Mutualism between co-introduced species facilitates invasion and alters plant community structure

Generalized mutualisms are often predicted to be resilient to changes in partner identity. Variation in mutualism-related traits between native and invasive species however, can exacerbate the spread of invasive species (‘invasional meltdown’) if invasive partners strongly interact. Here we show how invasion by a seed-dispersing ant ( Myrmica rubra ) promotes recruitment of a co-introduced invasive over native ant-dispersed (myrmecochorous) plants. We created experimental communities of invasive ( M. rubra ) or native ants ( Aphaenogaster rudis ) and invasive and native plants and measured seed dispersal and plant recruitment. In our mesocosms, and in laboratory and field trials, M. rubra acted as a superior seed disperser relative to the native ant. By contrast, previous studies have found that invasive ants are often poor seed dispersers compared with native ants. Despite belonging to the same behavioural guild, seed-dispersing ants were not functionally redundant. Instead, native and invasive ants had strongly divergent effects on plant communities: the invasive plant dominated in the presence of the invasive ant and the native plants dominated in the presence of the native ant. Community changes were not due to preferences for coevolved partners: variation in functional traits of linked partners drove differences. Here, we show that strongly interacting introduced mutualists can be major drivers of ecological change.

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An invasive ant distribution database to support biosecurity risk analysis in the Pacific

Pacific Conservation Biology ◽

10.1071/pc17004 ◽

2017 ◽

Vol 23 (3) ◽

pp. 258 ◽

Cited By ~ 2

Author(s):

Monica A. M. Gruber ◽

Meghan Cooling ◽

Allan R. Burne

Keyword(s):

Invasive Species ◽

Risk Analysis ◽

Native Species ◽

Small Island ◽

Accurate Information ◽

Analysis Tool ◽

Invasive Ants ◽

Invasive Ant ◽

Conflicting Information ◽

The Pacific

Invasive species are one of the most serious threats to biodiversity. Up-to-date and accurate information on the distribution of invasive species is an important biosecurity risk analysis tool. Several databases are available to determine the distributions of invasive and native species. However, keeping this information current is a real challenge. Ants are among the most widespread invasive species. Five species of ants are listed in the IUCN list of damaging invasive species, and many other species are also invasive in the Pacific. We sought to determine and update the distribution information for the 18 most problematic invasive ant species in the Pacific to assist Small Island Developing States with risk analysis. We compared the information on six public databases, conducted a literature review, and contacted experts on invasive ants in the Pacific region to resolve conflicting information. While most public records were accurate we found some new records had not yet been incorporated in the public databases, and some information was inaccurate. The maintenance of public databases faces an enormous challenge in balancing completeness (~15 000 ant species in this case) with accuracy (the impossibility of constantly surveying) and utility.

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Allelopathic disruptions of biotic interactions due to non-native plants.

Plant invasions: the role of biotic interactions ◽

10.1079/9781789242171.0270 ◽

2020 ◽

pp. 270-280

Author(s):

Lauren M. Smith-Ramesh

Keyword(s):

Invasive Species ◽

Mycorrhizal Fungi ◽

Native Species ◽

Invasive Plant ◽

Native Plants ◽

Biotic Interactions ◽

Resident Species ◽

Negative Impacts ◽

And Performance ◽

Native Invasive

Abstract Allelopathy, or the process by which plants influence the growth and performance of their neighbours through the release of chemicals, may play a key role in mediating the impacts of non-native invasive species on their neighbours. The Novel Weapons Hypothesis purports that non-native invasive species are in part successful because they produce harmful allelochemicals to which resident species are particularly susceptible because residents lack a shared evolutionary history with the invader. While allelopathic non-native invaders may reduce the growth and performance of neighbours through direct phytotoxicity, they may more often exert negative impacts through disruption of biotic interactions among resident species. Allelopathy by non-native plants may disrupt mutualisms between resident plants and microbes, plant-herbivore interactions or existing competitive and facilitative interactions among resident plants. For example, several non-native plants are known to disrupt the mutualism between resident plants and mycorrhizal fungi, reducing resident plant fitness to the benefit of the invader. Allelopathic non-natives may also disrupt interactions among resident plants and their herbivores when allelochemicals also influence herbivore behaviour or fitness. Alternatively, biotic interactions can also be protective for resident species, which may be less susceptible to the impacts of non-native species when their mutualisms are intact. As we advance our understanding of allelopathy and its role in mediating the impacts of invasive plant species, we may gain new insights by viewing invasions within a network context rather than focusing on pairwise interactions.

