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Toward a unified ecology
TREE vol. 8, no. 3, March
7993
Dissident Theorists
Toward
a Unified Ecology
by Timothy F.H. Allen and T.W. Hoekstra, Columbia University Press, 1992. $52.00 hbk (xiv + 384 pages) ISBN 0 23106978 9
by Daniel B. Eatkin, Oxford University Press, 1990. f8.95 pbk (xii + 24 1 pages) lSBN 0 19 507469 6 Ecology’s job is to make sufficient sense of the kinds, numbers and spatio-temporal distribution of organisms in nature to permit valid predictions, despite nature’s apparent complexity. ‘Complexity’ is a scapegoat for our inability to answer questions. The most satisfactory way to vanquish complexity is to explain it away by discovering simple laws as organisms are ‘explained’ by evolution. Failing such deep insights, one may choose to study simple aspects of complex systems. Faunistically depauperate islands or deserts, or supposedly simple organisms like bacteria or hydra permit ecological work to proceed. Another approach, which has been used by some theorists, is to make simplifying assumptions, producing less complex surrogate systems for study. For example, organisms might be enumerated without reference to age or physiological state and environments assumed constant, or if they vary, are assumed to follow tractable statistical distributions. Examples of this sort of theory can be found in both old and new anthologies’,‘. Objections have been raised to the mathematical form of some main line theories3 and to the shortage of field tests of plausible theoretical conclusion@. In the absence of specific tests, heaps of old published data are ‘mined’ for information to support, or cast doubt on, theoretical conclusions. Unfortunately there are necessarily biases in how items in ‘data mines’ are chosen and interpreted”. Despite its problems, theoretical ecology has generated seeming truisms which are accepted by the public and used in managerial contexts. Among these are: ‘nature will approach some kind of constancy’ and ‘a lack of human interference is the best way to permit nature to manifest constancy’. Botkin’s book explicitly denies these statements. He presents clear examples showing that the relatively cheap and easy policy of ‘preserving’ ecosystems by leaving them free of human disturbance will not work, unless we are content to take our chances on the outcome.
112
Neither benign neglect nor a Clementsian avatar of the Goddess Gaia can be expected to maintain an ecologically satisfactory world. Longtimescale phenomena and rare perturbations shatter ecological steady states. The world of ecology may be green, but in terms of stability the world is ‘red’, in the sense of being dominated by long-wavelength processes. We must decide what is ecologically desirable in real political and social contexts, and then develop actual management programs. This requires more than simplified general theory. Also, after an ecosystem has come to a desirable state we must develop custodial procedures to make sure it stays that way. These are valid and urgent conclusions. They are also dangerous, since they can serve as an excuse for ecological destruction to masquerade as beneficent management. A first step in defence against mismanagement is to read Botkin’s book. Fortunately, it is written as elegant, personal, prose essays which make reading a pleasure. The next step is to accept that every ecological problem must be treated as a special case to some degree7. But are there no general theoretical guidelines? Must we start from scratch when attempting to answer each of the innumerable questions that may be presented to us? Are we in the awkward situation in which simplified theory is dangerous and sufficiently complex theory is impossible? Are we to be defeated by complexity? There is no universally valid way of dealing with complexity in all its aspects’. Formal complexity is part of mathematics and computer science, but so far this has not been too helpful to biology since, paradoxically, rigorous analyses of complexity are only feasible within a circumscribed (i.e. simplified) domain’. Biology has had some success dealing with complexity of single organisms by dissection. Dissecting a body reveals organs, tissues and ultimately cells, which often prove amenable to study. Properties of these subsumed parts are part of an explanation for observations on the whole organism. Allen and Hoekstra propose an intellectual dissection of ecology. Unlike the dissection of individuals, dissection of ecological systems takes more than merely laying back skin. They make the strong point that distinctions between apparent specializations within ecology such as population, landscape and community ecology are in one sense illusions.
