Parasitoid community ecology

BOOK Kruuk sees otters existing ‘at the edge of a precipice’: they live in a relatively uncommon, linear habitat, where they must cover great distances to satisfy their needs. They specialize in prey that are difficult to capture and young animals require considerable time to acquire the necessary skills, Foraging in cold water is so energetically expensive that large quantities of prey must be captured in a short time. Finally, toxic sub stances are more likely to accumulate in aquatic habitats than elsewhere. As a consequence, he feels that otter populations are highly vulnerable and that it is likely that ‘only a small increase in a pollutant, a decrease in prey population, a severe winter or a drought may have effects much more dramatic than for many other similar-sized species’. I found this book fascinating. Although no doubt biased because of my own interest in otters, 1recommend it to anyone interested in carnivore ecology and conservation. Katherine Rails National Institution,

Zoological Park, Smithsonian Washington, DC 20008, USA

References 1 Mason, C.F. and McDonald, S.M. (1986) Otters, Conservation and Ecology, Cambridge University Press 2 Ralls, K., Hatfield, B. and Siniff, D.B. (1995) Can. J. Zoo/.

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3 Macdonald, D.W. (1983) Nature 301,379-384 4 Mason, C.F. (1989) Luhn 32,97-131

The Middle Palaeolithic: an ecological reassessment Honor Among Thieves by M. C. Stiner Princeton University Press, 1994. f46.50 hbk (xxii + 447 pages) ISBN 0 69103456 7

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erhaps it is because the Neanderthals are the last group of archaic humans to occupy Europe before the arrival of ‘anatomically modern’ humans that their relationship to the modern humans has characterized the way in which we conceive their ways of lifelrz. The issue of continuity versus replacement has dominated debate about the Neanderthals. Briefly, those favouring ‘continuity’ see the archaics evolving into modern humans, while their opponents claim that Neanderthals were supplanted in Europe, 35-40 000 years ago, by a behaviourally sophisticated and anatomically modern population; an event widely termed the ‘Upper Palaeolithic Revolution’. The focus on this behavioural TREE

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revolution has tended to portray Neanderthal behavlour as limited and stereotypical because their stone-tool technology (Mousterian) lacks the dynamic and diverse typology of Upper Palaeolithic assemblages. The gross differences between the two technologies have prompted speculation about the behaviour of Neanderthals -speculation that has distinguished archaic from modern without much analysis of its functional basis. Stiner takes a different view and examines the behavioural record in the context of resource acquisition strategies, drawing her inferences from the fossil fauna coupled with information derived from studies of modern species. This approach starts from the eco logical basics, first examining behaviour in the light of the general needs and capabilities of the wider predator guild, and then proceeding to address the specific aspects of hominid ecology, coming to stone tools last of all. Using this methodology, Stiner draws some heterodox conclusions about the behaviours contributing to the Mousterian study sites. Foremost among these is that Neanderthal resource acquisition behaviour is not uniform. A picture emerges of a tremendous variability not usually associated with archaic Homo: some assemblages, attributed to scavenging activity, show a bone acquisition strategy dominated by ungulate heads. In other horizons, meaty elements from prime-aged prey predominate, demonstrating a strikingly modern acquisition strategy. These archaic people had foraging strategies at least as diverse as the most flexible carnivores, coupled with low tool-type diversity. This is not to say that Stiner found no variation in artifacts. In collaboration with ‘Steve Kuhn, she compares the variation in modification histories of tools to the inferred pattern of foraging, relating the relative degree of use of tool cores to the patterns of landscape usage of their manufacturers. One of the most thought-provoking suggestions in this book is that there is change within the Middle Palaeolithic. Hunting strategies of the Neanderthals converge upon those of late Upper Palaeolithic people well before the end of the Middle Palaeolithic, changing from a more opportunistic way of life that dominated the assemblages before 55000 years ago. The analysis of the lithics indicates a shift to less ephemeral occupation of sites during the sameperiod coupled with a shift in emphasis towards a platformstyle core reduction technique ‘reminiscent of the Upper Paleolithic’, producing more blade material from the relatively limited raw materials available in the more centrally fo cused foraging strategy. Stiner’s material, although admirably stratified and well excavated compared to the majority of Upper Pleistocene collections residing in Europe’s museums, derives from a small number of caves in Latium, North Italy. She does not therefore trumpet a gen-

