Recent Invader Research Articles

Multiple introduction events expand the range of the invasive brown alga Rugulopteryx okamurae to northern Spain.

The brown alga Rugulopteryx okamurae is one of the most recent and aggressive marine invaders known, with a non-native range that spans from the western Mediterranean to the southern Iberian Peninsula, and the European Macaronesian archipelagos. Here, we provide the first record of its presence at three disjunct sites from northern Spain, supported by morphological and molecular evidence. Rugulopteryx okamurae was discovered in the port of Bilbao in the northeastern Atlantic of Spain, more than 1200km away from the nearest invaded location previously known. It was also found at two separate sites in northwestern Spain: San Amaro, a small inlet at the entrance of the port of A Coruña, and Monteferro-Playa América, a site close to aquaculture facilities and the port of Vigo. In two locations, R. okamurae was found to cover up to 100% of the bottom, suggesting that it may behave as an aggressive invader in northern Spain. Our findings confirm the propensity of R. okamurae for long-distance dispersal and reveal that this invader is expanding its range northwards along the European Atlantic coast.

Warming effects on the life cycles of two parasitic copepods with different invasion histories.

Climate change may exacerbate the impact of invasive parasites from warmer climates through pre-existing temperature adaptations. We investigated temperature impacts on two closely related marine parasitic copepod species that share the blue mussel (Mytilus edulis) as host: Mytilicola orientalis has invaded the system from a warmer climate <20 years ago, whereas its established congener Mytilicola intestinalis has had >90 years to adapt. In laboratory experiments with temperatures 10-26°C, covering current and future temperatures as well as heat waves, the development of both life cycle stages of both species accelerated with increasing temperature. In the parasitic stages, the growth of the established invader increased evenly from 10°C to 22°C, whereas the recent invader barely grew at all at 10°C and grew faster already at 18°C. In contrast, temperature had little effect on the transition success between life cycle stages. However, the highest temperature (26°C) limited the egg development success of the established invader and the host entry success of both species, whereas the infection success of the established invader increased at 18°C and 22°C. In general, our experiments indicate that the main effect of temperature on both species is through development speed and not life cycle stage transition success. Based on regional long-term temperature data and predictions, the numbers of completed life cycles per year will increase for both parasites. The established invader seems better adapted for low current temperatures (around 10°C), whereas the more recent invader barely develops at these temperatures but can cope in high temperatures (around 26°C). Hence, pre-existing temperature adaptations of the recent invader may allow the species to better cope with heat waves.

Counter-gradient variation in gene expression between fish populations facilitates colonization of low-dissolved oxygen environments.

The role of phenotypic plasticity during colonization remains unclear due to the shifting importance of plasticity across timescales. In the early stages of colonization, plasticity can facilitate persistence in a novel environment; but over evolutionary time, processes such as genetic assimilation may reduce variation in plastic traits such that species with a longer evolutionary history in an environment can show lower levels of plasticity than recent invaders. Therefore, comparing species in the early stages of colonization to long-established species provides a powerful approach for uncovering the role of phenotypic plasticity during different stages of colonization. We compared gene expression between low-dissolved oxygen (DO) and high-DO populations of two cyprinid fish: Enteromius apleurogramma, a species that has undergone a recent range expansion, and E. neumayeri, a long-established native species in the same region. We sampled tissue either immediately after capture from the field or after a 2-week acclimation under high-DO conditions, allowing us to test for both evolved and plastic differences in low-DO vs high-DO populations of each species. We found that most genes showing candidate-evolved differences in gene expression did not overlap with those showing plastic differences in gene expression. However, in the genes that did overlap, there was counter-gradient variation such that plastic and evolved gene expression responses were in opposite directions in both species. Additionally, E. apleurogramma had higher levels of plasticity and evolved divergence in gene expression between field populations. We suggest that the higher level of plasticity and counter-gradient variation may have allowed rapid genetic adaptation in E. apleurogramma and facilitated colonization. This study shows how counter-gradient variation may impact the colonization of divergent oxygen environments.

