Process and pattern in evolution

Process and pattern in evolution

‘REE vol. 5, no. 3, March 7990 the methodology as if it were the goal, rather than the means, of advances in research. By following the development ...

320KB Sizes 1 Downloads 15 Views

‘REE vol. 5, no. 3, March


the methodology as if it were the goal, rather than the means, of advances in research. By following the development of new methods, this book allows us to see the development of key questions in plant physiological ecology. These questions are of two kinds: first, there is an increasing focus on finding physiologically based answers to ecosystem-level questions; secondly, there are ever more detailed investigations of the functioning of individual plants, organs, tissues and cells in natural environments. The ecosystem-level questions are several. How is the productivity of an ecosystem determined? What resources are limiting? How do the components of the ecosystem interact? The approaches to answering these questions are at the same time increasingly physiological and increasingly integrative. Individual productivity and its limitation are examined in detail using controlledenvironment and field studies of photosynthesis, growth, water and nutrient relations. Modelling approaches allow the extension of such results to the ecosystem level with increasing accuracy, due to the development of improved methods for quantification of canopy structure; and some methods, such as eddy correlation’,* approaches to en-

ergy balance, directly produce field measurements that constitute integrated responses over large areas. Stable- and radioactive-isotope techniques allow the determination of the importance of different ecosystem processes3, and of the role of the individual in these processes and in interactions with other individuals4. At the other end of the spectrum, interest in achieving a detailed understanding of the physiological processes of plants in the field has led to the development of field extensions of laboratory methods. Heat-pulse techniques measure water flux within Isotope techindividual plants5. niques allow us to examine the allocation of carbon to different plant [email protected] Pressure probes to measure the water status of cells’ may eventually be suitable for use in the field. Chlorophyll fluorescence techniques to assess levels of damage to photosystem function8 are beginning to make the transition from the laboratory to the field. Other questions that are fundamental to plant physiological ecology and its methodology include those of how to define different types of plant ‘stress’ or physiological damage. It is also of increasing interest to be able to determine the costs of survival in terms of energetic and resource investment in structures, growth and

defense, and consequently to assess the losses due to herbivory. Such stresses and costs can affect plant reproduction and fitness as well as competitive interactions. Clearly, to some degree all plant ecology is ultimately physiological, and this book is potentially very useful to all plant ecologists.

gredients. The Introduction promises contributions from astronomers, chemists, geologists, philosophers, physicists, anthropologists, behaviourists, biochemists, cell and developmental biologists, ecologists, geneticists, molecular biologists, palaeontologists, physiologists, systematists and others. To fulfil this promise the book goes from cosmology to cultural evolution, taking in genome structure, the cell, and the plant and animal kingdoms on the way. Winston Churchill once rejected a pudding because it ‘lacked a theme’, and there is a certain culinary confusion on the menu here as well. However, not much gets left out taphonomy to tit-for-tat behaviour, phenetics to Pangaea, extinctions to exon shuffling and Australopithecus to adaptive landscapes all find a place. The treatment is admirably up to date, although this does mean that the author has occasionally leapt on to passing bandwagons that came to a halt before getting anywhere. There is nothing more tired than yesterday’s slang, and it is already odd to see terms such as punctuated equilib-

rium and developmental constraint presented as if they are live issues in evolutionary biology. The breadth of the book means that it is shallow in parts: which is perfectly acceptable in a textbook. However, it is locally hard to follow and even sloppy, and that is certainly not acceptable. For example, after quoting Fisher’s succinct comment on natural selection as a mechanism for generating improbability, this is explained as ‘those inherently better fit are more likely to predominate because of the nature of their inheritance, not because of deliberate action by the totality which we refer to as nature’. What can that mean? The discussion of modes of selection is also confused, with stabilizing and purifying selection treated as effectively interchangeable; selection against heterozygotes presented as a means of maintaining polymorphism; and the distinction between group and kin selection not clearly made. There are arithmetical errors in the treatment of inbreeding; and the Hardy-Weinberg theorem is derived in a baffling way. It is particularly odd to read in an account of speciation