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Allelopathy is pervasive in invasive plants

Biological Invasions ◽

10.1007/s10530-020-02383-6 ◽

2020 ◽

Author(s):

Susan Kalisz ◽

Stephanie N. Kivlin ◽

Lalasia Bialic-Murphy

Keyword(s):

Invasive Species ◽

Invasive Plants ◽

Native Species ◽

Invasive Plant ◽

Native Plants ◽

Plant Performance ◽

Native Plant ◽

Plant Phylogeny ◽

Plant Families ◽

Allelopathic Compounds

Abstract Invasive species utilize a wide array of trait strategies to establish in novel ecosystems. Among these traits is the capacity to produce allelopathic compounds that can directly inhibit neighboring native plants or indirectly suppress native plants via disruption of beneficial belowground microbial mutualisms, or altered soil resources. Despite the well-known prevalence of allelopathy among plant taxa, the pervasiveness of allelopathy among invasive plants is unknown. Here we demonstrate that the majority of the 524 invasive plant species in our database produce allelochemicals with the potential to negatively affect native plant performance. Moreover, allelopathy is widespread across the plant phylogeny, suggesting that allelopathy could have a large impact on native species across the globe. Allelopathic impacts of invasive species are often thought to be present in only a few plant clades (e.g., Brassicaceae). Yet our analysis shows that allelopathy is present in 72% of the 113 plant families surveyed, suggesting that this ubiquitous mechanism of invasion deserves more attention as invasion rates increase across the globe.

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Invasive ants reduce abundance of small rainforest skinks

Biodiversity and Conservation ◽

10.1007/s10531-022-02360-6 ◽

2022 ◽

Author(s):

Lori Lach ◽

Dylan Case ◽

Peter Yeeles ◽

Conrad J. Hoskin

Keyword(s):

Invasive Species ◽

Prey Abundance ◽

Unintended Effects ◽

Invasive Ants ◽

Invasive Ant ◽

Main Method ◽

Invertebrate Prey ◽

Lower Abundance ◽

The Tropics ◽

Direct Threat

AbstractInvasive ants are among the world’s most damaging invasive species, often directly or indirectly affecting native fauna. Insecticidal baits are the main method for suppressing or eradicating invasive ant populations, but their use must be considered against potential for unintended effects on native organisms. The invasive yellow crazy ant (Anoplolepis gracillipes) is widespread in the tropics, particularly on islands, where they have displaced a range of invertebrates. Effects of this ant on vertebrates, and in continental ecosystems generally, are less studied. We investigated the effects of yellow crazy ants and bait application on rainforest skinks and their invertebrate prey. We compared skink and skink prey abundance across four replicated rainforest site categories: high and low yellow crazy ant sites had both been baited but differed in yellow crazy ant activity; control sites had never had yellow crazy ants or been baited; and buffer sites had never had yellow crazy ants but had been baited. We recorded significantly lower abundance of two small skink species (Lygisaurus laevis and Saproscincus tetradactylus) in high yellow crazy ant sites compared to all other site categories. The differences persisted even after baiting reduced yellow crazy ant activity by 97.8% ± 0.04% (mean ± SD). A larger rainforest skink species (Carlia rubrigularis) was not negatively affected by yellow crazy ant invasion. Skink prey abundance was significantly lower in high yellow crazy ant sites compared to control sites and low yellow crazy ant sites, but not compared to buffer sites. These differences did not persist following baiting. We found no evidence that baiting negatively affects skinks or their invertebrate prey. Our data suggest that yellow crazy ants, but not the bait used to treat them, pose a direct threat to small rainforest skinks.

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Allelopathic disruptions of biotic interactions due to non-native plants.

Plant invasions: the role of biotic interactions ◽

10.1079/9781789242171.0015 ◽

2020 ◽

pp. 270-280

Author(s):

Lauren M. Smith-Ramesh ◽

Keyword(s):

Invasive Species ◽

Mycorrhizal Fungi ◽

Native Species ◽

Invasive Plant ◽

Native Plants ◽

Biotic Interactions ◽

Resident Species ◽

Negative Impacts ◽

And Performance ◽

Native Invasive

Allelopathy, or the process by which plants influence the growth and performance of their neighbours through the release of chemicals, may play a key role in mediating the impacts of non-native invasive species on their neighbours. The Novel Weapons Hypothesis purports that non-native invasive species are in part successful because they produce harmful allelochemicals to which resident species are particularly susceptible because residents lack a shared evolutionary history with the invader. While allelopathic non-native invaders may reduce the growth and performance of neighbours through direct phytotoxicity, they may more often exert negative impacts through disruption of biotic interactions among resident species. Allelopathy by non-native plants may disrupt mutualisms between resident plants and microbes, plant-herbivore interactions or existing competitive and facilitative interactions among resident plants. For example, several non-native plants are known to disrupt the mutualism between resident plants and mycorrhizal fungi, reducing resident plant fitness to the benefit of the invader. Allelopathic non-natives may also disrupt interactions among resident plants and their herbivores when allelochemicals also influence herbivore behaviour or fitness. Alternatively, biotic interactions can also be protective for resident species, which may be less susceptible to the impacts of non-native species when their mutualisms are intact. As we advance our understanding of allelopathy and its role in mediating the impacts of invasive plant species, we may gain new insights by viewing invasions within a network context rather than focusing on pairwise interactions.

