Landscape Ecol DOI 10.1007/s10980-006-9001-6

BOOK REVIEW

Testing Basic Ecological, Evolutionary, and Biogeographical Principles Using Invasive Species D. F. Sax, J. J. Stachowicz and S. D. Gaines (eds), Species Invasions: Insights into Ecology, Evolution, and Biogeography. Sinauer Associates, Inc., Sunderland, MA, USA, 2005, 480 pp, 56 illus, Casebound, US$74.95, ISBN: 0-87893-821-4; Paper, US$49.95, ISBN: 0-87893-811-7

Cynthia D. Huebner

Received: 9 March 2006 / Accepted: 27 March 2006 Ó Springer Science+Business Media B.V. 2006

Sax et al. argue in Species Invasions: Insights into chapters with discussions on taxon cycles, genetic Ecology, Evolution, and Biogeography that spe- bottlenecks, random drift, hybridization, intro- cies invasion is an on-going experiment and a gression, selection on environmental and additive research tool with which to test fundamental and nonadditive genetic effects, niche evolution, ecology, evolution, and biogeography tenets. The sexual selection, evolution of reproductive isola- authors recognize the importance of the applied tion, and the adaptive significance of sexual and single-species approaches that currently reproduction as they relate to invasive species dominate invasion research, but state invasive and rate processes The biogeography section is species provide three unique characteristics that organized around six chapters with discussions on make them model research systems: (1) ecological unique geographic evolutionary trajectories, spe- processes can be observed in real time, (2) place, cies homogenization over space and time, popu- time, and characteristics of introductions are of- lation spread and range expansion, scaling ten known, such that rate processes can be fol- patterns, and species dynamics in terms of island lowed, and, (3) because different species have biogeography theory. been introduced in abundance in different loca- The concepts covered are broad enough to be tions, it may be possible to examine and compare of interest to most researchers focusing on inva- such species-additions over a variety of spatial sive species, even if their taxa of interest are not and temporal scales. included as support for each concept. Several The book is organized in three sections—ecology, chapters in the evolution and biogeography sec- evolution, and biogeography. The five chapters in tions include additional descriptions of basic the ecology section focus on species interactions, concepts that may make them more accessible to niche saturation, induced changes in ecosystem ecologists, especially students, who may be processes, extinction, and infectious diseases, focusing on more applied invasion problems. The emphasizing that invasive species provide an biogeography section will be of most interest to opportunity to study each of these topics in real landscape ecologists, with the chapter on popu- time. The section on evolution includes six lation spread being the strongest. Kinlan and Hastings summarize several population spread models ranging from the linear rates modeled by & C. D. Huebner ( ) reaction-diffusion equations to the accelerating USDA Forest Service Northeastern Research Station, Morgantown, WV 26505, USA rates of patchy spread defined by stochastic non- e-mail: [email protected] linear integro-difference models as well as

