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Book reviews

Hepper, P. G. 1991. Kin Recognition. Cambridge University Press, 455 pp. Price &60.00H/b. ISBN O-52 1-37267-4.

Nearly thirty years ago, kin recognition was part of a theory in search of evidence. Nowadays, there is evidence aplenty for kin recognition abilities, but the possible functional significance of these abilities is often obscure. This is one of the themes of Hepper’s book. Another is the important distinction between kin recognition (the ability to identify kin) and kin discriminution (behaving diff- erentially towards kin); for example, Barnard and Aldhous argue cogently that correlations between kinship and mate choice may arise for reasons unrelated to kin discrimination. This distinction is reflected in the arrangement of this book, as the early chapters tend to focus more on function and the later ones on mechanism.

The incentive to demonstrate kin discrimination in some taxa has apparently been stronger than the methodology will bear. Bernstein gives some hair-raising examples from early studies of non-human primates, in which independent measures of paternity were lacking, and concludes “...it is not surprising that males, assumed to be fathers of infants because they behaved preferentially to- wards those infants, behaved preferentially towards infants that they had pre- sumably fathered”. Even when kinship is independently assessed. findings may fail to replicate. One can scarcely argue with Bernstein’s assessment that correlations between matrilineal kinship and preferential behaviour have been demonstrated, whereas correlations between patrilineal kinship and preferential behaviour have not.

Better methodological examples are to be found amongst the work on am- phibians and social insects. In consequence, the mechanisms by which larval anurans recognise kin are well documented, although, as Waldman’s thoughtful overview makes clear, the functions of kin discrimination in tadpoles are not understood. Possibilities include parental care, territorial maintenance and incest avoidance; findings suggest effects of kinship on larval growth rates; but the spectre of anuran kin recognition as an epiphenomenon (maybe of species re- cognition, or of immune function) refuses to go away. All the more reason, then, for considering the evolutionary role of the major histocompatibility complex in social vertebrates (Boyse, Beauchamp, Yamazaki and Bard): the extreme diversity of MHC genotypes not only permits the generation of individual odour- types but almost certainly promotes outbreeding and MHC disparity, which in turn confer a wide range of specific immune responses to antigens of various pathogens.

Much is also to be learned from studying the birds (Beecher) and the bees (Getz). Beecher places the emphasis squarely on recognition as both a communi- cation and a decision problem, which “...gives the individual to be recognised (the potential sender) equal billing with the recognizer (the receiver)“. Failure to discriminate can be traced to any of four components of recognition, each poten-

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tially subject to natural selection: inadequate signature information, inability to perceive signature information that is present, a decision not to discriminate, or lack of appropriate discrimination behaviour. The decision model predicts that in colonial species, where parent-offspring recognition is subject to strong selection, there will also be selection for strong signature information, whereas in non-colo- nial species signature information will be weaker. The prediction is triumphantly vindicated in the comparison between creching and non-creching swallows; for example, the bank swallow signature system means that approximately 83 more individuals can be identified, to the same degree of precision, than in the case of the closely-related (but non-creching) rough-winged swallow.

The notion of recognition as a communication problem is also considered by Getz in the context of olfactory signals in the honeybee; evidence here suggests that knowledge of own and of nestmate’s signature are both taken into account. The empirical issues are complex, and Getz does them full justice, speculating meanwhile on parallels between optimal discrimination and optimal foraging, and the possibility that a nestmate recognition system may “piggy-back” on a mate- avoidance system, or perhaps on a system of co-operative behaviour.

Co-operation and reciprocity are the themes of Ligon’s chapter, in which he assesses the relative importance of kinship and reciprocal altruism in various avian and mammalian species. He concludes that complex co-operation, including recip- rocal altruism, can develop and be maintained in the absence of kinship, as evidenced by exchanges of aid between different species; that co-operation never- theless occurs most commonly amongst kin; and that the relative importance of reciprocal altruism and kinship will vary from case to case.

