"Malcolm"  wrote in message
news:c455or$2hl2$1{at}darwin.ediacara.org...
>
> "crognum"  wrote in message
> >
[snippage]

> I can't think of a good example of two closely related
species where one is
> clearly parasitic whilst another is free-living.

Sure---proto-human husbands and wives! :) (You guess which
is which.) (BTW, are males and females technically
considered to be sub-species?) However, somewhere on the way
to becoming modern humans, the parasites became
simbiotic--it's interesting to wonder exactly why/how.
Hmm...             ...tonyC [bachelor]


> However you might want to look at the yellow-billed
oxpecker, Buphagus
> africanus, and its relative the red-billed oxpecker,
Buphagus
> erythrorhynchus. These birds clean ticks from large
mammals, but also take
> blood form wounds, so are part way to parasitism. B.
erythrorhynchus seems
> to benefit its host less, so it might be the more
parasitic of the two - I
> haven't researched this properly but you will find plenty
of material on the
> web.
>
>
>
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