Humans are not part of nature? No wonder the planet is sick.....
On Tue, May 11, 2010 at 10:15 PM, Geoffrey Patton <[email protected]
>wrote:
> This has been an especially interesting and worthwhile discussion,
> particularly on the ethics front. My ethics derive from an ecologist
whose
> name I can no longer recall but whose mantra was that Nature took
millions
> of years to sort out the current state and any human-caused change is,
> by
> definition, adverse. Where people have a hand in it, it is bad,
regardless
> of any perceived shot-term benefit. Pedagogical but true in my view.
>
> Cordially yours,
> Geoff Patton, Ph.D. 2208 Parker Ave., Wheaton, MD 20902
301.221.9536
>
> --- On Tue, 5/11/10, James Crants <[email protected]> wrote:
>
> From: James Crants <[email protected]>
> Subject: Re: [ECOLOG-L] Ecology Terminology and associated phenomena
> Colonizing species etc
> To: [email protected]
> Date: Tuesday, May 11, 2010, 10:47 AM
>
> I think I have not made my arguments clearly enough. I merely intended
> to summarize my moral case for suppressing invasives as part of my
summary
> of the off-forum conversation. My numbered paragraphs were intended to
> address the claim that there is no ecological difference between native
and
> exotic species, and the claim that there is no ecological difference
> between
> human-mediated dispersal and dispersal by any other agent. My
> responses
to
> Matt's responses to those paragraphs are below:
>
>
> JC(1) Exotic species, on average, interact with fewer species than
> native
>
> > species, and their interactions are weaker, on average. In
particular,
> > they have fewer parasites, pathogens, and predators, counted in
> > either
> > individuals or species. This is especially true of plants, and
> especially
> > non-crop plants. I suspect, but have not heard, that exotic plants
also
> > have fewer mycorrhizal associates than native ones, but I doubt that
they
> > have significantly fewer pollinators or dispersers. Meanwhile, back
> > in
> > their native ranges, the same species have the same number of
> associations
> > as any other native species.
> > MC(1) Natural selection only produces interactions good enough to
persist
> > under prevailing conditions; there is no gold standard. By
> > definition,
> 50%
> > of all species interact with fewer species than average, and 50% of
all
> > interactions are weaker than average. Preferring stronger, more
complex
> > interactions means preferring more tightly-coupled (and therefore)
> > 'riskier'
> > systems with a higher likelihood of failure.
> >
> JC (1b) The argument about how many species interact with fewer species
> than
> average misses my point. I'm saying that, if you counted the
> biological
> interactions for each native species and each exotic species in some
> area
> (could be a square meter, could be the world), I believe you would find
> that
> the average number for exotic species would be significantly lower than
the
> average for exotic species. Thus, exotic species are ecologically
> different
> from native species.
>
> Actually, having more interactions may mean greater stability, on
average,
> since some of those interactions are functionally redundant. I would
have
> to brush up on my community ecology to be sure I'm not being overly
> simplistic, but I know this is true in pollination systems; pollinators
> that
> interact with more angiosperm species have greater population
> stability,
on
> average, and angiosperms with more pollinator species have greater
> reproductive stability, on average (though I don't know if this leads
> to
> greater population stability for long-lived species).
>
> I'm not sure what you mean by "systems with a higher likelihood of
> failure." It seems to me that failure is a matter of human values not
> being
> realized. If, by "failure," you mean "rapid change," well, that hardly
> seems to be a problem for you. I would have to agree that systems
managed
> to promote natives at the expense of exotics are more prone to failure
than
> those where any and all ecological outcomes are deemed acceptable, but
> that's only because "failure" in the former group means invasion and
> domination by exotic species, while there is no such thing as "failure"
in
> the latter group.
>
> >
> > JC(2) Very-long-distance dispersal by humans confers a fitness
advantage
> > over very-long-distance dispersal by other agents, on average, for
> > two
> > reasons. First, humans often disperse organisms in groups, such
> > as containers of seeds, shipments of mature plants and animals, or
large
> > populations contained in ballast water, allowing them to overcome the
> Allee
> > effects (lack of mates, inbreeding depression) their populations
> > would
> face
> > if introduced as one or a few individuals. We also often take pains
> > to
> > maximize the establishment success of organisms we disperse, by
shipping
> > healthy, mature plants and animals and propogating them when they
arrive,
> > while non-human dispersal agents usually introduce small numbers of
> > organisms, often nowhere near their peak fitness potential (e.g.,
seeds,
> > spores, starving and dehydrated animals).