Elsewhere in the book, new light is shed on some old concepts. Imprinting may involve the learning of individual, rather than species, characteristics; there is a predisposition to learn certain stimulus characteristics; and this predisposition may require experience at a particular time and/or changes in internal state such as a hormonal ‘surge’ (Johnson). Early learning during sensitive periods is also a characteristic precursor of nestmate recognition in ants and social wasps (Jaisson). Not all learning need be postnatal, though: Robinson and Smotherman argue persuasively for the role of prenatal experience in the onotogeny of kin recognition. In vertebrates, a wide range of sensory modalities may be employed in estimating genetic relatedness, but, as Halpin observes, many kin recogni- tion studies have examined only one modality. Kin recognition cues should not be assumed to be invariably salient, either: a female may manipulate the re- sponses of a male so as to reduce the likelihood of infanticide and increase the likelihood of paternal behaviour towards offspring other than his own, and parental state is a potentially important mechanism in this process (Elwood). Finally, Porter reviews recognition abilities in humans and concludes that the development of mutual parent-offspring recognition is necessary for the forma- tion of social bonds.

There is a bit of taxonomic overlap, and some of the chapters are better than others, but overall the book provides a good mixture of theory and evidence from some of the foremost workers in the field. It is also well produced (although the

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subject index is a little under-inclusive). Anyone interested in kin recognition will want to possess it; at &60. whether they will be able to afford to is another matter.

Pamela Wells Dept. of Psychology Goldsmiths College New Cross London SE14 6NW, U.K.

Krause, G. 1990. Biogenetische Interphiinotypen. Verlag Paul Parey, Berlin und Hamburg. 197 pp. ISBN: 3-489-64834-X.

The title is unorthodox, and so is the entire book. Nowhere in this text are we allowed to derive comfort from concepts, reasoning, or language with which we are familar. We are faced with a very personal morphological “Weltbild”, developed during a life-long occupation with comparative and experimental embryology, finalized and written down fifteen years after the author’s retirement from the chair of Comparative Anatomy which he held in the Zoology Department of the University of Wiirzburg. The book is about embryology and evolution, a theme that is sometimes thought to belong to the past, but that has certainly regained importance in recent years.

The current renaissance of the discussion of developmental factors in evolution has two roots. One lies in evolutionary theory, where different fields of study indicated independently that some major problems of organismic evolution ~ such as non-adaptive characters, morphological novelties, trends, or stasis - require the inclusion of lineage-specific internal properties of organisms for their explana- tion. The second root lies in developmental biology. Here it was realized that developmental theories are incomplete if they cannot account for the evolutionary modifiability of developmental systems, and a growing number of experimental studies shows that these questions are empirically accessible. Thus, embryology and developmental biology, liberated from the Haeckelian stigma, begin to assume a new role in evolutionary theory. The main concern now is the mechanistic relation- ship between evolutionary and developmental processes. Heterochrony, develop- mental constraint, and the generation of morphological novelty have emerged as the major issues in the current discussion.

Left behind as a result of this change of emphasis are the older themes, the parallels between ontogeny and phylogeny, recapitulation, and the relevance of embryonic characters for the elucidation of phylogenetic relationships. This has sometimes led to the notion that recapitulation was disproved, which it was not. In fact, very few developmental biologists would deny that recapitulatory stages of organization can be seen in the development of almost every organ. But it has become unfashionable to speak about them. Krause, however, sees recapitulated

142 Book reviews

characters as true tracks of morphological evolution and he intends to bring them into a system. His reasoning is roughly this: If we leave aside the problems of homology, the problems of taxonomy, and the problems of phylogenetic recon- struction, and if, instead, we concentrate purely on the recapitulated embryonic characters (interphenes) in all available ontogenies, and if we order them according to the most parsimonious transformation required to get from one to the next ~ which is the picture of the organismic world we would obtain? From the point of view of the author, this is a legitimate approach because his primary intent is not to reconstruct phylogeny directly from ontogeny, but to identify true pathways of morphological transformation. Unavoidably, however, suggestions for alternative taxonomic groupings emerge.

