h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

dear sir,i want a clearcut but brief concept of evo devo

Um... I have no idea what you're talking about. Can you be more specific?

"Evo" is a cool Mitsubishi rally car and "Devo" is a wacky American pop band.

What are you asking?

H.

"Evo-Devo" is short for "Evolutionary Development" (biologists should NEVER be allowed to name anything). It's a pretty new field which primarily looks at "homeotic genes", i.e., "master genes" that control the expression, turn on or off, other genes. These genes, it turns out, are mightily important in the development of living things from zygote to embryo to adult.

*It is the specific pattern of gene expression, which decides what the form of the animal/plant will be.* And this gene expression changed through time by the switching on or off on genes by the master genes. Not all genes are turned on at all times remember.

That's the "devo" bit. The "evo" part deals with the fact that these master genes tell us a lot about the history of evolution, and that one small change in a homeotic gene or two can lead to drastic changes in an organisms body plan. Recently, researchers showed how a mutation in two genes in segmented animals (think worms and centipedes) gave rise to the insect-type body plan. Also in the fruitfly (drosophila) when you damage a certain gene it turns off the expression of a bunch of genes which made the fly's antenna, having the effect of turning the antenna into a leg! This hinted that insects' antennae are evolution-adapted legs as controlled by a gene cluster that arose in the past and controlled by a single master gene during development.

So basically, whilst studying the genetics of development (of which we know suprisingly little at the moment) biologists stumbled upon the effects of evolution, giving a new insight into the field.

Thanks for your interest and managing to get through my rather long entry

Ste