Steve Brooks of The Natural History Museum entitled his review (Brooks 2009) of this book, “Aren't dragonflies great study organisms?” His enthusiastic statement sums up the purpose of the volume: to review the use and value of dragonflies and damselflies (Order Odonata) in the development of ecological and evolutionary theory. The intent of the editor, Alex Córdoba-Aguilar, is to approach the subject via some of the fundamental issues of ecology and evolutionary biology rather than by treating the Odonata from an evolutionary and ecological perspective, which was done magnificently by the late Philip Corbet (1999). It's a testimonial to these animals as superb and successful subjects for a wide array of experimental and theoretical studies, and the book encourages biologists to develop new, innovative and effective ways to expand the use of odonates in this research.
Compared to most other insects, odonates are large, easy to observe and identify, even on the wing. They are easily located—they are widely distributed geographically and are frequently abundant and concentrated near water. They are readily captured and marked for experimental purposes in the field. Even the larvae of many species, which generally are less well-known but longer lived than the adults, are often rather easy to collect, rear and study in the laboratory. The diverse and fascinating behavior of odonates invites the testing of a myriad of hypotheses important in understanding evolution. For example, consider the contributions that Jon Waage's (1979, 1984) ground-breaking discoveries of sperm displacement behavior and morphology in Odonata contributed to our understanding of reproductive behavior, reproductive success, mating systems and sexual selection. Dragonflies and damselflies are especially suited for studies of topics such as natural and sexual selection, sexual interaction and reproductive isolation, competition, demographics, phenology and the evolution of polymorphism and color patterns. With the increased interest in conservation, habitat deterioration and climate warming, odonates are high on the list of organisms useful in conservation biology.
The book consists of a Forward by Philip Corbet, that most influential of odonatologists, an Introduction by the editor and 19 chapters written by some of the best known contemporary researchers of the Odonata. Eight of the chapters are ecological in content; eleven are more in the realm of evolutionary biology. There is a glossary of terms. The book is a useful overview of ecology and evolution in the Odonata but, more importantly, as the editor stresses, it showcases many of the ways that dragonflies and damselflies have been used as research tools in the examination of a wide variety of biological questions.
For example, in the Ecology section, some topics range from mark-recapture studies and demography to dragonfly migration; from community structure to seasonality-imposed plasticity in larval life histories; from the use of dragonflies in the assessment and monitoring of aquatic habitats to their suitability as research subjects in conservation biology. One innovative paper that caught my eye is Valuing dragonflies as service providers, by John Simaika and Michael Samways, which introduces a framework for quantifying the value of services provided by ecosystems and their components. The service-providing unit (SPU) quantifies the quality of the ecosystem services provided by particular species or groups of species. Such evaluations are a practical tool for the conservation of biodiversity. Odonata species provide services at the population level in diverse ways—pest regulators, indicators of habitat health, cultural icons, food in some societies, and so on. They also may have negative effects and such populations are deemed service antagonizing units (SAU). The predation of pollinators is an example.
The Evolution chapters examine issues such as larval morphological defenses (abdominal spines), territoriality, flight mechanics and performance, sexual dimorphism and polymorphism, cryptic female choice, parasite-mediated selection and premating reproductive isolation. There is one glaring omission. It's disappointing that systematics is so frequently left out of discussions of evolutionary research. Perhaps it's a result of the erroneous idea that phylogenetic systematics is not hypothesisbased. Cladograms, with their data matrices, are testable hypotheses of evolutionary relationships and are powerful predictors—critical to the elucidation of evolutionary patterns of all sorts. The order Odonata is tailor-made for systematic studies, for there is an extensive array of useful characters present in both adult and larval stages. These characters range from morphological to behavioral, from ecological to molecular. The fossil record is unusually rich. Biogeographical and other research is enhanced because large collections of accurately identified material from many regions of the world are available. There is a wealth of cladistics work on the Odonata that should have been explored and summarized in at least one chapter— from biogeographical hypotheses of Quaternary radiations (Turgeon et al. 2005) and the effects of Gondwana's breakup (Carle 1995) to studies of evolutionary rates (Hasegawa and Kasuya 2006); from the adaptive radiation of the endemic Hawaiian Megalagrion (Jordan et al. 2003) to more general investigations of taxon evolution (Ware et al. 2007) and the evolution of structure (Bybee et al. 2008).
Most of the authors present a brief summary and a few lines about potential future research in each of the chapters. Nevertheless, it would have been instructive to see a final concluding chapter, written by the editor or another contributor, summarizing the merits of dragonflies and damselflies in broad ecological or evolutionary research agendas. Future research possibilities in the various topics could be explored in a more integrated manner. One obvious theme for discussion would be the encouragement of more research on the larval stage, which is poorly represented in this volume. This is largely because larvae are harder to study than adults, show less fascinating behavior and consequently are more poorly known. This is not to say that there is little in the literature about them. They are logical subjects for all kinds of studies from water quality and pollution to habitat fragmentation, from predation to life-histories, from population dynamics to adaptation.
This is an impressive book prepared by experts who successfully promote the value and potential of dragonflies and damselflies as subjects of ecological and evolutionary research. The benefits of studying these wonderful insects should be examined by anyone committed to research in these fields.