Pre-Lab: Evolution of the
Pepper Moths
Evolution – Any change over
time in the relative
frequencies of alleles in a
population – (not an
individual organism)!!!
Dark and light moths
Natural Selection on a single-gene trait
• Can lead to changes in allele
frequencies and thus to
evolution • Ex: Classic example of natural
selection is 'industrial
melanism' (getting darker) of
the peppered moth in
England.
1. Before Industrial
Revolution(1850’s):
• Light colored
moths blend in
with light color
lichen growing
on tree bark
2. During the Industrial Revolution
• Smoke particles accumulate on
the Lichen of trees, causing the
light moths to be more visible
and the rare dark variety to
blend in.
Pepper Moth Mutant
• A black mutant was first
observed in Manchester in
1849. Within a century, this
black form had increased to
90%
• Two forms of the same
organism exist: a white one
and a black one
Camouflage
• An advantage for survival
because of protection against
predators
• The Manchester moth case
demonstrates the advantage of
camouflage in Natural Selection
Internet Simulation
• Peppered Moth Internet Simulation
• Click on the web site link below to begin:
• http://www.techapps.net/interactives/pepper
Moths.swf