A population, landscape or ecosystem can always be more clearly understood if, and only if, its hierarchical properties are constantly kept in mind in the correct way. Populations are sometimes entities within communities, which are within ecosystems, but subtle corrections must be made for special circumstances. This requires a particular sophisticated mind set. Failing correct understanding of hierarchies in ecology, an illusion of complexity will be created. Allen and Hoekstra claim that the complexity of ecology lies in the minds of ecologists, not in nature! Most of their book is designed to provide guides to the appropriate mind set. Entities must be located as to scale in time and space. The ecology of large long-lived organisms differs from that of small ones”. Also, what is discovered may hinge on the scale of investigation. For example, shortterm correlations between phytoplankton and zooplankton abundances may even have a different sign from long-term correlations. Within constraints of temporal and spatial scale an entity is explained in terms of what is subsumed within its hierarchical position and is constrained by being a part of some larger or higher entity. Investigators and their subjects become deeply intertwined. These issues are certainly interesting to consider, but unfortunately it seems difficult to demonstrate their validity in any usual empirical sense. While dissection into hierarchies sometimes does eliminate certain aspects of complexity, there is reason to believe that conceptualizing a heuristic hierarchical structure may not always be possible”. Alien and Hoekstra use a great deal of argument by analogy and aphorism, in the style of ‘general systems theory’. In different contexts ecosystems are likened to nodes in flow diagrams, mental artifacts and a basket of bagels. There are also too many minor proofreading errors (De Chardin’s first name was not ‘Tiers’). It is, in spots, difficult reading. Botkin demonstrates that simplifications of ecology are dangerous. Allen and Hoekstra demonstrate that the complexity of ecology is neither hopeless nor easily resolved. Both conclusions must be kept in mind whenever problems of applied ecology arise. Both books demonstrate that cliches cannot be trusted when it really matters.
Lawrence
B. Slobodkin
Dept at Ecology and Evolution, SUNY, Stony Brook, NY 11794,USA
TREE
vol. 8, no. 3, March
1993
1 Scudo. F. and Zeigler, JR (1978) The Golden Age of Ecology, Springer-Verlag 2 Real, L. and Brown,
J.H. (1991)
Foundations of Ecology, University of Chicago Press 3 Matson, P. and Berryman, A., eds (1992) Ecology73,1529-1566 4 Peters, R. (1991) A Critique for Ecology, Oxford University Press 5 Hairston, N.G., Sr (1989) Ecological Experiments:
Purpose,
Design,
and
Execution, Cambridge University Press 6 Ferson, S. et a/. (1986) Am. Nat. 127, 571-576
~----
7 Slobodkin.
L. (1988) HoScience
38,
337-342
8 Slobodkin,
L. (1992) Simplicity and Complexity in Games of the Intellect, Harvard University Press 9 Sober, E. (1975) Simplicity, Clarendon press 10 Andrews, J. (1991) Comparative Ecology of Microorganisms and Macroorganisms, Springer-Verlag
11 Bechtel, W. and Richardson, RX. (19931 Discovering Complexity: Decomposition and Localization as Strategies in Scientific Research, Princeton University Press
____ pPlantain Ecology Plantago: A Multidisciplinary
edited by P.J.C. Springer-Verlag, fxiii + 368 pages)
Study
Kuiper and M. Bos, 1992. f85.50 hbk lS&V 3 540 53632 9
It is not so often that one sees a complete book devoted to the results of research into the biology of a plant species that has no apparent economic value. It is also remarkable that this research has been made possible through a consistent funding over a prolonged period to a multidisciplinary group of researchers in the fields of ecology, genetics and plant physiology to pursue a highly coordinated research into the demographic, physiological and genetic properties of plant species in relation to the properties of their grassland habitat. They became known as the grassland species research group and their joint publications number well over 200. It is even more remarkable to observe that in the heydays of Popperism such a broad descriptive enterprise was launched and financed in the confidence that coordinated multidisciplinary fact gathering would provide new insights into the core of ecology: the functioning of the plant in its environment. Given the many primary publications and the many theses written during the project, the editors and authors must be praised for the fact that they were willing to stick out their necks and try to report on and account for the project as a whole in this coordinated fashion. This makes it possible to judge not only the separate papers but also the degree of cohesion achieved in one of the larger scientific enterprises in plant ecology over the last IO-15 years. The project as a whole bears the clear signs of its origin in the 1970s. Then, it was hypothesized that it is through selection on life-history traits that evolution proceeds and that such processes are best studied
