From: Scott Chase (osteopilus@yahoo.com)
Date: Sun 24 Apr 2005 - 06:44:21 GMT
Aunger uses the term "parasitoid" in a manner on page
226 that strains its ecological definition. He uses it
in the sense of hypersimplifying trends in
replicators: "parasites on parasites on parasites".
The typical ecological example of parasitoidism is an
intermediate condition between predation and
parasitism, such as when wasps uses a host as a depot
for their eggs and these hatch to consume the host.
I've heard of birds like cuckoos being referred to as
parasitoids (Minkoff, _Evolutionary Biology_, 1983,
page 165) which lay eggs in host species nest so the
young can take resources from the surrogate "parents"
like a parasite would. Alcock, though on page 27-8 of
_Animal Behavior_ (5th ed), refers to this situation
as brood parasitism. Nonetheless I fail to see how
Aunger's use of the term "parasitoid" makes sense.
On page 61 Aunger strains the definition of parasitism
when he says that "some parasites don't inflict
penalties on their hosts." If so, this would cease
being a parasitic relationship wouldn't it? He really
gets creative when he says: "The bacteria in our gut
are also parasites, but their relationship with us is
one of mutual benefit, or symbiosis." I don't even
know where to begin. Why have distinctive concepts for
symbiotic "living together" relationships like
parasitism and mutualism when people muddle them up
like this? Based on Table 15.1 on page 217 of Robert
Smith's _Elements of Ecology_ (3rd ed) where part of
my treatment of parasitoidism comes from we have clear
distinctions made where in mutualism both organisms
benefit and in parasitism "fitness of one is reduced;
fitness of the other is increased" much like
predation. Some cases might not be straightforward and
a parasite could evolve away from parasitism to
mutualism where it would cease to be a parasite, but
Aunger isn't being very clear on what he means by his
usage of these terms.
It's hard enough to rid people of the kneejerk
equation of symbiosis and mutualism as synonyms and
I'm trying my hardest to give up on this futile
effort. Making mutualism, parasitism, and symbiosis
synonymous would mean we might as well throw all of
these words in the garbage can.
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