Matching field-based ranges in brackish water gradients with experimentally derived salinity tolerances of Conrad’s false mussel (Mytilopsis leucophaeata cochleata) and zebra mussel (Dreissena polymorpha)

The invasive alien false mussels Mytilopsis leucophaeata cochleata and Dreissena polymorpha (Dreissenidae) have established populations in the North Sea canal in the Netherlands that connects the harbours of Amsterdam with the North Sea. The favourable and unfavourable salinity ranges of both species were earlier studied in long-term outdoor mesocosm experiments. Their occurrence in salinity gradients in estuaries or canals connecting seaways to freshwater harbours provides information on their salinity tolerance under field conditions. By the combination of laboratory experiments and field data using the same source population a high predictability can be expected for establishment of the gradients facilitated by constructions. The reliability of experimentally derived salinity-tolerance limits for both dreissenid species was tested using data on their distribution in a salinity gradient of the littoral zone along the North Sea canal. The mussels used for the survival experiments in mesocosms were also collected from this canal. Favourable salinity ranges for adult survival in the mesocosms were 0.2 – 17.5 for M. leucophaeata cochleata and 0.2 – 6.0 for D. polymorpha. Unfavourable salinities were outside these ranges and led to high and fast mortality of these species. Mytilopsis leucophaeata cochleata was present over nearly the whole length of the North Sea canal with the highest densities close to the sea sluices where also the highest salinities and water temperatures were measured. Their densities in the canal decreased gradually at larger distances from the sea. Dreissena polymorpha co-exists with M. leucophaeata cochleata at the east end of the canal with low salinity due to the influence of freshwater of the river Rhine. The occurrence of D. polymorpha was restricted to a salinity below 4 and M. leucophaeata cochleata only occurred at a salinity above 1.5 (maximum value measured in the canal 9.2). Shorter salinity gradients with lower salinity ranges provided additional information on the co-existence of both species. Co-existence was observed at a salinity range of 1.5–3.3 (own data), 1.0–3.5 (Van Couwelaar and Van Dijk 1989), both in the North Sea canal, and 0.2–2.8, in the Canal through Voorne (Janssen and Janssen-Kruit 1967). These data correspond with studies of both species by Walton (1996) in the Hudson River (salinity range 0–3). Found salinity ranges in the North Sea canal for both species match with the tolerance results obtained by mesocosm experiments. A new invading dreissenid mussel Dreissena rostriformis bugensis and a mytilid Ischadium recurvum occur in the North Sea canal since 2006 and 2012, respectively. Competition between recent and earlier invaders is likely when salinity tolerances are similar. It has already been observed that D. rostriformis bugensis outcompetes D. polymorpha under freshwater conditions (Bij de Vaate et al. 2014; Matthews et al. 2014). Ischadium recurvum has the potential to colonize large parts of the canal and to be a strong competitor of M. leucophaeata cochleata (Goud et al. 2019). Since January 2022, the new ‘Zeesluis IJmuiden’ with the biggest locks in the world is in use, affecting the probability of population establishment of new introduced and invasive alien mussel species.

Temporal and spatial refugia modify predation risk for non-native crabs in rocky intertidal habitats.

Populations of the non-native Asian shore crab, Hemigrapsus sanguineus, now dominate the rocky intertidal of southern New England, USA. High abundances suggest the recent invader may have experienced enhanced success as a result of enemy release. While larvae and juveniles may serve as a food source for ecologically important species, little is known about predation of mature H. sanguineus or the influence of habitat on predation pressure. To assess natural predation rates of adult H. sanguineus, crabs were tethered in the intertidal at Clarks Cove in New Bedford, MA. Crabs were left in situ for half of a tidal cycle then observed for signs of predation. Results of separate high and low tide trials showed that adult crabs were preyed upon at both high and low tide, though at a significantly higher rate during high tide during both daytime and nighttime, suggesting predation by aquatic species is greater than that by terrestrial species. To investigate the role of habitat as refuge from predation, a laboratory experiment manipulated the complexity of habitat provided to crabs in the presence of a native fish predator. Results indicate better refuge is provided by more complex shelter. Together, findings suggest that fish, crabs, and/or diving birds are important predators for H. sanguineus in the invaded range and that habitat refuge acts to reduce predation pressure.

