Predict Invasion Success Research Articles

Trained quantity discrimination in invasive red-eared slider and a comparison with the native stripe-necked turtle

Little is known about the behavioral and cognitive traits that best predict invasion success. Evidence is mounting that cognitive performance correlates with survival and fecundity, two pivotal factors for the successful establishment of invasive populations. We assessed the quantity discrimination ability of the globally invasive red-eared slider (Trachemys scripta elegans). We further compared it to that of the native stripe-necked turtle (Mauremys sinensis), which has been previously evaluated for its superior quantity discrimination ability. Specifically, our experimental designs aimed to quantify the learning ability as numerosity pairs increased in difficulty (termed fixed numerosity tests), and the immediate response when turtles were presented with varied challenges concurrently in the same tests (termed mixed numerosity tests). Our findings reaffirm the remarkable ability of freshwater turtles to discern numerical differences as close as 9 vs 10 (ratio = 0.9), which was comparable to the stripe-necked turtle’s performance. However, the red-eared slider exhibited a moderate decrease in performance in high ratio tests, indicating a potentially enhanced cognitive capacity to adapt to novel challenges. Our experimental design is repeatable and is adaptable to a range of freshwater turtles. These findings emphasize the potential importance of cognitive research to the underlying mechanisms of successful species invasions.

Phenotypic trait differences betweenIris pseudacorusin native and introduced ranges support greater capacity of invasive populations to withstand sea level rise

AbstractAimTidal wetlands are greatly impacted by climate change, and by the invasion of alien plant species that are being exposed to salinity changes and longer inundation periods resulting from sea level rise. To explore the capacity for the invasion ofIris pseudacorusto persist with sea level rise, we initiated an intercontinental study along estuarine gradients in the invaded North American range and the native European range.LocationSan Francisco Bay‐Delta Estuary; California, USA and Guadalquivir River Estuary; Andalusia, Spain.MethodsWe compared 15 morphological, biochemical, and reproductive plant traits within populations in both ranges to determine if specific functional traits can predict invasion success and if environmental factors explain observed phenotypic differences.ResultsAlienI. pseudacorusplants in the introduced range had more robust growth than plants in the native range. The vigour of the alien plants was reflected by expression of higher leaf water content, fewer senescent leaves per leaf fan, and more carbohydrate storage reserves in rhizomes than plants in the native range. Moreover, alien plants tended to show higher specific leaf area and seed production than native plants.I. pseudacorusplants in the introduced range were less affected by increasing salinity and were exposed to deeper inundation water along the estuarine gradient than those in the native range.Main ConclusionsFunctional trait differences suggest mature populations ofI. pseudacorusin the introduced range have greater adapted capacity to adjust to environmental stresses induced by rising sea level than those in the native range. Knowledge of these trait responses can be applied to improve risk assessments in invaded estuaries and to achieve climate‐adapted conservation goals for conservation of the species in its native range.

Six decades of museum collections reveal disruption of native ant assemblages by introduced species

There is a looming environmental crisis characterized by widespread declines in global biodiversity,1,2,3,4,5,6 coupled with the establishment of introduced species at accelerated rates.7,8,9,10,11,12,13,14 We quantified how multi-species invasions affect litter ant communities in natural ecosystems by leveraging museum records and contemporary collections to assemble a large (18,990 occurrences, 6,483 sampled local communities, and 177 species) 54-year (1965-2019) dataset for the entire state of Florida, USA. Nine of ten species that decreased most strongly in relative abundance ("losers") were native, while nine of the top ten "winners" were introduced species. These changes led to shifts in the composition of rare and common species: in 1965, only two of the ten most common ants were introduced, whereas by 2019, six of ten were introduced species. Native losers included seed dispersers and specialist predators, suggesting a potential loss of ecosystem function through time, despite no obvious loss of phylogenetic diversity. We also examined the role of species-level traits as predictors of invasion success. Introduced species were more likely to be polygynous than native species. The tendency to form supercolonies, where workers from separate nests integrate, also differed between native and introduced species and was correlated with the degree to which species increased in their rank abundances over 50 years. In Florida, introduced ants now account for 30% of occurrence records, and up to 70% in southern Florida. If current trends continue, introduced species will account for over half of occurrence records in all Florida's litter ant communities within the next 50 years.

