Book Reviews

Genetics - A Molecular Approach (3rd edn). T. A. Brown. Chapman and Hall, London. 1998. Pp. 469. Price £27.50, paperback. ISBN 0 412 79870 0.

There are two commonly used alternative strategies for teaching a comprehensive genetics course to first year undergraduates reading biology. The first builds on the genetics taught in biology classes in secondary schools, which in the UK at least, is largely concerned with inherited phenotypes of diploid organisms. Thus, students are familiar with dominance and recessivity, Punnett squares, sex linkage, and to some extent, meiosis. On entering higher education this knowledge may be used as a basis for a more detailed study of meiosis, leading on to genetic mapping in diploids and haploids, and only then dealing with gene function, complementation, and the molecular aspects of genetics. The course thus effectively follows the history of genetics. The philosophy of this first approach is that in starting with diploid organisms we initially stay closer to human genetics, which is intrinsically more interesting than bacterial, phage or yeast genetics, and from which many examples can be drawn. Restimulating interest in biology after the grind of school examinations is often of high priority.

The second strategy is the one used in this book, namely that of starting with DNA and its replication, moving on into gene function, protein synthesis and gene regulation, and only then dealing with the classical genetics of both diploids and haploids. The rationale here is that genetics is easier to understand once one appreciates what genes are and what they do. Furthermore it is a more fashionable approach in this era of the Human Genome Project, where almost every issue of any newspaper contains some reference to isolation of genes or genetically modified organisms.

In the final analysis it probably doesn't matter very much which method is used. This text is almost stridently molecular and only comes to classical genetics very late on. It never discusses population genetics. Its major strength is that it is very clearly written and not at all dry. The author has striven perhaps too hard for simplicity, to a point where students may find it too easy, and where complexities are sometimes ignored. For example, in discussion of control of gene expression, the lac repressor is said to bind to the DNA at a single site that overlaps the promoter so that RNA polymerase binding is prevented. In fact, as has been known for about 10 years, the repressor can bind simultaneously at two sites, thus causing the DNA to form a loop, and does not block RNA polymerase binding but prevents it from unwinding the DNA to allow transcription to begin. Oversimplification such as this, sometimes made me wonder whether the book was intended for a secondary school readership. I noted a number of other errors: two that particularly grated were that E. coli has 2400 genes (in fact more than 4000), and that during initiation of protein synthesis in bacteria, the ribosome first binds the upstream initiation sequence and then, somehow primed for recognition, searches on down to the initiation codon. In fact the two sequences are bound simultaneously.

A feature of the book that I liked was the provision of blue boxes either in the wide margins or interspersed within the text. These explained more difficult points, took the discussion a little deeper or gave thumbnail sketches of some of the notable personalities in genetics. I also, on the whole, liked the figures. They were clear, spare, not at all flashy and only contained two colours: blue and black. However, even more than in most texts, they tended to be misleading as to scale.

I do not feel very competent to make judgements about the coverage, but I was surprised that complementation was barely mentioned. Our students tend to have difficulty with this important concept. I was also surprised that tetrad analysis was given so much space in a brief discussion of eukaryotic mapping and in the section on making maps for the Human Genome Project, that radiation hybrid mapping was omitted. Otherwise, for a text so wedded to the molecular, the coverage seemed good. I particularly liked the chapter on the human genome.

Overall, Genetics — A Molecular Approach is a good read and I enjoyed it. However, it has sufficient defects that we shall recommend it to our students as we did the second edition, as a useful but not essential supplement to our main genetics text.

Evolutionary Biology (3rd edn). Douglas J. Futuyma. Sinauer Associates, Inc., Sunderland, Massachusetts. 1997. Pp. 794. Price £26.95, hardback. ISBN 0 87893 189 9.

I am pleased to be able to report the enhanced fitness of a ‘hopeful monster’. Futuyma uses this Goldschmidtian term to describe the latest edition of his book, which many would agree is already well established as the leading ‘senior undergraduate’ text in Evolutionary Biology worldwide. It is indeed true that the new edition has reached a more monstrous bulk than its predecessors, having added a further nine chapters and 200 pages — enough for a book in itself to most of us. However, the extra material is largely to accommodate additional topics, and so to render the book even more comprehensive, rather than to facilitate an increase in verbosity.

The overall structure of the book has been greatly modified compared to the second edition. The main change (in effect a ‘throwback’ to the original) is to put the diversity, phylogeny, history and geography of life before population genetics and evolutionary ecology. This structure follows the ‘pattern before process’ urgings of the cladists. I find this sequence much preferable to the previous (inverted) one; I agree with Panchen (1992) that we need to deal with the explanandum (that which we seek to explain) before the explanans (the explanation itself).

