Invasive success and the evolution of enhanced weaponry
TL;DR: The results of this study suggest that increased allelopathy in invasive I. glandulifera might have been selected for by other processes and call for biogeographical experiments that will examine not only the novelty but also the evolution of allelopathic effects in invasive plants.
Abstract: A key hypothesis that has been proposed to explain plants’ invasive success suggests that some invasive species produce allelochemicals that are novel against naive neighbours at the introduced range and therefore provide an advantage there (novel weapons hypothesis – NWH). However, a seldom-studied hypothesis suggests that invasive populations could not only possess novel weapons, but might also evolve their enhanced production. Moreover, so far no study has examined both the novelty and evolution of allelopathic effects. Here, we examined these two hypotheses in a set of experiments with the highly invasive plant Impatiens glandulifera. In the first experiment, we examined the evolution of allelopathic ability by comparing the inhibitory effects of leaf extracts from native versus invasive I. glandulifera on the germination success of its dominant neighbour Urtica dioica. In the following experiments, we examined the NWH by comparing the germination success of U. dioica seeds collected at the native versus invasive range of I. glandulifera, in response to either leaf extracts or soil trained with invasive I. glandulifera. The results of the first experiment indicate that invasive I. glandulifera exert a stronger inhibitory effect on the germination of U. dioica compared to their native counterparts, providing support for the hypothesis that allelopathic ability can evolve at the invasive range. However, the results of the two following experiments reveal no difference in the response of U. dioica from the native versus invasive range of I. glandulifera, to the allelopathic effects of either the leaf extracts or the trained soil. These results therefore do not provide support for the NWH, and suggest that increased allelopathy in invasive I. glandulifera might have been selected for by other processes. The results of this study call for biogeographical experiments that will examine not only the novelty but also the evolution of allelopathic effects in invasive plants.
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TL;DR: A Geographical Perspective on Germination Ecology: Tropical and Subtropical Zones and Biogeographical and Evolutionary Aspects of Seed Dormancy.
Abstract: Introduction. Ecologically Meaningful Germination Studies. Types of Seed Dormancy. Germination Ecology of Seeds with Nondeep Physiological Dormancy. Germination Ecology of Seeds with Morphophysiological Dormancy. Germination Ecology of Seeds with Physical Dormancy. Germination Ecology of Seeds in the Persistent Seed Bank. Causes of Within-Species Variations in Seed Dormancy and Germination Characteristics. A Geographical Perspective on Germination Ecology: Tropical and Subtropical Zones. A Geographical Perspective on Germination Ecology: Temperate and Arctic Zones. Germination Ecology of Plants with Specialized Life Cycles and/or Habitats. Biogeographical and Evolutionary Aspects of Seed Dormancy. Subject Index.
410 citations
Journal Article•
TL;DR: In this article, a 50+ year chronosequence of Alliaria petiolata invasion was studied and the authors found that a marked decline in its phytotoxin production and a consequent decline in their impact on three native species, across a 50 + year timeline of invasion.
Abstract: Invasive species can quickly transform biological communities due to their high abundance and strong impacts on native species, in part because they can be released from the ecological forces that limit native populations. However, little is known about the long-term dynamics of invasions; do invaders maintain their dominant status over long time spans, or do new ecological and evolutionary forces eventually develop to limit their populations? Alliaria petiolata is a Eurasian species that aggressively invades North American forest understories, in part due to the production of toxic phytochemicals. Here we document a marked decline in its phytotoxin production and a consequent decline in their impact on three native species, across a 50+ year chronosequence of Alliaria petiolata invasion. Genetic evidence suggests that these patterns result from natural selection for decreased phytotoxin production rather than founder effects during introduction and spread. These patterns are consistent with the finding of slowing A. petiolata population growth and rebounding native species abundance across a separate chronosequence in Illinois, U.S. These results suggest that this invader is developing evolutionary limits in its introduced range and highlight the importance of understanding the long-term processes that shape species invasions and their impacts.
196 citations
TL;DR: A meta-analysis of 384 studies that measured allelopathic effects of one species on another species or itself reveals that allelopathy could contribute to success of alien plants and the negative relationship between phylogenetic distance and allelelopathy indicates that alle lopathy might contribute to coexistence of closely related species or dominance of single species.