Transient dynamics in plant–pollinator networks: fewer but higher quality of pollinator visits determines plant invasion success

Invasive plants often use mutualisms to establish in their new habitats and tend to be visited by resident pollinators similarly or more frequently than native plants. The quality and resulting reproductive success of those visits, however, have rarely been studied in a network context. Here, we use a dynamic model to evaluate the invasion success and impacts on natives of various types of non‐native plant species introduced into thousands of plant–pollinator networks of varying structure. We found that network structure properties did not predict invasion success, but non‐native traits and interactions did. Specifically, non‐native plants producing high amounts of floral rewards but visited by few pollinators at the moment of their introduction were the only plant species able to invade the networks. This result is determined by the transient dynamics occurring right after the plant introduction. Successful invasions increased the abundance of pollinators that visited the invader, but the reallocation of the pollinators' foraging effort from native plants to the invader reduced the quantity and quality of visits received by native plants and made the networks slightly more modular and nested. The positive and negative effects of the invader on pollinator and plant abundance, respectively, were buffered by plant richness. Our results call for evaluating the impact of invasive plants not only on visitation rates and network structure, but also on processes beyond pollination including seed production and recruitment of native plants.

Intercontinental comparison of phylogenetic relatedness in introduced plants at the transition from naturalization to invasion: A case study on the floras of South Africa and China

Invasive species may pose significant threats to biodiversity and ecosystem structure and functioning. The number of introduced species that have become invasive is substantial and is rapidly increasing. Identifying potentially invasive species and preventing their expansion are of critical importance in invasion ecology. Phylogenetic relatedness between invasive and native species has been used in predicting invasion success. Previous studies on the phylogenetic relatedness of plants at the transition from naturalization to invasion have shown mixed results, which may be because different methods were used in different studies. Here, I use the same method to analyze two comprehensive data sets from South Africa and China, using two phylogenetic metrics reflecting deep and shallow evolutionary histories, to address the question whether the probability of becoming invasive is higher for naturalized species distantly related to the native flora. My study suggests that the probability of becoming invasive is higher for naturalized species closely related to the native flora. The finding of my study is consistent with Darwin's preadaptation hypothesis.

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

Invasive 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.

Invasion success on European coastal dunes

Many invasive plants are threatening the already highly vulnerable habitats of coastal dunes in Europe. Setting priority target species to control is mandatory for an effective planning of invasion management strategies at European level. This can be possible after identifying the species that currently have greater invasion success, in consideration of their ecological traits and origin. We quantified the three main components of invasion success for the extra-European alien plants found on European coastal dunes: local abundance, regional distribution and niche breadth, and related them to their life forms and origins. We found that life form was a better predictor of invasion success. In particular, geophytes and therophytes were the species with the greatest invasion success. Quite surprisingly, alien plants from Africa appeared as the group with slightly higher mean invasion success although this result was no statistically significant. We also highlighted the species deserving special attention. Among these,Xanthium orientale,Erigeron canadensisandOenotheragr.biennisshowed the widest levels of niche breadth and regional distribution, and had overall the greatest invasion success, but other species also had high levels in one of the three components of invasion success.

Warming indirectly increases invasion success in food webs.

Climate warming and biological invasions are key drivers of biodiversity change. Their combined effects on ecological communities remain largely unexplored. We investigated the direct and indirect influences of temperature on invasion success, and their synergistic effects on community structure and dynamics. Using size-structured food web models, we found that higher temperatures increased invasion success. The direct physiological effects of temperature on invasions were minimal in comparison with indirect effects mediated by changes on food web structure and stability. Warmer communities with less connectivity, shortened food chains and reduced temporal variability were more susceptible to invasions. The directionality and magnitude of invasions effects on food webs varied across temperature regimes. When invaded, warmer communities became smaller, more connected and with more predator species than their colder counterparts. They were also less stable and their species more abundant. Considering food web structure is crucial to predict invasion success and its impacts along temperature gradients.