Krause arrives at astonishing conclusions. For example, in contrast to most current texts, he regards asymmetric (spiralian) cleavage as primitive to symmetric (equal) cleavage. He also questions whether the dichotomy between protostomia and deuterostomia can be upheld. But possibly his most unorthodox conclusion is that the neurenteric canal, a communication between the neural tube and the archenteron of vertebrates, corresponds to the u-shaped gut of the ectoprocta (bryozoans) and pterobranchia. The neural tube of vertebrates would thus be derived from the alimentary canal of hemichordates and tentaculates, which are therefore regarded as ancestral relatives of the chordates. All these startling conclusions, and many more, are reached by the classic method of comparative embryology. In his analysis Krause considers the ontogenies of a majority of animal classes, each summarized in a color plate, including many of the rarely treated “odd” groups.

It is interesting that a book can be written without reference to any of the current themes in the field to which it intends to contribute. However, if we perceive the book as the exposition of a heuristic method, it is of interest to all those pondering the problems of development and evolution. The book can also be recommended to those who have an interest in the history of scientific ideas, especially in the classic German tradition of morphology, which is thereby extended into the present. I feel it is my duty, though, to warn non-native speakers of German of the complicated language and the idiosyncratic terminology used in this unique document of typological, neo-Haeckelian, and visionary thinking.

Gerd B. Miiller Department of Anatomy Wahringerstr. 13 A- 1090 Wien, Austria

McKinney, F. and Jackson, J. B. C. 1991. (Original edition 1989): Bryozoan Evolution. University of Chicago Press, Chicago and London. 238 pp. $18.25. ISBN: o-226-56047-3.

The Bryozoa is a relatively minor animal phylum. An understanding of its evolutionary biology, however, may present an excellent opportunity for disentan-

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gling the causative plexus of evolution, or the interplay between adaptation to local conditions, phylogenetic heritage, and pure chance. A necessary precondition is of course that the complex functional biology of these clonal animals and their colonies be brought together with their fossil record so that these two aspects of bryozoology can mutually elucidate each other. This is exactly what Frank K. McKinney and Jeremy B. C. Jackson undertook in their little book.

They begin with a rather short but surprisingly comprehensive and lucid exposi- tion of bryozoan anatomy and functional biology, followed by a brief discussion of bryozoan taxonomy, both in the living biota and in the geological past. The bulk of the book covers a number of biological characteristics of the Bryozoa, such as their growth forms, life histories, and feeding modes, which are put in the context of adaptation as the main controlling factor. Finally, a brief chapter enumerates some overwhelming evolutionary patterns that appear in the history of the Bryozoa when considered on the geological timescale. These major trends concern changes in dominance hierarchy of various growth forms, budding patterns, zooidal polymor- phism, and taxonomic groups.

These trends are all given a strictly adaptive explanation. And although a rigorous testing of the appropriate hypotheses is lacking, the conclusions sound nonetheless quite convincing. Most certainly, however, they call for further re- search. As a starting point for future undertakings, the book is indeed invaluable, for it shows very clearly how much exciting work can be done with both living and fossil bryozoans (there is, for instance, a short overview of the beautiful work of Cheetham and Jackson on the punctuated pattern of evolution of the fossil Metrarabdotos); and it also shows where are the gaps that must be filled before our knowledge of bryozoan evolution can truly advance. One such gap is genetics.

I strongly recommend this book both as an introduction for anyone interested in the Bryozoa, and as an example of the successful marriage of biological and paleontological approaches to evolution.

