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need to brush up your algebra, calculus, etc., to embark on modelling population dynamics. Case studies on fisheries and forest stand management occupy the following two chapters, while some modelling of elephant, seal, fruitfly and potato tuberworm populations are examined in the last chapter. Each example emphasizes one or a few aspects of the model development and its use in resource management. This section is not as heavy going as the first part of the book and, as the authors recommend, should be looked through first. Getz’s and Haight’s work will contribute much to the understanding of

Sophie des Clers

the power and limitations of existing models. Comparing the population dynamics of fish and forests will certainly help fisheries scientists separate model development from sampling problems. The agestructured fisheries models have also much to gain from the stagestructured approach of the forest managers. And time will tell if forest managers find equally useful this broadening of their horizons. To build up your mathematical understanding of age- and stagestructured population models, you should definitely have this (not so) little yellow book on your shelf, next to, say, the equally indispensible navy blues and bright green4 ones.

1 Anon. (1972) Nature239,477-478 (Obituary) 2 Leslie, P.H. (1945) Biometrika33, 183-212 3 Nisbet, R.M. and Gurney, W.S.C. (1982) Modelling Fluctuating Populations, John Wiley & Sons 4 Metz, J.A.J. and Diekmann. O., eds (1986) The Dynamics of Physiologically Structured Populations (Lect. Notes Biomath. 68), Springer-Verlag

tine rodents (mainly the montane vole, Microtus montanus) in terms of environmental cues differentiating cohorts in a given breeding season. Essentially, they find that for body size and growth rate there is extreme phenotypic plasticity of cohort life histories, which relates to available food resources and length of growing season. Lastly, Bujalski shows that in bank voles (Clethrionomys glareohs) the maturation rate and density of reproductively active females are restricted by territoriality, with availability of food resources playing a minimal role in life history variation. The next section, on ‘Body Size as a Life History Character’, introduces the one common thread that runs through the volume (and indeed most studies of mammalian life histories): namely, that body size correlates significantly with practically all life history characters. The premise is that body size places limits on physiological investment, which in turn correlates with energy allocation for life history patterns. Chapters in this section develop a number of themes on size effects, such as scaling biological (physiological) time rather than chronological time with species differences (Lindstedt and Swain), and treating body mass as the intermediate variable between selection and life history variation both within populations (Sauer and Slade) and among species (Zeveloff and Boyce). The problem with the allometric approach is that causal mechanisms are unclear. For example, the observation that body mass explains 6491 % of the variation of all life histories in mammalian carnivores3 does not reveal the relative influence of

metabolism, pelvic structure, teat number or any number of other morphological variables that directly impinge on the allometry of life histories. More importantly, these factors may not reflect one-to-one correlations with body mass, so that size alone as an explanatory factor may be misleading. As with other areas of ‘allometricks’4, experimental studies are long overdue for determining why size-dependent relations exist. The section on ‘Genetics of Life History Characteristics’ fills a critical void in life history analyses as well as producing some rather surprising results. Boag and Boonstra, following a useful review of available quantitative genetic techniques, show that in meadow voles (Microtus pennsylvanicus) traits such as body weight, growth rate, and age or weight at sexual maturity are unlikely to be heritable in nature; moreover, maternal effects exert a major influence on sibling resemblance. The other chapters, by Leamy and Bradley on growth rates in laboratory populations of rats and by Dobson on plasticity in litter size and body weight in Columbian ground squirrels (Spermophilus columbianus), reaffirm the idea that mammalian life histories are likely to be low in heritability. The main message from these chapters is that, contrary to previous thinking, there is substantial phenotypic plasticity of life history characteristics in mammals, which will make evolutionary analyses difficult. The largest section is on ‘The Comparative Method in Life History Studies’. A burgeoning of statistical analyses of interspecific variation in life histories has occurred in the last five years. I suspect this is due

Renewable Resources Assessment Group, Centre for Environmental Technology, Imperial College of Science, Technology and Medicine, 8 Prince’s Gardens, London SW7 lNA, UK

References

Life History Patterns Evolutionof LifeHistoriesof Mammals: Theory and Pattern

edited by Mark S. Boyce, Yale University Press, 1988. $45.00 (xvi + 373 paged ISBN 0 300 04084 9 Life history patterns represent various reproductive characters and the probabilities of survival at each age during a life span. Life history traits such as gestation period, growth rate, age between successive births and age at first reproduction are generally thought to have evolved in response to demographic and other environmental demands, although genetic variance and evolutionary history impose some constraints. Mammals possess a number of features that give interesting twists to these issues; for example, all mammals provide parental care and rear young during a phase of lactation. Despite considerable theoretical advances and empirical data bases, a coherent theory of mammalian life history evolution has remained elusive’,*. The aim of this book, derived from papers given in 1985 at the International Theriological Conference, is critically to summarize major approaches to the study of mammalian life history evolution. Following a brief introduction by the editor, on various theoretical models, the first section comprises three chapters on ‘Pattern and Process in Mammal Life History Variation’. Cameron and McClure analyse geographic variation in life history traits of the hispid cotton rat (Sigmodon hispidus) and show that litter size is correlated with latitude, longitude and body size. Negus and Berger assess life histories of micro-

