I have a suggestion: Let's develop a list of known mechanisms which can
(a) increase genome size and/or (b) increase an organism's number of
interacting metabolic pathways. Then, when someone offers a definition
for "information" or "complexity," this list may prove useful
in arguing *specifically* whether some of those listed mechanisms --- or
some combination of them --- is capable of meeting those definitions of
"increased information" or "increased complexity."
I'll get the ball rolling. I would appreciate anyone adding to this
list of mechanisms, or providing specific examples of these mechanisms
occurring in nature (both examples which have been *observed* and
examples which can be reasonably inferred from data). Also, feel free
to suggest better definitions and explanations for items on the list
below.
This list may not settle the debate, but it will at least give us a
handle on the repertoire of available evolutionary mechanisms.
1) Mechanisms above the species level:
--------------------------------------
1a) Speciation. When a species population splits into two or more
reproductively isolated groups, and both groups survive and drift apart
genetically, the total number of different genes in the environment
increases.
2) Mechanisms at the species-population level:
----------------------------------------------
2a) New alleles. When mutation introduces a new allele and that allele
incorporates into the population, the genetic diversity of that species
increases.
3) Mechanisms to increase the size of an organism's genome:
-------------------------------------------------------------
3a) Gene duplication.
3b) Horizontal gene transfer (from another species, or from a virus).
3c) Allopolyploidy.
4) Mechanisms to increase the number of proteins an organism produces:
(without changing genome size)
----------------------------------------------------------------------
4a) New splice variants. Mutations can occasionally lead to the
production of new splice variants, increasing the total number of
different proteins that the genome can produce.
4b) Mutation after gene duplication.
5) Mechanisms to increase metabolic pathway interactions:
---------------------------------------------------------
5a) New metabolic functions via mutation. Mutations can sometimes cause
a protein to begin interacting with a metabolic pathway with which it
did not interact before (without that protein losing its original
functions).
I'll leave it at that for now. I know there are other mechanisms by
which new genetic material can be inserted into genomes, but I don't
know their technical names or details, so I'll leave that for other
experts to fill in.
Loren Haarsma