Propagule pressure and native community connectivity interact to influence invasion success in metacommunities

Abstract Invasive alien plants challenge ecosystems restoration. Thus, understanding factors determining the establishment of invasive plants is crucial to improve restoration outcomes. Some key drivers of invasibility of plant communities have been studied, but results are inconsistent, and combined effects have not been addressed. We investigated the contribution of three drivers of invasion success during early phases of restoration, i.e., biotic resistance, invasive propagule pressure, and environmental fluctuations.We compared the contribution of these drivers in a series of mesocosms experiments using designed grasslands as a model system, and Solidago gigantea as invasive model species. Two grassland communities were designed according to competitive trait hierarchies with different sowing patterns, reflecting variation in biotic resistance. We then manipulated invader propagule pressure and applied different scenarios of environmental fluctuation, i.e., flood, heat, and N fertilization. Alien biomass was considered as proxy for invasion success, while native biomass represented restoration success.There were consistent effects of biotic resistance to S. gigantea invasion via competitive trait hierarchies in the three experiments. Communities dominated by species with high-competition traits were more resistant regardless of environmental fluctuation. Clumped seeding of the native community reduced invasibility, whereas larger invasive propagule size increased invasion. The effects of environmental fluctuation were less consistent and context-dependent, thus playing a secondary role when compared to biological drivers of invasion. Restoration initiatives on grasslands impacted by invasive plants should consider biotic resistance of the restored community as a key driver and the importance of controlling further arrivals of invasive species during community assembly.

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Competitive trait hierarchies of native communities and invasive propagule pressure consistently predict invasion success during grassland establishment

Biological Invasions ◽

10.1007/s10530-021-02630-4 ◽

2021 ◽

Author(s):

Sandra Rojas-Botero ◽

Johannes Kollmann ◽

Leonardo H. Teixeira

Keyword(s):

Invasive Plants ◽

Biotic Resistance ◽

Propagule Pressure ◽

N Fertilization ◽

Invasion Success ◽

Native Community ◽

Environmental Fluctuation ◽

Native Communities ◽

Key Driver ◽

Early Phases

AbstractInvasive non-native plants challenge ecosystems restoration, and understanding the factors that determine the establishment of invasive plants is crucial to improve restoration outcomes. However, the drivers of invasibility of plant communities are not sufficiently clear, and combined effects are not understood. Therefore, we investigated the contribution of the main drivers of invasion success during early phases of restoration, i.e., biotic resistance, invasive propagule pressure, and environmental fluctuations. We compared the contribution of these drivers in a series of mesocosms experiments using designed grasslands as a model system, and Solidago gigantea as invasive model species. Two grassland communities were designed according to competitive trait hierarchies with different sowing patterns, reflecting variation in biotic resistance. We then manipulated invader propagule pressure and applied different scenarios of environmental fluctuation, i.e., flood, heat, and N fertilization. Invasive biomass was considered as proxy for invasion success, while native biomass represented restoration success. There were consistent effects of biotic resistance to S. gigantea invasion via competitive trait hierarchies in the three experiments. Communities dominated by species with high-competition traits were more resistant regardless of environmental fluctuation. Clumped seeding of the native community reduced invasibility, whereas high non-native propagule density increased invasion. The effects of environmental fluctuation were less consistent and context-dependent, thus playing a secondary role when compared to biotic drivers of invasion. Restoration initiatives on grasslands impacted by invasive plants should consider biotic resistance of the restored community as a key driver and the importance of controlling further arrivals of invasive species during community assembly.

