ASBS Newsletter – Book Review

The Compleat Cladist
A Primer of Phylogenetic Procedures

written by E.O. Wiley, D. Siegel-Causey, D.R. Brooks, and V.A. Funk

(From ASBS Newsletter Number 76, September 1993)

Publisher: University of Kansas Museum of Natural History Special Publication No. 19. 1991. x+158 pp. ISBN 0-89338-035-0.
Available from: Museum of Natural History, 602 Dyche Hall, University of Kansas, Lawrence KS 66045, U.S.A.

In some of my other book reviews, I've made the odd caustic remark about the often woeful way in which cladistics is discussed in general taxonomic books. By and large (with one exception, see Austral. Syst. Bot. Newsletter 71: 35), these introductions seem to be written by people who do not have any depth of knowledge about cladistics, and who have very little practical experience with cladistic analyses of biological groups. Consequently, these introductions vary from dubiously inadequate to definitely inaccurate.

So, just to even things up a bit, maybe it's about time that I reviewed an introduction to cladistics that has been written by people whom no-one could ever claim were not died-in-the-wool fundamentalist cladists. Can cladists write an introduction to cladistics that is not inadequate and/or inaccurate? Can cladists write an introduction to cladistics that contains information that is both necessary and sufficient for a working understanding of the topic? Can cladists write an introduction to cladistics that is readable by non-cladists?

The answers to these questions are, not surprisingly, "yes" and "no". This book contains few inadequacies, almost no inaccuracies, all of the necessary information, most of the sufficient information, and it should be readable (and understandable) by anything that can be placed in a one-to-one relationship with Homo sapiens. That's as good a recommendation as you'll ever get from me.

However, I have heard that this book was not always of a high standard. A number of people are acknowledged for "valuable comments" on early drafts of the book, and, if rumour is to be believed, many of these comments were aimed at removing outrageous inaccuracies. If so, then these people deserve our thanks as well (and perhaps we should conclude that some cladists are no better at introducing cladistics than are any other people).

Perhaps the most bizarre remaining feature of the book is the complete contradiction between the title of the book and its sub-title. The authors freely claim that their book is neither "compleat" nor complete, so why use this ridiculous title? The sub-title is, in fact, a much more accurate description of the Contents of the book itself.

The book is basically a practical workbook designed to accompany a university teaching course, but it can easily be read as a free-standing work. There are seven chapters, each of which introduces a particular topic in simple straightforward language, and most of which then contain detailed worked examples of simple analyses, followed by a set of exercises for the reader to try for themselves. All of the worked examples and exercises can easily be done by hand, since it is the general principles behind the analyses that the book focuses on, and the answers to all of the exercises are at the back of the book. Each chapter also provides a good (i.e. selective) guide to the original literature on each topic, and the book is almost worth its price for this feature alone.

The chapters include:- Introduction, terms, and concepts; Basic phylogenetic techniques; Character argumentation and coding; Tree building and optimization; Tree comparisons; Classification; and Coevolutionary studies. This covers all of the necessary topics for an appreciation of cladistic techniques, and I suppose that one could argue that the topics are also sufficient for such an appreciation. The only misleading title is the last one, since all of the examples in the chapter are about biogeographic studies rather than co-evolution in the strict sense.

The book thus takes the reader through a logical and carefully-constructed sequence of topics, explaining the essentials, and describing clearly how the techniques work. None of the topics are treated lightly, but neither are the essentials lost in a mass of detail. The book thus presents a nice balance for the beginning student or the older taxonomist who wants to find out what the fuss is all about.

The inadequacies of the book mostly arise from a desire (completely understandable) not to go into too much detail about some of the topics. For example, tree-building is restricted to the Hennig and Wagner techniques only (with a brief mention of branch-swapping), and only descriptive parsimony is considered as a criterion for choosing the optimal phylogenetic tree (with a brief mention that maximum likelihood and least squares methods also exist). This means that the book really is nothing more than a primer on these topics (which is, after all, all that it claims to be). The best introduction to the niceties of the broad range of cladistic analyses that are currently available is still the chapter by David Swofford and Gary Olsen in Molecular Systematics (edited by David Hillis and Craig Moritz; Sinauer Associates).

