What's the difference between metamorphosis and evolution? Well, let's break it down! We already know that EVOLUTION is about how a species changes over time. With the proper context, evolution occurs in the alleles (DNA segments) and causes advantageous, neutral or negative effects on an individual depending on the genes they get or inherit from their parents.
Metamorphosis is a bit different in comparison. For starters, it operates on the individual. An insect, frog or crustacean (lobsters, crabs etc.) transform through the process of metamorphosis because of the evolution that happened through the generations. Because of evolution, metamorphosis happens.
Metamorphosis doesn't have good, bad, or neutral changes when a tadpole turns into a frog. The metamorphosis of a tadpole is going to show consistent change that makes sure the tadpole will always be a frog with all the needed frog traits. If a frog develops with five legs instead of four, that would be a mutation caused by evolution outside of metamorphosis.
The development of the tadpole into the frog is the metamorphosis change. You can think of metamorphosis like puberty.
When you're looking at the source of evolution and the source of metamorphosis, there's a distinct difference. When two parents create a baby, the genes will mix and match to create the zygote (egg) that grows in the womb to become a human. For more information on mutations, click HERE. The mutations (good, bad, neutral) will influence whether the child can survive in the environment.
Hormone Driven Change
Metamorphosis works because of the genes that are already there in a creature that already exists. Something will cause a fluctuation in hormones that signals the process of change. Although metamorphosis is still being studied by scientists and there's still a lot we don't know, we do know that the hormones aren't species-specific. If you have the hormones necessary to cause and regulate the change or molting process, that will be enough to develop into an "adult" stage. The kind of changes that occur with metamorphosis includes physical, behavioral, and even biochemical changes.
Different Kinds of Metamorphosis
Metamorphosis happens in different ways. The caterpillar goes through stages of development called "HOLOMETABOLOUS DEVELOPMENT." There are multiple changes it goes through before becoming an "adult" or butterfly. You have the egg, larvae (caterpillar), cocoon or pupa, and then the adult stage with wings. A common fruit bug will have the same stages without going through as many physical changes. It may shed its skin to become a bigger version of the same looking insect and the process will repeat until death.
You can have evolution occurring without developing metamorphosis in a species, but in order to have metamorphosis occur, evolution must have happened to develop that quality. The world is a beautiful and crazy place and metamorphosis is still being studied today as a part of what happens when evolution occurs.
Lecture Notes: Dr. Daniel Marschalek, Entomology, Fall 2018
"Insects" Australian Museum
"Frog facts" Kidzone
"Holometabola" John R. Meyer Department of Entomology NC State University