In general, this book is clearly written and easy to read — even more so than the previous editions as a result of a deliberate move to a more ‘relaxed’ style, as Futuyma notes in the Preface. There is a little duplication of material here and there, but not enough to worry about. An example involves his treatment of ‘character displacement’. Throughout the book, Futuyma uses bold print to define important terms - a very good idea. It would seem reasonable to define each term only once. However, ‘character displacement’ is defined twice using this method - first on page 260, then again on page 554. (Luckily, the two definitions are approximately the same!). The advantage of such duplication is that it makes each section more self-contained, which is important in an undergraduate text; the disadvantage is a contribution to the book’s ‘monstrosity’.

I was of course keen to see whether and how Futuyma dealt with the recent explosion of work on the evolution of development. I did not have far to go to find a reference to this field of endeavour — line 7 of the Preface to be specific. Here, we are told that ‘Subjects such as evolutionary developmental biology and evolutionary physiology are growing with new vigor’.

The main discussion of the evolution of development is in Chapter 23. For the most part this chapter, like the others, is clear and accurate. However, in a few places I found the discussion a little misleading. For example, now that we know that the Bithorax Complex in Drosophila consists of three transcription units (Ultrabithorax, Abdominal A and Abdominal B), is it misleading to talk of ‘the bithorax gene’ (p. 665). Also, I would have preferred to see the section on homology (p. 669) called ‘The Concept(s) of Homology’ or simply ‘Homology’ rather than ‘The Problem of Homology’. Admittedly, advances in comparative developmental genetics have added some twists to the concept — for example, when genes that are clearly homologous have broadly similar expression patterns in appendages that are clearly not homologous (see Abouheif et al. 1997). However, such findings are best viewed in a positive light as refining our ideas on the nature of homology, rather than in a negative light as being ‘problematic’.

But these are minor quibbles. Basically, this is a well-written book. It is also a nicely produced book (except for the loss of the tail-end of the last chapter). And at £26.95 (hardback), it is an absolute bargain. So, would I recommend its purchase? Absolutely.

Plant Life Histories — Ecology, Phylogeny and Evolution. Jonathan Silvertown, Miguel Franco and John L. Harper (eds). Cambridge University Press, Cambridge. 1997. Pp. 313. Price £19.95, paperback. ISBN 0 521 57495 1.

This book will have a few chapters of great interest for many different kinds of biologists although, like many edited volumes, it suffers from a lack of coherence, and there is even a feeling of controversy between different contributors. For me, the highlights of the book are the two chapters on the evolution of plant reproductive traits, i.e. my own research area (the chapter by Barrett, Harder and Worley, which makes use of a fine-scaled phylogenetic dataset for an interesting comparative analysis, and particularly the chapter by Schoen, Morgan and Bataillon, which reviews some new theoretical results and does not use comparative methods). The third chapter in the section on reproductive traits (Hamrick and Godt's discussion of genetic diversity patterns is plants) also deals with an interesting topic. It is more up-to-date than their 1990 review of these data, in that new data have been added (although phylogenetic information on the taxa included is not made use of). However, the patterns are treated almost entirely as empirical observations and little attempt is made to explain why they might occur, and the diversity measures used are not explained to readers who might not know how they behave.

Readers with different interests will find other chapters of greater value, but the overly empirical attitude just criticised is evident in several of them. The book's one common theme is the use of comparative methods to test ecological or evolutionary hypotheses, and this is perhaps too little common ground, given that there is no single comparative method but a set of different techniques that can be applied to try and ask different kinds of questions. No chapter lays out the rudiments of the methods, or reviews what kind of phylogenetic information is needed for the methods to be used, so it is often unclear whether the crude phylogenies used by many of the studies (often the results from the Chase-coordinated rbcL analysis) are fine enough or reliable enough to support the tests that are done. A similar feeling of lack of deep critical thought arises elsewhere, for instance the use in some chapters of r and K selection without even brief review of how useful these concepts may be. Several chapters are silent about why comparative tests are best for testing their questions of interest. A more critical attitude would have made for more satisfactory reading. Only the chapter by Westoby, Leishmann and Lord is exciting to read, and argues issues with passion. Overall, there is too much of an impression that any question that interests one can be studied by some kind of comparative test. The focus in this book is rather limited to this kind of test, and only occasionally do we see how such results can be integrated with other information to help answer interesting biological questions.

The Origin Of Animal Body Plans: A Study In Evolutionary Developmental Biology. Wallace Arthur. Cambridge University Press, Cambridge. 1997. Pp. 338. Price £45.00, hardback. ISBN 0 521 55014 9.

Wallace Arthur has no axe to grind in his excellent new book on evolution and development. He steers a pragmatic middle course between the two complementary approaches to ‘evo-devo’. One of these approaches puts the emphasis on diversity, and tries to explain evolution by looking for differences in developmental mechanisms. Relatively few workers have adopted this approach. By contrast, many other biologists place the emphasis on homology and the conservation of developmental mechanisms across large evolutionary distances.