Antoni Hoffman Institute of Paleobiology Polish Academy of Sciences Al. iwirki i Wigury 93 PL-02-089 Warszawa. Poland

Jean Gayon. 1992: Darwin et I’aprks-Darwin, Histoire de l’hypothbe de sklection naturelle Editions Kim&, Paris. 453 pp. FF 250. ISBN 2-908212-14-s.

There has been a drastic change in the attitude of scientists to the history of their field. They no longer want to read a self-gratifying story concentrating on the growth of knowledge, but prefer realism, clearly showing the meanders, the misunderstandings, and even the social prejudices of their predecessors. Historians

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have been able to meet these needs. Books such as William B. Provine’s Origins qf Theorrticd Populution Genetics, or Peter Bowler’s Eclipse of’ Darwinism have become popular among evolutionary biologists. They show that what used to be called “classical Darwinism” ~ the theory of natural selection ~ never was classical. For decades it was thought to be wrong. Now, nothing is left of previously flourishing old-fashioned evolutionary schools. And yet, of the last hundred years, half of them were spent arguing about the veracity of natural selection. Jean Gayon explores this gloomy period and interprets it as a time of maturation, during which natural selection ~ which he considers to be the essence of Darwinism - steadily followed a path which eventually determined our modern understanding.

The key to Gayon’s approach is the subtitle of his book: “a history of the hypothesis of natural selection” (my emphasis). To summarize it briefly, Gayon tries to demonstrate in over 450 pages that Darwin had taken the risk of formu- lating the main element of his theory as a falsifiable statement. His theory was dependent on a particular mechanism of inheritance which, he knew, would probably not be discovered for decades, and which, if it turned out to be different from his assumptions, could wreck the whole enterprise. Some of Darwin’s con- temporaries like T. H. Huxley disagreed with his stubborn linking of the great discovery of evolution to such a speculative idea as selection. Gayon’s thesis is that this “one long argument”, as Darwin said, was intentional and doomed his followers to a long quest for the rules of inheritance.

From this follows an approach which, at first glance, could appear against current fashions in the history of science. Gayon considers only debates between those (Galton, Weismann, the biometricians, the Mendeliens, & c.) who were later to count in the history of population genetics. Neo-Lamarackianism or orthogene- sis, he argues, were never alternatives to Darwinism. The real struggle was not between them and the Darwinians, but within the Darwinian camp. These prede- cessors were not forerunners. “It was war”, he says in a metaphor. In this view of history, there is no room for a well-ordered succession of Kuhnian scientific revolutions. The whole theory is present from the beginning, but it is not proven, and the heirs fight around an inaccessible treasure.

Most of the book is a critical survey of the struggle between Darwin, Jenkins and Galton; between Wallace and Weismann; between statisticians and geneticists. The chapter on Weldon and his astonishing project to record natural selection in the field from statistical measures is, to me, one of the high points of the book. These studies were a dead end from the outset, although they were a great moment of intensive research. Because biometricians concentrated on the popula- tion level, Gayon accords this school full scientific status, refusing to simply dismiss it because of its eugenic agenda. Science, the author argues, is above all an activity aimed at solving problems. It must therefore be analysed on this basis. Socio-political criticism, though relevant, is not sufficient. The biometrical program was more flawed by its refusal to consider unobservable things such as genes than by its eugenic views. Its approach to statistics has however been essential in the history of evolutionary theory.

Book reviews 14.5

It would be unfair to present Gayon’s book as pure history. In fact, this aspect of the book, although remarkable, relies heavily on secondary sources. The book is mainly that of a philosopher, to whom history is merely a way of carrying out a “rational reconstruction” of a concept. He defends the following thesis: natural selection, as we now define it, was already fully present in the “Origin of Species”. This explains the feeling we have of understanding so easily a book written in such old words. For Gayon, Darwin’s familiar strangeness is conceptually founded.