Valerie Kapos BotanyDept,Universityof Cambridge, Cambridge CB23EA,UK

References 1 Shuttleworth,

W.J. (1988) Proc. R. Sot. London Ser. 6 233,321-346 2 Shuttleworth, W.J. et al. (1984) Q.J.R. Meteorol. Sot. 110, 1143-l 162 3 Medina, E., Montes, G., Cuevas, E. and Rokzandic, Z. (1986) J. Trap. Ecol. 2, 207-217 4 Caldwell, M.M., Eissenstat, D.M. and Richards, J.H. (1985) Science 229, 384-386 5 CermBk, J., Jenik, J., Kutera, J. and tidek, V. (1984) Oecologia 64, 145-151

6 Mordacq, L., Mousse&, M. and Deleens. E. (1986) Plant Cell Environ. 9. 735-739 7 Cosgrove, D.J., van Volkenburgh, E. and Cleland, R.E. (1984) Wanta 162, 46-54 8 Winter, K., Osmond, C.B. and Hubick, K.T. (1986) Oecologia 68, 224-230

Eclectic Evolution Processand Pattern in Evolution by Charlotte J. Avers, Oxford University Press, 1989. f28.00 (xvi + 590 pages) ISBN 0 19 505275 7 There are lots of books about evolution, but very few evolution textbooks. Because they cannot leap into the past, evolutionists - be they muscular Darwinist, stark theoretician, or just plain daft - have never hesitated to leap into print. Bookshop shelves are crowded with convincing but contradictory treatments of what evolution is all about. This confuses today’s students whose academic diet, largely limited as it is to boil-inthe-bag biology, has taught them to prefer pabulum to polemic. What undergraduates need to reassure them that the molecules they study were probably not created on October 28th 4004 BC is evolution with most of the bones taken out: a terse, simple and even bland account which explains just why -to quote a famous phrase - ‘nothing in biology makes sense except in the light of evolution’. Aversstrivesfor blandness but fails because of the richness of her in-


TREE vol. 5, no. 3, March 1990

that ‘transitional forms that connect ancestral and descendant species are often missing in both living and fossil groups’. Surely the absence of transitional forms in living creatures is what speciation is all about! However, a real sense of enthusiasm about evolution does help to disguise the occasional indigestible item, and a student who persists with the book should emerge quite convinced by the evidence for the

existence of evolutionary change, even at the cost of a certain feeling of confusion about how it happens - a feeling that is, after all, shared by most of those who are actually in the evolution business. Avers is obviously writing for an American audience (which is fair enough, as most evolutionists are Americans), but this does mean that some sections read oddly on this, the more disillusioned, shore of the Atlantic. Is

it actually the case that ‘the existence of a deity is accepted by a large majority of evolutionists, as well as by creationists’? And would we feel obliged to mention this in a text on any other subject?

are several such cases in this book, particularly in the treatment of competition theory. The chapter on ‘Modeling Competition’ discusses only three basic models: LotkaVolterra competition (and its extension to the community matrix), Tilman’s resource ratio model, and Rosenzweig’s isoleg model of density-dependent habitat selection. There is no mention of the studies of Armstrong and McGehee’, showing how two species can coexist on only one resource. Also missing is a discussion of the stochastic models for species coexistence developed by Chesson2s3 and others (instead we are given the usual, and wrong, impression that stochastic environments somehow allow species to coexist without niche or life history differentiation). The discussion of Tilman’s model should also have noted the mathematical proofs of Hsu et aL4 for the basic theory, as well as some of the cautionary comments of Abrams5. The list could go on’and on. The strong points of this book are in the discussion of approaches to the study of competition. There is much here of value to graduate students who are trying to decide what systems or organisms to work on, how to use comparative and experimental studies to look at competition, or how best to make their results general and of interest to a broad range of ecologists. There are many details of these chapters (3-5) with which I do not agree, butthe discussion is stimulating and ittoucheson problems that everyone who studies competition must wrestle with. I did find Keddy’s treatment of a number of topics unsettling, including his discussion of resource partitioning versus ‘dominance control’ and his ‘paradox of resource limitation’. Keddy’s ideas here are at variance with much of the literature and, as the book cover states, his approach is certainly ‘controversial’. In summary, I feel that this book is simply incomplete. Keddy’s treatment of the recent animal literature

