Evolutionary Conservation Biology. Régis Ferrière, Ulf Dieckmann, and Denis Couvet, eds. Cambridge Studies in Adaptive Dynamics, Cambridge University Press, United Kingdom, 2004. 428 pp., illus. $95.00 (ISBN 0521827000 cloth).
Evolutionary Conservation Biology is an ambitious attempt to integrate genetics, ecology, and demography in order to manage species from a conservation biology perspective. Written in the style of an advanced textbook, it provides a current review of key topics in conservation, population biology, and evolutionary ecology. The book consists of 19 chapters by 30 contributing authors, including some of the leading writers in their fields. It is divided into five parts dealing with the theory of extinction (part A), the pace of adaptive response to environmental change (part B), the genetic and ecological bases of adaptive responses (part C), spatial structure (part D), and community structure (part E).
Part A consists of three chapters that consider the theory of extinction at scales ranging from the individual to the metapopulation. The goal of this section is to introduce the theoretical tools needed to evaluate the risk of extinction. This part would have been stronger had it been possible to evaluate the theoretical considerations by comparing them to empirical studies. For example, the only genetic model incorporated into the theory is one based on thousands of loci that each have two alleles (a wild allele and a mutant allele); the mutant allele at each locus has a very small deleterious effect. The actual parameter values used in this model (mutation rates and selection coefficients at many individual loci) cannot be estimated empirically in real populations. Some effort to relate the amount of inbreeding depression expected with this model to estimated values of inbreeding depression (Keller and Waller 2002) would have been very helpful.
Part B is the strongest section of the book. Its four chapters do an excellent job of considering the theory and presenting empirical examples of adaptive response to environmental change. Dick Frankham and Joel Kingsolver are especially effective as they address the possible importance of adaptation for the long-term survival of species facing abiotic environmental change.
Part C is a mixture of three chapters that do not seem to present a coherent theme of the genetic and ecological bases of adaptive responses. Michael Whitlock and Reinhard Bürger offer a good discussion of the fixation of new mutations in small populations and the role it may play in extinction by “mutational melt-down.” Also in this section, Ulf Dieckmann and Régis Ferrière argue that “evolutionary suicide” (the adaptive increase by individual selection of genotypes that may accelerate the probability of population extinction) “occurs for a rich variety of ecological settings.” However, they do not present any empirical examples or discuss when conservation biologists should be particularly concerned about this possibility.
Part D consists of four chapters that deal with spatial structure. Unfortunately, there is little integration between the genetic chapter in this section, by Oscar Gaggiotti and Denis Couver, and its counterpart in part A on the spatial dimensions of population viability, by Mats Gyllenberg, Ilkka Hanski, and John Metz. Each of these two chapters is a valuable contribution to the literature; however, the editors make no apparent attempt to integrate them. For example, some consideration of how genetic data from natural populations can be used to construct and use more realistic models of population viability would have been useful.
Part E contains three chapters that deal with community structure, including coevolution, ecosystem dynamics, and the interaction between rare species and their close relatives. Michael Loreau, Claire de Mazancourt, and Robert Holt make the important point in their chapter on ecosystem evolution and conservation that the species-based approach and the ecosystem- or habitat-based approach to conservation are not in conflict with each other. They demonstrate the importance of considering both of these approaches in their consideration of plant–herbivore interactions.
Many of the individual chapters in this volume are excellent current reviews of a variety of relevant topics. Nevertheless, the book suffers from a problem common in such collections: The treatment is extremely uneven. For example, the primary chapter on population viability, by Wilfried Gabriel and Régis Ferrière, is extremely mathematically sophisticated. It jumps right into diffusion theory for stochastic models and bases many of its conclusions on the concept of quasi-stationary distribution. The chapter on spatial dimensions of population viability, by Mats Gyllenberg, Ilkka Hanski, and Johan Metz, continues in this vein. Consider the following conclusion about the extinction probability of a metapopulation:“The process can be described in terms of its quasi-stationary distribution, which is given by the left eigenvector (normalized to a probability distribution) that corresponds to the dominant eigenvalue of the transition matrix Q restricted to the transient class Ξ\O” (p. 74). This contrasts starkly with the description of measuring genetic variation in Oscar Gaggiotti and Denis Couver's chapter on genetic structure in heterogeneous environments, which explains that the mean percentage of heterozygous loci per individual is estimated by dividing the number of heterozygous individuals by the total number of individuals (p. 230).
The editors' goal is laudable. Nevertheless, the ambitious integration of genetics and ecology that they aimed for will not be found in this book. The individual chapters are generally solid reviews of theory, but they contain very little consideration of how that theory relates to real populations or to empirical information from populations. There is also a complete absence of any consideration of molecular genetic data. For example, the term “microsatellite” does not even occur in the index.
Throughout the book, genetic considerations seem to be treated at a much more basic level than are ecological considerations. For example, the discussion of heterozygous advantage as a mechanism for maintaining genetic variation (p. 123) considers only loci with two alleles. Also in that chapter, the term “linkage dis-equilibrium”is defined incorrectly. Linkage disequilibrium is the nonrandom association between alleles at two loci in a population. The definition on page 125 states that “particular alleles are inherited together more often than expected under Mendel's laws on independent assortment.”This is a definition of linkage, not of linkage disequilibrium. Close linkage is one common cause of linkage disequilibrium, but linkage disequilibrium can also occur in the absence of linkage (e.g., because of hybridization).
Perhaps the biggest weakness of this volume is that it does not recognize many of the previous efforts of conservation biologists to achieve the same goals as those of its authors. (For example, the 1981 book Conservation and Evolution, by Otto H. Frankel and Michael E. Soulé, is not cited.) Conservation biology had its roots in the very integration of evolution with genetics and ecology that this book attempts.
Evolutionary Conservation Biology contains a number of excellent reviews of a variety of current topics in conservation, and I am happy to have it on my bookshelf. Nevertheless, I cannot recommend it to a general audience. It does not achieve its goal of integrating genetics and ecology. In addition, the treatment is far too theoretical to be of value to practicing conservation biologists who are responsible for managing species.