Abstract: Allelopathy (i.e. chemical interactions between plants) is known to affect individual performance, community structure and plant invasions. Yet, a quantitative synthesis is lacking. Here, we performed a meta-analysis of 384 studies that measured allelopathic effects of one species (allelopathy plant) on another species or itself (test plant). Overall, allelopathy reduced plant performance by 25%, but the variation in allelopathy was high. The type of method affected the allelopathic effect: compared to leachates, allelopathy was more negative when residues of allelopathy plants were applied, and less negative when soil conditioned by allelopathy plants was applied. The negative effects of allelopathy diminished with study duration, and increased with concentrations of leachates or residues. Although allelopathy was not significantly related to lifespan, life form or domestication of the interacting plants, it became more negative with increasing phylogenetic distance. Moreover, native plants suffered more from leachates of naturalised alien plants than from leachates of other native plants. Our synthesis reveals that allelopathy could contribute to success of alien plants. The negative relationship between phylogenetic distance and allelopathy indicates that allelopathy might contribute to coexistence of closely related species (i.e. convergence) or dominance of single species.
109 citations
TL;DR: The findings support the idea that the selection pressure of enemy release at the introduced range might attenuate over time, leading to the evolutionary recovery of enemy resistance.
Abstract: Summary
The success of invasive plants has often been attributed to their rapid evolution at the introduced range. In particular, release from native enemies has been suggested to select for an evolutionary shift in resource allocation patterns from herbivore defence to increased size. Such evolutionary processes can take place not only between the native and invasive ranges but also within the invasive range over time, but this premise has been very seldom studied.
In this study, we examined the potential for post-invasion evolution in two traits hypothesized to facilitate plant invasion success, that is herbivore resistance and allelopathic ability. We studied these traits in the invasive plant Impatiens glandulifera by comparing plants from its native populations and from populations across its invasion chronosequence.
Results of common-garden experiment and chemical analyses revealed that plants from native populations or older populations within the invasive range show greater resistance to the generalist herbivore, Deilephila elpenor, coupled with greater production of the secondary defence compound 2-methoxy-1,4-naphthoquinone glycoside. In contrast, no differences were found between populations in their allelopathic effect on the germination of the co-occurring neighbour, Urtica doica. Finally, results from a field survey suggested that older populations within the invasive range incur greater attack rates from local herbivores compared to more recently established populations.
Synthesis. Our findings support the idea that the selection pressure of enemy release at the introduced range might attenuate over time, leading to the evolutionary recovery of enemy resistance. This study emphasizes the importance of incorporating the effect of time since introduction when examining evolutionary or ecological processes of plant invasions.
50 citations
Cites methods from "Invasive success and the evolution ..."
...Data available from the Dryad Digital Repository http://dx.doi.org/10.5061/ dryad.85b2f (Gruntman et al. 2016)....
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TL;DR: Observed evolutionary convergence for multiple plant traits, between the natural and manipulative experiments, emphasizes the role of insect herbivores as key drivers of plant adaptation and geographic differentiation.
Abstract: Summary
Herbivory can drive rapid evolution of plant chemical traits mediating defensive and competitive ability. At a geographic scale, plant populations that escape selection from their ancestral herbivores may evolve decreased defence and increased competitiveness. While contrasts between native and invasive populations of plants lend support to this hypothesis, such experiments cannot establish causal links between herbivory and evolved invasive phenotypes.
Here, we conducted geographic contrasts, and coupled these with long-term selection experiments that directly test for evolutionary responses to herbivore exclusion. In common gardens, we contrasted Solidago altissima genotypes that were historically exposed or protected from herbivory across two experimental time-scales: (i) a natural experiment where plant populations evolved either with native herbivory (in Minnesota and New York) or evolved relatively free from herbivory for ˜100 years in Japan, and (ii) a 12-year manipulative experiment where plants were either exposed to ambient herbivory or treated with insecticide.
In both experiments, plant populations responded to herbivore release by evolving increased production of root allelochemicals and interspecific competitive ability against Poa pratensis. While plant resistance to a beetle herbivore did not diverge between plant origins, we still observed parallel evolutionary shifts in leaf secondary metabolite and protease inhibitor production, which may confer resistance to diverse herbivore species.
Synthesis. Observed evolutionary convergence for multiple plant traits, between the natural and manipulative experiments, emphasizes the role of insect herbivores as key drivers of plant adaptation and geographic differentiation.
31 citations
References
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01 Jan 2014
4,366 citations
Book•
10 Jun 1998
TL;DR: A Geographical Perspective on Germination Ecology: Tropical and Sub-tropical Zones as discussed by the authors, Temperate and Arctic Zones, and Semi-Arctic Zones: Temperate, Subtropical, and Arctic zones.