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Predicting range-shift success potential for tropical marine fishes using external morphology

Biology Letters ◽

10.1098/rsbl.2016.0505 ◽

2016 ◽

Vol 12 (9) ◽

pp. 20160505 ◽

Cited By ~ 9

Author(s):

Shannen M. Smith ◽

Rebecca J. Fox ◽

Jennifer M. Donelson ◽

Megan L. Head ◽

David J. Booth

Keyword(s):

Fish Larvae ◽

Climatic Conditions ◽

Invasion Success ◽

Range Shift ◽

Tropical Fish ◽

Range Shifts ◽

Native Community ◽

The Family ◽

Moorish Idol ◽

New Habitats

With global change accelerating the rate of species' range shifts, predicting which are most likely to establish viable populations in their new habitats is key to understanding how biological systems will respond. Annually, in Australia, tropical fish larvae from the Great Barrier Reef (GBR) are transported south via the East Australian Current (EAC), settling into temperate coastal habitats for the summer period, before experiencing near-100% mortality in winter. However, within 10 years, predicted winter ocean temperatures for the southeast coast of Australia will remain high enough for more of these so-called ‘tropical vagrants’ to survive over winter. We used a method of morphological niche analysis, previously shown to be an effective predictor of invasion success by fishes, to project which vagrants have the greatest likelihood of undergoing successful range shifts under these new climatic conditions. We find that species from the family of butterflyfishes (Chaetodontidae), and the moorish idol, Zanclus cornutus , are most likely to be able to exploit new niches within the ecosystem once physiological barriers to overwintering by tropical vagrant species are removed. Overall, the position of vagrants within the morphospace was strongly skewed, suggesting that impending competitive pressures may impact disproportionately on particular parts of the native community.

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Community Structure Affects Annual Grass Weed Invasion During Restoration of a Shrub–Steppe Ecosystem

Invasive Plant Science and Management ◽

10.1614/ipsm-d-13-00021.1 ◽

2014 ◽

Vol 7 (1) ◽

pp. 1-13 ◽

Cited By ~ 8

Author(s):

Phil S. Allen ◽

Susan E. Meyer

Keyword(s):

Community Structure ◽

Native Species ◽

Propagule Pressure ◽

Alternative Hypothesis ◽

Perennial Grasses ◽

Invasion Success ◽

Sagebrush Steppe ◽

Annual Grass ◽

Shrub Steppe ◽

Steppe Communities

AbstractEcological restoration of shrub–steppe communities in the western United States is often hampered by invasion of exotic annual grasses during the process. An important question is how to create restored communities that can better resist reinvasion by these weeds. One hypothesis is that communities comprised of species that are functionally similar to the invader will best resist invasion, while an alternative hypothesis is that structurally more complex and diverse communities will result in more effective competitive exclusion. In this field experiment, we examined the effects of restored community structure on the invasion success of three annual grass weeds (downy brome, jointed goatgrass, and cereal rye). We created replicated community plots that varied in species composition, structural complexity and density, then seeded in annual grass weeds and measured their biomass and seed production the following year, and their cover after 1 and 3 yr. Annual grass weeds were not strongly suppressed by any of the restored communities, indicating that it was difficult for native species to completely capture available resources and exclude annual grass weeds in the first years after planting. Perennial grass monocultures, particularly of the early seral grass bottlebrush squirreltail, were the most highly invaded communities, while structurally complex and diverse mixtures of shrubs (big sagebrush, rubber rabbitbrush), perennial grasses (bluebunch wheatgrass and bottlebrush squirreltail) and forbs (Lewis flax, Utah sweetvetch, hairy golden aster, gooseberryleaf globemallow) were more resistant to invasion. These results suggest that restoration of sagebrush steppe communities resistant to annual grass invasion benefits from higher species diversity; significant reduction of weed propagule pressure prior to restoration may be required.

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Invasion genomics uncover contrasting scenarios of genetic diversity in a widespread marine invader

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.2116211118 ◽

2021 ◽

Vol 118 (51) ◽

pp. e2116211118

Author(s):

Cornelia Jaspers ◽

Moritz Ehrlich ◽

José Martin Pujolar ◽

Sven Künzel ◽

Till Bayer ◽

...

