Invasion Biology: Critique of a Pseudoscience
Invasion Biology: Critique of a Pseudoscience, David I. Theodoropoulos, Awar Books, 2003, ISBN O-9708504-1-7
This book illuminates a few issues, obscures many others and is sure to irritate any invasion biologist that reads it. The thesis of the book is that invasion biologists, abetted by the World Conservation Union (IUCN), the US National Invasive Species Council (NISC), the herbicide industry and other organizations, have foisted an ideological canard on an unwitting public. The author argues that not only is there no reason for concern about invasive species, but that in fact we should move more species more quickly, not only as a tool to conserve rare species, but on the general principle that increasing the number of species in any location is good. The argument is so extreme that the reader may legitimately wonder whether this logic extends to the Asian bird flu virus.
The book consists of an Introduction plus 13 chapters in three sections. Part I, on “Nature, Dispersal, and Reaction,” contains six chapters dealing with the core scientific issues, definitions and many case studies. If there is a useful part of the book, this is it. Part II, “Why? Psychology, Politics, and Pseudoscience,” contains five chapters in which the crudest of sociological, psychological and political indictments are leveled against invasion biology. Finally, Part III, on “Humanity and Diversity,” contains two chapters, a “Recapitulation and Conclusion” and an “Afterword.”
Like most polemicists, Theodoropoulos has erected a straw person on a few kernels of truth. While most of the book, especially Part II, is so loosely argued that no substantial response is warranted, the kernels of truth are worth careful consideration by biologists, even if they are extended to illogical conclusions by the author. I will comment primarily on these kernels of truth.
Theodoropoulos is correct in criticizing the appeals by many invasion biologists to the balance of nature, the natural state of ecosystems or the natural rate of invasions as normative benchmarks. There are two problems with grounding ethical choices on these patterns or processes. The first, on which Theodoropoulos builds his case, is that given the temporal variability in patterns and processes of nature, appeals to maintaining patterns or processes in a natural state are certainly not straightforward (Pickett et al, 1992). In reality, this is not the damning criticism that Theodoropoulos makes it out to be, but ecologiste and environmentalists would do well to be more explicit about their ethical assumptions.
The second, which Theodoropoulos does not seem to recognize, is that moving from “is” to “ought” (the naturalistic fallacy) is logically problematic (Moore, 1903). The state of nature is not irrelevant to ethical judgments, but it can rarely be determinate either. More sophisticated relationships between observations of nature and ethical principles are possible and necessary (e.g., Callicott, 1982, Lodge and Hamlin, forthcoming). Those concerned with environmental management and policy must come to terms with this issue not only in invasion biology, but also in many other aspects of environmental ethics.
The problem for Theodoropoulos is that he does not provide any well-grounded alternative to these problematic approaches. Instead he simply asserts as an ethical standard that biodiversity (species richness) is good, and that more is better. Theodoropoulos parts ways with invasion biologists in rejecting the distinction between indigenous and nonindigenous. This distinction is, of course, contingent on a specified temporal and spatial context (which ecologists do not always adequately acknowledge) but that contingency does not render the distinction useless. On his argument that the distinction is baseless, Theodoropoulos concludes that the human goal should be to add species to every ecosystem. No empirical or logical defense is provided for this choice. Indeed it seems to suffer substantially on both empirical and philosophical grounds.
Another kernel of truth is that humans benefit from many nonindigenous species and, therefore, no blanket condemnation of nonindigenous species is warranted. While some popular literature demonizes all nonindigenous species, it would be hard, if not impossible, to find a scientist who would do so. Thus Theodoropoulos makes his case from extremist views and from misinterpreting many cases in which invasion biologists use “nonindigenous” (or synonyms) when what they really mean is harmful nonindigenous species. The author would be justified in criticizing this sloppy terminology. Moreover substantive issues are embedded in defining “invasive” and “harm” (Lodge and Shrader-Frechette, 2003), but no helpful way forward is provided here.