Salinity tolerance and geographical origin predict global alien amphipod invasions

Invasive alien species are driving global biodiversity loss, compromising ecosystem function and service provision, and human, animal and plant health. Habitat characteristics and geographical origin may predict invasion success, and in aquatic environments could be mediated principally by salinity tolerance. Crustacean invaders are causing global problems and we urgently require better predictive power of their invasiveness. Here, we compiled global aquatic gammarid (Crustacea: Amphipoda: Gammaroidea) diversity and examined their salinity tolerances and regions of origin to test whether these factors predict invasion success. Across 918 aquatic species within this superfamily, relatively few gammarids (n = 27, 3%) were reported as aliens, despite extensive invasion opportunities and high numbers of published studies on amphipod invasions. However, reported alien species were disproportionately salt-tolerant (i.e. 32% of brackish-water species), with significantly lower proportions of aliens originating from freshwater and marine environments (both 1%). Alien gammarids also significantly disproportionally originated from the Ponto-Caspian (20% of these taxa) when compared with all ‘other' grouped regions (1%), and principally invaded Eurasian waters, with translocations of salt-tolerant taxa to freshwaters being pervasive. This suggests habitat characteristics, alongside regional contexts, help predict invasibility. In particular, broad environmental tolerances to harsh environments and associated evolutionary history probably promote success of aliens globally.

Diversity within mutualist guilds promotes coexistence and reduces the risk of invasion from an alien mutualist.

Biodiversity is an important component of healthy ecosystems, and thus understanding the mechanisms behind species coexistence is critical in ecology and conservation biology. In particular, few studies have focused on the dynamics resulting from the co-occurrence of mutualistic and competitive interactions within a group of species. Here we build a mathematical model to study the dynamics of a guild of competitors who are also engaged in mutualistic interactions with a common partner. We show that coexistence as well as competitive exclusion can occur depending on the competition strength and on strength of the mutualistic interactions, and we formulate concrete criteria for predicting invasion success of an alien mutualist based on propagule pressure, alien traits (such as its resource exchange ability) and composition of the recipient community. We find that intra guild diversity promotes the coexistence of species that would otherwise competitively exclude each other, and makes a guild less vulnerable to invasion. Our results can serve as a useful framework to predict the consequences of species manipulation in mutualistic communities.

Species traits predict stream‐fish invaders in an Appalachian (U.S.A.) river basin

Abstract We compared the influence of biological traits (morphology, physiology, reproduction, and life history), ecological traits (geographic distribution, habitat associations, food habits), and introduction attributes (propagule pressure, human use of a species, residence time) on invasion success of native and introduced stream fishes during the colonisation and spread stages in an Appalachian (U.S.A.) river basin. Colonisation success was positively related to residence time, benthic feeding, an equilibrium life‐history strategy, and nest spawning. Successful spread was associated with tolerance to increased temperature and an equilibrium life‐history strategy. The spread of introduced fishes was negatively related to gamefish status. No effect of propagule pressure was detected. Traits linked to invasion success were consistent with the hypothesis that human land‐use practices increase the invasibility of highland catchments by creating novel conditions better suited to lowland and equilibrium invaders. We found biological traits to be more useful than ecological traits in predicting invasion success and suggesting invasion mechanisms. Parental care and nest association can facilitate invasions over large spatial extents for both native and introduced fishes. Analyses of suites of traits can reveal mechanisms of invasions and tactics for controlling them; such mechanisms and tactics may be system‐specific and scale‐dependent.

Population Genetic Structure and Diversity of the Invasive Island Apple Snail Pomacea maculata (Perry, 1810) in South Carolina and Georgia

Population genetics is a valuable tool in understanding various aspects of biological invasions, such as pathways of invasions, predicting invasion success, and determining dispersal capabilities. The island apple snail (Pomacea maculata), which is native to South America, is an invasive gastropod currently established in several southeastern states in the United States, including South Carolina and Georgia. Despite its known negative impacts in invaded regions, knowledge of P. maculata specific to South Carolina is limited, and an in-depth analysis of the population genetic structure of P. maculata in South Carolina and Georgia has not been conducted. The present study aimed to genetically characterize P. maculata individuals from three locations in South Carolina and five locations in Georgia using a suite of 14 microsatellite markers. Population genetic structure was determined using pairwise FST comparisons, isolation by distance analysis, and a likelihood-based approach. Genetic diversity indices, effective population size, inbreeding coefficients, and Garza–Williamson indices, which is the mean ratio of number of alleles to the range in allele size in a population and can be used to detect recent reductions in population size, were all calculated. Significant genetic structure was observed in all sampling locations, apart from the two sites in Kingsland, GA; a weak correlation was found between genetic distance and geographic distance across all the sites; and genetic diversity was low across all loci at the eight sites. Garza–Williamson indices all showed likely recent reductions in population size. These results indicate that the populations in South Carolina and Georgia were probably the result of separate introduction events and that these populations are genetically isolated. The low genetic diversity observed could indicate that these populations are susceptible to eradication efforts and/or stochastic environmental changes.