Previously introduced braconid parasitoids target recent olive fruit fly (Bactrocera oleae) invaders in Hawai’i

The olive fruit fly Bactrocera oleae (Diptera: Tephritidae) was detected on Maui and Hawai’i Islands in 2019, affecting yields and quality of the state’s emerging olive oil industry. Given previous parasitoid releases to control other invasive frugivorous tephritids in Hawai’i, we were interested in determining whether these parasitoids were naturally targeting recent olive fly invaders in field, if local olive cultivar differences affected parasitization rates, and if there was a seasonal pattern of parasitization that could inform future management decisions. To address these questions, we collected data from olive growing in Hawai’i during 2021 and 2022. During the fruiting season we collected monthly samples and reared out B. oleae in the lab. We detected two previously introduced braconid wasps: first Diachasmimorpha tryoni during 2021 and 2022 and later Fopius arisanus during the 2022 collection. Cultivar effects were limited to a single site in our study, where more D. tryoni were reared from ‘Arbequina’ olives. Seasonality of olive fruit fly and parasitoid activity was earlier in lower elevation sites, as expected based on tree phenology and temperature-dependent insect development. This represents the first report of D. tryoni parasitism activity against B. oleae and may reflect elevational effects combined with the ecological complexity in interactions between multiple invasive arthropod pests, their invasive and cultivated plant hosts, and introduced braconid parasitoids.

New data on the distribution of anthropochorous species of land molluscs in western regions of Ukraine and possible approaches to their classification

On the basis of own data, materials transferred to the laboratory of malacology or the malacological collection of the State Museum of Natural History of the National Academy of Sciences of Ukraine in Lviv, as well as a critical analysis of observations in two citizen science databases (iNaturalist, UkrBIN), new records of some anthropochorous land mollusc species in Western Ukraine, and in particular, in Lviv and its immediate surroundings, are described. In tabular form, the temporal and spatial presence in the western part of Ukraine of 23 species that could appear here only due to anthropochory is analyzed. Maps of the findings of Cepaea nemoralis, Deroceras caucasicum, Oxychilus draparnaudi, and O. translucidus in and near Lviv are given. Known reliable localities of C. nemoralis in Volyn, Ivano-Frankivsk, Lviv, Rivne, Ternopil, and Khmelnytskyi regions are listed. Similar information is presented for the related species Cepaea hortensis from all administrative regions of Western Ukraine, except for Lviv region, where this species is widespread in settlements. According to the time of penetration into Western Ukraine, among the anthropochorous species of land molluscs, relatively recent invaders prevail, which were first reliably discovered not earlier than in the 1990s. At the turn of the 20th and 21st centuries, optimal conditions for the introduction and subsequent acclimatization in urbanized biotopes of many adventitious species of land molluscs, in particular thermophilic species of Mediterranean or Crimean origin, emerged in Western Ukraine. In addition to global warming, this was facilitated by the intensification of trade and transport links with other regions of Ukraine and other European countries, as well as the activities of garden centres. Besides the time of entry into the analyzed area, anthropochorous species of land molluscs can be classified according to the ways of this penetration (from other regions of Ukraine or from other European countries located to the west of it), the nature of their present distribution in Western Ukraine, as well as the ability or inability to enter natural biotopes outside settlements.

Niche and Range Shifts of Aedes aegypti and Ae. albopictus Suggest That the Latecomer Shows a Greater Invasiveness.

The yellow fever (Aedes aegypti) and Asian tiger (Ae. albopictus) mosquitos are major vectors of global mosquito-borne pathogens. However, their niche and range shifts, the underlying mechanisms, and related relative invasion rates remain scarcely known. We examined the niche and range shifts between the native and invasive Ae. aegypti and Ae. albopictus populations through dynamic niche and range models and the largest occurrence record datasets to date. We detected substantial niche and range expansions in both species, probably because the introduced populations have more opportunities to acclimate to diverse environmental conditions than their native counterparts. Mitigating climate change could effectively control their future invasions, given that future climate changes could promote their invasiveness. Additionally, compared to the introduced Ae. aegypti, the more recent invader Ae. albopictus had greater niche and range expansion over its shorter invasion history. In terms of the range shifts, Ae. albopictus had an invasion rate approximately 13.3 times faster than that of Ae. aegypti, making it a more invasive vector of global mosquito-borne pathogens. Therefore, considering its higher invasion rate, much more attention should be paid to Ae. albopictus in devising our strategies against prevailing global mosquito-borne pathogens than Ae. aegypti. Since small niche shifts could result in their large range shifts, niche shifts might be a more important indicator for biological invasion assessments.