Theodoropoulos is also correct in pointing out that scientists have sometimes overstated the evidence that nonindigenous species cause extinctions of native species. Some scientists have also pointed this out (Gurevitch and Padilla, 2004). The basic problem is that rarely can one factor be isolated as the single cause of the decline of imperiled species. Usually multiple factors operate, and interact. Theodoropoulos interprets the available evidence to one extreme: his implication is that if other factors are simultaneously occurring then only they are to blame. The author makes a compelling case that other factors cause extinctions; and no invasion biologist would disagree. However, Theodoropoulos does not make a strong case that invasive species do not cause extinctions. The well-documented reality is that invasive species have caused many extinctions, but that in many other cases we cannot be sure how important nonindigenous species are relative to other factors like habitat destruction.
Some assessments of the economic impact of invasive species are also correctly criticized as being too simplistic (e.g., Pimentel, 2000). Such studies ignore the sometimes substantial benefits of species that also cause great environmental harm (e.g., domestic cats). Theodoropoulos would have the reader believe that such problems undermine the overall conclusions that many nonindigenous species impose a high cost on society, when in fact these conclusions are certainly robust. For example, a large number of species exist in North America that society would happily eradicate because everyone agrees that their net effect is overwhelmingly bad, e.g., West Nile virus, Chestnut blight, Asian tiger mosquito, emerald ash borer, Eurasian watermilfoil.
Thus, even where Theodoropoulos recognizes real points of weakness in invasion biology in ethical foundations, empirical evidence and interpretation of evidence, he greatly exaggerates the importance of these points. He does not offer any constructive alternatives. Risk analysis and cost-benefit analysis, especially if they include diverse perspectives and stakeholders, are practical techniques that could be used to weigh Theodoropoulos’ concerns against competing interests by other members of society. Yet, risk analysis gets very scant, selective and negative treatment (e.g., p. 72 and ch. 10) that is largely inaccurate with respect to increasingly rigorous tools for identifying potentially harmful species (Groves et al., 2001; Kolar and Lodge, 2002). Broadly representative groups that grapple with these issues of trade-offs with respect to accidental and intentional introductions of species, especially the U.S. Invasive Species Advisory Committee (ISAC), are inaccurately described as being “a ‘stacked deck,’ filled with persons with a vested interest in … promoting ‘invader’ fears” (p. 139-140). As the first chairperson of ISAC, I know this description is false. In reality, about 20% of the members of this committee represent groups that clearly have a vested interest in promoting, or at least tolerating, the introduction of species, e.g., the pet industry, the shipping industry, the horticulture industry.
The major thesis and rhetorical flavor of Part II is illustrated at the beginning of Chapter 8 (p. 99, italics are the author’s) : “The conceptual structure of invasion biology is identical in all key points to that of racist, xenophobic, nationalistic, and fascist ideologies. This will be apparent to anyone familiar with the literature.” Instead, this will be an astonishing assertion to many familiar with the literature. Perhaps Theodoropoulos and I have a fragment of common ground in my objection to the choice of the term “alien” (instead of “nonindigenous”) by the authors of the Clinton administration Executive Order 13112 that created the National Invasive Species Council. This choice may have been motivated by its political resonance with fears of human immigration, and thus be partly grounded in racism. Nevertheless, the overall description of the contents of the scientific literature and the motivations of those involved is ridiculously extreme. It is an ugly caricature, and seriously misleading. To what extent social constructs are embedded in invasion biology would be an interesting question for a serious historical or sociological analysis. We do not get that in this book.
Part III presents a view of species dispersal and integration into existing ecosystems of nonindigenous species that is veryidiosyncratic and ungrounded in empirical evidence. I recommend Cox (2004) as a thorough and technically grounded alternative filled with accurately described examples of the selection pressures that indigenous species impose on nonindigenous species and vice-versa. Yes, coadaptation (Cox’s word) and integration (Theodoropolous’ word) of nonindigenous species occurs, but it does not follow, as Theodoropoulos suggests, that we should always welcome species additions.
