2 of 2 people found the following review helpful:
4.0 out of 5 stars
Though jargon-laden, gem-studded, August 14, 2005
This review is from: Ecological Versatility and Community Ecology (Cambridge Studies in Ecology) (Hardcover)
This book is on ecological versatility and its bearings on community ecology, not a community-ecology book in itself. The main thrust of the book is simple but intriguing, the exploration of ecological "noise" as it is reflected in what community ecologists would call niche breadth, and biogeographers would perhaps generically call distribution (Mac Nally calls ubiquity to spatial versatility). Much of the book is devoted to ecological versatility (seven chapters), with only one chapter on ubiquity. A preface, a wrap-up recapitulation, a glossary, two appendices, and an index complete the main body of the book. At first glance it would appear that the author is just staking a claim on the creation of new ecological jargon (e.g., versatility and ubiquity), but when one reads the book from cover to cover, there certainly seems to be need of some well-defined new terms for the oft-ignored aspects of plasticity or opportunism in resource use. I completely agree with Mac Nally that community ecologists have been mostly blinded in studying specialization, which seems to be rather rare in Nature though surely spectacular, and not the unglamorous generalization (which is exceedingly commonplace). I generally liked this book, I learned quite a few things, but still have some criticisms that I will detail below.
The book's preface is just that, although one may mark later that two of the most influential references for Mac Nally's rationale are Fox and Morrow (1981) and Futuyma and Moreno (1988). Chapter 1 lays the groundwork for the remainder of the text. Ecological versatility is defined as "the degree to which organisms can fully exploit the available resources in their local environment." Resource utilization is considered separate from exploitation, which in essence is fitness gained by utilizing resources. Although this distinction is much emphasized, in the remainder of the text Mac Nally comes to grips with the reality that fitness is extremely difficult to measure. Ubiquity denotes "the diversity of habitat types that the populations of a species occupy." This meaning seems plain enough. Formal, and slightly different definitions of versatility and ubiquity are found in the glossary.
Chapter 2 elaborates further the definition, implications, and measurement of versatility. Two maladies that permeate most of the text are fully expressed in this chapter: (a) A tendency to make detailed phenomenological distinctions whose importance sometimes appears rather obscure (e.g., perfect and imperfect substitutability and complementarity of resources), whereas others seem obviously important (ordering and aliasing of resources, use versus availability). (b) A definite tilt toward arguing with the reader every new issue that is introduced. This is curious; an analysis of the subtext suggests an excessive eagerness to convince others that Mac Nally's reasoning is indeed valid. Perhaps it makes good sense to talk about the talking when students are concerned, but to established researchers the reiteration only makes it longer to get to the point.
Chapter 3 is an extensive --though in my view, incomplete-- review of published studies of ecological versatility. It is interesting to see ecologists doing meta-analyses of their own discipline (yes, this is no simple revisionism, but a critical assessment of evidence). I think that Mac Nally forgot an essential keyword in his bibliographical search: opportunism. Most studies of opportunism in community ecology are devoted to the issue of versatility as defined by this author. Despite this important omission, Mac Nally hits his mark fine. His statistics are illuminating, and his remarks well thought out. New terms are introduced: conformance versus nonconformance indices of versatility (i.e., resource utilization gauged or not gauged to availability). Although the distinction is commendable, it is hardly applicable in field situations. The issue of how to gauge what is effectively available to any consumer has been an elusive feature in community ecology, except for very atypical situations (e.g., nectarivorous hummingbirds feeding on flowers, primary-space users --if space is a resource, which I doubt).
Chapter 4 explores the potential role of interspecific interactions in determining versatility. Herbivory (both by small and large herbivores), parasitism (including parasitoids), predation (essentially carnivory and insectivory), omnivory (an epiphenomenon much whipped-up by food-web theorists, in my view), and mutualism, are each examined as potential factors affecting the degree of versatility. Interesting distinctions are drawn in this chapter: for instance, the immense ecological and evolutionary gulf that exists between macro- and micro-herbivores, as well as among predators. This chapter is the most natural-history oriented of the entire book.
