http://evolution.berkeley.edu/evolibrary/article/medicine_04
"But the probability that the patient hosts a mutant virus that happens to
be resistant to several different drugs at the same time is much lower.
Although multiple-drug-resistant HIV strains do eventually evolve, drug
cocktails delay their evolution."
But it is suggested that if resistance crops up taking a drug vacation
could result in resurgence of nonresistant strains before next round of
drugs.
Could unprotected sex between HIV patients taking 3 drug cocktail pose long
term risk for success of treatment? If so that is gene flow. But I don't
know if HIV virus mingles in the human genome and recombines amongst
strains.
>
Why doesn't gene flow have an effect on the Lenski experiment?
>
If they took measures to eliminate potential for gene flow it wouldn't be a
factor.
https://en.m.wikipedia.org/wiki/E._coli_long-term_evolution_experiment
"Lenski chose an E. coli strain that reproduces only asexually, lacks any
plasmids that could permit bacterial conjugation, and has no viable
prophage. As a consequence, evolution in the experiment occurs only by the
core evolutionary processes of mutation, genetic drift, and natural
selection."
Yet under these unnatural lab constraints we still witness the following
pointer to incipient speciation of subclones. Evolution is amazing isn't
it?
https://www.ncbi.nlm.nih.gov/m/pubmed/15999245/
"Abstract
We investigated the phylogenetic history of a balanced polymorphism that
evolved in an experimental population of Escherichia coli. Previous work
showed that two ecologically and morphologically distinct types, designated
L (large) and S (small), arose by generation 6000 and coexisted for more
than 12,000 generations thereafter. Here, we performed RFLP analyses using
Insertion Sequence elements to resolve the phylogenetic history of L and S.
Specifically, we sought to determine whether the derived S morph was
monophyletic, indicating a long history of coexistence with L or,
alternatively, S was repeatedly regenerated from L, indicating a series of
periods with only transiently stable coexistence. Phylogenetic analysis of
some 200 clones collected throughout the history of this population
demonstrates that S is monophyletic. We then performed competition assays
using clones of both morphs from different generations to determine whether
either or both lineages continued to undergo genetic adaptation. Indeed,
both lineages continued to adapt, and their continued evolution contributed
to fluctuations in their relative abundance over evolutionary time. Based
on their phylogenetic history and independent evolutionary trajectories, S
and L fulfill Cohan's criteria for being different asexual species."
>
> Don't you think these replicators have any fruits of labor they want to share?
>
Given the contrived nature of the experiment itself, all descendants of a
fully asexual founder "strain Bc251" your question is irrelevant to what
happens in the larger bacterial community. That would be similar to asking
questions about modern people based on steampunk or goth subculture.