Invasion Ecology INVASION ECOLOGY - ESF

PrefaceIt has been our experience that placing the reams of observations, examples, andresearch within the broad context of invasion ecology gets more difficult as thefield grows each year. Not only does relevance change with new insights, but thefield itself requires an intense understanding of multiple disciplines. Invasionecology by its nature is integrative, requiring its practitioners to understand(at the least) economics, evolution, population genetics, biogeography, and ecology. Indeed, those studying biological invasions must not only understand these contributing fields, they must combine them in order to find ways to control theflow and impact of non-native species. This is a tall order. We discovered early in writing this book that we could not cover all aspects and examples of invasionswithin a single text. Not only are different disciplines integrated into the study ofinvasions, but different ecologists have distinct motivations behind their research.We ultimately decided to produce an overview of the invasion process from thepoint of view of an applied ecologist. Thus, we hope to highlight the salientresearch findings associated with each invasion stage (i.e., transport and introduction, establishment, spread, impact), while explicitly considering how thesefindings support societies’ efforts to prevent the influx of non-native species andcontrol those that cause ecological harm. We would also humbly like to apologizeto the many excellent invasion ecologists (including some of our friends) whosework we did not include.This textbook is designed to be used in senior-level courses for undergraduatesand in graduate courses. We purposefully take a very broad view of biologicalinvasions with the hope that students and instructors will find the book useful asa primer to the growing field of invasion ecology. We have tried to make thechapters accessible and interesting to read while conveying the history and complexity of current debates, and we offer readings that we think complementeach chapter. We have assumed students have at least completed a basic ecologycourse and can read calculus equations without fainting (or we suggest theyassume a seated position while reading Chapters 7 and 8). The boxes placedthroughout each chapter are integral to the material there, and we strongly

xPrefacer ecommend that students and instructors do not skip over them. Given ourgoal of producing a comprehensive textbook, readers will not find appreciableamounts of new material here; instead we hope they will find some insightfulorganization and interesting juxtapositions.To further this effort, at the end of each chapter we provide a set of suggestedarticles for use as companion readings. These “foundational papers” are thebooks and articles that laid the groundwork for various aspects of the chapter’stopics. These are the works we suggest as “must reads” to anyone interested inpursuing invasion ecology as part of their graduate education. Others may d isagreeabout which articles we included in these lists, but at the very least they providea starting point for the student just entering the field. We also include a list offurther reading, which are articles that delve more deeply into the issues we present or are key syntheses of relevant literature on a particular topic. We suggest that those using this book in a graduate or undergraduate class incorporatethese articles into their reading assignments. These suggested papers should makestudent discussions of the topics we present in each chapter a bit more lively.We made a few key decisions concerning the breadth of material we cover thatmay leave some readers frustrated. Invasion ecology interfaces with a varietyof fairly distinct subdisciplines such as biocontrol, agro-ecology, weed science,epidemiology, ecological economics, and environmental law. We do not coverthese particular topics in any real depth here but attempt to point to otherresources for interested readers. Our decision not to cover the area of biocontrolextensively is likely to receive the most criticism. We do consider some examplesof biocontrol in detail; however, it quickly became apparent that the traditionsand experience of biocontrol practitioners were somewhat specific and differedfrom those of many more broadly defined ecologists. We simply could not dojustice to this history within the page limits of this book. There is so much toexplore in the crossover between invasions, biocontrol, and conservation biologythat it deserves its own consideration.We have organized the book primarily around the stages of the invasion process (transport and introduction, establishment, spread, impact), but we madethe decision to pull three additional topics out of our sequence and present themas cross-stage syntheses. These topics are evolution (Chapter 11), management(Chapters 12 and 13), and the effects of climate change on invasion dynamics(Chapter 14). We could have incorporated these topics into each of the invasionstages we use as the structure for the book and discussed the stage-specific aspectsof each topic. Ultimately, though, we felt there was more to be gained from presenting these topics as synthetic whole chapters so that we could follow keythreads and explain cross-stage changes without disrupting other organizationalstructures. For example, management options change drastically as one movesfrom the transport and release stage to the post-establishment stages, and statingthese changes seems less useful than explaining them.We have endeavored not to break too much new ground in this book butinstead to strike a balance between breadth and depth in coverage of invasionecology. If we have broken new ground at all, it was because it was necessary topresent a coherent picture of the overwhelming variety of research results inone area. We have also tried to incorporate a variety of examples that cross