Physical virology: how physics is enabling a better understanding of recent viral invaders.

The online version contains supplementary material available at 10.1007/s12551-023-01075-4.

Invaders they are a‐changing†: A recent, unexpected surge of invasive loaches in Catalonia

Abstract Risk analyses for invasive species often assume that the characteristics of future invaders will resemble those already successful, but these features may change. Here, we use data from more than 3,500 fish sampling events, sequencing of mitochondrial and nuclear genes and analyses of several traits describing non‐native fish to describe the irruption and rapid expansion of non‐native loaches in Catalonia, north‐east Iberian Peninsula, and framing this surge in the knowledge of previous invasions. We report the establishment of at least five (Cobitis bilineata, Misgurnus anguillicaudatus, Misgurnus bipartitus, Paramisgurnus dabryanus, and a yet undescribed Barbatula species) non‐native loach species in Catalonia, most of which are currently spreading. Furthermore, one of the two regionally native loach species (Cobitis paludica) has been introduced and is spreading through river basins where it is not native. Genetic analyses were fundamental to understand loach invasions, by clarifying specific statuses, identifying the origin of non‐native populations and/or detecting independent introduction events. Genetic results also highlighted the unresolved taxonomy of loaches, particularly for European Barbatula. Loaches are recent, diverse, and successful invaders whose traits differ from those of most previously established invasive fish species, signalling potential weaknesses of prevention of biological invasions based on prohibited species lists. We call for the development of more flexible management tools (e.g. based on fish traits and not only on species identities) and prioritising prevention and rapid responses to new introductions.

History of Colonization of Jeju Island (Republic of Korea) by the Water Fleas (Crustacea: Cladocera) Is Reflected by the Seasonal Changes in Their Fauna and Species Associations

The aim of this paper is to study the species composition, structure and seasonal dynamics of the cladoceran fauna and species associations in inland water bodies of Jeju Island (Republic of Korea). Only 47 taxa were found in 199 samples. Such faunal paucity could be explained by the existence of only a few types of aquatic environments on Jeju Island as compared to continental China and the Far East of Russia, with their great diversity of water types. We have demonstrated a high significance of the tropical species on Jeju. Our data confirm seasonal faunistic changes in the continental waters of Jeju Island. The rate of tropical taxa is highest in September, after the monsoon season, while the Far Eastern endemic taxa are more common in winter. At the same time, the contribution of Boreal taxa to the fauna of the island is low even in winter. Species associations have been revealed based on binominal distribution; they change significantly from summer to winter. However, a contribution of Boreal taxa to the species associations also is minimal (even in winter), whereas tropical taxa contribute to them greatly (including in winter). We can propose a rough scheme of faunal formation exploring the whole set of obtained information. Initially, at the earlier stages of the island formation, its fauna was consisted of some pre-Pleistocene taxa. Then, during the Pleistocene time, Jeju Island was secondarily interconnected with more southern territories, and tropical species have colonized it. Recent Boreal cladoceran invaders arrived at the island water bodies later when they were already inhabited by formed associations, and for this reason only few of them were able to settle down there. Such a scheme is a hypothesis which needs to be checked by the future phylogeographic studies.

