Shannon A. Meadley Dunphy

Bio: Shannon A. Meadley Dunphy is an academic researcher from University of Toronto. The author has contributed to research in topics: Seed dispersal & Myrmica rubra. The author has an hindex of 2, co-authored 2 publications receiving 58 citations.

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

Abstract: 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.

An invasive slug exploits an ant-seed dispersal mutualism

Abstract: Plant-animal mutualisms, such as seed dispersal, are often vulnerable to disruption by invasive species. Here, we show for the first time how a non-ant invasive species negatively affects seed dispersal by ants. We examined the effects of several animal species that co-occur in a temperate deciduous forest-including native and invasive seed-dispersing ants (Aphaenogaster rudis and Myrmica rubra, respectively), an invasive slug (Arion subfuscus), and native rodents-on a native myrmecochorous plant, Asarum canadense. We experimentally manipulated ant, slug, and rodent access to seed depots and measured seed removal. We also video-recorded depots to determine which other taxa interact with seeds. We found that A. rudis was the main disperser of seeds and that A. subfuscus consumed elaiosomes without dispersing seeds. Rodent visitation was rare, and rodent exclusion had no significant effect on seed or elaiosome removal. We then used data obtained from laboratory and field mesocosm experiments to determine how elaiosome robbing by A. subfuscus affects seed dispersal by A. rudis and M. rubra. We found that elaiosome robbing by slugs reduced seed dispersal by ants, especially in mesocosms with A. rudis, which picks up seeds more slowly than M. rubra. Taken together, our results show that elaiosome robbing by an invasive slug reduces seed dispersal by ants, suggesting that invasive slugs can have profound negative effects on seed dispersal mutualisms.

The community ecology of invasive species: where are we and what\'s next?

Abstract: Alien species are continually introduced in most regions of the world, but not all survive and coexist with the resident native species Approaches analyzing the functional (or phylogenetic) similarity between invasive species and native communities are increasingly employed to infer the processes underlying successful invasions and to predict future invaders The relatively simple conceptual foundations have made these approaches very appealing and therefore widely used, often leading to confusion and hampering generalizations We undertook a comprehensive review and synthesis of the functional similarity approach in invasion community ecology to clarify its advantages and limitations, to summarize what has been learned thus far, and to suggest avenues for future improvement We first present the methodological state of the art and provide general guidelines Second, by organizing the published literature around seven key questions in invasion ecology we found cumulative evidence that: at large spatial scales phylogenetic relatedness of invasive and native species is a good predictor of invasion success, but a poor predictor of invasion impacts; at fine spatial scales, community resistance to invasion tends to increase with native species diversity and with similarity to the invaders, consistent with patterns emerging from biotic interactions In general, the processes filtering invaders appear to vary across species’ invasion stage and along environmental gradients Nonetheless, we found conflicting evidence for differences in community assembly processes between invasive and native species, and between the invader's native and adventive ranges Finally, we propose four important avenues for overcoming some of the identified methodological and conceptual limitations of the approach, in particular by integrating observational and experimental analyses and by explicitly considering species’ demographic rates and complex biotic interactions Although the functional similarity approach bears intrinsic limitations, it still offers many opportunities in invasion community ecology at large spatial scales This article is protected by copyright All rights reserved

Risks to pollinators and pollination from invasive alien species.

Abstract: Invasive alien species modify pollinator biodiversity and the services they provide that underpin ecosystem function and human well-being. Building on the Intergovernmental Science-Policy Platform for Biodiversity and Ecosystem Services (IPBES) global assessment of pollinators and pollination, we synthesize current understanding of invasive alien impacts on pollinators and pollination. Invasive alien species create risks and opportunities for pollinator nutrition, re-organize species interactions to affect native pollination and community stability, and spread and select for virulent diseases. Risks are complex but substantial, and depend greatly on the ecological function and evolutionary history of both the invader and the recipient ecosystem. We highlight evolutionary implications for pollination from invasive alien species, and identify future research directions, key messages and options for decision-making.

When does invasive species removal lead to ecological recovery? Implications for management success

Abstract: The primary goal of invasive species management is to eliminate or reduce populations of invasive species. Although management efforts are often motivated by broader goals such as to reduce the negative impacts of invasive species on ecosystems and society, there has been little assessment of the consistency between population-based (e.g., removing invaders) and broader goals (e.g., recovery of ecological systems) for invasive species management. To address this, we conducted a comprehensive review of studies (N = 151) that removed invasive species and assessed ecological recovery over time. We found positive or mixed outcomes in most cases, but 31% of the time ecological recovery did not occur or there were negative ecological outcomes, such as increases in non-target invasive species. Ecological recovery was more likely in areas with relatively little anthropogenic disturbance and few other invaders, and for the recovery of animal populations and communities compared to plant communities and ecosystem processes. Elements of management protocols, such as whether invaders were eradicated (completely removed) versus aggressively suppressed (≥90% removed), did not affect the likelihood of ecological recovery. Our findings highlight the importance of considering broader goals and unintended outcomes when designing and implementing invasive species management programs.

The Role of Symbiotic Microbes in Insect Invasions

Abstract: The number of insect species transported to non-native regions is increasing, and, once established, these invasive insects have serious impacts on the environment and regional economies. Recent research highlights several cases of insect invasions facilitated by symbiotic microbes. Symbioses impact biological invasions, but few reviews have addressed the role of symbiotic microbes in insect invasions. Focusing on the insect–microbial symbiosis, we show the importance of microbial symbionts in determining the pest status of insects at insect–microbial levels, insect–plant–microbial levels, and other multispecific levels. Drawing on examples from different ecosystems, we review the key mechanisms and principles whereby facultative/mutualistic microbes affect insect invasions and coevolve with the invasive insects. We propose a conceptual framework for assessing the role of symbiotic microbes in insect invasions that promises improved risk analyses, spread and impact modeling, and management of invasive ins...