Prefacexit axonomic groups and geopolitical boundaries. However, most readers willquickly recognize the following biases: (i) we predominantly study birds, aquaticorganisms, and plants; (ii) we live in North America; and (iii) at some point inour lives we have each lived and worked in California. Such biases are perhapsunavoidable, and we welcome input from our colleagues around the world justin case a third edition of this book is warranted.We decided to produce a second edition of this book in 2009, and it has been aslow march toward this final product, yet this new edition is truly a major r evision.We have added two new chapters (Chapters 13 and 14), substantially modified,reworked and rewritten the remaining 12 chapters, and included almost 300 newreferences in this second edition. Our progress was impeded in part by our ownfecundity, with the production of four new humans over the last couple of years. Thisnear doubling of our “population” meant that we could no longer indulge in longworking sessions that included both beers and Oreos, and instead had to be satisfiedwith Skype meetings. Despite this limitation, it was an enjoyable undertaking andmade us realize how much we value the friendships this book has allowed us to forge.Delving back into the literature was almost more d aunting than having children. Theannual production of published papers on invasion ecology has itself doubled from600 to nearly 1200 since we wrote the first edition. This growth in the field reinforces the need for a textbook such as this but also makes the production of such abook a Herculean task. We are certain that there are very good recent papers we haveoverlooked, and we each regret some of the excellent papers that we found andloved but could not include here due to space or complexity constraints.If we achieve any success with this text, it will have much to do with the help wehave received from our families, partners, colleagues, and friends. In particular wewould like to thank those colleagues who provided “friendly” peer review foreach of the original chapters. These folks are Kama Almasi, Tim Blackburn, CiniBrown, Phillip Cassey, Jeff Corbin, Curt Daehler, Susan Harrison, David Holway,Ruth Hufbauer, Theo Light, Kelly Lyons, Peter Moyle, Katriona Shea, Dov Sax,Dan Simberloff, and Betsy Von Holle. Our gratitude also goes out to those authorswho shared original figures and photos with us including Towns Peterson, DaveRizzo, and Marcel Holyoak. This edition was helped tremendously by feedbackwe obtained from professors who used this book in the classroom. We thankSudeep Chandra, Tony Ricciardi, Jim Darling, Laura Meyerson, J. Michael Reed,J. Thaxton, and John Waring for their unvarnished feedback. We owe our respective academic departments our thanks as they not only put up with our distractionbut also provided the space and resources we needed to work. We owe a specialthanks to our original editor at Blackwell, Sarah Shannon, who initially contactedJulie to propose the book, to our current editors there, as well as to Ward Cooperand Kelvin Matthews, and the Wiley-Blackwell production staff. Finally, we dedicate this book to Tabby, Henry, Tanner, Crystal, Sarah, and Matteo and thankthem for their unconditional love demonstrated by their patience with our distracted brains.Julie L. Lockwood – New JerseyMartha F. Hoopes – MassachusettsMichael P. Marchetti – California

CHECK OUT THEINVASION ECOLOGY(Second Edition)Companion Websiteby visitingwww.wiley.com/go/invasionecologyClick now and gain access to Downloadable versions of the illustrationswithin the book Downloadable versions of the tableswithin the book