DISTRIBUTION OF SOME PONTO-CASPIAN AND ALIEN COPEPODS (CRUSTACEA, COPEPODA) IN PLANKTON OF THE DON RIVER BASIN

In 2018-2019, the zooplankton was studied in the Don River from the source to the mouth including the Tsimlyansk Reservoir, Volga-Don shipping canal, and the upper part of Taganrog Bay of the Sea of Azov. Habitats of two Ponto-Caspian species of copepods ( Heterocope caspia and Eurytemora caspica ) and of three alien species, Mediterranean copepod Calanipeda aquaedulcis , a representative of the neritic zone Acartia ( Acanthacartia ) tonsa and East Asian euryhaline Thermocyclops taihokuensis were found. For the first time, the findings of T. taihokuensis were recorded in the Don River upstream and downstream of the Tsimlyansk Reservoir and in water bodies of the Volga-Don shipping canal. It is shown that the Ponto-Caspian Eurytemora caspica inhabits the Don River basin and Taganrog Bay of the Sea of Azov. The European copepod E. affinis which was previously recorded in the region was not found in the studied areas of the basin. The occurrence (&gt;80% of samples) of the Ponto-Caspian species and Calanipeda aquaedulcis was the highest. A recent invader Thermocyclops taihokuensis reached the maximum abundance (&gt;100 000 ind./m). By an example of the Tsimlyansk Reservoir, it is found that the way of the spread of the Ponto-Caspian and alien species in the Don River basin may be large-scale activities on the introduction of planktonic and benthic invertebrates conducted in the 1950-1970s in order to improve the food supply of valuable fish species. The history of dispersal of the studied copepod species and their population characteristics are discussed.

Gamma diversity: derived from and a determinant of alpha diversity and beta diversity. An analysis of three tropical landscapes

Using three taxonomic groups of beetles we examine how alpha and beta diversity influence the species richness of a landscape (gamma diversity), and vice versa. That is, how the species richness of a landscape – which is a historical and biogeographical phenomenon – contributes to the values of alpha diversity (1) at a given site, (2) in a community, (3) in terms of cumulative species richness by community, and also contributes to (4) the intensity of species exchange between communities. To explore this question, we used two subfamilies of Scarabaeoidea: Scarabaeinae and Geotrupinae, and the family Silphidae. In all analyses these three taxonomic groups are considered as a single indicator group: the copronecrophagous beetles. Information is also included on the subfamily Aphodiinae (Scarabaeoidea), coprophagous beetles not included in the indicator group. Several types of vegetation located in three landscapes (tropical, transition and mountain) were studied, and these are located along an altitudinal gradient in the central part of the state of Veracruz, Mexico. We base this study on the following concepts. The alpha diversity of an indicator group reflects the number of species that use a given environment or resource in a given place or community. Spacial beta diversityis related to the response of organisms to spatial heterogeneity. Gamma diversity depends primarily on the historical and geographic processes that operate on the mesoscale level and is also affected by alpha and beta diversity. It is on this scale of landscape that human actions, such as the modification and fragmentation of vegetation, have their most important effects. These are, however, often beyond the scope of ecological analyses carried out on a local scale. In the three landscapes, sampling was carried out regularly at 67 sites, with complementary sampling at another 69 sites. Twenty-six types of vegetation communities were studied. A total of 16,152 specimens representing 60 species were captured (52 species of Scarabaeinae, 4 Geotrupinae and 4 Silphidae). In the tropical landscape the community richest in species was low deciduous forest. In the transition landscape, cloud forest was the richest. Each of these communities is the most representative of their respective altitudinal bands. In contrast, the greatest species richness in the mountain landscape occurred in the mountain grasslands and pastures; types of community favoured by or even created by human intervention. This is explained by the expansion of heliophilous species from the Mexican High Plateau into these areas. In the tropical landscape the species richness of the pastures is similar to that of its forests, but with a partially different composition which is characterized by the dominance of heliophilous and coprophagous species; the latter, in addition to the more ubiquitous species that are shared with the tropical forest. In the transition landscape the cloud forest and the coffee plantations with polyspecific shade are important in the context of conserving the fauna. This type of community offers arboreal cover and occupies the majority of this landscape, allowing the groups of insects studied to move between remnant fragments of cloud forest. On the landscape scale but not locally, the fragmentation of natural communities does not appear to have reduced the number of species for the beetles of the indicator group. In each landscape disturbance by human activity appears to have been overcome for distinct reasons. In the tropical landscape we find the heliophilous beetle fauna characteristic of pastures, and this has increased by two species of recent invaders. In the transition landscape, the coffee plantations with polyspecific shade create a communication matrix, while in the mountain landscape the expansion of the mountain pastures has made conditions more favourable for heliophilous species. These results are not necessarily expected for other groups of organisms.

