HI All,

Peter Borst offere a stunning paper:
Epigenetic inheritance based evolution of antibiotic resistance in bacteria
http://www.biomedcentral.com/1471-2148/8/52

If you haven't taken the time to read it, suggests that we take a new look
at varroa resistance to miticides, antibiotic resistance by bacteria,
parasite resistance by bees, and at bee breeding mechanisms in general.

Let me lift a few quotes and add comments:

"In this report we present data strongly supporting the conclusion that
evolution can occur without mutation....Within an isogenic [genetically
identical] population of E. coli there is random variation in the expression
levels of genes, creating phenotypic variation. This epigenetic variation
shows an element of heritability. Some cells with elevated expression of
genes conferring antibiotic resistance survive antibiotic selection, as do
sufficient progeny to allow colony formation."

The implication is that genetically identical varroa or bees still have
variation in gene expression that can be selected for survival, and be
passed on to offspring without any mutation of the DNA.

"The endogenous E. coli AmpC gene represents a cryptic gene, normally not
significantly expressed, but when activated capable of conferring potent
antibiotic resistance."

Some genes are "cryptic"--you don't see them expressed except under
exceptional circumstances, such as when a chemical is applied, a parasite
attacks, or the environment changes.

"On the other hand, once a gene expression pattern is established there are
epigenetic memory mechanisms capable of preserving the gene expression state
for multiple generations"

We can still breed for this sort of gene expression, and it can be passed on
to future generations.  But it will be lost unless the "challenge" that
initiated it is maintained.

This sort of non genetic change has been termed "paramutation."   As Pete
has pointed out, recent research is turning much of what we thought that we
knew about evolution and inheritance on its head!

Randy Oliver

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