1An Introduction to Invasion EcologyOverviewPublic and academic recognition of the problems associated withbiological invasions has grown exponentially over the past fewdecades. The reasons for this growth are threefold. First, the negative effects of some non-native species have grown too largeto ignore. Second, over time the number of species transportedinto novel locations has grown, so that the overall number ofidentified problems has also grown. And lastly, with so manyinvasive species, it is very hard to do ecological field researchwithout encountering non-native species and potentially including them in investigations even if those investigations are forbasic research. Non-native species offer new interactions with thepotential for new insights, and curious scientists rarely pass upthe opportunity to explore such new avenues. Thus, increasingnumbers of scientists are managing and studying non-native species to minimize the effects of biological invaders, to satisfy basicecological curiosity, or both. In this introductory chapter we precisely define what we mean by a non-native species, settle on ageneral terminology for use throughout the book, and providesome exploration of what we mean by the “invasion process.”Invasion Ecology, Second Edition. Julie L. Lockwood, Martha F. Hoopes, and Michael P. Marchetti. 2013 Julie L. Lockwood, Martha F. Hoopes, and Michael P. Marchetti.Published 2013 by Blackwell Publishing Ltd.

2Invasion EcologyWhat are invaders and why do we care about them?One of the principal ways in which speciation occurs is through geographic isolation (i.e., vicariance speciation; Mayr 1963). Physical features such as oceans,mountains, ice sheets, and river valleys represent boundaries to the movement ofindividuals between populations of the same species. Over time these separatedpopulations diverge via drift and selection, with each population eventually forming a unique species. This process generally happens on long, geological timescales. On those same time scales, we also see climatic and geological events thatremove barriers and allow individuals to disperse over long distances and intopreviously unreachable areas. During these events, some species expand theirranges to intermingle with new communities and sample new habitats. For example, during the Miocene when the isthmus of Panama emerged from the sea tolink North and South America, North American mammals moved south whilebirds and plants of the South American rainforests tended to move north (i.e., theGreat American Interchange; Marshall et al. 1982). Such relatively rapid expansion of species groups is unusual enough to deserve special recognition, and paleontologists and ecologists have long been interested in why some species expandtheir ranges successfully in these events (while others do not) and have given thesespecies a whole host of names (e.g., immigrants, waifs, colonizers; see Table 1.1).As long as humans have had the ability to disperse across continents, they havealso helped many other species breach geographic boundaries. Domesticated animals and plants have trailed along as human settlers have moved into novelterritory (Crosby 1986). Almost certainly, representatives of non-domesticatedspecies have hitched a ride in clothes, on boats or wagons, and within or ondomesticated animals. Like the groups of mammals, birds, and plants thatexpanded their geographical ranges in the Great American Interchange, speciesmoving with humans encountered locations that were previously out of theirreach, and some of them successfully colonized these novel environments. Thesesuccessful colonizers, however, achieved this new distribution with the help ofhumans. In the same way that ecologists distinguish between human-mediatedand natural extinction of species, they also distinguish between natural andhuman-mediated rapid range expansion. This book concentrates exclusively onthose species that found their way out of their native range and into a novel location via human actions.There is ongoing discussion within the scientific community as to whetherrange expansions aided by humans are substantively different from range expansions that follow shifts in the earth’s paleoclimate (e.g., Vermeij 2005). Weaddress this debate in Chapter 2. Suffice it to say here that, compared with natural range expansion, humans have massively increased the rate at which speciescolonize new areas, and they have substantially changed the geographic patternsof invasion. This is not to say that there is little to be learnt from examining invasion patterns in the paleontological record. It is never wise to ignore the lessonsof history.One of the reasons for the debate about natural and human-aided colonizationand range expansion is to determine whether invasion, like extinction, deserves