123 Landscape Ecol individual-based models for systems rich in data. Loss of genetic diversity in response to genetic Their summary integrates dispersal dynamics, bottlenecks or founder events appears to be demography, and shape and heterogeneity of in- uncommon in successfully established invaders, vaded areas. In doing so, they postulate which life possibly due to multiple introductions. Resolving history traits (e.g., long-distance dispersal, lack whether invasive species are responding primarily of Allee effects, active dispersal) and environ- to Fisher’s natural selection theory or Wright’s mental factors (e.g., homogeneous, two-dimen- random genetic drift theory (or, more likely, sional areas) will result in the most rapid spread both) is a proposed endeavor. The relatively high by comparing spread rates and dispersal distances genetic diversity afforded to invasive species in- of several taxonomic groups with a more detailed deed may be the key to their dominance over comparison of terrestrial and marine invasions. some native species, who may not be able to Labra, Abades, and Marquet’s use of minimum respond as quickly to short-term environmental spanning trees and the North American Breeding changes and whose niches are not evolving. Bird Survey to show that invasive and native While an interesting summary of allelopathy species respond similarly at variable scales will and soil microbial interactions, the chapter on likely lead to analogous studies with other taxa. evolutionary trajectories by Callaway, Hierro, Sax, Brown, White, and Gaines use island bio- and Thorpe appears to be out of place. Although geography theory to show that overall species it is clear that species located in geographically richness (more so for vascular plants and less so different places may have developed different for birds) has generally increased over the past species interactions, it is the evolution (not the few centuries. The latter may appear to negate location) of interactions (some of which may be homogenization via loss of native species as a classified as facilitative) between plant species consequence of invasion. However, McKinney and soil biota that is of most interest. Calling and Lockwood summarize several studies that these interactions examples of coevolution or re- indicate increased species richness is likely to ciprocal evolutionary change may be questioned occur only at larger spatial extents; conversely, by the more conservative evolutionary biologists, homogenization is more likely to occur in in- but that is of less concern than the lack of a tensely disturbed sites, such as urban areas. description for the geographic mosaic concept Vermeij argues, albeit with somewhat limited (aside from referencing its founder). This chapter, support, that when homogenization and loss of if placed in the ecological section, may have native species do occur, they are only short-term helped connect the chapters of this section with consequences. He further states that invasion may the other two sections. one day be seen as essential to the long-term The chapter on interactions in the ecology vigor of ecosystems as mutations today are seen section by Bruno, Fridley, Bromberg, and Bert- as essential to the long-term evolution of species ness summarized the need for further research on and populations. Such statements may motivate all types of interactions because the presumed researchers to clarify the short- and long-term importance of lack of predators on invaders and impacts of invasion on species dynamics and competitive superiority of invaders has been re- ecosystems. futed by several studies and other research indi- Four chapters in the evolution section—(1) cates facilitation deserves more intensive study. taxon cycles by Ricklefs, (2) genetic bottlenecks Unfortunately, Stachowicz, and Tilman’s chapter in alien plant species by Novak and Mack, (3) on community saturation appears to ignore mechanisms of evolutionary change by Wares, interactions other than competition by focusing Hughes and Grosberg, and (4) niche evolution by on resource utilization as the key to understand- Holt, Barfield and Gomulkiewicz—are compre- ing community saturation and the role of diver- hensive and likely of interest to landscape ecolo- sity. Likewise, Blackburn and Gaston’s reminder gists who hope to improve predictions of species that humans are perhaps the most detrimental of spread and understand the role of genetic ver- invaders is timely but focuses on the effects of one sus ecological processes in invasion lag times. interaction (predation) on avian extinction.

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Lafferty, Smith, Torchin, Dobson, and Kuris’ required to keep invasion research both grounded chapter on infectious diseases is also a discussion and progressive. While I was hoping the authors of predator–prey (parasite–host) interactions, would more directly link, even hypothetically, though the authors do briefly connect these species interactions and the consequent changes interactions with evolutionary theory in terms of in ecosystem processes with native and exotic host resistance and speciation via enemy-release. species evolution or distributions, the book D’Antonio and Hobbie’s summary of invasion motivates the readers to do so themselves. There effects on ecosystem processes includes some are a few repetitive uses of examples (e.g., the potential challenges when using invasive species large ground finch of Daphne Major) as well as that the evolution and biogeography sections claims of ‘‘beyond the scope’’ in several chapters, under-represent. These challenges include differ- which are disappointing to come across because entiating covarying environmental factors (e.g., the subject in question could be included in the human-mediated disturbance) from factors solely perceived scope of the book. Despite these associated with the invasion. The chapters in the relatively minor problems, I find the book well- ecology section appear to be characterized by the written, informative, and idea-generating. Conse- species-specific approach that the authors wish to quently, I recommend this book to anyone move beyond. However, it may be these species- seeking new perspectives on invasion theory, specific approaches that make the challenges including researchers with both applied and basic easier to discern. questions about native and exotic colonizers and A combination of reductionist (species-specific invaders. or applied) and holistic approaches may be

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