Butterflies shed light on organisms' ability to adjust to their environment.

1. Wings of change
Butterflies shed light on
organisms’ ability to adjust to
their environment

2. What does it take to thrive in a
changing world? Being able to
alter one’s developmental
trajectory in response to the
environment can be a big boon.
But such “plasticity” may also
come with a cost – such as lower
reproductive rates. Improving our
understanding of how organisms
meet the demands of changing
world is more important than
ever today, as human actions
create new and unusual habitats.

3. Emilie Snell-Rood, assistant
professor in the Department of
Ecology, Evolution and Behavior, is
doing just that, using butterflies
as research subjects. Why
butterflies? “There are a lot of
good natural history records
because people love to watch
butterflies,” she explains.
Butterflies also exhibit a large
amount of variation among
species and reproduce quickly.
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4. (Plus, they’re fun to be around.)
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5. One trait that has been linked to
survival in shifting environments
is brain size.
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6. Changes in diet over the last 2
million years may have
contributed to the evolution of
large brains in humans. Is diet a
generally important driver in
brain evolution? To answer this
question, Snell-Rood is looking at
brain size across more than 40
species of butterflies that feed on
different plants as caterpillars. For
instance, this Rocky Mountain
Parnassian uses stonecrop
(Sedum) as a host plant, while
other caterpillars feed on
cabbage, milkweed, pine, grass,
or even other insects!
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7. Junior scientist Anne Espeset
spends a lot of time dissecting
and then measuring brains of
hundreds of butterflies.
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8. With the help of undergraduate
research assistant Ihab Mikati, the
lab is also measuring eye size (a
proxy for brain volume) in
museum specimens of more than
60 butterfly species and looking
at how it relates to the quality of
the species’ known diets.
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9. A better understanding of
nutritional ecology can shed light
on whether a species might thrive
in a changing environment.
“Some species can deal with
much more variable diets, so they
have more resilience to change,”
Snell-Rood says. “Understanding
adaptations to low-quality and
high-quality diets could inform a
lot of human health questions.”
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10. In addition to exploring why
species might differ in cognitive
responses to new environments,
Snell-Rood is also studying
responses to these environments
directly – for example, responses
to changing nutrient dynamics
caused by human use of fertilizer
on crops and lawns.
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11. Snell-Rood’s lab is looking at the
link between nutrition and ability
to choose the fittest mates. In
cabbage white butterflies, the
brightness of a male’s wings is
associated with the amount of
nitrogen they’ve gotten from
their environment – a measure of
the survival value they can
provide to their offspring. This
cue provided females butterflies a
cue about relative fitness when
nitrogen was scarce. But does it
still today, when farm fertilizer
makes it abundant?
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12. To find out, Snell-Rood is raising
normal and genetically inferior
male cabbage whites on low-
nitrogen and high-nitrogen diets,
then watching how they pair up
with females. “Is the female’s
ability to distinguish between
low- and high-quality males
disrupted when we flood the
system with nitrogen?” she asks.
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13. In a follow-up study, Snell-Rood
also plans to compare the ability
to survive on different nitrogen
diets for cabbage whites collected
in North Dakota, where nitrogen
fertilizer is common, and those
from populations with less
fertilizer use, such as northern
Wisconsin. “We predict butterflies
from areas with less fertilizer use
will retain the ability to survive on
a low-nitrogen diet,” she says. In
contrast, she suspects the loss of
“honest” signals of mate quality
in butterflies from high-nitrogen
areas will make it less likely their
offspring can cope with low
nitrogen.
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14. Snell-Rood is also studying yet
another dimension of human-
induced change. She’s comparing
cabbage white populations from
environments with diverse
vegetation with others collected
from canola monocultures in
North Dakota.
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15. By raising the captured
butterflies’ young on various diets
in the lab, she seeks to learn how
food specialization (for instance,
on an agricultural crop) might
affect fitness.
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16. Snell-Rood hopes improved
understanding of how living
things adjust to a shifting
environment will shed light on
how we can help nature thrive in
the face of human-induced
alterations to habitat. “Given the
current rate of environmental
change, we may not have a lot of
time,” she says.
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17. Mary Hoff, writer
Jonathan Pavlica, photographer
Stephanie Xenos, editor
Katie Hoffman, production
Copyright 2012
University of Minnesota
College of Biological Sciences
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