Biological Invasions

Molfini, M.; Zapparoli, M.; Genovesi, P.; Carnevali, L.; Audisio, P.; Di Giulio, A.; Bologna, M. A.

doi: 10.1007/s10530-020-02274-wpmid: N/A

Invasive alien species (IAS) are considered one of the largest drivers of biodiversity loss worldwide and the negative impacts of IAS can also affect human health and economy. More than 12,000 alien species occur in Europe. Terrestrial invertebrate species are the largest proportion of alien animal species and represents one of the most impacting groups in Europe. The most important European policy against alien species is the EU Regulation 1143/2014, which provides for the development of priority lists of IAS of relevant concern aimed to allow the optimization of intervention measures. Italian policy implemented the EU Regulation with the Legislative Decree No 230/2017 that provides the adoption of a list of IAS of national concern. Aim of this work is to present a preliminary prioritized list of alien terrestrial invertebrate species (ATIS) present in Italy, thus providing an useful tool to identify species to be included in the list of IAS of national concern. We defined criteria for assessing the species and ranking them in a prioritized list on the basis of the magnitude of their potential impact on wild native biodiversity. We identify 233 relevant ATIS, among the 1126 species included in the Italian Alien Terrestrial Invertebrate Database, on which the evaluation process started. After the evaluation process, 109 ATIS with considerable impacts on biodiversity were selected and prioritized. We ranked the species in four priority categories by matching their distribution in Italy with the magnitude of their possible impact on biodiversity.

Rothman, Shevy B. S.; Gayer, Kfir; Stern, Nir

doi: 10.1007/s10530-020-02277-7pmid: N/A

In this study, we document the introduction of the Australian endemic Istiblennius meleagris into the Mediterranean Sea, probably via shipping, and its expansion along the Israeli coastline. Taxonomic confirmations were based on both morphological and molecular approaches. This is the first evidence of a non-indigenous benthic fish colonizing the rocky intertidal zone in the eastern Mediterranean, thus raising concerns regarding the future integrity of the native fish community in this ecosystem.

Garcia-Raventós, Aina; Martins, Filipa M. S.; Teixeira, Amilcar; Sousa, Ronaldo; Froufe, Elsa; Varandas, Simone; Lopes-Lima, Manuel; Beja, Pedro; Filipe, Ana Filipa

doi: 10.1007/s10530-020-02279-5pmid: N/A

The number of non-native freshwater fishes in the Iberian Peninsula has been greatly increasing. In this study, individuals of the genus Phoxinus were detected in 18 out of 138 stream sites sampled across the Douro Basin in 2017 and 2018. A total of 26 individuals were barcoded using partial cytochrome c oxidase subunit I (COI) and cytochrome b (cytb) genes for species identification and determination of geographical origin. Molecular data provided the first record of a second Phoxinus species in western Douro (Portugal, Iberian Peninsula), with haplotypes closely matching those found in the Charente River (southern France). This species is suspected to be a recent introduction associated with the use of minnows as live bait by freshwater anglers, which was facilitated by human movements between France and Portugal. Individuals from watercourses in eastern Douro (Spain) were genetically assigned to Phoxinus bigerri, an introduced species previously known for that region, which confirms reports of introduction events from Ebro to Douro Basin probably also related to freshwater angling and facilitated by geographic proximity. The potential ecological impacts of this genus in the region are unknown and need further investigation.

Nogueira Tavares, C.; Brauns, M.; Hille, S.; Krenek, S.; Borcherding, J.; Weitere, M.

doi: 10.1007/s10530-020-02281-xpmid: N/A

Ponto-Caspian gobies have invaded many river systems in the northern hemisphere, but their colonization patterns often remain unrecognized at the early stages of invasion. Here, we analyzed the ongoing invasion of the round goby Neogobius melanostomus (Pallas, 1814) in the Elbe River (Germany) by combining literature research with electrofishing and environmental DNA (eDNA) sampling. Along the surveyed 517 km, abundances peaked in the upper and lower sections, while low or no goby abundances were detected in the middle section. Combining the results of the field survey and literature data, we inferred four dispersal modes, jointly appearing during the colonization. (1) Human mediated transport, which was responsible for the initial colonization of the tidal Elbe and for a jumpy expansion to the upstream sections. (2) Fast downstream colonization, which was particularly observed for juvenile individuals. (3) Slow upstream migration, which was also recorded for another goby species, the bighead goby Ponticola kessleri (Günther, 1861) and (4) Lateral invasion via a major shipping canal in the middle river section. The eDNA analyses generally supported these conclusions and showed a high sensitivity and thus increased detection strength at low goby densities. Our study showed that the location of the first occurrence, as well as the dispersal mode, strongly determines the invasion process of non-native gobies.

