So, Mr. Patton, if you could, would you re-introduce smallpox and polio? It took nature millions of years to get them working properly on the human population. Martin Meiss
2010/5/12 Jan Ygberg <jygb...@gmail.com> > Humans are not part of nature? No wonder the planet is sick..... > > On Tue, May 11, 2010 at 10:15 PM, Geoffrey Patton <gwpatt...@yahoo.com > >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 <jcra...@gmail.com> wrote: > > > > From: James Crants <jcra...@gmail.com> > > Subject: Re: [ECOLOG-L] Ecology Terminology and associated phenomena > > Colonizing species etc > > To: ECOLOG-L@LISTSERV.UMD.EDU > > 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 >