From this follows the most ambitious and perhaps the most vulnerable step of the argument: the chapter where Gayon compares Darwin with Wallace. He seeks to show that the former went much further than the latter in his ontologi- cal premises. A first difference is that Darwin only understood that selection acted upon individuals, not “varieties”. Another difference is in the use of the argument of artificial selection. Wallace opposed it to natural selection (although not using the expression). In Darwin’s view, Gayon says, artificial and natural selection were two aspects of one process. In other words, and this is the second aspect of his thesis, “natural” selection was not a pure metaphor in Darwin’s thought.

This idea goes against current opinion and will probably be criticized. I found it questionable, until I remembered a paragraph in the “Descent of Man” where Darwin discusses sexual selection by females upon males: “This latter kind of selection, he writes, is closely analogous to that which man unintentionally, yet effectually, brings to bear on his domesticated productions, when he pre- serves during a long period the most pleasing or useful individuals, without any wish to modify the breed”. This supports what Gayon sometimes calls “a legitimate metaphor” and elsewhere the “ultimate undivided” nature of the two processes.

“Darwin et I’apres-Darwin”, is certainly an important landmark in under- standing the history and the meaning of the concept of selection. The reader will find some well argued ideas and some very fine analyses, all of which are good examples of how to grapple with the manifold aspects of a concept. Its main weakness is that it is written in French. Even if it is courageous for a small French company to publish such a big book in a country where Darwinism is so poorly understood, it is probably not the best way to insure it the readership it deserves. In addition, the publishing itself is technically deficient. Not to speak of the many typing errors, the drawings (especially the reproductions of Galton’s and Weldon’s original figures) are so badly treated that they nearly ruin the book. This book should be translated into English and be widely discussed throughout the scientific community, especially in a more carefully produced edition.

Michel Veuille Laboratoire de Biologie et Gtnetique Evolutives. CNRS 9 1198 Gif-Cedex, France

146 Book reviews

Foundations of Ecology. Just classic, nothing new. Classic papers with commen- taries, edited by L. A. Real and J. H. Brown, Univ. of Chicago Press, 1991. ISBN: o-226-70594-3.

This book contains 40 classic contributions to ecology spanning almost 100 years of the discipline. The earliest was published in 1887, the latest, in 1974. These papers are distributed over six sections, each representing a logical subdivision of ecology, e.g. history, methodology and theory. Each section begins with an in- troductory commentary. This book is dedicated to the students who will write the classics of tomorrow and the royalties go to support graduate and postdoctoral research in ecology.

The purpose of this volume, according to the editors, is to provide a collection of papers that have made a substantial contribution to our thinking about ecological processes. The book achieves this admirably, though many papers that also meet these criteria were left out because of lack of space. But why do we need such a book full of papers, many of which most ecologists already have in their filing cabinets? Yes, it is handy to have these papers, the ones that everybody refers to, at your fingertips, and yes, we still have a lot to learn from these classic papers (Lawton, 1991) but this seems a weak justification for publishing this collection. On the other hand, such a collection of classic papers with commentaries could provide the reader with new insights, new ideas and new interpretations. Therefore we examined the commentaries to see what new wisdom they imparted. The answer was, unfortunately, not much. Some of the commentaries were very good. They were well and clearly written, and showed how the classic papers in that section had influenced further developments in ecology. Some were really very disappointing, offering not much more than a brief synopsis of the papers that followed.

Although, the book contains little additional information to that found in the papers, they still have a lot to say for themselves and the organisation also provides insight. Collections of papers on different kinds of systems, organisms and questions render the common elements in these very diverse papers accessible and even obvious. What do papers on thrips, pollen profiles, predation and energy flow have in com- mon’? In fact, the common element in the papers in “Case studies in natural systems” (Part 5) is the process of acquiring the information presented. All these papers in- clude a large descriptive component, sometimes representing several years of observation, which proved necessary to develop theory and further insights. This contrasts with the current tendency of constructing theory and then looking des- perately for applicable data, a practice that leads to theory being far ahead of tests.