Keyword(s):

Genetic Diversity ◽

Propagule Pressure ◽

Invasion Success ◽

Invasion Dynamics ◽

The Past ◽

Marine Invasive Species ◽

Successful Establishment ◽

Low Levels ◽

International Conventions ◽

Dominant Paradigm

Invasion rates have increased in the past 100 y irrespective of international conventions. What characterizes a successful invasion event? And how does genetic diversity translate into invasion success? Employing a whole-genome perspective using one of the most successful marine invasive species world-wide as a model, we resolve temporal invasion dynamics during independent invasion events in Eurasia. We reveal complex regionally independent invasion histories including cases of recurrent translocations, time-limited translocations, and stepping-stone range expansions with severe bottlenecks within the same species. Irrespective of these different invasion dynamics, which lead to contrasting patterns of genetic diversity, all nonindigenous populations are similarly successful. This illustrates that genetic diversity, per se, is not necessarily the driving force behind invasion success. Other factors such as propagule pressure and repeated introductions are an important contribution to facilitate successful invasions. This calls into question the dominant paradigm of the genetic paradox of invasions, i.e., the successful establishment of nonindigenous populations with low levels of genetic diversity.

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Are Introduced Alien Species More Predisposed to Invasion in Recipient Environments If They Provide a Wider Range of Services to Humans?

Diversity ◽

10.3390/d13110553 ◽

2021 ◽

Vol 13 (11) ◽

pp. 553

Author(s):

Kowiyou Yessoufou ◽

Annie Estelle Ambani

Keyword(s):

South Africa ◽

Invasive Species ◽

Alien Species ◽

Propagule Pressure ◽

Phylogenetic Signal ◽

Dna Barcode ◽

Alien Plants ◽

Invasion Success ◽

Alien Invasive Species ◽

Unexpected Finding

The drivers of invasion success of alien species remain, to some extent, a matter of debate. Here, we suggest that the services (the benefits humans obtain from a species) provided by alien plants could predict their invasion status, such that alien species providing more services would be more likely to be invasive than not. The rationale for this expectation is that alien species providing multiple services stand a better chance of being introduced in various numbers and multiple times outside their native range (propagule pressure theory). We investigated this hypothesis on alien woody species in South Africa. First, we defined 12 services provided by all the 210 known naturalized alien woody plants in South Africa. Then, we tested for a phylogenetic signal in these services using a DNA barcode-based phylogeny. Finally, we tested for potential links between the services and invasion status by fitting GLM models with appropriate error families. We found a phylogenetic signal in most services, suggesting that closely related species tend to provide similar services. Counter-intuitively, we consistently found that alien non-invasive species tend to provide more services, or even unique services, in comparison to alien invasive species. Although alternative scenarios are plausible to explain this unexpected finding, we speculate that harvesting alien plants for human benefits may limit their invasion ability. This warrants further investigation.

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Long-Term Coexistence of Two Invasive Vespid Wasps in NW Patagonia (Argentina)

10.21203/rs.3.rs-1020520/v1 ◽

2021 ◽

Author(s):

Ana Julia Pereira ◽

Maité Masciocchi ◽

Juan Carlos Corley

Keyword(s):

Species Coexistence ◽

Biotic Resistance ◽

Negative Impact ◽

Niche Overlap ◽

Invasion Success ◽

Nest Density ◽

Native Community ◽

Wasp Species ◽

Vespula Germanica

Abstract In Patagonia (Argentina) two non-native vespid wasps became established in the last decades. Vespula germanica was first detected in 1980 while V. vulgaris arrived some 30 years later. Both species can have a strong negative impact on agriculture, natural environment and on outdoor human activities. Invasion success -the establishment and spread of a species- may be influenced negatively by the degree of interaction with the resident native community, and alien species already present. The sequential arrival of these two wasps allows us to understand key questions of invasion ecology. Additionally, recognizing the outcome of the invasion by vespids in Patagonia -a region lacking native social wasps-, may help plan species-focused mitigation and control strategies. We explored long term species coexistence through the deterministic Lotka-Volterra competition model, using site-specific field data on prey captured (to estimate niche overlap) and current nest densities in sites. Food items carried by workers were similar but there is some degree of segregation. V. germanica nest density in shared sites, and in sites without coexistence, were 3.14 and 3.5 respectively, being higher for V. vulgaris with 4.71 and 5.33. The model predicts stable co-existence of both species in the invaded range, yet a higher abundance of V. vulgaris should be expected. Added to evidence on other foraging behavioral attributes of both wasp species and the invasion patterns observed in other regions, it is likely that the prior presence of V. germanica does not contribute significantly to the biotic resistance of the invaded range for V. vulgaris

