Caterpillar vs Butterfly DNA
Date: August 2002
How does the DNA of a caterpillar compare with the
DNA of the butterfly/moth that it eventually becomes ?
eg. If you were to genetically fingerprint both forms, would they be the
same or different ?
If they are different, how different ? - and how does the restructuring occur?
If they are the same, how do they have such different morphology/behaviour etc. ?
The DNA of any organism is the same in every cell of its body except in
its eggs or sperm, which have half the amount. The DNA in your toe cells
is the same DNA that is in your stomach cells. So the caterpillar and the
butterfly cells have the same DNA. The cells have the ability to turn
genes on and off at different stages in their life cycle. So the
caterpillar is using its caterpillar genes and the butterfly is using its
butterfly genes. When you were an embryo some different genes were
functioning than the genes you have now.
Sorry for the delay. The caterpillar and butterfly DNA are the same. The
organism contains DNA that encodes for both body forms. During metamorphosis,
some new genes are turned on that modify the body shape of the organism and
produce the final butterfly body shape. In addition, many of the same genes
are expressed in both body forms.
My lab used to work a lot with fruit flies, a similar organism. In the larval
stage (the "maggot"), there are tiny pockets of cells set aside very early in
development that will give rise to the adult fruit fly structures. During
metamorphosis, these pockets of cells grow to form the legs, wings, etc. of
the fly, while many of the tissues of the larva decay. Some parts of the
larva do not decay, but are modified and reused in the adult. An example
be parts of the nervous system.
Paul Mahoney, PhD
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Update: June 2012