Hybridization as a stimulus for the evolution of invasiveness in plants
TL;DR: This model does not represent the only evolutionary pathway to invasiveness, but is clearly an underappreciated mechanism worthy of more consideration in explaining the evolution ofinvasiveness in plants.
Abstract: Invasive species are of great interest to evolutionary biologists and ecologists because they represent historical examples of dramatic evolutionary and ecological change. Likewise, they are increasingly important economically and environmentally as pests. Obtaining generalizations about the tiny fraction of immigrant taxa that become successful invaders has been frustrated by two enigmatic phenomena. Many of those species that become successful only do so (i) after an unusually long lag time after initial arrival, and/or (ii) after multiple introductions. We propose an evolutionary mechanism that may account for these observations. Hybridization between species or between disparate source populations may serve as a stimulus for the evolution of invasiveness. We present and review a remarkable number of cases in which hybridization preceded the emergence of successful invasive populations. Progeny with a history of hybridization may enjoy one or more potential genetic benefits relative to their progenitors. The observed lag times and multiple introductions that seem a prerequisite for certain species to evolve invasiveness may be a correlate of the time necessary for previously isolated populations to come into contact and for hybridization to occur. Our examples demonstrate that invasiveness can evolve. Our model does not represent the only evolutionary pathway to invasiveness, but is clearly an underappreciated mechanism worthy of more consideration in explaining the evolution of invasiveness in plants.
Citations
More filters
TL;DR: It is concluded that management limiting gene flow among introduced populations may reduce adaptive potential but is unlikely to prevent expansion or the evolution of novel invasive behaviour.
Abstract: Invasive species are predicted to suffer from reductions in genetic diversity during founding events, reducing adaptive potential. Integrating evidence from two literature reviews and two case studies, we address the following questions: How much genetic diversity is lost in invasions? Do multiple introductions ameliorate this loss? Is there evidence for loss of diversity in quantitative traits? Do invaders that have experienced strong bottlenecks show adaptive evolution? How do multiple introductions influence adaptation on a landscape scale? We reviewed studies of 80 species of animals, plants, and fungi that quantified nuclear molecular diversity within introduced and source populations. Overall, there were significant losses of both allelic richness and heterozygosity in introduced populations, and large gains in diversity were rare. Evidence for multiple introductions was associated with increased diversity, and allelic variation appeared to increase over long timescales (~100 years), suggesting a role for gene flow in augmenting diversity over the long-term. We then reviewed the literature on quantitative trait diversity and found that broad-sense variation rarely declines in introductions, but direct comparisons of additive variance were lacking. Our studies of Hypericum canariense invasions illustrate how populations with diminished diversity may still evolve rapidly. Given the prevalence of genetic bottlenecks in successful invading populations and the potential for adaptive evolution in quantitative traits, we suggest that the disadvantages associated with founding events may have been overstated. However, our work on the successful invader Verbascum thapsus illustrates how multiple introductions may take time to commingle, instead persisting as a 'mosaic of maladaptation' where traits are not distributed in a pattern consistent with adaptation. We conclude that management limiting gene flow among introduced populations may reduce adaptive potential but is unlikely to prevent expansion or the evolution of novel invasive behaviour.
1,588 citations
Cites background from "Hybridization as a stimulus for the..."
...…to the hypothesis that many invasions might be successful as a direct result of influxes of genetic variation from multiple introduction events (Ellstrand & Schierenbeck 2000; Allendorf & Lundquist 2003; Facon et al. 2003; Kolbe et al. 2004; Bossdorf et al. 2005; Frankham 2005; Lockwood et al.…...
[...]
...…are predicted to augment Mendelian trait diversity in founding populations by raising both Ne and population growth rate, but even greater increases can be realized if there is differentiation across the geographical distribution of populations in the source region (Ellstrand & Schierenbeck 2000)....
[...]
...Given the prevalence of genetic bottlenecks in successful invading populations and the potential for adaptive evolution in quantitative traits, we suggest that the disadvantages associated with founding events may have been overstated....
[...]
...Multiple introductions seem to be common in invasions (Ellstrand & Schierenbeck 2000; Bossdorf et al. 2005; Novak & Mack 2005), and they can bring together unusually large amounts of variation and novel genetic combinations (Box 1)....
[...]
TL;DR: Elton's "The Ecology of Invasions by Animals and Plants" as mentioned in this paper is one of the most cited books on invasion biology, and it provides an accessible, engaging introduction to the most important environmental crises of our time.
