Is ecology irrelevant?

BOOK REVIEWS University of the Witwatersrand, South Africa. We thank the Andrew Mellon Foundation for their support, and H. de Kroon and two anonymous referees for their helpful suggestions.

References 1 Groom, M.J. and Pascual, M.A. (1998) The analysis of population persistence: an outlook on the practice of viability analysis. In Conservation Biology for the Coming Decade (Fiedler, P.L. and Karieva, P.M., eds), pp. 4–27, Chapman & Hall 2 Boyce, M. (1992) Population viability analysis. Annu. Rev. Ecol. Syst. 23, 481–506 3 Menges, E.S. (1998) Evaluating extinction risks in plant populations. In Conservation Biology for the Coming Decade (Fiedler, P.L. and Karieva, P.M., eds), pp. 49–65, Chapman & Hall 4 Menges, E.S. (2000) Population viability analyses in plants: challenges and opportunities. Trends Ecol. Evol. 15, 51–56 5 Chesson, P.L. and Warner, R.R. (1981) Environmental variability promotes coexistence in lottery competitive systems. Am. Nat. 117, 923–943 6 Chesson, P.L. and Huntley, N. (1989) Short-term instabilities and long-term community dynamics. Trends Ecol. Evol. 4, 293–298 7 Hairston, N.G. et al. (1996) Overlapping generations: the storage effect and the maintenance of biotic diversity. In Population Dynamics in Ecological Space and Time (Rhodes, O.E. et al., eds), pp. 109–145, University of Chicago Press 8 Chesson, P.L. (1994) Multispecies competition in variable environments. Theor. Popul. Biol. 45, 227–276 9 Grubb, P. (1977) The maintenance of species richness in plant communities: the importance of the regeneration niche. Biol. Rev. 52, 107–145 10 Eriksson, O. (1996) Regional dynamics of plants: a review of evidence for remnant, source-sink and metapopulations. Oikos 77, 248–258 11 Hubbell, S.P. and Foster, R.B. (1986) Canopy gaps and the dynamics of a neotropical forest. In Plant Ecology (Crawley, M.J., ed.), pp. 77–96, Blackwell

Is ecology irrelevant? Community Ecology in a Changing World by J.H. Lawton Ecology Institute, Germany (Excellence in Ecology 11), 2000. $62.95 hbk (xxvii 1 227 pages) ISBN 0 932 2205

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ohn Lawton has done as much as anyone in the past 30 years to shape the field of ecology. As his ‘reward’ for winning the 1996 Ecology Institute Prize, Lawton has written a frank assessment of what we know about community ecology, and what we need to learn in the upcoming years. This monograph features plant–insect interactions and experiments conducted in the Silwood Park

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12 Pake, C.E. and Venable, D.L. (1985) Is coexistence of Sonoran desert annuals mediated by temporal variability in reproductive success? Ecology 76, 246–261 13 Bond, W.J. and Midgley, J.J. Ecology of sprouting in woody plants: the persistence niche. Trends Ecol. Evol. (in press) 14 Pickett, S.T.A. and McDonell, M.J. (1989) Seed bank dynamics in temperate deciduous forest. In Ecology of Soil Seed Banks (Leck, M.A. et al., eds), pp. 123–147, Academic Press 15 Comins, H.N. and Noble, I.R. (1985) Dispersal, variability and transient niches: species coexistence in a uniformly variable environment. Am. Nat. 126, 706–723 16 Heppell, S. et al. (2000) Elasticity analysis in population biology: methods and applications. Ecology 81, 605–606 17 Doak, D.F. et al. (1994) Modeling population viability for the desert tortoise in the western Mojave desert. Ecol. Appl. 4, 446–460 18 Pfister, C.A. (1998) Patterns of variance in stagestructured populations: evolutionary predictions and ecological implications. Proc. Natl. Acad. Sci. U. S. A. 95, 213–218 19 Ehrlen, J. (1999) Modelling and measuring plant life histories. In Life History Evolution in Plants (Vuorisalo, T.O. and Mutikainen, P.K., eds), pp. 27–61, Kluwer Academic Publishers 20 Warner, R.R. and Chesson, P.L. (1985) Coexistence mediated by recruitment fluctuations: a field guide to the storage effect. Am. Nat. 125, 769–787 21 Grant, A. and Benton, T.G. (2000) Elasticity analysis for density-dependent populations in stochastic environments. Ecology 81, 680–693 22 Clark, J.S. et al. (1999) Interpreting recruitment limitation in forests. Am. J. Bot. 86, 1–16 23 Pake, C.E. and Venable, D.L. (1996) Seed banks in desert annuals: implications for persistence and coexistence in variable environments. Ecology 77, 1427–1435 24 Chesson, P.L. and Huntley, N. (1988) Community consequences of life history traits in variable environments. Ann. Zool. Fenn. 25, 5–16 25 Claus, M.J. and Venable, D.L. (2000) Seed germination in desert annuals: an empirical test of adaptive bet hedging. Am. Nat. 155, 168–186