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Effects of invasive plant patch size and distance on the pollination and reproduction of native boreal plants

Botany ◽

10.1139/cjb-2015-0233 ◽

2016 ◽

Vol 94 (12) ◽

pp. 1151-1160 ◽

Cited By ~ 1

Author(s):

Katie V. Spellman ◽

Christa P.H. Mulder ◽

Matthew L. Carlson

Keyword(s):

Invasive Species ◽

Seed Production ◽

Invasive Plants ◽

Native Species ◽

Patch Size ◽

Invasive Plant ◽

Native Plants ◽

Invasion Process ◽

Melilotus Albus ◽

Boreal Plants

In pollinator-limited ecosystems in the earliest stages of the invasion process, the effects of invasive plants on the pollination and reproduction of co-flowering native plants may be particularly sensitive to the distance between native and non-native plants. Our study tests how the distance from invasive plant patches affects the pollination and reproduction of two native boreal shrubs. We established circular sites with plots of flowering Vaccinium vitis-idaea L. and Rhododendron groenlandicum (Oeder) Kron and Judd spanning from 1 to 40 m from the site center. In 2011 and 2012, we added flowering non-native Melilotus albus Medik. to the center of sites in small patches (40 individuals) or large patches (120 individuals) and left other sites as controls. In some cases, the effects of M. albus were uniform across the 40 m distance, such as the change in V. vitis-idaea seed production when large patches of M. albus were added. In other cases, relationships with distance were found, and changes in percent pollination or seed production occurred most rapidly over the first 10 m from the patch. Our data supports the hypothesis that the detectable impact an invasive species has on the pollination of native species is affected by the spatial scale over which it is evaluated.

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Who’s invading what? Systems thinking about invasive species

Canadian Journal of Plant Science ◽

10.4141/cjps07116 ◽

2007 ◽

Vol 87 (5) ◽

pp. 993-999 ◽

Cited By ~ 11

Author(s):

B. M. H. Larson

Keyword(s):

Invasive Species ◽

Human Population ◽

Invasive Plant ◽

Sociology Of Science ◽

Invasion Biology ◽

Ecological Systems ◽

Ecological Change ◽

Invasive Plant Species ◽

Per Se

While invasive plant species have dramatic and varied effects, this paper examines the focus of this symposium on their “threat to native biodiversity and ecosystems”. This claim implies that there is (i) an enduring something, (ii) it is native, and (iii) it is under threat from invasive species. I examine these implications in turn, first considering the role of the observer in invasion biology, particularly in preferring a nature characterized by stability rather than flux. Second, I examine the concept of “native” given that humans are thoroughly embedded within natural ecological systems. Third, I demonstrate how our exclusion of humans conditions us to consider invasive species a primary threat rather than one among many interacting causal agents of global change; in particular, recent evidence indicates that these agents, which include human-caused disturbances and global warming (not to mention human population growth and global trade), may overwhelm the effects of invasive species per se. For these and other reasons, some ecologists have argued that ecological change is inevitable and that our concerns about invasive species are unjustified. I discuss these issues and suggest ways for ecologists to conduct engaged research through appropriate advocacy and engagement with stakeholders dealing with local invasive species. Key words: Advocacy, culture, philosophy of nature, sociology of science

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Fire effects on the ant community in areas of native and exotic vegetation

Sociobiology ◽

10.13102/sociobiology.v66i1.3178 ◽

2019 ◽

Vol 66 (1) ◽

pp. 44

Author(s):

Juan Manuel Arcusa

Keyword(s):

Invasive Species ◽

Invasive Plant ◽

Natural Disturbance ◽

Fire Effects ◽

Recovery Phase ◽

Buenos Aires Province ◽

Management Tools ◽

Southeastern Part ◽

Ant Community ◽

Mountain Grassland

Acacia melanoxylon is an invasive species of the mountain grassland of the southeastern part of the Buenos Aires province, Argentina. Fires are a natural disturbance, characteristic of the area, and favor the germination of this invasive plant. However, they are used as the first step in management systems for the Acacia species. Moreover, the use of ants in monitoring programs is very scarce for Argentina. The objectives of this work are: 1) to analyze the response and resilience capacity of native and invaded sites by A. melanoxylon after a fire for controlling this invasive species; 2) to detect groups of ants considered to be indicators of the recovery phase subsequent to the burning; and 3) to apply the concept of groups of disturbances, proposed by Roig and Espadaler, as an effective tool for monitoring. The sampling design consisted of three replicates of 10 pitfall traps for each environment, native and invaded. Ant species were grouped into functional groups, trophic guilds, and disturbance groups. The fire did not generate significant changes in the richness and abundance of ants in the mountain grassland. However, it generated a positive effect on the sites invaded by Acacia during the first year after the fire. The groups of minimum specialists of vegetation and the dominant Dolichoderinae are considered good bioindicators. Finally, the disturbance indicators can be considered reliable management tools if the biology of the species that compose it is known beforehand.