Reading this collection of papers, we were also struck by the general lack of ecological genetics. It was mentioned in the commentaries to Parts 3 and 6, respectively by Kingsolver and Paine, and Lubchenco and Real, but cleverly avoided in the selection of papers. If we try to classify the style of ecology represented in this book, we would have to agree with Kingsolver and Paine in calling it the ecology of average individuals (p. 315).

What did we learn from this book? We had already read a number of these papers, but having them together allowed us to recognize the common elements. In addition, this book demonstrates the evolutionary change that ecology itself has

Book reviews 147

undergone over the past century, from purely descriptive vegetation research, through population dynamics to modern experimental research. Despite the rather variable quality of the commentaries the whole of this volume is indeed more than the sum of its parts.

References

Lawton, J. H. 1991. Warbling in different ways. Oikos 60: 273-274.

Hans P. Koelewijn and Jacqui A. Shykoff Nederlands Instituut voor Oecologisch Onderzoek Afdeling Populatiebiologie van Planten Boterhoeksestraat 22 6666 GA Heteren, The Netherlands

Haynes, G. 1991. Mammoths, mastodants and elephants: biology, behavior and the fossil record. Cambridge University Press, Cambridge. 413 p. ISBN:O-521-38435-4

One of the most intriquing mysteries in paleobiology concerns the comparatively sudden, mass extinctions of many large mammalian herbivores, particularly mastodonts and mammoths, during the late Pleistocene. The most widely enter- tained hypotheses concerning the ultimate demise of these creatures are climatic change leading to catastrophic die-offs and megafaunal overkill by human hunters. Evaluations of these hypotheses rely largely on information in the fossil record which is often too ambiguous to allow one to make definitive conclusions. Thus, interpretations of fossil assemblages are typically restricted to the realm of simple description or educated speculation. Certainly, archaeology is at a disadvantage relative to scientific disciplines which routinely conduct experiments to eliminate one or another candidate hypothesis. In this book, however, Haynes is able to link the experimental approach with archaeology and shows us a way around limitations in the fossil record. Recognizing that declines in modern elephant populations, due to recent climatic change (drought) and poaching, are reminiscent of circumstances in the late Pleistocene, Haynes is able to use information about causes of mass mortalities in modern elephant populations to reevaluate the hypotheses about causes of patterns in fossil mastodant and mammoth bone assemblages.

The book is divided into three main sections. The first section establishes a taxonomic, anatomical and behavioral link between modern elephants and their prehistoric cousins the mastodonts and mammoths. Haynes examines the relation- ship between social structure, habitat use and life history attributes of modern elephants. He shows how these characteristics affect survival and reproduction especially as they relate to the demographic structure of stable and declining populations. He then argues that similar demographic attributes may be expected in

148 Book rewews

mastodont and mammoth populations that existed under similar ecological circum- stances. In the second part of the book, Haynes describes actualistic studies of mass deaths of modern elephants owing to mortality agents such as starvation during droughts and wholesale culling of populations by humans. Moreover, he provides detailed accounts of subsequent utilization of elephant carcasses by humans. He is also able to trace the time course of bone site disturbance and preservation over the span of ten years. These actualistic studies provide characteristic demographic profiles in bone assemblages that can be matched to both the demographic structure of the live population prior to the mass death and the mortality agent leading to the bone assemblage. This sets the stage for the third section of the book in which Haynes reevaluates the patterns in classic fossil mastodant and mammoth bone sites. Haynes uses the demographic profiles of elephant bone sites arising from different mortality agents as templates for evaluating patterns in fossil bone assemblages. In this respect, he is better able to reconstruct the events that most likely led to the different mammoth and mastodont bone assemblages. It turns out that the demographic structure of many fossil assemblages fail to match demo- graphic patterns of modern elephant bones resulting from mass kills or even selective harvests by humans. Consequently, the work casts doubt on the hypothesis that human hunters were the ultimate cause of megafaunal extinctions in the late Pleistocene. Rather, the demographic profiles in the fossil record suggest that human populations probably took advantage of animals that were already in a weakened state due to climatic change producing unfavorable ecological conditions.

