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Home Q & A Board Biology-Related Homework Help Genetics and Developmental Biology
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lgb lgb
wrote...
13 years ago

Please do not explain the mechanism of metamorphosis.  Explain only by stepwise evolutionary methods, how metamorphosis may evolve.
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wrote...
#1
13 years ago
Metamorphosis is just like normal development in an embryo, the same classes of enzymes, reactions and anatomy changes take place."Many observations have indicated that cell death plays a considerable role during physiological processes of multicellular organisms, particularly during embryogenesis and metamorphosis." (wikipedia).

When you have an insect that has, for example, two forms, like a caterpillar and a moth, the two stages are so completely different that they no longer compete with each other. The moth eats nectar, and the caterpillar eats leaves. There is no competition between the two, as there would be in a continually developing insect that ate both at some point. This lessening of interspecies competition was a great help in allowing the species to propagate itself. Along with the lessening of the competition was the ability to take over new niches. A caterpillar and a butterfly could occupy different places in the ecosystem - this allowed for great diversification - another thing that has helped insects becomes so successful
http://www.madsci.org/posts/archives/2000-06/960566507.Ev.r.html.
iJASonyou Author
wrote...
#2
13 years ago
kano7 really really nailed it.

All I would add is that a metamorphosis from one type of animal to another is quite common in nature (tadpoles to frogs, polyps to medusa, aquatic embryos to air-breathing organisms, maggots to flies, etc. etc.).  Organisms have hormonal clocks (everything from daily circadian rhythms, to monthly menstrual cycles, to yearly seasonal cycles, to specific stages in development over a lifetime).   When these hormonal clocks go off, genes execute ... and things happen.  These are all just genes playing out their programs ... programs that have developed over millions of years of evolutionary development.  

In other words, the sequential and timed execution of these genes, as controlled by endochrinology, is a far more complex issue than their evolution.
wrote...
#3
13 years ago
Here:
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