Congeneric Native Species Research Articles

Differential effects of transgenerational plasticity on morphological and photosynthetic properties between an invasive plant and its congeneric native one

Phenotype of plant offspring may be affected by particularly maternal environmental conditions, which is named as transgenerational plasticity. Transgenerational plasticity enhances the fitness of offspring under the maternal environmental conditions. Transgenerational plasticity may promote the successful invasion of alien plants, particularly those with clonal growth. However, few studies have compared transgenerational plasticity between alien invasive clonal plants and their congeneric native ones. A pot experiment with the invasive herb Wedelia trilobata and its congeneric native species Wedelia chinensis was conducted to investigate effects of light conditions (low vs. high light treatment) experienced by mother ramets on morphological and photosynthetic properties of offspring ramets subjected to the low light treatment. Compared with those of offspring ramets from mother ramets subjected to the high light treatment, leaf area, potential maximum net photosynthetic rate (Pmax) and biomass accumulation of offspring ramets from mother ramets subjected to the low light treatment were significantly greater in W. trilobata than W. chinensis. Opposite pattern was observed in number of offspring ramets. We conclude that effects of transgenerational plasticity on growth performance could be species-specific between invasive plant and its congeneric native one. Positive effect of transgenerational plasticity on number of offspring ramets was not transformed into growth advantages of native species W. chinensis during its later establishment. However, favorable effects of transgenerational plasticity on capturing light resource could enhance competitive ability and promote successful invasion of W. trilobata.

Woody invaders are more highly colonized by arbuscular mycorrhizal fungi than congeneric native species.

Invasive species tend to possess acquisitive plant traits that support fast growth and strong competitive ability. However, the relevance of symbioses with arbuscular mycorrhizal fungi (AMF) to the fast growing, acquisitive strategy of invasive species is still unclear. We measured AMF colonization in roots of five congeneric pairs of invasive and native eastern North American woody species (10 species total; 4 lianas, 6 shrubs) that were grown in a monoculture common garden experiment in Syracuse, NY. We then examined the relationships of AMF colonization to above and belowground traits of these species. Total AMF colonization and arbuscule colonization were greater in invasive compared to native woody species, a pattern that was more distinct in congeneric shrubs than congeneric lianas. The level of AMF colonization was also positively correlated with traits indicative of rapid plant growth and nutrient uptake. The concordance of a resource-acquisitive strategy with higher AMF colonization suggests that symbioses with AMF may be part of the strategy by which invasive woody plants of eastern North America are able to maintain fast growth rates and outcompete their native counterparts.

Invader abundance and contraction of niche breadth during replacement of a native gammarid amphipod.

The introduction of non‐native species to new locations is a growing global phenomenon with major negative effects on native species and biodiversity. Such introductions potentially bring competitors into contact leading to partial or total species replacements. This creates an opportunity to study novel species interactions as they occur, with the potential to address the strength of inter‐ and intraspecific interactions, most notably competition. Such potential has often not been realized, however, due to the difficulties inherent in detecting rapid and spatially expansive species interactions under natural field conditions. The invasive amphipod crustacean Gammarus pulex has replaced a native species, Gammarus duebeni celticus, in river and lake systems across Europe. This replacement process is at least partially driven by differential parasitism, cannibalism, and intraguild predation, but the role of interspecific competition has yet to be resolved. Here, we examine how abundance of an invasive species may affect spatial niche breadth of a native congeneric species. We base our analyses of niche breadth on ordination and factor analysis of biological community and physical parameters, respectively, constituting a summative, multidimensional approach to niche breadth along environmental gradients. Results derived from biological and environmental niche criteria were consistent, although interspecific effects were stronger using the biological niche approach. We show that the niche breadth of the native species is constrained as abundance of the invader increases, but the converse effect does not occur. We conclude that the interaction between invasive G. pulex and native G. d. celticus under natural conditions is consistent with strong interspecific competition whereby a native, weaker competitor is replaced by a superior invasive competitor. This study indicates a strong role of interspecific competition, alongside other known interactions such as differential intraguild predation, in rapid and expansive species replacements following biological invasions.