26 Higgins, S.I. et al. (2000) Fire, resprouting and variance: a recipe for grass–tree coexistence in savanna. J. Ecol. 88, 213–229 27 Damman, H. and Cain, M.L. (1998) Population growth and viability analyses of the clonal woodland herb, Asarum canadianense. J. Ecol. 86, 13–26 28 Herrera, C.M. et al. (1998) Annual variability in seed production by woody plants and the masting concept: reassessment of principles and relationship to pollination and seed dispersal. Am. Nat. 152, 576–594 29 Ehrlen, J. and van Groenendael, J. (1998) Direct perturbation analysis for better conservation. Conserv. Biol. 12, 470–474 30 Baskin, C.C. and Baskin, J.M. (1998) Seeds. Ecology, Biogeography and Evolution of Dormancy and Germination, Academic Press 31 Harper, J.L. and White, J. (1974) The demography of plants. Annu. Rev. Ecol. Syst. 23, 481–506 32 Romme, W.H. et al. (1997) A rare episode of sexual reproduction in aspen (Populus tremuloides Michx.) following the 1988 Yellowstone fires. Nat. Areas J. 17, 17–25 33 Gill, A.M. (1981) Fire adaptive traits of vascular plants. In Proceedings of the Conference on Fire Regimes and Ecosystem Properties (Mooney, H.A. et al., eds), pp. 208–230, USDA Forest Service, General Technical Report WO-26 34 Tilman, D. et al. (1994) Habitat destruction and the extinction debt. Nature 371, 65–66 35 Bond, W.J. (1989) Describing and conserving biotic diversity. In Biotic Diversity in Southern Africa (Huntley, B., ed.), pp. 2–18, Oxford University Press 36 Silvertown, J. et al. (1996) Interpretation of elasticity matrices as an aid to the management of plant populations for conservation. Conserv. Biol. 10, 591–597 37 Drechsler, M. et al. (1999) Modelling the persistence of an apparently immortal Banksia species after fire and land clearing. Biol. Conserv. 88, 249–259

Ecotron, which has become a worldrenowned research facility largely through Lawton’s efforts. The distinction he draws between local rules of engagement and regional processes is vivid, and needs to be more widely heeded by ecologists. A second topic that is elaborated on concerns the role of biodiversity in ecosystem processes; here Lawton mixes wry common sense with a synthesis of experiments to produce one of the most pragmatically insightful discussions of biodiversity I have read. A final emphasis is global climate change (especially CO2 increases) and impacts on communities that cannot be predicted by studying a few species in isolation. Looking beyond the specifics, Lawton is perhaps most compelling when discussing research strategy. Lawton resolutely challenges the adequacy of small-scale reductionist experiments as our primary research tool. Unless we start doing things differently,

‘the best ecology journals will increasingly be packed with neat little studies that are fun to do and interesting to read, but take the subject essentially nowhere’ (p. 183). By focusing on tractable ‘mini questions’ for which results are rapid and easy to analyse, ecologists are making themselves irrelevant. What Lawton wants to see more of is whole system manipulations of intact natural communities. For example, to predict the outcome of rising CO2 levels, we need to fumigate intact forests and grasslands. Lawton also writes eloquently about the value of microcosms or experiments in controlled environment facilities such as the Ecotron. Lawton admits that microcosm studies are no substitute for field experiments, but finds them useful because they might allow whole system manipulations that cannot easily be performed in the field. I personally have written in support of such experiments1, but also feel uncomfortable about them getting ‘too much press’ and TREE vol. 15, no. 12 December 2000

BOOK REVIEWS averting our attention from the need for good natural history. I am most swayed by Lawton’s remark that these microcosm experiments can ‘provide justification for much bigger and more expensive field experiments’ (p. 175) – I think we have seen that this is exactly the case with respect to biodiversity studies. After reviewing his research career and the status of community ecology in general, Lawton concludes that ecologists are to blame for not conducting their science in a way that adequately addresses our environmental crises. To correct our failings, Lawton makes concrete suggestions about how we need to do science differently. He advocates studying fewer systems, but each in greater depth than is current practice. He believes that there should be much more standardization of protocols and of how field measurements are made and reported. He champions large coordinated experiments that are repeated in many different places (such as the European Union’s funding of the BIODEPTH biodiversity experiments in seven different countries). To implement such dramatic change in the culture of ecology, Lawton argues we need to explicitly start training our graduate students to be better at team research. Lawton’s vision for ecology will be disturbing to many readers, especially American readers, for whom stubborn individualism is a matter of pride. Lawton’s ecology of the future seems awfully corporate, with its massive coordinated ecological experiments implying strong scientific hierarchies. Lawton himself has the insight he currently has because he picked his own little bracken (Pteridium aquilinum) patch in which to work, by himself, with no standardized protocols. Lawton collaborated, but was never a member of a team until his later years – and then he was team leader. What will Lawton’s vision mean for our youngest most creative scientists just getting started? Graduate students might well be stifled in such a world, or fail to develop the breadth of natural history experiences that protect big science from silly endeavors. Yet, I have to agree Lawton has a point. Ecology must start to answer some major practical questions or be justly sentenced to the comfortable obscurity of a ‘hobby science’. As long as there is a place for naturalists, and independent researchers pottering about in intertidal pools or bracken patches, Lawton’s vision has much to recommend it. In addition, many of the changes Lawton calls for, such as increased standardization of methods and data reporting, represent scientific maturity without any toll extracted. If independent investigators can find ways to make small and important contributions within the brave new world of internationally coordinated experiments, the changes advocated by Lawton might keep ecology from being irrelevant. TREE vol. 15, no. 12 December 2000