Funk, Jennifer L.; Parker, Ingrid M.; Matzek, Virginia; Flory, S. Luke; Aschehoug, Erik T.; D’Antonio, Carla M.; Dawson, Wayne; Thomson, Diane M.; Valliere, Justin

doi: 10.1007/s10530-020-02267-9pmid: N/A

Invasion ecology has grown to include scientists with diverse skill sets who focus on a range of taxa and biomes. These researchers have the capacity to contribute to practical management solutions while also answering fundamental biological questions; however, scientific endeavors often fail to meet the perceived needs of practitioners involved in on-the-ground invasive plant management. One way that researchers have sought to bridge the gap between research and practice is by surveying managers to identify areas of study that are underexplored in invasion ecology. In this paper, we build on these efforts by reviewing the current state of knowledge and suggesting new directions for research in seven areas of plant invasion ecology that are highly relevant to management: seedbanks, dispersal and spread, life history, impacts, climate change, distribution, and succession. These topics were previously identified as urgent research priorities by land managers and are underrepresented in the invasion ecology literature. In addition to highlighting key knowledge gaps for these seven areas of research, we propose steps that academics can take to cultivate academic–practitioner relationships and remove barriers to conducting management-focused research, such as co-producing research questions with managers, addressing issues of working at management-appropriate spatial and temporal scales, and considering non-traditional funding and labor sources for long-term monitoring. Greater communication and collaborative selection of basic research questions will ensure that the goals of management and invasive species research remain aligned.

Sowersby, Will; Lehtonen, Topi K.; Ravinet, Mark; Barluenga, Marta; Wong, Bob B. M.

doi: 10.1007/s10530-020-02264-ypmid: N/A

Ecological specialisation is hypothesised to play a major role in the evolution of phenotypic diversity, especially following the colonisation of novel habitats. For example, cichlid fishes provide some of the most remarkable evidence for rapid ecological diversification. Here, we capitalised on a recently (≤ 40 years ago) introduced population of red devils (Amphilophus labiatus) in Australia to investigate adaptive phenotypic responses to a novel environment. We used stomach content analyses, morphometrics and laboratory experiments to test for covariation between diet and size of an important trophic trait, lip size. We found that, while maximum lip size in the study population was smaller than in the species’ natural range, the proportions of algae, insects and fish remains in the diet covaried with lip size. However, contrary to predictions, we found no evidence for lip development to be plastic under laboratory conditions in relation to substrate complexity or food manipulation, nor did we find any relationship between lip morphology and feeding performance in adults. Single nucleotide polymorphism data, in turn, suggested that the introduced population has reduced standing genetic variation, which potentially influences both phenotypic plasticity and diversity, in comparison to native populations. Together, the results suggest that morphological variation in a key trophic trait can respond rapidly to diet in a novel environment, despite reduced genetic diversity in the population.

Jacobson, Staffan; Hannerz, Mats

doi: 10.1007/s10530-020-02262-0pmid: N/A

The large-scale introduction of lodgepole pine (Pinus contorta ssp. latifolia, LP) into Swedish forests was initiated around 1970, and currently 520,000 hectares of the forest land are dominated by the species. Even though the tree has mostly serotine cones, adapted to open after forest fires, it has proved able to self-regenerate in Sweden. This study is the first to present, scientifically, the extent of self-regeneration covering the whole current range of LP-forests in Sweden. LP-saplings were recorded for three years, 2015–2017, in 8194 subplots distributed over 214 randomly selected LP-stands from latitude 59.6–66.9°N and altitude 88–710 m asl. Of all subplots, 3% contained LP-saplings, and regeneration was found in 53% of all stands. The probability of finding LP-saplings was significantly dependent on the plots’ distance from the edge of the LP-stand, and 78% of all saplings were found within and up to 15 m beyond the stand edge. Most, 63%, of the plots with LP were found on disturbed ground such as wheel tracks, roadsides and where there had been site preparation. The results show that LP can naturally spread under a range of conditions in the studied region. The regeneration is, however, concentrated in particular stands and should be possible to control with monitoring programmes and measures to eradicate self-dispersed trees in unwanted areas.

