Population biologists back in the lab: Stability in Model Populations

Stability in Model Populationsby L.D. Mueller and A. Joshi. Princeton University Press, 2000. US$29.95/£19.95 pbk (xi + 319 pages) ISBN 0 691 00733 0Recent developments in the field of population biology have greatly strengthened the connection among investigations of field and laboratory systems and theoretical approaches, with resulting insights into what determines the abundances of plant and animal populations and the level of diseases. The current volume by Mueller and Joshi describes part of these exciting developments by looking primarily at single-species laboratory systems, and the analyses necessary to understand them. The question of how this work furthers our understanding of natural systems is directly addressed, and the book is a nice addition to this long-standing discussion. Because the detail included about the systems addressed is so extensive, one small drawback is that the context for the studies in a larger sense is not as well addressed – the book is definitely not an introduction to the field of population biology.The context for the book goes back to the earliest investigations in population biology early in the last century – the theoretical work of Lotka and Volterra, which was complemented by the early laboratory experiments of Gause on microorganisms. The theories focused on the effects of ecological interactions, and what allowed species to persist, that is how competitors, or predator and prey, could coexist. At around the same time, Nicholson and Bailey developed their theory of host–parasitoid systems, and Kermack and McKendrick formulated the basic models of disease dynamics. In all cases, the match between theory and data was essentially qualitative. These studies, perhaps with the exception of those on disease dynamics, began the real emphasis of population biology on the role and importance of stability as a conceptual tool for understanding biological populations.Since then, there have been several themes that provide both background and rationale for this book. First, the role of laboratory studies greatly diminished, although there has been somewhat of a recent revival of interest. Second, the importance of stability as a central concept was boosted by the work of May, beginning in the 1970s, and others since then. Third, in the past decade, there has been dramatic progress in the analysis of time series of population data and consequent quantitative connections between theoretical approaches and field data. This work has begun to answer fundamental questions about what regulates populations in nature. Studies of the dynamics of human diseases 1xMeasles as a case study in nonlinear forecasting and chaos. Grenfell, B.T. et al. Philos. Trans. R. Soc. London Ser. A. 1994; 348: 515–530CrossrefSee all References1 have played a central role in both our understanding of population dynamics in general, and in developing the methodological approaches used to understand other systems – unfortunately, this literature is not reviewed in the current volume.Mueller and Joshi argue that model laboratory populations are a key way in which to approach questions of population regulation. They focus on stability of populations as the theme, and review the history of stability as a concept in population biology, and the mathematical approaches to stability in simple models. Of much more interest is the overview of statistical approaches for connecting models to data, which until now, has been mostly covered only in research papers 2xNonlinear demographic dynamics – mathematical models, statistical methods, and biological experiments. Dennis, B. et al. Ecol. Monogr. 1995; 65: 261–281CrossrefSee all References2, and most ecology students still view statistics as primarily focused on hypothesis testing rather than on model fitting and prediction. This section is, however, more of a guide to the available literature, than a self-contained exposition. The bulk of the book focuses on a review of several well-investigated, single population laboratory systems.The authors use the study of these single-population systems to emphasize the utility of laboratory studies and the advantages of using theory in conjunction with empirical approaches. The three systems (Tribolium, blowflies and Drosophila) all present opportunities for creating mechanistic models and for testing how well they match laboratory data. The authors explain clearly how these systems have been effectively used to look at different aspects of population regulation, and simultaneously emphasize the similarities in the approaches used. The book is a good introduction to one aspect of recent advances in population biology, and provides the rationale for further studies of laboratory systems.