Chapter 5 was for me the most difficult to wade through. Excessive use of ecological jargon and of phenomenological distinctions with doubtful usefulness contributes little toward making it readable. Although largely building on Roughgarden's seminal differentiation of between- and within-phenotype components of niche breadth, Mac Nally manages mess up this basic conceptual layout. Excessive reasoning from a contingency-table framework confounds both Mac Nally and his readers. Surely, a combination of two rows and two columns will always render four cells, but not all of them will make ecological sense. By way of example "facultative specialization" sounds like nonsense to me, and should be disposed of the ecological lexicon as quick as possible. Obviously, if specialization is facultative, then it must be an epiphenomenon. In this same chapter, the section on exploitation strategies is brain racking. "Coherent", "resource-like", "specialized, and "incoherent" versatility defy easy comprehension unless one has a contingency-table branded in the brain. Although Mac Nally should be commended for his organizational zeal, I would have liked to see some weeding out of incoherent terminology.
Chapter 6 is a good one. It deals with the effects of population dynamics on versatility, and instead of using Lotka-Volterra analytical explorations, applies commonsensical computer simulations. Functional and numerical responses of consumers in relation to utilization pressure are given a fresh look. One may take issue with the ecological validity of phenomenological distinctions such as "hard" versus "soft" exploitation (in the first, the consumer is unable to adjust its consumption rate), but with an open mind some benefits of simulating such strategies come to light. The fate of ecological polymorphisms under constant and variable scenarios of resource use and users I found particularly interesting. The salute to metapopulation theory is a little out of context in this chapter, but it conveys an idea of the complexity of the study of versatility.
Chapter 7 deals with the effects of interspecific competition on versatility. Sorry to say so, but this chapter I found too long and rather boring. I wonder whether the view of competition being the major structuring force of ecological communities still prevails. Whipping a dead horse leads nowhere. Indeed, the main lesson that I took from this chapter was that, indeed, MacArthur was a genius who still has ecologists dealing with his thoughts 25 years after his untimely death. Another good lesson for me was to be informed of the existence of "glyphs" that synthesize the results of multivariate analyses. The best section of this chapter was, again, Mac Nally's interesting and straightforward simulations of competing species through time, depending on whether they display "hard" or "soft" strategies of resource use. The invasibility part of the chapter does not seem to me to shed much light on the subject, although I do prefer Mac Nally's simulation approach than MacArthur and Levins' analytical one. Although it is not Mac Nally's fault, it annoys me is that we community ecologists are still re-playing the same things that MacArthur did with much more elegance (and with the excuse that little community ecology was known back in the sixties). The overemphasis on exploitation competition at the expense (and virtual ignorance) of interference competition requires industrial-strength medicine, administered frequently and in large doses.
Chapter 8 brings us back to natural history. Ubiquity is the expression of versatility at the spatial scale. Mac Nally does a good job at reviewing and placing under new light previous studies of habitat use and geographical distribution. Unnecessary (and forgettable) jargon unfortunately finds its way even to this late-coming chapter: the abstruse-sounding "coenocline" surely is a synonym of the plain "gradient." Concentrating on substance, though, I found interesting the multivariate arrangement of positioning, density, and ubiquity as descriptors of species' distributions (the so-called niche pattern), and the application of real data to this hyperspace. Discussion about the relationship of ubiquity and versatility (complementarity and supplementation patterns) is a welcome addition to this area of community ecology. Although this chapter has all the appearance of having been put together hurriedly, and thus seems half-cooked, it is a very stimulating one.
Chapter 9, being a recapitulation and commentary of the previous ones, is anticlimactic. It just repeats or re-states what we have already read in the previous 300 pages, with no new insights to justify its inclusion, or at least, its length. A glossary follows, an absolute necessity given the profuse ecological jargon and neologisms used in this book. Appendix A contains a compilation of the studies analyzed to reach conclusions stated in Chapter 3, and a summary of frequently used measures of...
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