Questions for ‘How a moth went to the dark side’

butterfly gene

The gene variant responsible for some of these butterflies getting yellow stripes is the same one seen in changing the color of moth wings to black (from speckled gray). New data uncovering this gene help explain some iconic examples of evolution. 


To accompany feature “How a moth went to the dark side” 


Before Reading: 

1.   Species can morph in shape and color over time as a result of evolution. How long — minutes, years, centuries, millennia — do you think it takes those changes to show up?

2.   What do you think is responsible for making those changes to a species?

During Reading: 

1.   What major transformation in society coincided with a darkening of peppered moths in Britain?

2.   Why did the black form of the species come to dominate in polluted regions?

3.   Did pollution “make” the moths black? If not, explain what did. 

4.   Explain “natural selection.” 

5.   What are microRNAs?  

6.   What does SNP stand for — and what is a SNP?  

7.   What is a jumping gene, and what type of microbe has it been compared to?

8.   What is an intron?

9.   In the Heliconius butterfly species, what advantage do these insects get from a yellow band on their wings?  

10.  According to this story, the timing of wing-scale development can affect what attribute in Heliconius butterflies?

After Reading: 

1.  The change in peppered-moth wing color has been described as an example of natural selection. But if the condition that “drove” this change within the species’ population was pollution, does the term natural selection seem appropriate? Explain your reasoning.

2.  With pollution controls, the “typical” version of peppered moths again came to dominate much of the species’ original range. What allowed them to make that comeback (hint: which were available to come back)? If the motley-winged variant hadn’t been able to make a comeback, what might have been the reason? And what might ultimately have happened to the species, at least locally, if only the black-winged moths were living in this cleaner environment? Explain your reasoning.


1.   In peppered moths, a region of about 400,000 DNA bases seemed to hold the long-sought gene mutation leading to dark peppered-moth wings. The difference showed up in a portion that was almost 22,000 DNA bases long. What share of the original region did this smaller one comprise (on a percent basis)?

2.   Ilik Saccheri found a transposable element in 105 of 110 carbonaria moths. What percent of these moths had that jumping gene?