J
Biologists can check if these two moths are related by the wing patterns. If the moths have
the same wing pattern then they might be related.
Response K
Get a blood sample from the moths and release the moths back into the wild and test the
blood sample if there was a gene mutation or not.
Response L
Biologists can research the area and the evidence found can show that the moths live in
the same type of habitat and the same type of moths prefer a certain type of environment to
live in and surround themselves with.
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