Arthur argues for a diversity of patterns in animal development rather than a universal one. Yet he also recognises that there are common themes, such as the increasing difference between species as they advance through development. Arthur addresses this phenomenon using an ‘inverted cone’ model, one of the many things in the book which I found useful and thought-provoking. Citing experiments on Drosophila development, he argues that changes in early development have greater phenotypic effect than changes made at later stages — hence the inverted cone. Looking at this model I can imagine, contrary to expectations, that early developmental stages may be major targets for natural selection; divergence in late stages could in part reflect tiny modifications in earlier stages.

The concept of ‘body plan’, the central theme of the book, could have been explored more fully. For example, is the body plan a set of conserved developmental fields, or is it simply a cluster of taxic homologies seen in adults? However, Arthur's book is very broad in its scope, and its author acknowledges that he is writing at the interface between a large number of disciplines. These include systematics, genetics, palaeontology, molecular embryology, ecology and other fields. One cannot expect a fully developed synthesis to emerge from these disparate fields in the near future but I think that bringing so much diverse material together has been very helpful; as an embryologist I learned a great deal from reading the book.

Such a wide-ranging review also makes it clear that there is something missing from the modern synthesis. But what is it? To me, the great under-explored territory in ‘evo devo’ is diversification within taxa. For example, I feel sure that we will be able to understand why bats have big forelimbs, or why snakes have no legs, by undertaking comparative molecular studies on early developmental stages. It's time to blow the cobwebs off the old comparative embryology books and start looking at how the embryos of different species do things differently. A useful first step in the rehabilitation of comparative embryology would be to revise Haeckel's drawings, reproduced by Arthur, which imply that evolution has no effect on early vertebrate development. But wait — I can hear the sound of axes grinding....

Advances in Biometrical Genetics. P. Krajewski and Z. Kaczmarek (eds). Institute of Plant Genetics, Polish Academy of Sciences. 1997. Pp 318. Price $25.00, paperback. ISBN 83 85583 16 5

Advances in Biometrical Genetics presents the proceedings of the tenth meeting of EUCARPIA, section ‘Biometrics in Plant Breeding’, which was held as Pozna´n, Poland from 14 to 16 May 1997. This meeting is a three-yearly event and the proceedings of each meeting are published under the title Biometrics in Plant Breeding. This is the first time that the proceedings have been published under a different title, which in my view is not entirely justified. A cursory look through the book convinces the reader that a majority of the articles are breeding orientated and there are hardly any papers which deal with pure biometrical or quantitative genetic theory/methodology.

The Biometrics group meetings are usually a European affair and the tenth meeting was no exception. The list of participants shows that nobody came from outside Europe. Even the invited speakers were all European and it is a pity that no-one was invited from North America where a great deal of DNA marker and QTL work is currently going on. Further, the meeting was dominated by Polish, French and Dutch scientists who contributed almost 65% of the papers, only 7 contributions came from Germany and UK and nobody contributed from Italy. Nevertheless, all major groups working on QTL location/marker analysis and other important aspects of biometrical/quantitative genetics (in Europe) were represented at the meeting.

The book is divided into two parts; the invited papers give a good coverage to g×e interactions, QTL analysis, optimizing breeding plans and applications of doubled haploids in breeding and genetical research, which were the main themes of the meeting. I particularly enjoyed reading the reviews by Jansen (QTL mapping) and Snape (use of doubled haploids in breeding and genetical research) while the articles by Calinski et al. and Geiger and Tomerius also summarized the latest thinking on g×e interaction and optimal breeding plans eloquently.

The 45 contributed papers are organised in authorship order and it is frustrating to search for articles on a particular theme unless one is familiar with the authors' specializations. Among the four themes, most papers (11) are on g×e interactions and these cover the specific problems facing the breeding of crops like maize, barley and sugar beet etc. The nine papers on DNA markers and QTL location give an extended coverage to the whole range of research from the use of molecular markers in linkage analysis to marker-based selection. There are four papers on uses of anther culture and doubled haploidy in plant breeding, another four on DUS testing and several others on topics such as genetic diversity, genetic distance/similarity, recurrent selection and response to selection. Finally, Rebai et al. describe the characteristics of the MultiCrossQTL software package which can be used for QTL mapping in complex populations derived from mating designs such as diallels and factorials, van Ooijen and Maaliepard provide information on a new version of MapQTL that has become available on the world wide web and Law et al. apply the SERGEN package to analyse variety-by-environment interactions.

In general, the book presents a wide review of the use of biometrical methods in plant breeding and is well worth reading. However, it is not for beginners and therefore can not be recommended as a major text to undergraduate or postgraduate students. Finally, although the book reads very well, it could do with language editing which would have improved its quality even further.