Aedes koreicus, a vector on the rise: Pan-European genetic patterns, mitochondrial and draft genome sequencing.

BackgroundThe mosquito Aedes koreicus (Edwards, 1917) is a recent invader on the European continent that was introduced to several new places since its first detection in 2008. Compared to other exotic Aedes mosquitoes with public health significance that invaded Europe during the last decades, this species’ biology, behavior, and dispersal patterns were poorly investigated to date.Methodology/Principal findingsTo understand the species’ population relationships and dispersal patterns within Europe, a fragment of the cytochrome oxidase I (COI or COX1) gene was sequenced from 130 mosquitoes, collected from five countries where the species has been introduced and/or established. Oxford Nanopore and Illumina sequencing techniques were combined to generate the first complete nuclear and mitochondrial genomic sequences of Ae. koreicus from the European region. The complete genome of Ae. koreicus is 879 Mb. COI haplotype analyses identified five major groups (altogether 31 different haplotypes) and revealed a large-scale dispersal pattern between European Ae. koreicus populations. Continuous admixture of populations from Belgium, Italy, and Hungary was highlighted, additionally, haplotype diversity and clustering indicate a separation of German sequences from other populations, pointing to an independent introduction of Ae. koreicus to Europe. Finally, a genetic expansion signal was identified, suggesting the species might be present in more locations than currently detected.Conclusions/SignificanceOur results highlight the importance of genetic research of invasive mosquitoes to understand general dispersal patterns, reveal main dispersal routes and form the baseline of future mitigation actions. The first complete genomic sequence also provides a significant leap in the general understanding of this species, opening the possibility for future genome-related studies, such as the detection of ‘Single Nucleotide Polymorphism’ markers. Considering its public health importance, it is crucial to further investigate the species’ population genetic dynamic, including a larger sampling and additional genomic markers.

The spread of Lessepsian fish does not track native temperature conditions

Abstract Global warming is enabling tropical invaders to expand into regions, where unsuitable climate conditions used to prevent the survival or reproduction. Here, using the occurrence data of 22 Lessepsian fish in the Mediterranean Sea, we aimed at (1) gaining a deeper understanding of temperature match dynamics over the spatio-temporal spread of each invasion event and (2) testing the hypothesis that successful invasions require a temperature match, as assumed in several bioinvasion risk assessments. For each species, we identified the areas of the Mediterranean lacking a temperature match with native ranges over the past six decades. We found that some species, particularly recent invaders, have spread far beyond temperature matching conditions. The populations at the expanding edge of the range are often found in sites that have experienced increases in temperature. Temperature match positively correlates with species spread rate and after 1990, higher temperatures in the Mediterranean provided analogous conditions for a growing number of non-indigenous species. Our results warn against the general use of temperature-based climate matching in bioinvasion risk and provide guidance for the application of species distribution models that incorporate temperature to marine bioinvasion research.

Increasing abundance of an invasive C4grass is associated with larger community changes away than at home

AbstractAimWe evaluated stands of the invasive grass,Sporobolus cryptandrusin its native North American range and its non‐native European range, where it is a recent invader. Our aim was to reveal how the species’ increasing abundance affects functional diversity and the ecosystem service‐provisioning capacities of plant communities in both ranges.LocationSand grasslands in the Kiskunság, Hungary and in Montana, USA.MethodsAll vascular plant species and their relative abundances were recorded in a stratified random manner in 1 m × 1 m plots in each range, using the following cover categories ofSporobolusas strata: 1%–25%, 26%–50%, 50%–75%, and 75%–100%. The functional characteristics of the plant communities in the two continents were compared. We performed comparisons of the communities both with and without includingSporobolus.ResultsIncreasingSporoboluscover resulted in a lower functional diversity and species richness, reduced average specific leaf area and increased the height of whole plant communities in both ranges but these effects were significantly stronger in the non‐native stands.Sporobolusalso negatively affected the cover of insect‐pollinated plant species and the proportion of native perennials, switching the rest of the community from perennial‐dominated to annual‐dominated. In plant communities withoutSporobolus, increasingSporoboluscover led to a higher specific leaf area and seed mass in both ranges, but average height was decreasing along theSporobolusabundance gradient in the native range, whereas it was increasing in the non‐native range.ConclusionsThe spread ofSporobolus, away from its native range, leads to the impoverishment of host communities and compromises the biomass and floral resource‐provisioning capacity of the vegetation to higher trophic levels. Tackling the spread of this new invader should therefore be a priority task.