> > MC(2). JC appears to be arguing that once rare occurrences are no
longer
> > rare. I agree. But I draw the opposite conclusion, because he is
> arguing
> > that to generate such changes is morally wrong, while I am just
> > saying:
> > when
> > these conditions prevail, long distance dispersal becomes normal.
> >
> JC(2b) I'm not saying anything (here) about whether the recent
> commonness
> of
> previously-rare dispersal events is morally wrong. I'm countering the
> argument that human-mediated dispersal confers no fitness advantage
> over dispersal by any other agent. Others may be aware of an invasive
> exotic species that was not imported by humans in far greater numbers
than
> we could reasonably expect from any other agent, even if it had 100,000
> years to work, but I am not.
>
> Furthermore, most invasive species were carefully planted and tended
across
> large areas. Others may know of a dispersal agent that takes such care
of
> the species it disperses AND has any realistic potential of dispersing
> something over 1,000 miles, but I do not. Human-mediated dispersal is
> unlike dispersal mediated by any other agent.
>
>
> > JC(3) Although the population dynamics of invasive species do not
differ
> by
> > what agent introduced them (whether humans brought them, some other
agent
> > did, or they evolved in situ), it is ecologically consequential that
> human
> > activities are generating so many more invasive species than natural
> > processes usually do. Aside from maybe continents or oceans merging
> > through
> > plate tectonics, nothing non-human introduces such a flood of new
species
> > to
> > new environments as we humans have in the last several centuries.
> > MC(3). See MC(2). What was once normal is no longer normal.
> 'Ecologically
> > consequential' in this context is standing in for 'morally
> consequential'.
> > Ecologically, change is change.
> >
> JC(3b) By this logic, ice ages are ecologically inconsequential. I'm
> not
> making a moral judgement (here). I'm only pointing out that humans
> have
> accelerated the frequency of invasion by new species by many orders of
> magnitude, and that this is having the sort of dramatic ecological
effects
> you would, in theory, expect it to have. Again, this goes toward
> countering
> the claim that there is no ecological difference between human-mediated
> dispersal and dispersal by other agents. If we are increasing the
> probability of intercontinental dispersal by many orders of magnitude
over
> what you find for all other agents combined, there is an ecologically
> important difference between human-mediated dispersal and dispersal by
> other
> agents.
>
> >
> > JC(4) To arrive at the conclusion that the terms "native" and
> > "exotic"
> (or
> > "alien") are ecologically meaningless, you must approach the issue
> > this
> > way: if there is no set of criteria by which one can reliably
categorize
> > an
> > organism as native or exotic in the absence of historical evidence,
> > the
> > distinction is meaningless. I think the valid approach is this: if
> there
> > is no set of criteria by which one can reliably distinguish the
category
> > "native species" from the category "exotic species" (*after* the
> > categorization is done based on geographic history), the distinction
> > is
> > meaningless. By analogy, the first approach is like saying that
> > there
is
> > no
> > difference in height between men and women because one cannot
> > reliably
> > identify the height of a person by their sex, while the second
> > approach
> is
> > like saying that there is a difference in height between men and
> > women
> > because men are, on average, significantly taller than women.
> > MC(4). JC undermines his argument here by trying to make the
difference
> > between natives and aliens morally inconsequential. I think we can
> assume
> > that he sees no moral imperative emerging from the statistical
likelihood
> > that men are (and have been) taller than women. But we know he
believes
> a
> > moral imperative emerges from the claims he makes in (1-3). So his
> analogy
> > isn't really an analogy. A better analogy would be a claim that men
> are,
> > on average, more politically powerful than women, evaluated in light
> > of
a
> > moral claim that no such difference should exist. But even that
analogy
> > would only recommend equalizing average fitness; leveling the playing
> > field.
> > And it flies in the face of the "past = desired future" formula
inherent
> in
> > anti-alien sentiment. Finally, if Williamson's legendary '10s' rule
> > is
> > even
> > remotely accurate, the aliens are already disadvantaged by multiple
> orders
> > of magnitude. Long distance transport is now vastly more likely, but
> > establishment at the other end is still a long shot.
> >
> JC(4b) Again, I'm not making a moral argument at all. You (and others)
> have
> said that native and exotic species cannot be distinguished
> ecologically.
> One way I've seen other people arrive at this conclusion is by
> observing
> that there are no ecological criteria that can perfectly predict
> whether
a
> species is native or exotic (e.g., there are invasive natives, there
> are
> exotic plants with more insect herbivores than related natives, etc.).
I'm
> saying that this approach is like trying to predict people's sex based
> on their height, noting that you often guess wrong this way, and
concluding
> that sex is not relevant to height.
>
>
>
>
>
--
Jan Ygberg
Juan Fanning 380
Lima 18
Peru
INT+(511) 446 1099