Abstract: Introduction. Ecologically Meaningful Germination Studies. Types of Seed Dormancy. Germination Ecology of Seeds with Nondeep Physiological Dormancy. Germination Ecology of Seeds with Morphophysiological Dormancy. Germination Ecology of Seeds with Physical Dormancy. Germination Ecology of Seeds in the Persistent Seed Bank. Causes of Within-Species Variations in Seed Dormancy and Germination Characteristics. A Geographical Perspective on Germination Ecology: Tropical and Subtropical Zones. A Geographical Perspective on Germination Ecology: Temperate and Arctic Zones. Germination Ecology of Plants with Specialized Life Cycles and/or Habitats. Biogeographical and Evolutionary Aspects of Seed Dormancy. Subject Index.
4,307 citations
University of California, Irvine1, University of Montana2, University of California, Riverside3, University of Notre Dame4, University of Vermont5, Kansas State University6, State University of New York at Plattsburgh7, Rockefeller University8, Vanderbilt University9, University of New Orleans10, University of California, Santa Cruz11
TL;DR: In this article, the introduction of invasive species and identifying life history stages where management will be most effective are discussed. And evolutionary processes may be key features in determining whether invasive species establish and spread.
Abstract: ■ Abstract Contributions from the field of population biology hold promise for understanding and managing invasiveness; invasive species also offer excellent opportunities to study basic processes in population biology. Life history studies and demographic models may be valuable for examining the introduction of invasive species and identifying life history stages where management will be most effective. Evolutionary processes may be key features in determining whether invasive species establish and spread. Studies of genetic diversity and evolutionary changes should be useful for
3,280 citations
University of Tennessee1, Centre national de la recherche scientifique2, International Union for Conservation of Nature and Natural Resources3, Swedish University of Agricultural Sciences4, Missouri Botanical Garden5, University of Paris-Sud6, University of Girona7, Institut national de la recherche agronomique8, Charles University in Prague9, Academy of Sciences of the Czech Republic10, University of Minho11, University of Porto12, Paul Sabatier University13, Spanish National Research Council14
TL;DR: Recent progress in understanding invasion impacts and management is highlighted, and the challenges that the discipline faces in its science and interactions with society are discussed.
Abstract: Study of the impacts of biological invasions, a pervasive component of global change, has generated remarkable understanding of the mechanisms and consequences of the spread of introduced populations. The growing field of invasion science, poised at a crossroads where ecology, social sciences, resource management, and public perception meet, is increasingly exposed to critical scrutiny from several perspectives. Although the rate of biological invasions, elucidation of their consequences, and knowledge about mitigation are growing rapidly, the very need for invasion science is disputed. Here, we highlight recent progress in understanding invasion impacts and management, and discuss the challenges that the discipline faces in its science and interactions with society.
2,346 citations
TL;DR: There are very few valid generalizations about invasive species, so that it is only possible to make weak, probabilistic predictions about which species will invade (Gilpin 1990; Daehler & Strong 1993).
Abstract: There are very few valid generalizations about invasive species, so that it is only possible to make weak, probabilistic predictions about which species will invade (Gilpin 1990; Daehler & Strong 1993). A phenomenon that has not received much attention, however, is the observation that, in alien environments, plants tend to be more vigorous and taller, producing more seeds than in their native distribution (Crawley 1987). The seed production of Chrysanthemoides monilifera (native to Sout'l Africa) in Australia and of Acacia longifolia (native to Australia) in South Africa is an order of magnitude higher where the plants are aliens (Noble 1989). The vigour and success of aliens in areas where they have been introduced has been attributed to both, more favourable environments, and to the release from natural phytophagous enemies (Crawley 1987). These alternatives can be evaluated according to two theories relating to resource allocation. The optimal defence hypothesis predicts that plants with limited resources will show trade-offs in biomass allocation among maintenance, growth, storage, reproduction, and defence (Coley et al. 1985; Bazzaz et al. 1987; Fagerstrom 1989; Herms & Mattson 1994; Lerdau et al. 1995). The environmental constraint hypothesis (Bryant et al. 1988), however, predicts that the evolution of defence mechanisms against herbivory will result in only minor reductions in growth. Resource availability is then the primary force determining whether there is surplus photosynthate available for allocation to secondary metabolism.
1,708 citations