Reinvasion Is Not Invasion Again

Biological invasions are a major driver of global environmental change, and there is well-developed theory for predicting invasion success. Managing the impacts of established invasive species is expensive and hugely problematic, but this ongoing challenge is largely about managing reinvasion—defined here as the reestablishment of a nonindigenous species in a location after control. We review conceptual and theoretical frameworks developed to understand initial invasions and identify how reinvasion differs because of three factors: (1) changes in the invader, (2) changes in the invaded environment, and (3) interactions among invaders and with local taxa. We find a distinct lack of theory about the processes involved in reinvasion, but theory is needed to develop systematic research to optimally manage reinvaders. We detail the circumstances under which reinvasion is fundamentally different from initial invasion, address management issues specific to understanding and managing reinvasion, and highlight promising opportunities for future research.

Species composition, functional and phylogenetic distances correlate with success of invasive Chromolaena odorata in an experimental test.

Biotic resistance may influence invasion success; however, the relative roles of species richness, functional or phylogenetic distance in predicting invasion success are not fully understood. We used biomass fraction of Chromolaena odorata, an invasive species in tropical and subtropical areas, as a measure of 'invasion success' in a series of artificial communities varying in species richness. Communities were constructed using species from Mexico (native range) or China (non-native range). We found strong evidence of biotic resistance: species richness and community biomass were negatively related with invasion success; invader biomass was greater in plant communities from China than from Mexico. Harvesting time had a greater effect on invasion success in plant communities from China than on those from Mexico. Functional and phylogenetic distances both correlated with invasion success and more functionally distant communities were more easily invaded. The effects of plant-soil fungi and plant allelochemical interactions on invasion success were species-specific.

Fish invasion in the river systems of Guangdong Province, South China: Possible indicators of their success

AbstractAlthough a large number of fish species have been introduced into Guangdong Province in Southern China, a few species, such as tilapia (Tilapia spp.), North African catfish Clarias gariepinus Burchell, mrigal carp, Cirrhinus mrigala (Bloch) and the sucker mouth catfish (Hypostomus sp.), have established natural populations and can be considered “successful invaders” in large rivers. The specific mechanisms underlying these contrasting results among different introduced fish species remain understudied. The relationship between multiple abiotic–biotic factors and the success of four invasive species was investigated using survey data for the Guangdong Province river ecosystem. In contrast to previous studies that have considered species‐specific traits, the focus was on economic, ecological and anthropogenic factors to predict invasion success. Four main predictive indicators were found: (1) successful invaders were of low or no commercial value; (2) successful invaders tolerated a wide range of environmental conditions, including poor water quality; (3) biodiversity loss accelerated the growth of non‐native populations; (4) human disturbance facilitated population growth and spread of invasive fish species. To lessen the impacts of invasive fish species, the selection of breeding species and breeding areas, maintenance of water quality and reduction in water pollution, protection of the diversity of fish species and reduction of human interference should be addressed.

Higher colonization pressure increases the risk of sustaining invasion by invasive non-indigenous species

Considerable attention has been focused on the concept of Propagule Pressure (number of individuals introduced and introduction events) as a predictor of invasion success (975 papers). Much less well studied is the role of Colonization Pressure (number of species introduced; 24 studies), the complement of propagule pressure. Here we review the invasion history of the Laurentian Great Lakes to predict the risk of a future invasive (i.e. producing adverse ecological effects on other species) non-indigenous species based upon the number of species introduced (colonization pressure), using the recorded history of invasions in this system as our starting point. Historically, 52% of the fishes that were introduced and became established in the Great Lakes were subsequently identified in the literature as invasive, whereas the value for invertebrates (16%) was much lower. Assuming future invaders have similar invasion attributes as those already present, the risk of getting at least one high impact species is positively and asymptotically related to the number of species introduced, though the rate is substantially higher for fishes than for invertebrates. Our study provides support for the contention that managers ought to focus initially on vectors transmitting multiple species when attempting to prevent invasion of their system by species likely to become problematic.

Invading a mutualistic network: to be or not to be similar.