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Field-based effects of allelopathy in invaded tallgrass prairie

Botany ◽

10.1139/b11-009 ◽

2011 ◽

Vol 89 (4) ◽

pp. 227-234 ◽

Cited By ~ 8

Author(s):

Jesse Harnden ◽

Andrew S. MacDougall ◽

Benjamin A. Sikes

Keyword(s):

Tallgrass Prairie ◽

Propagule Pressure ◽

Seedling Survival ◽

Population Expansion ◽

Growth Inhibitor ◽

Arbuscular Mycorrhizal ◽

Am Fungi ◽

Invasion Success ◽

Hyphal Length ◽

Fine Fescue

Allelopathic phytochemicals have been linked to invasion success, but their role in the invasion process remains unclear. Toxicity effects demonstrated with lab bioassays may be neutralized in soils, and their role in population expansion can be intertwined with nonallelopathic processes that also influence dispersal and establishment. Here, we use greenhouse experiments to test the soil-based impacts of invasive fine fescue ( Festuca rubra L.) on recruitment in tallgrass prairie. Fescue roots release the growth inhibitor m-tyrosine. Using root washes and fescue-conditioned soils to mimic field potency, we determined allelopathic impacts on recruitment, including intraspecific limitation. We also tested whether nonallelopathic factors (propagule pressure, disturbance, and fertility) influence invasion into constructed fescue and prairie mesocosms, and whether root washes inhibit arbuscular mycorrhizal (AM) fungi. We observed significant negative effects of fescue soils and root washes on germination and seedling survival, including on fescue itself. Mesocosm invasion, however, was determined more by nonallelopathic mechanisms (propagule pressure and rapid growth). In prairie mesocosms, fescue invasion was higher than its own understory, with no effects of disturbance or fertility. Tallgrass species had difficulty establishing in all environments, regardless of propagule pressure. Impacts on AM fungal hyphal length and spore production were insignificant. Our results suggest that nonallelopathic traits may be sufficient to explain fescue invasion, with allelopathy likely emerging as a final "coup de grâce" for recruiting native grasses once dominance has been attained. Allelopathic species, including fine fescue, may thus not necessarily be invasive unless nonallelopathic traits facilitate establishment prior to the accumulation of soil-based toxins.

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Soil fauna may buffer the negative effects of drought on alien plant invasion

10.1101/2021.07.26.453896 ◽

2021 ◽

Author(s):

Huifei Jin ◽

Liang Chang ◽

Mark van Kleunen ◽

Yanjie Liu

Keyword(s):

Biomass Production ◽

Plant Invasion ◽

Soil Fauna ◽

Plant Invasions ◽

Invasion Success ◽

Native Plant ◽

Native Community ◽

Alien Plant ◽

Grassland Species ◽

Effects Of Drought

Assessing how climate change affects the potential invasion risk of alien plants has garnered considerable interest in ecology. Although many studies have tested the direct effects of drought on alien plant invasion, less is known about how drought affects alien plant invasion indirectly via other groups of organisms such as soil fauna. To test for such indirect effects, we grew single plant of nine naturalized alien target species in pot mesocosms with a native community of five native grassland species under four combinations of two drought (well-watered vs drought) and two soil-fauna (with vs without) treatments. We found that drought decreased the absolute and the relative biomass production of the alien target plants, and thus reduced their invasion success in the native community. Inoculation with a soil fauna increased the biomass of the native plant community and thereby decreased the relative biomass production of the alien species. The increased invasion resistance due to soil fauna tended (p = 0.09) to be stronger for plants growing under well-watered conditions than under drought. Our multispecies experiment shows for the first time that soil fauna might help native resident communities to resist alien plant invasions, but that this effect might be diminished by drought.

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