I think Eden's calculations were based on the trp operon, where five
successive genes control five successive biochemical reactions in the same
order as they are specified in the operon. As far as I know these genes
share no functional similarity, unlike eukaryotic gene families or homeotic
proteins.
>
>Next, most functionally relevant genes that lie in tandem, share significant
>sequence similarity and could arise from gene duplication rather than by a
>process by which different genes are somehow sorted and ordered in the
genome.
Regardless of what mechanism you want to visualize for the genes
origination, you are going to have to explain this ordering as being other
than serendipitous. Even finding a perfectly good advantage to the order
does not make them jump up and rearrange themselves like some game of
musical chairs.
Somehow the pattern is present (presumably) in all metazoans with complex
developmental pathways. Thats pretty fundamental. Eden's calculations do
apply (with appropriate modifications for the 1000x lifespan of Drosophila
or whatever organism you want to use to get the genes rearranged in).
Art
http://chadwicka.swac.edu