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nection between chaos and mammalian life histories is as yet tenuous, this may be a valuable approach to life history evolution. Boyce concludes by pointing out major unresolved questions that emerge from the previous chapters, emphasizing that theoretical advances have surpassed data collection. This book is an excellent catalogue of examples, and is perhaps the best single exposition of the complexity and problems of life history studies. Nevertheless, its perspective is somewhat biased, for two reasons. First, in recognizing the general importance of size effects, all but three chapters deal with mammals no larger than a common oppossum. Second, despite the need for reductionism to single out particular variables in mammalian life histories, most chapters only consider two life history traits (usually litter size and growth rate); variables such as birth weight, weaning age and longevity are practically ignored. Mammals do not parcel out specific life histories independent of compensatory effects on other life history trait@. Thus, statements regarding reproductive investment or allocation of energy may be misleading7. These criticisms, though, may be

unfair given that the field as a whole has not treated these issues effectively. The concluding words of Stearns’ influential critique8 of life history evolution unfortunately still ring true for mammalian studies: ‘We do not yet have a general and reliable theory of life history evolution, and the crux of the problem is: What will be an empirically sufficient set of parameters in which to couch the theory?’

by B.E. Juniper, R.J. Robins and D.M. Joel, Academic Press, 1989. f75.00/ $750 hbk (368 pages) ISBN 012 392 7708

larly in the chapters on ecology and evolution. Too often the suggestions in the literature are reported at face value, with no comments on the logic of the ideas or the evidence supporting them.

The notion of plants as predators is somehow intrinsically attractive. What other plants have inspired both Charles Darwin’ and a Broadway musical? The last comprehensive, scientific review of carnivorous plants is nearly half a century old*, so the major update provided by Juniper et a/.‘s book is most welcome. The style of the book is encyclopedic, covering all major aspects of plant carnivory with the exception of horticulture. The coverage of the relevant literature is quite comprehensive, making this an excellent (if expensive) reference volume. However, this approach may contribute to the choppy organization of the book: several of the 19 chapters are only three pages long, and many chapter subsections are single paragraphs of less than 100 words. In addition, the literature cited is not always critically evaluated, particu-

The bulk of the book concerns the mechanisms of prey capture and digestion, and here it is at its best. Morphological and physiological studies of the attraction, capture, and retention of prey have advanced significantly in the past 15-20 years, largely because of new experimental tools. I found the discussions of the physiological mechanisms underlying ‘snap’ traps and ‘suction’ traps

particularly interesting. Labelling and other studies have demonstrated both the sites and activities of plant secretions, and the absorption and incorporation of amino acids that result from prey breakdown. As a result we now have a much clearer understanding of prey capture and digestion for many carnivorous species. Experiments dating back to Francis Darwin3 have demonstrated the importance of prey capture for growth and/or reproduction in carnivorous plants. Despite an extensive natural history literature4, however, many other aspects of the ecology of these plants remain poorly documented. The authors provide a useful summary of T.C. Gibson’s interesting dissertation research (University of Utah, 1983) on prey partitioning among Sarracenia species, which is otherwise unpublished. They also present a clear discussion of the work to date on the evolutionary and community ecology of the biota inhabiting pitcher plants. A central issue still unresolved for most carnivorous species5 is the nature of the interaction between the plant and its inhabitants; observational evi-

more to the seductive abundance of single-species data rather than an empirical need to verify theory. as vividly demonNevertheless, strated by Harvey and Read, comparative studies are at least becoming more careful in defining variables, methodological execution, and causal inference. The overall impression from this work is that, across broad taxonomic groups, body size and phylogeny are more influential than environmental variables. At lower levels, though - e.g. Smith’s work on the pikas (genus Ochotona) or Eisenberg’s study of didelphid marsupials -traits such as litter size and number of litters per year are tied to habitat productivity and seasonality. Clearly, an important problem for future comparative work is to sort out the reasons for similarity and divergence at hierarchical taxonomic levels. The final section contains two ‘Future Directions’ chapters. Schaffer introduces nonlinear dynamics as a possible method for coping with the bewildering plasticity and covariability of mammalian life histories. Like other intractable ecological life histories may be problems5, viewed as dynamical systems that but are inherently deterministic nonetheless chaotic. While the con-

John L. Gittleman Deptof ZoologyandGraduate Programs in Ecology and Ethology, University of Tennessee, Knoxville, TN 37916, USA

Rsferences 1 Partridge, L. and Harvey, P.H. (1988) Science 241,1449-l 455 2 Eisenberg, J.F. (1981) TheMammalian Radiations, University of Chicago Press 3 Gittleman, J.L. (1986) Am. Nat. 127, 744-771 4 Calder, W.A., Ill (1984) Size, Function, and Life History, Harvard University Press 5 Schaffer, W.M. and Kot, M. (1986) Trends Ecol. Evol. 1,58-63 6 McClure, P.A. (1987) in Reproductive Energetics in Mammals (Loudon, A.S.I. and Racey, P.A., eds), pp. 241-258, Oxford University Press 7 Gittleman, J.L. and Thompson, SD. (I 988) Am. Zoo/. 28,863-8?5 8 Stearns, SC. (1977) Annu. Rev. Ecol. Syst. 8,145-l 7i

Predatory Plants The Carnivorous Plants

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