Recognizing that the evidence in support of the authors thesis is not conclusive, the book at least demonstrates how we might use information from “experiments” on extant animal populations to unravel patterns in the fossil record in a scientifi- cally rigorous fashion. The book offers a wealth of information on the biology and archaeology of elephants, mastodonts and mammoths. The author has done a commendable job of researching the subject matter and he provides many detailed descriptions of major mastodont and mammoth bone sites. My only complaints are that the author tends to be too anthropomorphic in his descriptions of elephant behavior and, to support his thesis, he sometimes makes assertions about ecological similarities between elephants, mastodonts and mammoths that are based on weak evidence. Nevertheless, to be fair, the author does present other possible interpreta- tions of data so the reader may make up his or her own mind. The book is easy to read. Haynes has made every effort to explain the subject matter in a way that can be understood by individuals with widely different backgrounds. The book should appeal to readers seeking a thorough introduction to ecology and paleobiology of mastodonts, mammoths and elephants as well as professionals wishing to consider a different approach to examining the fossil record.

Oswald J. Schmitz Yale University, School of Forestry and Environmental Studies 370 Prospect St. New Haven, CT 06511, USA

Book reviews 149

Martin Lockley: Tracking Dinosaurs. A New Look at an Ancient World. 238 pp. Cambridge University Press, Cambridge 1991. Paperback $14.95. ISBN: O-521 - 42598-O.

It is a popular and very widespread myth that dinosaur tracks and traces occur quite rarely compared to dinosaur bones, the latter constituting therefore the main body of empirical evidence on dinosaur life. Martin Lockley, one of the world’s foremost experts on dinosaur trace fossils, has written a nice little book in order to dispel this myth and to present to the lay reader the vast variety of important evidence derived from dinosaur tracks and traces.

Lockley has done this job superbly. He explains very clearly and in the simplest words, how various dinosaur tracks and trace types originate and what is their paleobiological and paleoenvironmental significance. He properly emphasises an understanding of the state of preservation of tracks and traces: misinterpretation of imperfectly preserved trace fossils has frequently resulted in misconceptions of their meaning. Lockley further discusses the implications that dinosaur tracks and traces have for our modern understanding of locomotion as well as individual and social behavior of various dinosaur groups. Finally, he describes such oddities as plants and animals trampled by dinosaurs, and comes to his main and, I believe, most interesting point ~ to the so-called megatracksites, or locations unusually abound- ing in dinosaur tracks and traces, often revealing thousands and even hundreds of thousands of individual tracks or traces. These are indeed jewels of paleontological research. The book ends with a short guide to the most famous localities where dinosaur tracks and traces can be visited and looked at.

This is undoubtedly a nice, readable, and valuable book. I must admit, however, that I would prefer to have a more academic one, a book that would tell me not only how much can be deduced from dinosaur tracks and traces but also how to proceed with such a deduction, what are the assumptions and limitations that a researcher must struggle with in this area. In short, I feel that there is a need not only for a book on dinosaur tracks and traces written for true amateurs and tourists, but also for one oriented toward fellow scientists and graduate students. Lockley’s book does not fill the latter niche.

Antoni Hoffman, Institute of Paleobiology Polish Academy of Sciences Al. iwirki i Wigury 93 PL-02-089 Warszawa, Poland

S. Blackmore and S. H. Barnes (eds.), 1991. Pollen and Spores: Patterns of Diversification. Oxford Science Publications, 391~~. ISBN: O-19-857746-X.

