Although Jim Crants in a later post raised questions about whether by being
fuzzy we risk avoiding responsible for human actions, I have to take issue
with Roper's definitions. In large part this is because in some cases the
distinction between humans and (other) animals is not relevant.
Clearly in cases like the introduction of the rabbit to Australia we have a
clear case of introduction, 100% in fuzzy terms. But consider the following
cases:
When American Bison migrate they disperse parasites and disease organisms,
clearly this is a natural process.
When Bison are depleted due to human depredation they may travel in search
of mates, again dispersing parasites and disease organisms.
Indians used to stampede Bison over cliffs as a means of hunting them, the
survivors may flee and disperse parasites and disease organisms.
Cattle grazing in the lands where Bison used to be plentiful may disperse
parasites and disease organisms in the same way.
Human herders following the cattle may disperse parasites and disease
organisms on their clothing.
And so on. Are nomadic tribes totally different from migrating animals?
Crants later writes that "Invasive species biology loses most of its social
relevance if native and exotic species are not ecologically
distinguishable." but I do not think that we need to draw sharp lines
between them. Migrations can be blocked by fences and roads, nomads may be
confined within national boundaries. I don't think that invasive species
biology requires that every species be either totally invasive or totally
natural. And imagine what would happen if some exotic species that we blamed
on ballast water transport turned out to arrive via a parasitic life stage
on some migratory fish! All those papers to be withdrawn!
One of the greatest invasions in ecological history occurred when the
Mediterranean connected to the Atlantic Ocean. How fundamentally different
is that from the opening of the Suez or Panama canals?
Bill Silvert
----- Original Message -----
From: "James J. Roper" <jjro...@gmail.com>
To: <ECOLOG-L@LISTSERV.UMD.EDU>
Sent: segunda-feira, 10 de Maio de 2010 22:52
Subject: Re: [ECOLOG-L] Ecology Terminology and associated phenomena
Colonizing species etc
But that question is easy to answer. If humans put the species in a place
or it arrived in a place that it would not have gotten to on its own, then
it is introduced, otherwise it is native or natural.
James Crants wrote on 10-May-10 12:51:
In the discussion off-forum, we were unable to come to any conclusions
because we could not agree on answer to even the most fundamental
question:
is the distinction between exotic and native species ecologically
meaningful? If you can't agree on that, there's no point in going on to
ask
whether there's such a thing as an invasive exotic species, whethere
invasive exotics are a problem, and what, if anything, we should do about
it.