comparing closely related species or different populations within species over a range of habitats’,‘. The participants of the project clearly aimed at establishing the genetic basis for differences in traits (both physiological and morphological) that have a direct and quantifiable effect on demography and thereby on fitness under field conditions. Such differences were rigorously tested using (among other techniques) reciprocal transplant experiments. The book starts with a general overview of the genus, focusing on the five species common to northwestern Europe, characterizing not only their general biology (including morphology and breeding system), but also the physical and chemical properties of their habitat. The core of the book, however, is formed by a comparison between Plantago lanceolata and P. major and the ways in which they cope with environmental heterogeneity. The advantages of the multidisciplinary approach become visible when the authors are able to demonstrate the interplay between traits, their inheritance and their fitness value. This is especially true for a host of morphological traits ranging from seed characteristics to whole-plant morphology. Proof of this is abundant in this book and forms one of its major attractive points. Another major theme throughout the book is the importance of phenotypic plasticity for the adaptation of these species to their environment. Interestingly, this is dealt with at two levels: short-term plasticity in physiological responses to fluctuating levels in resources (light and nutrients) as well as longterm morphological responses to mean habitat differences. This brings out another interesting contrast that physiological traits are in general less variable on the scale of populations and represent more general mechanisms less open to
microevolutionary processes, compared to the morphological traits. Nevertheless, genetically determined plasticity proved to be the key factor in understanding the species’ adaptation to their habitats. Although the authors are somewhat cautious in their interpretation many of the established differences are not really advantageous when put to a test in the field - it is clear that reciprocal transplanting proved to be a powerful tool and that local adaptation is prevalent. This is achieved by syndrome-like combinations of genetic structure based on the breeding system and genetically determined morphological and physiological adaptations - including plasticity that vary between and within species. It is this well-documented variation that deserves the attention of those who perceive encompassing strategies in the adaptations of plants to their environments. Scientifically the project can be termed a success measured by any of the yardsticks that one can apply. Yet one wonders about the territoriality of the scientific enterprise. Discussing the importance of withinspecies diversity and plasticity, Wayne and Bazzaz3 support their case with four studies on plantains, none from this project. Although the book inevitably varies in quality between the various chapters, I have avoided singling out separate parts or separate authors. The book clearly had the intention of reporting on a joint project, the results of which could only be obtained through consistent long-term funding and an adequate coordination. One could rightfully ask whether this longterm financing of a project with clearly defined goals is not a better and cheaper alternative to prestigious centres of excellence generated de novo that seem to attract a lot of attention and funds these days. l am sure that anyone interested in life-history research in general, or in plantains more specifically, will find a lot of interest in this book. It is compulsory reading for anyone interested in setting up multidisciplinary research projects in Iplant) ecology.
JAI. van Groenendael Dept of Vegetation Science. Plant Ecology and Weed Science, Wegeningen Agricultural University. Bornsesteeg 69, NL-6708 PD Wsgeningen, The Netherlands References 1 Harper, J.L. (1967) 1 Ecol. 55, 242-270 2 Stearns, SC. (1977) Annu. Rev. Ecol. Syst. 8,145171 3 Wayne, P.M. and Barzaz, F.A. (1991) Trends Ecol. Evol. 6, 400-404
113
7993
Dissident Theorists
Toward
a Unified Ecology
by Timothy F.H. Allen and T.W. Hoekstra, Columbia University Press, 1992. $52.00 hbk (xiv + 384 pages) ISBN 0 23106978 9
by Daniel B. Eatkin, Oxford University Press, 1990. f8.95 pbk (xii + 24 1 pages) lSBN 0 19 507469 6 Ecology’s job is to make sufficient sense of the kinds, numbers and spatio-temporal distribution of organisms in nature to permit valid predictions, despite nature’s apparent complexity. ‘Complexity’ is a scapegoat for our inability to answer questions. The most satisfactory way to vanquish complexity is to explain it away by discovering simple laws as organisms are ‘explained’ by evolution. Failing such deep insights, one may choose to study simple aspects of complex systems. Faunistically depauperate islands or deserts, or supposedly simple organisms like bacteria or hydra permit ecological work to proceed. Another approach, which has been used by some theorists, is to make simplifying assumptions, producing less complex surrogate systems for study. For example, organisms might be enumerated without reference to age or physiological state and environments assumed constant, or if they vary, are assumed to follow tractable statistical distributions. Examples of this sort of theory can be found in both old and new anthologies’,‘. Objections have been raised to the mathematical form of some main line theories3 and to the shortage of field tests of plausible theoretical conclusion@. In the absence of specific tests, heaps of old published data are ‘mined’ for information to support, or cast doubt on, theoretical conclusions. Unfortunately there are necessarily biases in how items in ‘data mines’ are chosen and interpreted”. Despite its problems, theoretical ecology has generated seeming truisms which are accepted by the public and used in managerial contexts. Among these are: ‘nature will approach some kind of constancy’ and ‘a lack of human interference is the best way to permit nature to manifest constancy’. Botkin’s book explicitly denies these statements. He presents clear examples showing that the relatively cheap and easy policy of ‘preserving’ ecosystems by leaving them free of human disturbance will not work, unless we are content to take our chances on the outcome.