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era1Middle Palaeolithic revolution in behaviour. She downplays the significance of temporal changes, indicating that it is the ‘grain’ and range of Neanderthal strategies that concern her. She points to environmental changes, such as the proximity of the shore line, which clearly change the opportunities open to cave users, and thus the seasons of occupation and the material contributing to the archaeology. Of wider significance is Stiner’s closing comment concerning the tyranny of chronologies; she conservatively suggests that it would be appropriate to examine time frames that do not coincide with our predetermined notions of when change is likely to occur. Failing to do this denies us the chance to witness ‘contradictions’ to our expectations. While her analysis is cautious in this sense, her use of ecological inference is bold. Many would dispute Stiner’s interpretation of niche theory and her conception of competition in general, but it is vastly more significant that the principles of modern ecology are so systematically applied to the problem. Similarly, Klein has taken issue with some methods used in this volumes. However, it is only through constructive discussion of such explicit methodologies that a coherent science can be developed to elucidate ecological effects across a broader range of archaeological sites. This book is a comprehensive manifesto for a Pleistocene palaeoecology of hominids based on sound biological inference. Mark D. Leney Dept

of Biological Anthropology, Cambridge, Cambridge, UK

University CB2 3DZ

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References 1 Stringer, C. and Gamble, C. (1993) In Search the Neanderthals, Thames and Hudson 2 Trinkaus, E. and Shipman, P. (1993) The Neandetihals: 3

Changing

Jonathan Cape Klein, R.G.(1995) Science

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the Image of Mankind, 267, 1843-1844

Community structure Parasitoid Community Ecology edited by B.A. Hawkins and W. Sheehan Oxford University Press, 1994. f50.00 hbk (x + 516 pages) ISBN 0 19 854058 2

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nsect parasitoids reproduce by laying eggs in or on hosts, usually other insects. Virtually all species of insects are attacked by one or, more often, a number of parasitoid species. The number of parasitoid species probably lies between one and six million1 (for comparison: there are 9000 species of

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birds and 4000 species of mammals2). As well as being diverse, parasitoids have an important practical advantage over, for example, birds and mammals, in that hosts can be collected and reared to determine which species of parasitoids are attacking them. Using this method, the parasitoid load (the number of parasitoid species attacking a host species) and the host range (the number of host species attacked by a parasitoid species) can be determined - a vital first step in unravelling parasitoid community structure. In their book, Hawkins and Sheehan have assembled contributions of many of the leading parasitoid community ecologists. The book is subdivided into seven parts: (1) community size and structure: (2) host ranges; (3) tritrophic level interactions; (4) tropical communities; (5) dynamics; (6) biological control: and (7) overview. There is also a useful introduction by the editors, summarizing the seven sections. The individual chapters cover topics ranging from mutualistic viruses and their effect on host range, to population dynamics of host-parasitoid interactions and the role of parasitoid communities in biological control. Parasitoid community ecology is an exciting and rap idly growing field. What is holding it back is the lack of good field data. Currently, the two main approaches used are the analysis of databases, which can be based partly on rearings and partly on literature sources, and the construction of parasitoid webs. But both approaches have their pitfalls. Shaw argues that literature sources are too unreliable to be used, mainly because of misidentification of the parasitoid or the host. He strongly advocates setting up well-organized research collections. Memmott and Godfray present a quantitative parasitoid web from the tropics and discuss the problems with gathering data for such a web. These include biases in the data, which can result from differences in the likelihood of collecting parasitized and unparasitized hosts or the ease with which parasitoid species can be reared. A further problem is sample size. Parasitoid load and host range increase (linearly) with the number of samples. Only very rarely the sample is large enough for a plateau to be reached. Overall, this is a good book that provides a broad overview of the current state of parasitoid community ecology. It is a pity that the book is a little light on theory, although there are excellent chapters by Jones et al. and by Hochberg and Hawkins. The lack of theory is almost certainly owing to the relatively young age of the science, and to the complexity of the subject. But perhaps state of-the-art books like this should make a particular effort to shape a theoretical framework. It would also have been useful to have a chapter linking community ecology and the evolutionary ecology of parasitoids,

