In article <eesnyder.697953088 at beagle> eesnyder at boulder.Colorado.EDU (Eric E. Snyder) writes:
>>>Just as _Drosophila_ P-elements appeared to have
>>>arisen _de novo_ in the 1920s...
>>>I know that P-elements are believed to be of evolutionarily recent origin,
>>but THAT recent? (references please)
>>Yes, they are very recent. I don't have the original papers handy
>but a good start is Watson _et al._ _The Molecular Biology of the Gene_,
>I think at the end of Ch 20. If I remember the papers on the subject
>(ie. don't quote me), the presence of P-elements were assayed by squash
>blot of _Drosophila_ strains isolated in various years from various
>geographical localities. That hybridization was used as the assay
>suggests that mobile P-elements were not just the activation of a
>previously dormant transposable element but rather entered _Drosophila
>melanogaster_ from outside the species.
>>The Watson text cites Kidwell, M. G. (1983) "Evolution of Hybrid Dysgenesis
>Determinants in _Drosophila melanogaster_." PNAS 80:1655-1659.
>>Anyway, I think seeing this sort of genomic evolution occuring on a
>human time scale is facinating. Can anyone think of other examples?
"Genomic evolution"? It sounds like the transfer of an exogenous agent
(aka virus) from one species to another. This happens all the
time: HIV in humans, canine distemper in everything from ferrets
to marine mammals to peccaries. Outside the viral realm we have
ehrlichiosis in humans (possible from animals), mad cow disease
from sheep, the rapid spread of a parasitic "incompatibility
factor" thru Drosophila species in California (see Nature 1991;353:
Since retrovirus-like elements like the P element can insert and
mutagenize, and be transferred endogenously, they can be agents
of evolution. Kazazian just found an apparently intact trans-
posable element was the cause of hemophilia in one patient,
which allowed them to show that the element is present in
normal people. So do we also have the potential to see more rapid