I'm also not sure how successful the presence of the exercises would be outside of a university setting. It is my experience (e.g. from having colleagues sit in on some of the subjects that I teach) that no-one but students who are forced to do them (e.g. by making them assessable) will ever bother to try the examples for themselves. This is a pity, because the process of having to think a problem through for yourself is one of the single most effective ways of reaching a true understanding of a particular topic; and this is doubly so for any topic involving data analysis techniques. Therefore, the exercises are actually an integral component of this book; but how many general readers are likely to reap any benefit in practice from their presence? (In case you're wondering, I did do the exercises when I read the book.)

One topic that could have usefully been expanded is the discussion of interpreting cladograms. I find, for example, that novices often don't realize just how many ways there are of drawing exactly the same tree (i.e. a tree that contains exactly the same phylogenetic information), and therefore they often treat identical trees as being different just because some of the branches have been rotated. This problem becomes even worse when you are dealing with unrooted trees (as often occurs when analysing molecular data, for example), and I have seen even experienced people mis-interpret such cladograms. I would even go so far as to suggest that this is the single biggest hurdle to overcome when teaching phylogenetic analysis (what's the point of getting the analysis right if you can't correctly interpret the answer?), and so I would personally have put much greater emphasis on this topic than do the authors.

Inaccuracies are few, and are usually minor, which is a relief. There are four typographical errata listed for the book, and I came across several more, including:- capitula on page 46 should be capitulum; a genus name is not italicized on page 47; page 51 refers to Exercise 4.5 instead of 4.4; Table 4.6 is identical to Table 4.5, and is thus redundant; the word "worst" appears to be missing from page 74; there seem to be four spurious lines on page 142 (which is a worry, because it is at the beginning of the answer to one of the exercises); and characters 3-1 and 4-1 are missing from one of the cladograms on page 149 (which is also an answer to one of the exercises).

There are also a few places where I could not follow what was being said (which may be a problem with me rather than with the book). For example, "basal bifurcations" are referred to on page 40, which seems to be an odd expression for the concept that the authors appear to be discussing at the time; I cannot see any reason for wanting to include fossils in a cladogram (page 106); and some of the biogeographic interpretations about dispersals (pages 125 and 158) are not clear to me.

I may as well list a few of my minor quibbles, while I'm about it (it's good therapy to get them off your chest, or so I'm told). Firstly, the language of the book is very carefully worded, almost to the point of pedantry. Those of you have read any of Ed Wiley's other works will instantly recognize the writing style, and it does not always make for easy reading. Furthermore, many of the examples and exercises are based on real data sets, and this often leads the authors to provide "hints" for some of the solutions, in order to avoid the imperfections that inevitably appear in the real world. The idea of using real data sets is generally a good one, because it makes the whole enterprise more realistic for the reader, but the limitations of this approach must be recognized, and a judicious mix of real and artificial data sets is usually the best option.

Some of the terminology may also surprise a few people. The authors have deliberately chosen to use the "transformation series / character" combination in place of the more common "character / character state" combination that appears in the literature. Their argument for doing so is logical, but any reader will have to be careful about potential confusion when transferring their reading to the original literature. The co-evolutionary section also refers to the "missing taxon" and "widespread species" problems, which seems to be a rather inconsistent mixture of terminology.

Moreover, I do not agree with the suggested treatments of polymorphic taxa - why not sub-divide them into monomorphic terminal taxa? Nor do I think that consensus trees are of much use in cladistic analysis - you can't plot characters onto them, and they are unlikely to actually represent the true phylogeny, so why not try and make a rational choice from among the competing trees? Nor do I agree with the claim that phylogeneticists are neither splitters nor lumpers when erecting a classification from their cladogram - all that possessing a phylogenetic tree does is formalize the way in which the cladist goes about the lumping or splitting.

Finally, in all except two places in the book, taxonomists are referred to as "she". This seems to me to be a bizarre solution to the almost universal male sexism that pervades most taxonomic books, because it is just as sexist to treat everyone as female. There are better solutions to the problem than this, the most effective suggestion to date being to treat people as plural (thus using "they" instead of "he" or "she").

All in all, this book is one of the best introductions to the process of cladistic analysis that I have read so far. It is specifically written to introduce the topics in a learn-by-doing fashion, which engenders a type of understanding (a "feel", if you like) that does not come from a purely theoretical introduction. The book is certainly nothing more than a primer, and I wouldn't want anyone to feel that they were an expert with nothing more than this book as a background. But as a starting point, you could do a lot worse (and many people have).

Reviewer: David Morrison
Department of Applied Biology
University of Technology, Sydney