No organism is currently present only within the ecosystem it originally
evolved in - including humans. That's what successful species do - they
expand their ranges. Current distributions probably have more to do
with historical contingencies - dispersal, random chance, etc. I think
Gleason and Whittaker did a fairly good job of arguing against such
Clementsian views of community structure; biotic interactions matter -
yes - but probably only to a small degree compared to abiotic factors.
It's also notable that the large majority of 'alien' species have
evolved do some degree in their invaded range - does that make them
'evolved in their current ecosystems?' It is extremely difficult to
develop a scientific rationale for what we consider 'alien' vs.
'native.' What about the South Florida tropical flora/fauna? Many
species in those systems only arrived on this continent only within the
last 5000 years - are they invasive? Are entire communities in the
everglades invasive?
On 9/11/2011 8:18 AM, Wayne Tyson wrote:
Warren and Ecolog:
Naw, Warren, you're making a valid point that sums up the situation
quite succinctly. I hope this will lead to the expression of more such
simple elegance.
I would add only that organisms and their habitats, both in a constant
state of change, fit together like a hand and a glove.
However, this means neither that all aliens must be extirpated, nor
that all will be well if nothing is done in every case where the
vastly accelerated and facilitated dispersal of organisms 'round the
globe by that species we call Homo sap. Of course, Nature will
ultimately bat last, and of course, much weed-bashing is
anthropocentric. But the President's letter absolving humans and their
introductions from the definition of "alien" should be contested by
all scientists, ecologists, and thinking individuals and their
organizations worthy of their designations.
WT
----- Original Message ----- From: "Warren W. Aney" <[email protected]>
To: <[email protected]>
Sent: Saturday, September 10, 2011 6:20 PM
Subject: Re: [ECOLOG-L] a non Ivory Tower view of invasive species
There can be a meaningful ecological difference between an organism that
evolved with an ecosystem and an organism that evolved outside of but
spread, migrated or was otherwise introduced into that ecosystem. An
organism that evolved with an ecosystem is considered a component that
characterizes that ecosystem. An introduced organism that did not evolve
with that ecosystem should at least be evaluated for its potential
modifying
effects on that ecosystem.
Am I being too simplistic?
Warren W. Aney
Senior Wildlife Ecologist
Tigard, OR
-----Original Message-----
From: Ecological Society of America: grants, jobs, news
[mailto:[email protected]] On Behalf Of Manuel Spínola
Sent: Saturday, 10 September, 2011 12:22
To: [email protected]
Subject: Re: [ECOLOG-L] a non Ivory Tower view of invasive species
With all due respect, are not we all invaders at some point in time?
Best,
Manuel Spínola
2011/9/10 David L. McNeely <[email protected]>
---- Matt Chew <[email protected]> wrote:
> We can compose effectively endless lists of cases where human
agency has
> redistributed biota and thereby affected pre-existing populations,
> ecological relationships and traditional or potential economic
> opportunities. Those are indisputable facts.
The House Sparrow is in North America by human hand.
> But what those facts mean is disputable.
House sparrows are in serious decline in Europe, probably as an
unintended
consequence due to human actions.
>
> I see effects; they see impacts.
> I see change; they see damage.
Many people see a need to eradicate non-natives. At the same time, many
people see a need to preserve natives.
With regard to the house sparrow ------ hmmm......... .
Where does the "arms race" that Matt mentioned further along in his post
lead?
mcneely
>