Macronutrient niches and field limitation in a woodland assemblage of harvestmen.

Description of animals' trophic niches helps us understand interactions between species in biological communities that are not easily observed. Analyses of macronutrient niches, that is, the range of macronutrient (protein:lipid:carbohydrate) ratios selected by generalist feeders, may be a useful alternative approach to inter-species comparisons of diets, especially within taxonomic assemblages of predators where species with similar nutritional requirements are likely to accept similar types of prey. Here we analysed the macronutritional niches of a woodland assemblage of seven harvestman species, all supposed to be predators with omnivorous tendencies. Five species (Mitopus morio, Leiobunum gracile, Oligolophus tridens, O. hanseni and Paroligolophus agrestis) were native and two species (Opilio canestrinii and Dicranopalpus ramosus) were recent invaders into the community. We compare the fundamental (FMN) and realized (RMN) macronutritional niche positions of the species using a 'double-test procedure', which provides information on whether the species were food limited in their natural habitat, and whether they were limited by specific macronutrients. All seven species were food limited and six species were non-protein limited in the field; of these, four species were carbohydrate limited, and in one species females were lipid limited and males were carbohydrate limited. These findings add to the notion that predators are mainly non-protein limited in the field. The FMN positions of the assemblage fell within 46%-50% protein, 29%-38% lipid and 16%-22% carbohydrate. The amount of carbohydrate in the self-selected diet combined with carbohydrate limitation confirms that the species are zoophytophagous. Two morphological clusters of species (large long-legged vs. small short-legged species) differed not only in microhabitat (upper vs. lower forest strata) but also in macronutrient selection, where large long-legged species selected higher proportion of carbohydrate than small short-legged species. Thus, morphologically similar species occupy the same habitat stratum and have similar macronutritional niches. We discuss the hypothesis that the invasive O. canestrinii might have an impact on native species as it allegedly had in urban environments previously. Two basic assumptions about interspecific resource competition were fulfilled, that is, high overlap of nutritional requirements and limitation by food and macronutrients.

It takes two to tango – Phylogeography, taxonomy and hybridization in grass snakes and dice snakes (Serpentes: Natricidae: Natrix natrix, N. tessellata)

Using two mitochondrial DNA fragments and 13 microsatellite loci, we examined the phylogeographic structure and taxonomy of two codistributed snake species (Natrix natrix,N. tessellata) in their eastern distribution area, with a focus on Turkey. We found evidence for frequent interspecific hybridization, previously thought to be extremely rare, and for backcrosses. This underscores that closely related sympatric species should be studied together because otherwise the signal of hybridization will be missed. Furthermore, the phylogeographic patterns of the two species show many parallels, suggestive of a shared biogeographic history. In general, the phylogeographies follow the paradigm of southern richness to northern purity, but the dice snake has some additional lineages in the south and east in regions where grass snakes do not occur. For both species, the Balkan Peninsula and the Caucasus region served as glacial refugia, with several mitochondrial lineages occurring in close proximity. Our results show that the mitochondrial divergences in both species match nuclear genomic differentiation. Yet, in the former glacial refugia of grass snakes there are fewer nuclear clusters than mitochondrial lineages, suggesting that Holocene range expansions transformed the glacial hotspots in melting pots where only the mitochondrial lineages persisted, bearing witness of former diversity. On the other hand, the deep mitochondrial divergences inN. tessellataacross its entire range indicate that more than one species could be involved, even though lacking microsatellite data outside of Turkey prevent firm conclusions. On the contrary, our microsatellite and mitochondrial data corroborate thatN. megalocephalais invalid and not differentiated from sympatric populations ofN. natrix. For Cypriot grass snakes, our analyses yielded conflicting results. A critical assessment of the available evidence suggests thatN. natrixis a genetically impoverished recent invader on Cyprus and taxonomically not distinct from a subspecies also occurring in western Anatolia and the southern Balkans. Based on combined mitochondrial and nuclear genomic evidence we propose that for grass snakes the following subspecies should be recognized in our study region: (1)Natrix natrix vulgarisLaurenti, 1768, southeastern Central Europe and northern Balkans; (2)Natrix natrix moreotica(Bedriaga, 1882), southern Balkans, western Anatolia, and Cyprus; and (3)Natrix natrix scutata(Pallas, 1771), eastern Anatolia, Caucasus region, Iran, northeastern distribution range (from eastern Poland and Finland to Kazakhstan and the Lake Baikal region). Thus,Natrix natrix cypriaca(Hecht, 1930) becomes a junior synonym ofN. n. moreoticaandNatrix natrix persa(Pallas, 1814) becomes a junior synonym ofN. n. scutata. Due to insufficient material, we could not resolve the status ofNatrix natrix syriaca(Hecht, 1930) from the Gulf of İskenderun, southeastern Turkey.

