About mutualism between human and E.coli

[dttom]

Though I think it won't be so appropriate to reply thread few years ago, but I still want to have a few words on genetic level or individual level of selection.

 

I should agree that for each time of selection (who dies, who lives), natural selection acts on individual level, so at genomic level; however, in long run, why shouldn't it act on genes' level, fostered by crossing over in meiosis? A complication arrives with speciation that, as genes in a genome are bundled together, if a gene could not be resolved (if a gene is resolved, it got the chances to be in different genomes (of course in different individuals) for natural selection) before microevolution occurs, probably the selection level could stay at a higher level than a gene.

 

When talking about a gene could only exert its effect in a given genetic environment (together with other genes), as in the case of any individual, I have to admit that this is definitely the fact. But does this fact affect or change the consideration in selective level is another matter. For me this is a fact stating that a gene could have different effects in different combinations of genes (actually I would prefer, and better to, use the word gene assembly), but as long as a gene could be resolved, it got the chances to be in different genomes, and individual gene effect could be selected by natural selection. The result could be a gene might exert more advantageous effect when combining with a set of other genes (actually this is usually the case as a phenotype, no matter is the traditional definition of phenotype or the extended phenotype, is usually determined not by a single gene), in this case, such a gene assembly would be advantageous if they have a low COV relative to each other (harder to resolved from each other), ultimate result might be fusion to a single gene (please beware of the use of the word 'gene', not cistron, a 'gene' here could refer to a number of encoded polypeptides) which is selected later as single unit (this might be refered to by someone as an evidence to support the allegation of selection at a level higher than gene, so for me it is not a matter of concept but a matter of definition, view of phenomenon and explanation).

[CharonY]

If you want to discuss this, maybe you should start a new thread. There are a couple of things in this thread that are somewhat inaccurate, but I do not want to revive arguments from two years back.