Ivan, Lori N.; Mason, Doran M.; Zhang, Hongyan; Rutherford, Edward S.; Hunter, Tim; Sable, Shaye; Adamack, Aaron T.; Rose, Kenneth

doi: 10.1007/s10530-020-02263-zpmid: 32624679

Bighead carp H. nobilis and silver carp Hypothalmichthys molitrix (collectively bigheaded carps, BHC) are invasive planktivorous fishes that threaten to enter the Laurentian Great Lakes and disrupt food webs. To assess the likelihood of BHC establishment and their likely effects on the food web of Saginaw Bay, Lake Huron, we developed a multi-species individual-based bioenergetics model that tracks individual bighead and silver carp, four key fish species, and seven prey biomass groups over 50 years. The model tracks the daily consumption, mortality and growth of all individuals and the biomass dynamics of interacting prey pools. We ran simulation scenarios to determine the likelihood of BHC establishment under initial introductions from 5 to 1 million yearling and older individuals, and assuming variable age-0 carp survival rates (high, intermediate, and low). We bounded the survival of age-0 BHC as recruitment continues to be one of the biggest unknowns. We also simulated the potential effects of an established population of 1 million bighead carp or silver carp assuming variation in age-0 survival. Results indicated that as few as 10 BHC could establish a population assuming high or intermediate age-0 survival, but at least 100,000 individuals were needed to establish a population assuming low age-0 survival. BHC had negative effects on plankton and planktivorous fish biomass, which increased with BHC density. However, piscivorous walleye Sander vitreus appeared to benefit from BHC establishment. The potential for BHC to establish and affect ecologically and economically important fish species in Saginaw Bay is a cause for concern.

Pascual-Rico, Roberto; Sánchez-Zapata, José Antonio; Navarro, Joan; Eguía, Sergio; Anadón, José Daniel; Botella, Francisco

doi: 10.1007/s10530-020-02265-xpmid: N/A

Exploitative competition implies an indirect interaction in which a resource exploited by one species is not available for another; e.g., when species share diet or habitat. It plays a key role in community structure and dynamics. Here we evaluated the niche overlap between the exotic aoudad (Ammotragus lervia) and the native Iberian ibex (Capra pyrenaica) where the species coexist in the Iberian Peninsula, along two main dimensions, the trophic niche and the environmental niche. Then we assessed the spatial segregation of the species. We expected that if a niche overlap was high, competition could drive spatial segregation to allow co-existence. We analyzed their trophic niche overlap by using the content of stable isotopes δ15N and δ13C in the hair of both species. To establish environmental niche competition, we compared the similarity in their habitat, estimated by environmental niche models based on the fine-scale presence records of each species obtained from field surveys. To test if spatial segregation occurred, we analyzed both species’ co-occurrence. Our results indicated that both species shared a similar trophic niche measured by stable isotopes, both species showed a similar distribution of suitable areas, and that both species’ environmental niches were more similar than expected. Finally, a negative spatial association was found between the aoudad and Iberian ibex. These results reveal that both species are ecologically similar and suggest that fine-scale spatial segregation might have favoured their co-existence in semiarid Mediterranean mountains. Our results show that integrating information on trophic and environmental niche overlap with fine scale spatial distribution might improve the study of competitive interactions among wild ungulates.

Calleja, F.; Ondiviela, B.; Puente, A.; Juanes, J. A.

doi: 10.1007/s10530-020-02266-wpmid: N/A

Physiological information has been successfully included in marine Species Distribution Models (SDM) before, but few have considered a previous development stage that could have affected the present-day distribution of the species at local scales. The aim of this study is to analyze the inclusion of physiological information of seedling survival on a correlative SDM based on adult present-day presences. The species were the invasive shrub Baccharis halimifolia and the native saltmarsh Juncus maritimus. For each species, five SDM were established using different approaches: using only experimentally derived physiological data, a correlative model with environmental predictors, additive combinations of presence/absence maps derived from the previous models, and a correlative model with the physiological data as a predictor variable. For B. halimifolia, the inclusion of the physiological data as a predictor variable yielded better results than with the other approaches; with J maritimus, this inclusion achieved an accuracy as high as the model with only environmental variables as predictors. The additive combinations generated less accurate models but offered possible advantages in future specialized studies. The results for B. halimifolia could extrapolate to other invasive species that rely on spreading high amounts of individuals and are more vulnerable in their early stages than in their growing and adult phases. Thus, this approach can improve the capacity for mapping invasive species’ distributions at local scales, and the conservation efforts to control biological invasions in estuaries and coastal ecosystems.