A window of opportunity: a recent exotic palm invader can still be eradicated in an Atlantic Forest Protected Area

Exotic palms are introduced as ornamental all over the world, with some of them become invasive. Here, we characterize the population status and the stage of invasion of the exotic palm Caryota urens in an Atlantic Forest Protected Area, southeastern Brazil. Palms were sampled in 2019 and 2020, in fifteen 10 x 10 m plots, placed from an alley of planted reproductive palms. All individuals inside plots were marked and classified in ontogenetic stages. The number of sampled individuals was 110 in 2019 and 114 in 2020; palms were recorded in six plots in 2019 (the furthest 330 m from the alley) and in eight plots in 2020 (the furthest 420 m from the alley). In 2020, most palms were on the earlier ontogenetic stages (seedlings and infants, 86 %), but we also recorded juveniles (10.5 %) and immatures (3.5 %), values similar to those found in 2019. The population structure observed and the natural expansion of the species inside the forest indicate that the palm has successfully established in the area and has become invasive. Management actions should be taken urgently in an attempt to contain the spreading to new locations or eradicate this palm from this protected area.

The polyphagous shot hole borer beetle: Current status of a perfect invader in South Africa

The polyphagous shot hole borer (PSHB) beetle is a recent invader in South Africa. Together with its fungal symbiont, Fusarium euwallaceae, it can rapidly kill highly susceptible host plants. Its impact is most profound in urban areas, but it has also been found infesting important forestry, agricultural crop and native species. Since its first detection in 2012, PSHB has spread to all but one province in the country. The beetle–fungus complex has several biological traits that enhance its anthropogenically mediated dispersal, establishment and survival in novel environments – factors that have likely facilitated its rapid spread across the country. We review the history of the PSHB invasion in South Africa, its taxonomic status and the reasons for its rapid spread. We highlight its potential impact and challenges for its management. Finally, we provide an updated distribution map and list of confirmed host plants in South Africa. Of the 130 plant species identified as hosts, 48 of these (19 indigenous and 29 introduced) are reproductive hosts able to maintain breeding PSHB populations. These reproductive hosts may succumb to beetle infestations and act as ‘pest-amplifiers’. The economic impact on urban forests, plantation forestry and agricultural crops may be severe, but the ecological impact of PSHB invasion in native ecosystems should not be underestimated.Significance: We provide an updated host list and distribution map for South Africa of the globally significant tree pest, the polyphagous shot hole borer (PSHB, Euwallacea fornicatus). The South African PSHB invasion represents the largest outbreak of this pest in its global invaded range. PSHB was confirmed to infest 130 plant species in urban, agricultural, and native ecosystems in South Africa, including 44 previously unreported hosts. Impact in South Africa is in its infancy but will likely be substantial to local economies and ecosystems. Mitigation has proven difficult, but numerous research projects have been initiated throughout the country.