An Introduction to Invasion Ecology3special attention or is a natural process. As with extinction, the answer is that thenatural and human-aided processes share many characteristics. While examiningthe natural process may inform our understanding, there is no doubt that thehuman-aided process deserves and demands additional attention. There is ampleevidence that non-native species can cause serious ecological and economic problems (Mooney et al. 2005). Invasive species eat, compete, and hybridize withnative species often to the detriment of the natives. Invasion can result in the lossof native species and the loss of ecosystem services such as water filtration, soilstabilization, and “pest” control. More directly, most agricultural pests are nonnatives, and many new human diseases are “emerging,” meaning they are nonnative with us as novel hosts (Pimentel 1997). Invasive species clog waterways,impede navigation, destroy homes, and kill livestock and fisheries (Mooney et al.2005). Whether or not we think modern invasions are historically unique, theydemand our attention.The motivation for this book comes as much from this practical concern as itdoes from the more esoteric interest in invasion as an ecological fact of life. Thisapproach follows directly from the seminal work of Charles Elton (Box 1.1),who was one of the first to consider biological invaders as key drivers of ecosystem change and specifically of detrimental change (Davis 2006). The next seminal work on invasions, an edited volume by Baker and Stebbins (1965), took amore neutral stance. We (the authors) believe that biological invaders can act asuseful “probes” into the inner workings of nature. Often we know the origins ofnon-native species, can document their arrival, and can directly collect information on their activities in their new community. This information allows the studyof non-native species to become a powerful tool in our ecological and evolutionary arsenal (Sax et al. 2005; Cadotte et al. 2006a,b). Invasion ecology has swungback and forth through the years between an Eltonian view focused on invadersas problems and a less judgmental view, more oriented toward basic science.Interestingly though, the ascendency of the field has mirrored the rise in prominenceBox 1.1Unknown legendCharles Sutherland Elton (1900–1991) produced the foundational book onbiological invasions, The Ecology of Invasion by Animals and Plants, in 1958,just less than 10 years before his retirement from Oxford University in 1967.This classic book grew out of a series of three radio lectures Elton made forthe British Broadcasting Corporation (BBC) under the title “Balance andBarrier.” Within the book, Elton summarized a relatively obscure literatureon the impact and spread of non-native species that, at that time, was largelyconfined to the disciplines of entomology and plant pathology (Southwood &Clarke 1999). Perhaps because the original intent of the lectures was toreach a larger non-academic audience, The Ecology of Invasion by Animalsand Plants is a pleasure to read. Elton manages the nearly impossible taskof melding scientific rigor with an engaging and often witty writing style.

4Invasion EcologyBox 1.1 ContinuedAs Dan Simberloff relates in his Foreword to the 2000 reprinted edition,“A writer who can describe oysters as ‘a kind of sessile sheep’ and characterizeadvances in quarantine methods by the proposition that ‘no one is likely toget into New Zealand again accompanied by a live red deer’ is more than justa scientist pointing out an unrecognized problem.” Because of his ability tocommunicate effectively in writing, Elton’s book has today become the mostcited source in invasion biology (Richardson & Pyšek 2008).The predominant feeling one gets after reading The Ecology of Invasionby Animals and Plants is that Elton presaged nearly all the arguments withinthe field, and indeed there are very few topics that we cover in this text thatwere not originally discussed by him. Due to the era in which he wrote, hecould not have explored some currently hot topics (e.g., genetic diversity),was disinclined to pursue others (e.g., mathematics of population growthand range expansion), and given the rate at which global transportation hasgrown in 50 years, he could not have anticipated some emerging elements ofthe field (e.g., vector analysis; Richardson 2011). Nevertheless, one couldargue that we are all simply putting mechanisms behind many of the patternsElton noticed a half century ago. Of course, one could also make that argument for the majority of community and population ecology theories becauseElton also wrote Animal Ecology (1927), Voles, Mice and Lemmings:Problems in Population Dynamics (1942), and The Pattern of AnimalCommunities (1966). Within these volumes Elton laid out the foundationfor population cycles, food chains, pyramids of numbers, and the structureof communities. The first of these books was written in 85 days when Eltonwas in his late twenties (Southwood & Clarke 1999). If only we could all beso productive so early in our careers!Presaging where ecologists stand today (especially as our work relates tobiological invasions), Elton embraced the sociopolitical implications of hiswork and often steered his research agenda toward solving fundamentalsocietal problems. He founded the Bureau of Animal Populations in Oxfordduring World War II in part to satisfy the need to reduce the loss of storedgrains from over-abundant rodent populations (Southwood & Clarke 1999).He helped found The Nature Conservancy and sat on its Scientific AdvisoryBoard until 1957 despite the fact that he was “allergic to committees”(Nicholson 1987 as quoted in Southwood & Clarke 1999). Elton made thecritical connection between population cycles of ma

This book provides a synthesis of this rapidly growing fi eld of research and is an essential text for undergraduate and graduate students in ecology and conservation management