112
Neither benign neglect nor a Clementsian avatar of the Goddess Gaia can be expected to maintain an ecologically satisfactory world. Longtimescale phenomena and rare perturbations shatter ecological steady states. The world of ecology may be green, but in terms of stability the world is ‘red’, in the sense of being dominated by long-wavelength processes. We must decide what is ecologically desirable in real political and social contexts, and then develop actual management programs. This requires more than simplified general theory. Also, after an ecosystem has come to a desirable state we must develop custodial procedures to make sure it stays that way. These are valid and urgent conclusions. They are also dangerous, since they can serve as an excuse for ecological destruction to masquerade as beneficent management. A first step in defence against mismanagement is to read Botkin’s book. Fortunately, it is written as elegant, personal, prose essays which make reading a pleasure. The next step is to accept that every ecological problem must be treated as a special case to some degree7. But are there no general theoretical guidelines? Must we start from scratch when attempting to answer each of the innumerable questions that may be presented to us? Are we in the awkward situation in which simplified theory is dangerous and sufficiently complex theory is impossible? Are we to be defeated by complexity? There is no universally valid way of dealing with complexity in all its aspects’. Formal complexity is part of mathematics and computer science, but so far this has not been too helpful to biology since, paradoxically, rigorous analyses of complexity are only feasible within a circumscribed (i.e. simplified) domain’. Biology has had some success dealing with complexity of single organisms by dissection. Dissecting a body reveals organs, tissues and ultimately cells, which often prove amenable to study. Properties of these subsumed parts are part of an explanation for observations on the whole organism. Allen and Hoekstra propose an intellectual dissection of ecology. Unlike the dissection of individuals, dissection of ecological systems takes more than merely laying back skin. They make the strong point that distinctions between apparent specializations within ecology such as population, landscape and community ecology are in one sense illusions.
A population, landscape or ecosystem can always be more clearly understood if, and only if, its hierarchical properties are constantly kept in mind in the correct way. Populations are sometimes entities within communities, which are within ecosystems, but subtle corrections must be made for special circumstances. This requires a particular sophisticated mind set. Failing correct understanding of hierarchies in ecology, an illusion of complexity will be created. Allen and Hoekstra claim that the complexity of ecology lies in the minds of ecologists, not in nature! Most of their book is designed to provide guides to the appropriate mind set. Entities must be located as to scale in time and space. The ecology of large long-lived organisms differs from that of small ones”. Also, what is discovered may hinge on the scale of investigation. For example, shortterm correlations between phytoplankton and zooplankton abundances may even have a different sign from long-term correlations. Within constraints of temporal and spatial scale an entity is explained in terms of what is subsumed within its hierarchical position and is constrained by being a part of some larger or higher entity. Investigators and their subjects become deeply intertwined. These issues are certainly interesting to consider, but unfortunately it seems difficult to demonstrate their validity in any usual empirical sense. While dissection into hierarchies sometimes does eliminate certain aspects of complexity, there is reason to believe that conceptualizing a heuristic hierarchical structure may not always be possible”. Alien and Hoekstra use a great deal of argument by analogy and aphorism, in the style of ‘general systems theory’. In different contexts ecosystems are likened to nodes in flow diagrams, mental artifacts and a basket of bagels. There are also too many minor proofreading errors (De Chardin’s first name was not ‘Tiers’). It is, in spots, difficult reading. Botkin demonstrates that simplifications of ecology are dangerous. Allen and Hoekstra demonstrate that the complexity of ecology is neither hopeless nor easily resolved. Both conclusions must be kept in mind whenever problems of applied ecology arise. Both books demonstrate that cliches cannot be trusted when it really matters.
Lawrence
B. Slobodkin
Dept at Ecology and Evolution, SUNY, Stony Brook, NY 11794,USA
TREE
vol. 8, no. 3, March
1993
1 Scudo. F. and Zeigler, JR (1978) The Golden Age of Ecology, Springer-Verlag 2 Real, L. and Brown,
J.H. (1991)
Foundations of Ecology, University of Chicago Press 3 Matson, P. and Berryman, A., eds (1992) Ecology73,1529-1566 4 Peters, R. (1991) A Critique for Ecology, Oxford University Press 5 Hairston, N.G., Sr (1989) Ecological Experiments:
Purpose,
Design,
and
Execution, Cambridge University Press 6 Ferson, S. et a/. (1986) Am. Nat. 127, 571-576