This book contains papers presented at an international symposium entitled “Pollen and Spores: Patterns of Diversification”. The aim of both the symposium

1.50 Book reviews

and the book was to study the patterns of diversification and the diversity of pollen grains and spores, from 3 main points of view:

-ontogenic studies -systematics -diversity of the fossil record. The main concern of the editors, as they point out in the Introduction, is to

underline the necessity for palynologists to analyze and interpret their data, instead of merely piling up descriptions of pollen and spore morphologies. According to them, if such is not the case, palynology would soon become a “peripheral subject”. After reading this paragraph, the reader could reasonably expect that the data presented will be considered from an evolutionary point of view, and if such were the case in all the chapters, then this would indeed be a very stimulating and innovative book. However, although some chapters do bring new insights to the ways and means of pollen diversity, several are mostly constituted of descriptive data.

The first part of the book (Chapter 2 to 8) is devoted to studies of spores from extinct and extant species. The bulk of five of these chapters consists of morpholog- ical descriptions. For example, in Chapters 6 and 7, the authors extensively review the morphological characteristics of fossil and modern spores of two fern families. Chapters 3, 4 and 8 are more concerned with problems of evolutionary interest. In Chapter 3, the description of spores found in situ in Silurian land plants leads to several hypotheses with regard to the life-cycles of these plants. Chapter 4 presents evidence of the rapid change observed in spore morphology between early and late Ordovician, which suggests important modifications of the flora. Nevertheless, the authors themselves recognize that, due to the scarcity of the fossil record, their hypotheses are mainly speculative, which is a rather frustrating conclusion! On the other hand, Chapter 8 deals with the origin of seed plants and brings constructive evidence that seed plants all originate from relatively “advanced” heterosporous ancestors (whereas the very first land plants produced only one kind of spore, i.e. they were homosporous) and this may have happened several times, suggesting a polyphyletic origin of seed plants.

The second part of the book (Chapter 9 to 20) deals with Angiosperm pollen grains. Several chapters consist of extensive descriptions of pollen grains for systematic purposes. For example, Chapter 1 I detals with the pollen morphology of some extinct and extant Palmae genera, Chapter 13 with systematics of Acanthaceae which have very variable pollen morphology, Chapter 14 with exine morphology in the family Capparaceae, but the diversity of the pollen morphs is considered from a rather “static” point of view.

Several chapters are devoted to the phylogeny and diversification of fossil and modern Angiosperms. A study of early fossil Angiosperm reproductive structure, especially their stamens, draws interesting conclusions on their pollination biology (Chapter IO). Also, the phylogeny of early Angiosperms, based on cladistic analyses, gives important information on the possible patterns of diversification of this group (Chapter 9).

Lastly, a few chapters which consider the pollen grain as an organism in itself and which study its physiology, morphology and form in conjunction with the

Book reviews 151

selective pressures encountered are indeed very innovative. In Chapter 18, the structure of the intine is studied in relation to its function during the life of the pollen grain. Chapter 19 brings new insights into the concept of the male germ unit (i.e. the sperm and vegetative nuclei that are found at the tip of the pollen tube): the authors show that the sperm cell that will fuse with the egg is not chosen at random. Consequently, one must know which of the two sperm nuclei is the real male gamete; the study of sperm-specific genes and proteins might be very useful in understanding the processes of recognition between the male and female gamete. Chapter 20 presents results of a computer simulation of the best shape of pollen grains of underwater-pollinated plants. Since in these species, pollen grains are dispersed at random in water, there must exist strong selective pressures on the shape of pollen that maximize its probability of meeting a stigma. The authors show that the pollen shapes found in nature are the same in all water-pollinated species, and that there could be evolutionary convergence for this trait.

To conclude, the papers presented in this book are not of equal interest to the evolutionary biologist: if some are important contributions to the held of palynol- ogy, others consist of descriptive and static sets of data; this is precisely what should be avoided by palynologists today.

Isabelle Dajoz Laboratoire d’Evolution et Systematique des Vegetaux Batiment 362, Universiti Paris-Sud 91405 Orsay Cedex, France