Wings

[John Grehan]

Patrick Foley wrote:

>There are genes that spread within a genome, they are known as
>transposons, essentially runaway scraps of feral DNA, not quite as
>self-sufficient as viruses. They are common, but probably mostly just
>elevate mutation rates when they jump into the wrong genes, or anooyingly
>expensive to reproduce when too many copies are made.

The process I was referring is known as concerted evolution
and involves a process called molecular drive. It has been mostly studied in
the context of multigene families, and the research is still in its infancy (my
impression) despite the concept being around for about 15 years.

Gene conversion is I believe a rare peculiarity.

Perhaps not.
>
>The idea of orthogenesis is an old fuzzy one,

What was fuzzy about it? Its not as old as natural selection.

that basically says that a
>line of organisms tends to continue to evolve in the same direction,
>perhaps even in the absence of natural selection.

I don't think that definition applies since natural selection can also
result in a
line of organisms continuing to evolve in the same direction (using direction in
a non-teleological sense).

I can readily accept
>some versions of orthogenesis, but the less exciting concept of
>developmental constraints probably accounts for most of the phenomena
>called "orthogenesis".

The concept of constraint only explains the limitation on variation in
mutation. It
does not account for a concept of evolution taking place in a concerted manner
without requiring natural selection as the mechanism.

Sincerely, John Grehan