In fact, Lawton’s discussion of the future is complementary to other changes going on in ecology. Most notably, large public data bases on the Internet and synthetic analyses of these databases are becoming increasingly prominent. The National Center for Ecological Analysis and Synthesis (whose advisory board Lawton served on) has for the past five years championed group projects for data synthesis (as opposed to experiments), and has already affected how American ecologists view ‘group research’. In addition, the scale and urgency of many conservation problems is encouraging standardization and dramatic management experiments.Finally, large-scale observational studies might, with recent statistical advances2, become a new source of ecological insight, as yet untapped by ecologists. Big problems are prompting big changes in how we do ecology. Lawton’s book initiates a crucial, yet optimistic dialogue about the type of science that ecology needs to become. This is a book all ecologists should read and argue about.

Peter Kareiva Cumulative Risk Initiative, NWFSC/NMFS, 2725 Montlake Blvd East, Seattle, WA 98112, USA ([email protected])

References 1 Kareiva, P. (1989) Renewing the dialogue between theory and experiments in population ecology. In Perspectives in Ecological Theory (Roughgarden, J. et al. eds), pp. 68–88, Princeton University Press 2 Rosenbaum, P.R. (1995) Observational Studies, Springer-Verlag

Vegetarian dentition Evolution of Herbivory in Terrestrial Vertebrates: Perspectives from the Fossil Record edited by Hans-Dieter Sues Cambridge University Press, 2000. £50.00 hbk (x 1 256) ISBN 0 521 59449 9

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eing a carnivore is easy. Herbivory has always been harder: a long gut is required to extract nutrition from bulky plant material, as well as an intestinal flora of lignin-digesting microbes. In vertebrate history at least, the founders of all major clades have always been modest-sized generalist carnivores and/or insectivores, and herbivores evolved later. This may indeed be a truism across the animal kingdom. Serious diversification of herbivores came late in land vertebrate evolution. For their first 100 million years, during the Carboniferous and Early Permian, herbivores

were not abundant, and most of them seem to have been generalists. Eventually, in the Late Permian, herbivores diversified, and some of them became large. The first ‘modern’-style ecosystems arose, with six or seven herbivores living side-by-side and feeding on different plant materials, with a community of carnivores specializing on the different sizes of herbivores. These ecosystems collapsed at the time of the end-Permian mass extinction, 250 million years ago (Mya). It took 20 million years for ecosystems to recover to some extent in the Triassic. Eventually, the dinosaurs rose to dominance, and several groups became proficient herbivores, showing a range of feeding mechanisms: gut processing (the medium to gigantic sauropods, which swallowed masses of leaves that were ground up using stones in their stomachs); transverse grinding (the ornithopods, such as Iguanodon, which had a chewing mechanism in which their upper jaws moved laterally as the jaws closed, hence chopping the food before swallowing); orthal pulpers (the stegosaurs, ankylosaurs, and pachycephalosaurs, which mashed their food by simple up-and-down chomping); and orthal slicers (the ceratopsians, such as Triceratops, which cut the leaves and stems using a scissor-like motion of the closelypacked teeth above and below). After the extinction of the dinosaurs 65 Mya, the mammals famously diversified and rose to dominance on land. Much of the success of the mammals has been ascribed to their teeth, and particularly to their vast adaptability in form and function. Studies of modern mammals show that tooth shape can be a good guide to diet, and this allows palaeomammalogists to explore the modes of life of long-extinct groups. The ultrastructure of the enamel, detailed wear patterns and scratch marks, and even geochemical analysis of the nature of the carbon isotopes in the enamel, can further confirm the precise plants that were being eaten. The fossil record of mammals is superb, and palaeontologists are able to reconstruct ecosystems and feeding guilds, and plot their interactions with changing plant groups and small-scale habitat shifts. This book is partly a catalogue of the different groups of herbivorous terrestrial vertebrates, with one chapter on the late Palaeozoic and Triassic groups (Robert Reisz and Hans-Dieter Sues), three on the dinosaurs and three on the mammals. Paul Barrett and Paul Upchurch review the diets of sauro-podomorph dinosaurs, combining observations of tooth and jaw shapes, palaeoenvironments (based on geological evidence) and phylogenetic patterns to debate their diets and feeding styles. David Weishampel and Coralia Jianu concentrate on phylogenetic aspects and show the effects of correcting the known fossil record for ‘ghost ranges’ – those missing

0169-5347/00/$ – see front matter © 2000 Elsevier Science Ltd. All rights reserved.

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