Biological invasion remains a major threat to biodiversity in general and a disruptor to mutualistic interactions in particular. While a number of empirical studies have directly explored the role of invasion in mutualistic pollination networks, a clear picture is yet to emerge and a theoretical model for comprehension still lacking. Here, using an eco‐evolutionary model of bipartite mutualistic networks with trait‐mediated interactions, we explore invader trait, propagule pressure, and network features of recipient community that contribute importantly to the success and impact of an invasion. High level of invasiveness is observed when invader trait differs from those of the community average, and level of interaction generalization equals to that of the community average. Moreover, multiple introductions of invaders with declining propagules enhance invasiveness. Surprisingly, the most successful invader is not always the one having the biggest impact on the recipient community. The network structure of recipient community, such as nestedness and modularity, is not a primary indicator of its invasibility; rather, the invasibility is best correlated with measurements of network stability such as robustness, resilience, and disruptiveness (a measure of evolutionary instability). Our model encompasses more general scenarios than previously studied in predicting invasion success and impact in mutualistic networks, and our results highlight the need for coupling eco‐evolutionary processes to resolve the invasion dilemma.

The minimum founding population in dispersing organisms subject to strong Allee effects

Summary Dispersal can push population density below strong Allee thresholds ensuring the demise of small founding populations. As a result, for isolated populations of dispersing organisms, the minimum founding population size that enables establishment can be quite different from the Allee threshold. We derive an expression for the minimum founding population size for a general integrodifference equation model of a dispersing population with a strong Allee effect. We demonstrate the utility of the general model by using it to approximate minimum founding populations for the mountain pine beetle. The minimum founding population of the general model increases linearly with the mean squared displacement of the dispersing organism. Transient dynamics of the general model suggest that population density at the point of introduction will often decrease before increasing, even when the minimum founding population size is exceeded. Calculation of minimum founding population sizes may prove useful for predicting invasion success based on propagule size and for maximizing the success of species reintroductions when strong Allee effects exist.

Analysis of propagule pressure and genetic diversity in the invasibility of a freshwater apex predator: the peacock bass (genus Cichla)

An important step in invasive biology is to assess biological variables that could be used to predict invasion success. The study of genetics, evolution, and interactions of invasive and native species in invaded ranges provides a unique opportunity to study processes in population genetics and the capability of a species' range expansion. Here, we used information from microsatellite DNA markers to test if genetic variation relates to propagule pressure in the successful invasion of an apex predator (the Amazonian cichlid Cichla) into Southeastern Brazilian River systems. Invasive populations of Cichla have negatively impacted many freshwater communities in Southeastern Brazil since the 1960s. Reduction of genetic variation was observed in all invasive populations for both Cichla kelberi (CK) and Cichla piquiti(CP). For instance, heterozygosity was lower in the invasive range when compared to native populations from the Amazon basin (CP HE= 0.179/0.44; CK HE= 0.258/0.536 respectively). Therefore, despite the successful invasion of Cichla in southeast Brazil, low genetic diversity was observed in the introduced populations. We suggest that a combination of factors, such as Cichla's reproductive and feeding strategies, the "evolutionary trap" effect and the biotic resistance hypothesis, overcome their depauperete genetic diversity, being key aspects in this apex predator invasion.

Predictors of invasion success by Daphnia species: influence of food, temperature and species identity

Non-indigenous North American Daphnia ‘pulex’ has recently invaded lakes and reservoirs in South Island, New Zealand, that formerly contained only native Daphniacarinata. New Zealand is characterised by a wide range of freshwater ecosystems and low species diversity of planktonic crustaceans, particularly Cladocera. The potential success of a species to invade and establish in a new community is likely to be predicted more accurately when reproductive response norms and fitness of key resident species, as well as the non-indigenous species, have been established under a range of relevant environmental conditions. Based on the results of experiments to test aspects of reproduction and fitness of the invader, D. ‘pulex’, and D. carinata when grown together at a range of relevant temperatures (8–23 °C) and related photoperiods, I predict the species-specific potential of D. ‘pulex’ to be dispersed and colonise New Zealand lentic habitats, and the potential of D. carinata to persist with the invader in these habitats. Larger population densities of D. ‘pulex’ compared to D. carinata at higher temperatures and food level, and larger densities of D. carinata at low temperatures, imply a potential for both species to coexist in New Zealand lakes, facilitated by seasonal succession; increased water temperature and nutrient input associated with climate and land use changes appear likely to promote the wider establishment of D. ‘pulex’, with both negative and positive implications for the conservation and management of New Zealand’s freshwater ecosystems.