Overall, this book is poorly argued and poorly documented. In this review, I have disproportionately emphasized the few valid points that would be helpful for invasion biologists to consider as they move forward on the substantial research and policy frontiers confronting them. Invasion biologists do need to more carefully articulate the net positive values that many nonindigenous species bring to society (e.g., corn, soy beans), what exactly is meant by “invasive” and “harm,” and what ethical assumptions underlie prescriptions for invasive species management. If there is usefulness in this book, it is in raising these issues.
Unfortunately, the rhetoric with which Theodoropoulos raises these and other issues, and the lack of thoughtful resolution of them, renders the book nearly useless, and potentially harmful to nave readers. The sort of hyperbole that Theodoropoulos is so intent on criticizing is far, far more common throughout this book than in the scientific literature of invasion biology. And the misleadingly selective use of examples is far beyond manifestations of the same problem in any technical treatments of invasions. In conclusion, the author adopts the extreme position that ‘”Exchange, propagate, plant, and release’ should be the watchword” (p. 179). Theodoropoulos thus misses an opportunity to contribute meaningfully to the societal discussion about which species we want in certain places, which we do not want, and what sort of democratic risk analyses should be used to reach those decisions.
Only in the Afterword does the author admit that “Yes, a few cases of undesirable effects exist, and it is reasonable to take precautions to prevent the spread of a few species of agricultural pest” (p. 188). The reality is that many more than a “few cases” of harm exist, and they are not limited to agriculture. Nevertheless, Theodoropoulos’ recognition that prevention and control or harmful species is a reasonable societal goal is, of course, what drives much of the discipline of invasion biology. Some of the difficult frontiers of research in invasion biology, including how society can prevent the introduction of harmful nonindigenous species in the most cost effective way (i.e., without unduly curtailing trade), is the real issue that Theodoropoulos hardly recognizes and certainly does not contribute to solving.
LITERATURE CITED
CALLICOTT, J. B. 1982. Hume’s Is/Ought dichotomy and the relation of ecology to Leopold’s land ethic. Environmental Ethics, 4:163- 174.
PIMENTEL, D., L. LACH, R. ZUNIGA AND D. MORRISON. 2000. Environmental and economic costs of nonindigenous species in the United States. BioScience, 50:53-65.
GROVES, R. H., F. D. PANETTA ANDJ. G. VIRTUE (eds.). 2001. Weed risk assessment. CSIRO Publishing, Collingwood, Victoria, Australia.
GUREVITCH, J. AND D. PADiLLA. 2004. Are invasive species a major cause of extinctions? Trends in Ecology and Evolution, 19:470-474.
COX, G. W. 2004. Alien species and evolution: the evolutionary ecology of exotic plants, animals, microbes, and interacting native species. Island Press, Washington.
KOLAR AND D. M. LODGE. 2002. Ecological predictions and risk assessments for alien species. Science, 298: 1233-1236.
LODGE, D. M. AND K. SHRADER-FRECHETTE. 2003. Nonindigenous species: ecological explanation, environmental ethics, and public policy. Conservation Biology, 17:31-37.
_____ AND C. HAMLIN (eds.). Religion and the new ecology: environmental prudence in a World in flux. Notre Dame Press (forthcoming).
MOORE, G. E. 1903. Principia Ethica. Cambridge University Press, Cambridge.
PICKETT, S. T. A., V. T. PARKER AND P. L. FIEDLER. 1992. The new paradigm in ecology: implications for conservation biology above the species level, p. 66-87. In: P. L. Fiedler and S. K. Jain (eds.). Conservation biology: the theory and practice of nature conservation, preservation, and management. Chapman and Hall, New York.
DAVID M. LODGE,1 Professor, Department of Biological Sciences, University of Notre Dame, Notre Dame, Indiana 46556.
1 email: lodge.l@nd.edu
Copyright American Midland Naturalist Jul 2005