is especially deficient. There are no citations to the important work of Abrams, Case, Hubbell, Pacala, Schluter and E. Werner (to name a few); Grant is cited for only one study, Roughgarden for a review paper and a textbook, and Schoener for only three review papers. One must either conclude that Keddy is unaware of the original research by these leaders in the field, or that it is not part of ‘what needs to be reviewed’. Also, many promising new areas of study are ignored, including the development of stochastic competition models2s3, models and empirical studies that take into account the regional processes that influence local competitiot+, the impact of population size-structure or stagestructure on the interactions between species7, and the broad topic of complex interactions and indirect effect9. Many of the failings of simple competition theory based on niche partitioning and limiting similarity were the result of ignoring the processes outlined above, and significant future advances in the field must view competition as one process within the whole framework of interactions experienced by a species.

J.S. Jones Dept of Genetics and Biometry, University College London, London NW1 ZHE, UK

Condensing Competition Competition by Paul A. Keddy, Chapman & Hall (Population and Community Biology Series), 1989. f27.50 hbk, f 12.95 pbk (x + 202 pages) ISBN 0 412 31360 X


Competition is a key force in nature and is the subject of a vast and diffuse literature. Therefore, when asked to review a book entitled simply ‘Competition’, I was excited by the possibility that someone had actually summarized (and, I hoped, synthesized) this huge literature, and apprehensive about whether it could be done. When a book of only 200 pages arrived, it was clear that the job still remains. Keddy’s book is very spotty in coverage and quality; it provides a decent summary of the plant competition literature, an odd collection of studies of competition among animals, and a perplexing treatment of theory. Keddy’s strong emphasis on the plant literature (106 plant citations versus 54 for animals) is understandable, given his research interests, but it is also unfortunate in a general treatment of the subject. At the outset, Keddy states two objectives for the book: (I) to provide an overview of existing knowledge about competition, and (2) to organize this knowledge in such a way that new research paths are suggested. The book succeeds in the second objective, but fails in the first. Keddy takes an unorthodox approach to summarizing the existing literature on competition, and suggests that ‘In an area like the study of competition, with such a vast literature and well-established research traditions, a book which simply repeated what others have said and described the status quo would not only be of limited value, it would also probably be boring. This is my attempt to review what needs to be reviewed . ..I. I appreciate Keddy’s efforts to guard against a boring cataloging of examples. However, the danger in producing a selective review is that it presents a misleading treatment of the field through omission. There

Gary G. Mittelbach W.K. Kellogg Biological Station and Dept of Zoology, Michigan State University, Hickory Corners, MI 49060, USA References 1 Armstrong, R.A. and McGehee, R. (1980)Am. Nat. 115, 151-170 2 Chesson, P.L. (1988) Lect. Notes Biomath. 77, 51-71 3 Chesson, P.L. and Huntly, N. (1989) Trends Ecol. Evol. 4, 293-298 4 Hsu, S.B., Hubbell, S.P. and Waltman, P. (1978) Ecol. Monogr. 48,337-349 5 Abrams, P.A. (1988) Theor. fopul. Biol. 33,226-242 6 Roughgarden, J., Gaines, S. and Possingham, H. (1988) Science 241, 1460-I 466 7 Ebenman, B. and Persson, L., eds (1988) Size-structured Populations, Springer-Verlag 8 Kerfoot, W.C. and Sih, A., eds (1987) Predation, New England University Press