~----
7 Slobodkin.
L. (1988) HoScience
38,
337-342
8 Slobodkin,
L. (1992) Simplicity and Complexity in Games of the Intellect, Harvard University Press 9 Sober, E. (1975) Simplicity, Clarendon press 10 Andrews, J. (1991) Comparative Ecology of Microorganisms and Macroorganisms, Springer-Verlag
11 Bechtel, W. and Richardson, RX. (19931 Discovering Complexity: Decomposition and Localization as Strategies in Scientific Research, Princeton University Press
____ pPlantain Ecology Plantago: A Multidisciplinary
edited by P.J.C. Springer-Verlag, fxiii + 368 pages)
Study
Kuiper and M. Bos, 1992. f85.50 hbk lS&V 3 540 53632 9
It is not so often that one sees a complete book devoted to the results of research into the biology of a plant species that has no apparent economic value. It is also remarkable that this research has been made possible through a consistent funding over a prolonged period to a multidisciplinary group of researchers in the fields of ecology, genetics and plant physiology to pursue a highly coordinated research into the demographic, physiological and genetic properties of plant species in relation to the properties of their grassland habitat. They became known as the grassland species research group and their joint publications number well over 200. It is even more remarkable to observe that in the heydays of Popperism such a broad descriptive enterprise was launched and financed in the confidence that coordinated multidisciplinary fact gathering would provide new insights into the core of ecology: the functioning of the plant in its environment. Given the many primary publications and the many theses written during the project, the editors and authors must be praised for the fact that they were willing to stick out their necks and try to report on and account for the project as a whole in this coordinated fashion. This makes it possible to judge not only the separate papers but also the degree of cohesion achieved in one of the larger scientific enterprises in plant ecology over the last IO-15 years. The project as a whole bears the clear signs of its origin in the 1970s. Then, it was hypothesized that it is through selection on life-history traits that evolution proceeds and that such processes are best studied
comparing closely related species or different populations within species over a range of habitats’,‘. The participants of the project clearly aimed at establishing the genetic basis for differences in traits (both physiological and morphological) that have a direct and quantifiable effect on demography and thereby on fitness under field conditions. Such differences were rigorously tested using (among other techniques) reciprocal transplant experiments. The book starts with a general overview of the genus, focusing on the five species common to northwestern Europe, characterizing not only their general biology (including morphology and breeding system), but also the physical and chemical properties of their habitat. The core of the book, however, is formed by a comparison between Plantago lanceolata and P. major and the ways in which they cope with environmental heterogeneity. The advantages of the multidisciplinary approach become visible when the authors are able to demonstrate the interplay between traits, their inheritance and their fitness value. This is especially true for a host of morphological traits ranging from seed characteristics to whole-plant morphology. Proof of this is abundant in this book and forms one of its major attractive points. Another major theme throughout the book is the importance of phenotypic plasticity for the adaptation of these species to their environment. Interestingly, this is dealt with at two levels: short-term plasticity in physiological responses to fluctuating levels in resources (light and nutrients) as well as longterm morphological responses to mean habitat differences. This brings out another interesting contrast that physiological traits are in general less variable on the scale of populations and represent more general mechanisms less open to
microevolutionary processes, compared to the morphological traits. Nevertheless, genetically determined plasticity proved to be the key factor in understanding the species’ adaptation to their habitats. Although the authors are somewhat cautious in their interpretation many of the established differences are not really advantageous when put to a test in the field - it is clear that reciprocal transplanting proved to be a powerful tool and that local adaptation is prevalent. This is achieved by syndrome-like combinations of genetic structure based on the breeding system and genetically determined morphological and physiological adaptations - including plasticity that vary between and within species. It is this well-documented variation that deserves the attention of those who perceive encompassing strategies in the adaptations of plants to their environments. Scientifically the project can be termed a success measured by any of the yardsticks that one can apply. Yet one wonders about the territoriality of the scientific enterprise. Discussing the importance of withinspecies diversity and plasticity, Wayne and Bazzaz3 support their case with four studies on plantains, none from this project. Although the book inevitably varies in quality between the various chapters, I have avoided singling out separate parts or separate authors. The book clearly had the intention of reporting on a joint project, the results of which could only be obtained through consistent long-term funding and an adequate coordination. One could rightfully ask whether this longterm financing of a project with clearly defined goals is not a better and cheaper alternative to prestigious centres of excellence generated de novo that seem to attract a lot of attention and funds these days. l am sure that anyone interested in life-history research in general, or in plantains more specifically, will find a lot of interest in this book. It is compulsory reading for anyone interested in setting up multidisciplinary research projects in Iplant) ecology.
JAI. van Groenendael Dept of Vegetation Science. Plant Ecology and Weed Science, Wegeningen Agricultural University. Bornsesteeg 69, NL-6708 PD Wsgeningen, The Netherlands References 1 Harper, J.L. (1967) 1 Ecol. 55, 242-270 2 Stearns, SC. (1977) Annu. Rev. Ecol. Syst. 8,145171 3 Wayne, P.M. and Barzaz, F.A. (1991) Trends Ecol. Evol. 6, 400-404
113