" Ebola is one of my favorite pathogens. " Tara, you're zany.
A question, though. You say:
"They explain that it is the tendency of viruses which have been maintained within a single host population to have a high genetic diversity. An example they give of this is Hepatitis C, which has a number of different genotypes with worldwide distribution."
But this sounds a bit confusing to me. Are you saying that the world-wide human population is the "single host population" in the case of Hepatitis C? Am I mistakenly assuming "single host population" to relate to a specific geographical region?
The paper they cite for the Hep C info is J. Gen Virology (78 ) :321-28. According to that paper, there are a few genotypes of the virus that have spread world-wide (likely due to blood transfusions and other modern medical interventions). In those areas, the virus has little genetic diversity--there is one major genotype wtih few subtypes. But in geographic areas where the virus has long been endemic, there are numerous subtypes of the dominant genotype.
That probably doesn't make it very clear, so let me give an example. Say a type 1 Hep C virus has been introduced to a human population in N. America from its original "home" in Africa. This virus is genotype 1, and subtype 1b. As the virus spreads, the other infections in the same geographic region will also be 1b. But if you look in the region of Africa where this 1b originated, you'll also find 1a, 1c, 1d, 1e, 1f, 1g, etc. Seems to me that they're talking essentially about a founder effect.
I do think I'm being a bit confusing and not saying that well in the post; I'll modify.
Unless I have totally missunderstood, it doesnt seem confusing at all. Simply, an endemic pathogen will by way of mutation and selection be diverse within a stable population. A newly introduced varient will show little short term variation on its migration within that population. To my mind this would be akin to squirting a dye into a flask of water. A definite and distict path with gradual dispersion and relative dilution(via mutation)ensuing over time - somewhat elapsed of course.
Then again, my interpretation may not be accurate.
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