Abstract: Much as Rachel Carson's \"Silent Spring\" was a call to action against the pesticides that were devastating bird populations, Charles S. Elton's classic \"The Ecology of Invasions by Animals and Plants\" sounded an early warning about an environmental catastrophe that has become all too familiar today-the invasion of nonnative species. From kudzu to zebra mussels to Asian long-horned beetles, nonnative species are colonizing new habitats around the world at an alarming rate thanks to accidental and intentional human intervention. One of the leading causes of extinctions of native animals and plants, invasive species also wreak severe economic havoc, causing $79 billion worth of damage in the United States alone. Elton explains the devastating effects that invasive species can have on local ecosystems in clear, concise language and with numerous examples. The first book on invasion biology, and still the most cited, Elton's masterpiece provides an accessible, engaging introduction to one of the most important environmental crises of our time. Charles S. Elton was one of the founders of ecology, who also established and led Oxford University's Bureau of Animal Population. His work has influenced generations of ecologists and zoologists, and his publications remain central to the literature in modern biology. \"History has caught up with Charles Elton's foresight, and \"The Ecology of Invasions\" can now be seen as one of the central scientific books of our century.\"-David Quammen, from the Foreword to \"Killer Algae: The True Tale of a Biological Invasion\
1,321 citations
TL;DR: Recommendations are outlined on how to deal with the issue of plant invasions in standard floras with the aim of contributing to a better understanding between taxonomists and ecologists and allowing more detailed comparative analyses of alien floras of various regions of the world.
Abstract: The number of studies dealing with plant invasions is increasing rapidly, but the accumulating body of knowledge has unfortunately also spawned increasing confusion about terminology. Invasions are a global phenomenon and comparison of geographically distant regions and their introduced biota is a crucially important methodological approach for elucidation of the determinants of invasiveness and invasibility. Comparative studies of alien floras provide substantial new insights to our understanding of general patterns of plant invasions. Such studies, using information in previously published floras and checklists, are fundamentally dependent on the quality of the assessment of particular species with respect to their taxonomic identity, time of immigration and invasion status. Three crucial decisions should be made when defining the status of a plant species in a given region: (1) whether the taxon is native or alien to that region (origin status); (2) what is its position in the invasion process, i.e., when was it introduced (residence status); and (3) what is the degree of its naturalization and possible invasion (invasion status). Standard floras differ hugely in their treatment of non-native species and those with appropriate categorization of alien species according to their status are rather rare. The present paper suggests definitions of terms associated with plant invasions and places these into the context of floras. Recommendations are outlined on how to deal with the issue of plant invasions in standard floras with the aim of contributing to a better understanding between taxonomists and ecologists and allowing more detailed comparative analyses of alien floras of various regions of the world.
1,283 citations
Cites background from "Hybridization as a stimulus for the..."
...Similarly, in Washington State, U.S.A., two new tetraploid Tragopogon species (T. miscellus, T. mirus) originated through hybridization of completely alien, European material (Ellstrand & Schierenbeck, 2000)....
[...]
TL;DR: The goal is to initiate future research that investigates the broader conservation implications of homogenization and to promote a proactive style of adaptive management that engages the human component of the anthropogenic blender that is currently mixing the biota on Earth.
Abstract: Biotic homogenization, the gradual replacement of native biotas by locally expanding non-natives, is a global process that diminishes floral and faunal distinctions among regions. Although patterns of homogenization have been well studied, their specific ecological and evolutionary consequences remain unexplored. We argue that our current perspective on biotic homogenization should be expanded beyond a simple recognition of species diversity loss, towards a synthesis of higher order effects. Here, we explore three distinct forms of homogenization (genetic, taxonomic and functional), and discuss their immediate and future impacts on ecological and evolutionary processes. Our goal is to initiate future research that investigates the broader conservation implications of homogenization and to promote a proactive style of adaptive management that engages the human component of the anthropogenic blender that is currently mixing the biota on Earth.
1,270 citations
TL;DR: What is required to assess phenotypic plasticity at different levels is described and a new framework can be applied when testing both ecological or evolutionary oriented hypotheses, and therefore promises to bridge the gap between the two perspectives.
Abstract: Invasion biologists often suggest that phenotypic plasticity plays an important role in successful plant invasions. Assuming that plasticity enhances ecological niche breadth and therefore confers a fitness advantage, recent studies have posed two main hypotheses: (1) invasive species are more plastic than non-invasive or native ones; (2) populations in the introduced range of an invasive species have evolved greater plasticity than populations in the native range. These two hypotheses largely reflect the disparate interests of ecologists and evolutionary biologists. Because these sciences are typically interested in different temporal and spatial scales, we describe what is required to assess phenotypic plasticity at different levels. We explore the inevitable tradeoffs of experiments conducted at the genotype vs. species level, outline components of experimental design required to identify plasticity at different levels, and review some examples from the recent literature. Moreover, we suggest that a successful invader may benefit from plasticity as either (1) a Jack-of-all-trades, better able to maintain fitness in unfavourable environments; (2) a Master-of-some, better able to increase fitness in favourable environments; or (3) a Jack-and-master that combines some level of both abilities. This new framework can be applied when testing both ecological or evolutionary oriented hypotheses, and therefore promises to bridge the gap between the two perspectives.
