Experimental Evolution. Concepts, Methods, and Applications of Selection Experiments. Theodore Garland Jr and Michael R. Rose, editors.

I have been interested in experimental evolution for a long time. In July 1995, I organized a symposium for the meeting of the Society for the Study of Evolution in Montreal, Quebec entitled “Rapid Evolutionary Change in Wild Populations” to which I invited six field biologists (Scott Carroll, Rosemary Grant, Judy Myers, Dolph Schluter, Carmen Parmesan, and Sara Via) and no laboratory scientists. Imagine my disappointment then, when this book arrived and there was only one short chapter on field experiments. In that chapter, Irschick and Reznick argue that unlike laboratory selection experiments, field experiments inform us about mechanisms of population establishment, the prevalence of rapid evolutionary change, and the role of natural and anthropogenic catastrophic events. This seemed relatively little—considering the difficulty in funding long-term field experiments—so I continued to read the remaining 730 pages. Much of this book is about laboratory selection on microorganisms, insects, and mice. What surprised me was my favorite chapters were not those that I would have predicted from their titles. In Chapter 1, the editors argue that laboratory natural selection (LNS) experiments are fundamentally different from the more familiar artificial selection experiments. In LNS experiments, the researchers manipulate the environment, the surviving members of the population are freely allowed to breed, and the researchers periodically monitor the phenotype and genotype of the population over a number of generations. The benefit to studying experimental evolution in the laboratory is that the environmental conditions can be precisely controlled over time, thereby allowing replicate experimental populations to be simultaneously compared with both contemporary and historical control populations. However, the usefulness of LNS experiments as a method of understanding evolution in wild populations is challenged by Huey and Rosenzweig in Chapter 22. It is difficult to know if we should reject the hypothesis that temperature is the cause of geographical clines in wing size based on evidence from a LNS experiment in which Drosophila populations failed to develop a cline. In Chapter 4, Dykhuizen and Dean utilize modern Escherischia coli genomics techniques to show that the fitness of a genotype on particular substrates and in particular thermal environments can be predicted from “the bottom up” based on detailed knowledge of enzyme kinetics. Their research should impress field biologists who have tried to measure lifetime fitness. Towards the end of their chapter, they cheer on Drosophila workers who are taking a similar LNS approach. One of my favorite chapters (Chapter 10) was by Zera and Harshman on the life history physiology of insects. In that chapter, they find differences in lipid allocation between lines of sand crickets selected for long wings (LW) and for short wings (SW). The LW crickets divert more of their lipids to triglycerides, which are needed to sustain flight, whereas the SW divert more to phospholipids, which are important for egg production. This is exciting as it gives a physiological explanation for the negative genetic correlation between fecundity and the production of wings (Table 3 in Chapter 3 by Roff and Fairbairn). Chapter 11 “Behavior and Neurobiology” by Rhodes and Kawecki reviews the challenges in selecting for different behaviors. Lines of mice artificially selected for increased voluntary running behavior had an increased number of nuclei in the part of the brain secreting a stress hormone. This suggests that the mechanism by which increased voluntary running was attained was by activation of the stress response. This theme of indirect effects of selection is continued in Chapter 12 “Selection, Performance, and Physiology” by Swallow and colleagues. Mice selected for high rates of voluntary running showed a higher propensity to attack and kill crickets than did mice from control lines. Another favorite was Chapter 14: “Understanding Evolution thorough the Phages” by Ford and Jessup who investigate coevolutionary dynamics between viruses and their bacterial hosts. They review LNS studies that show that low levels of migration increase local adaptation of phages to environments with different levels of resources. This addition of migration between different environments allows realism with higher migration being correlated with the evolution of more virulent phages. I believe this volume is suitable for new graduate students enrolled in an evolutionary biology seminar course. The authors have made an effort to keep most of their chapters accessible to nonspecialists and most have included a detailed description of their experimental evolutionary research. Rather than allowing the students to fight over who gets to present the Speciation or Aging chapter I suggest a stochastic approach. Being assigned a topic at random might result in some interesting PhD theses on crickets or phages.

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