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along the lines of the last chapter of Godfray’s recent book3 on evolutionary biology of parasitoids. I would recommend the book to parasitoid ecologists and to people interested in community ecology in general. Marcel E. Visser Netherlands Institute of Ecology, 6666 ZG Heteren, The Netherlands

References LaSalle, J. and Gauld, I.D. (1992) Redia 74 (Appendice), 315-334 2 Wilson, E.O.(1992) The Divers@ oflife, Penguin 3 Godfray, H.C.J.(1994) Parasitoids, Behavioral and Evolutionary Ecology, Princeton University Press 1

Getting about the Arctic A Naturalist’s Guide to the Arctic by E. C. Pielou University of Chicago Press, 1994. $22.95/f15.99 pbk (xv + 327 pages) ISBN 0 226 66814 2

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his is a book about the Arctic by an arctician who has spent many years working in the North American and the High Arctic. It is wide in scope, covering the physical environment in its first four chapters and then dealing comprehensively with the biology (grouped under plant life, birds, mammals, fish and insects). Professor E.C.Pielou is an experienced ecologist, distinguished in many ways. The book is essentially a practical guide to the natural history of the Arctic region - from the sky, land and sea to its flora and fauna. An important feature of the book, especially for the amateur biologist, is the provision of field identification guides for the major groups of plants and animals. As a guide for naturalists and Arctic travellers (real or armchair), this book fulfils its role admirably. It is easy to read, comprehensible and well laid out, and the information is easy to locate. As a potential user, my criticisms are of the rather limited index and of the physical size of the book. Although it is available both in cloth and in paper binding, the format is large, raising some doubts about its portability (‘designed as a compact source of information for those who must limit their load-hikers, kayakers, canoeists, rafters, photographers’. .. so saysthe cover). At just over half a kilo, my copy just might not find its way into my backpack! The book is based almost entirely on the North American and High Arctic region, thereby missing out on the more comparative aspects that might have been covered if it had included some information on the Russian and Scandinavian Arctic regions.

The author could have taken advantage of the recent improvement in availability of material from Russia and the long-estab lished information base for Scandinavia. Having said that, much of the basic information (especially on the physical environment) in the book is common to all regions of the Arctic. It is refreshing to read a book about an important area of our planet that is so clearly written by someone who has lived and worked in the Arctic - someone who has breathed the northern air, experienced the fascination of Arctic light and midnight sun, and who has observed and so vividly recorded the environment and biology of her special part of the Arctic. Over 400 of her own drawings and maps illustrate Pre fessor Pielou’s book, contributing in no small measure to its clear, uncluttered and direct approach. It is an attractive and highly readable account. In the present climate of increasing awareness of global changes, this guide provides an exceptional insight into the natural history of the Arctic region for the armchair ecologist, fieldworker and explorer. The information is readily accessible for those wishing to get up to speed on the Arctic and for those politicians and administrators who have the time (and the will) to delve into this comprehensive guide. I will be recommending it to all my friends and colleagues involved with things Arctic. Bill Block British Antarctic Survey, Natural Environment Research Council, High Cross, Madingley Road, Cambridge, UK CB3 OET

Seeing the wood for the trees Bird Life of Woodland and Forest by R.J. Fuller Cambridge University Press, 1995. f29.95 hbk (xiii + 244 pages) ISBN 0 52133118 8

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abitat loss is recognized as one of the major causes of a worldwide loss of bie diversity, with much of the current wave of extinctions directly due to human activity’. Such habitat loss frequently begins with fragmentation; an initial dissection, usually by roads, being rapidly followed by clearance and development until the original landcover is reduced to a scatter of ‘islands’ across the modified landscape. British woodland is a good example of a fragmented habitat, but is unusual compared with the situation in much of the world’s boreal forests (where the chance to preserve large TREE

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