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Experts’ moral views on gene drive technologies: a qualitative interview study

BMC Medical Ethics ◽

10.1186/s12910-021-00588-5 ◽

2021 ◽

Vol 22 (1) ◽

Author(s):

N. de Graeff ◽

Karin R. Jongsma ◽

Annelien L. Bredenoord

Keyword(s):

Invasive Species ◽

Epistemic Uncertainty ◽

Field Trials ◽

Interview Study ◽

Gene Drive ◽

Agricultural Pests ◽

Stepping Stones ◽

Vector Borne Diseases ◽

Qualitative Interview Study ◽

The Status

Abstract Background Gene drive technologies (GDTs) promote the rapid spread of a particular genetic element within a population of non-human organisms. Potential applications of GDTs include the control of insect vectors, invasive species and agricultural pests. Whether, and if so, under what conditions, GDTs should be deployed is hotly debated. Although broad stances in this debate have been described, the convictions that inform the moral views of the experts shaping these technologies and related policies have not been examined in depth in the academic literature. Methods In this qualitative study, we interviewed GDT experts (n = 33) from different disciplines to identify and better understand their moral views regarding these technologies. The pseudonymized transcripts were analyzed thematically. Results The respondents’ moral views were principally influenced by their attitudes towards (1) the uncertainty related to GDTs; (2) the alternatives to which they should be compared; and (3) the role humans should have in nature. Respondents agreed there is epistemic uncertainty related to GDTs, identified similar knowledge gaps, and stressed the importance of realistic expectations in discussions on GDTs. They disagreed about whether uncertainty provides a rationale to refrain from field trials (‘risks of intervention’ stance) or to proceed with phased testing to obtain more knowledge given the harms of the status quo (‘risks of non-intervention’ stance). With regards to alternatives to tackle vector-borne diseases, invasive species and agricultural pests, respondents disagreed about which alternatives should be considered (un)feasible and (in)sufficiently explored: conventional strategies (‘downstream solutions’ stance) or systematic changes to health care, political and agricultural systems (‘upstream solutions’ stance). Finally, respondents held different views on nature and whether the use of GDTs is compatible with humans’ role in nature (‘interference’ stance) or not (‘non-interference stance’). Conclusions This interview study helps to disentangle the debate on GDTs by providing a better understanding of the moral views of GDT experts. The obtained insights provide valuable stepping-stones for a constructive debate about underlying value conflicts and call attention to topics that deserve further (normative) reflection. Further evaluation of these issues can facilitate the debate on and responsible development of GDTs.

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Interactions between invasive plants and heavy metal stresses: a review

Journal of Plant Ecology ◽

10.1093/jpe/rtab100 ◽

2021 ◽

Author(s):

Jian Li ◽

Zhanrui Leng ◽

Yueming Wu ◽

Yizhou Du ◽

Zhicong Dai ◽

...

Keyword(s):

Invasive Species ◽

Invasive Plants ◽

Native Plants ◽

Escape Behavior ◽

Negative Influence ◽

Plant Litter ◽

Global Changes ◽

Native Plant ◽

Anthropogenic Contamination ◽

The Impact

Abstract Global changes have altered the distribution pattern of the plant communities, including invasive species. Anthropogenic contamination may reduce native plant resistance to the invasive species. Thus, the focus of the current review is on the contaminant biogeochemical behavior among native plants, invasive species and the soil within the plant-soil ecosystem to improve our understanding of the interactions between invasive plants and environmental stressors. Our studies together with synthesis of the literature showed that a) the impacts of invasive species on environmental stress were heterogeneous, b) the size of the impact was variable, and c) the influence types were multidirectional even within the same impact type. However, invasive plants showed self-protective mechanisms when exposed to heavy metals (HMs) and provided either positive or negative influence on the bioavailability and toxicity of HMs. On the other hand, HMs may favor plant invasion due to the widespread higher tolerance of invasive plants to HMS together with the “escape behavior” of native plants when exposed to toxic HM pollution. However, there has been no consensus on whether elemental compositions of invasive plants are different from the natives in the polluted regions. A quantitative research comparing plant, litter and soil contaminant contents between native plants and the invaders in a global context is an indispensable research focus in the future.

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