1,147 citations
Cites background from "Hybridization as a stimulus for the..."
...…2005; Williams et al. 2005), but also because they inform about other genetic processes that may contribute to genetic change in the introduced range, such as founder effects (Brown &Marshall 1981; Barrett & Husband 1990) and inter- or intraspecific hybridization (Ellstrand & Schierenbeck 2000)....
[...]
References
More filters
4,002 citations
TL;DR: Aproximately 50,000 nonindigenous (non-native) species are estimated to have been introduced to the United States, many of which are beneficial but have caused major economic losses in agriculture, forestry, and several other segments of the US economy, in addition to harming the environment.
Abstract: [Extract] Aproximately 50,000 nonindigenous (non-native) species are estimated to have been introduced to the United States. Some of these are beneficial; for example, species introduced as food crops (e.g., corn, wheat, and rice) and as livestock (e.g., cattle and poultry) now provide more than 98% of the US food system, at a value of approximately $800 billion per year (USBC 1998). Other exotic species have been introduced for landscape restoration, biological pest control, sport, pets, and food processing, also with significant benefits. Some nonindigenous species, however, have caused major economic losses in agriculture, forestry, and several other segments of the US economy, in addition to harming the environment. One study reported that 79 exotic species had caused approximately $97 billion in damages during the period 1906–1991 (OTA 1993).
2,922 citations
"Hybridization as a stimulus for the..." refers background in this paper
...In the United States alone, the damage wrought by invasive species totals approximately $122 billion per year (Pimentel et al., 2000)....
[...]
Book•
06 Jan 2012
TL;DR: The first book on invasion biology, and still the most cited, Elton's masterpiece provides an accessible, engaging introduction to one of the most important environmental crises of the authors' time.
Abstract: Much as Rachel Carson's "Silent Spring" was a call to action against the pesticides that were devastating bird populations, Charles S. Elton's classic "The Ecology of Invasions by Animals and Plants" sounded an early warning about an environmental catastrophe that has become all too familiar today-the invasion of nonnative species. From kudzu to zebra mussels to Asian long-horned beetles, nonnative species are colonizing new habitats around the world at an alarming rate thanks to accidental and intentional human intervention. One of the leading causes of extinctions of native animals and plants, invasive species also wreak severe economic havoc, causing $79 billion worth of damage in the United States alone. Elton explains the devastating effects that invasive species can have on local ecosystems in clear, concise language and with numerous examples. The first book on invasion biology, and still the most cited, Elton's masterpiece provides an accessible, engaging introduction to one of the most important environmental crises of our time. Charles S. Elton was one of the founders of ecology, who also established and led Oxford University's Bureau of Animal Population. His work has influenced generations of ecologists and zoologists, and his publications remain central to the literature in modern biology. "History has caught up with Charles Elton's foresight, and "The Ecology of Invasions" can now be seen as one of the central scientific books of our century."-David Quammen, from the Foreword to "Killer Algae: The True Tale of a Biological Invasion"
2,530 citations
Book•
30 Jan 1997
TL;DR: This chapter discusses natural hybridization in the context of reproductive parameters, species concepts, and the role that technology has played in shaping human evolution.
Abstract: Chapter 1 Natural Hybridization: Definitions and History Chapter 2 Natural Hybridization and Species Concepts Chapter 3 Natural Hybridization: Frequency Chapter 4 Reproductive Parameters and Natural Hybridization Chapter 5 Natural Hybridization: Concepts and Theory Chapter 6 Natural Hybridization: Outcomes Chapter 7 Natural Hybridization: Emerging Patterns
2,053 citations
"Hybridization as a stimulus for the..." refers background in this paper
...We are well aware that not all hybridization leads to increased fitness or adaptive evolution (Arnold, 1997)....
[...]
...Anderson & Stebbins, 1954; Stebbins, 1959, 1969; Abbott, 1992; Arnold, 1997; Lewontin & Birch, 1966; Weiner, 1994)....
[...]
...We are well aware that not all hybridization leads to increased fitness or adaptive evolution ( Arnold, 1997 )....
[...]