Post‐filling phase ichthyofaunal community and fishery potential of Chitsuwa Reservoir, a small tropical reservoir in Zimbabwe

AbstractMany small reservoirs exist throughout Southern Africa, and with adequate management have the potential to contribute significantly to food security. The fisheries and limnology of the newly created Chitsuwa Reservoir in Zimbabwe were studied with the objective of generating information to support the development, management and sustainable use of fisheries to enhance the socio‐economic status of riparian communities. Based on gill nets of various mesh sizes, it was confirmed that the reservoir is presently inhabited by a fairly diverse fish community comprising ten species belonging to five families (Clarias gariepinus; Coptodon rendalli; Labeo cylindricus; Marcusenius macrolepidotus; Micropterus salmoides; Momyrus longirostris; Oreochromis mossambicus; Oreochromis niloticus; Serranochromis microcephalus; and Tilapia sparrmanii). Oreochromis niloticus dominated the reservoir with respect to both abundance, biomass and catch. The index of relative importance revealed O. niloticus and M. macrolepidotus were the most important species. Results from the Canonical Correspondence Analysis revealed a clear division of the fish species that followed the environmental variables. Although fisheries may benefit from the invasive M. salmoides and the established O. niloticus, their presence in the reservoir is a cause for concern for conserving native congeneric species that risk extirpation through documented mechanisms. The results of the present study suggest sound management of the reservoir is required to raise its potential of supporting the livelihoods of the surrounding communities with a predicted annual fish yield of 61.5 t/year. Management of this reservoir should involve the local communities, empowering them so that they practice sustainable non‐destructive fishing methods.

Correction to: Invasive Italian wall lizards outcompete native congeneric species in finding food in a Y‑maze

Correction to: Invasive Italian wall lizards outcompete native congeneric species in finding food in a Y‑maze

Invasive Italian wall lizards outcompete native congeneric species in finding food in a Y-maze

Invasive Italian wall lizards outcompete native congeneric species in finding food in a Y-maze

Exotics are more complementary over time in tree biodiversity–ecosystem functioning experiments

Abstract The Biodiversity–Ecosystem Functioning (BEF) literature proposes that ecosystem functioning increases with biodiversity because of complementarity in resource‐use among species, associated with functional diversity. In this study, we challenge the trait‐based ecology framework by comparing congeneric exotic (European) and native (North American) tree species showing similar resource‐use functional trait values. The trait‐based framework suggests that two functionally equivalent species should play similar roles in a community, resulting in similar interactions and performances. However, several studies showed that when growing in mixtures, exotic species that are functionally equivalent to native species benefitted from enemy release, resulting in a reduced apparent competition. We hypothesize that exotic species should be more productive than native species because the exotic species benefit from reduced apparent competition due to enemy release rather than from possessing more competitive resource‐use functional traits. We study a diversity experiments, part of the International Diversity Experiment Network with Trees (IDENT), composed of two identical sites, each with two orthogonal diversity gradients: species richness and functional diversity. The functional gradient consists of species combinations of equal richness but increasing functional diversity, using different combinations of species provenance to assess the relationship between productivity, functional diversity and species provenance, independently of species richness. We grew a total of 12 species (six native and six exotic) in different combinations of one‐, two‐ and six‐species mixtures. The exotic species were selected based on their functional equivalence to their native congeneric species. Eight years after planting, we found that exotic species were more productive than native species, but only at high functional diversity. Results indicate that exotic species overall benefit from a reduced apparent competition, and that exotic‐increased productivity at high functional diversity is consistent with the enemy release hypothesis. After 8 years, exotic species were more productive overall than their native counterparts, but only in the most functionally diverse communities. This study represents a first step in understanding the relative importance of complementarity in resource‐use and apparent competition in a context of an exotic tree species invasion. A free Plain Language Summary can be found within the Supporting Information of this article.

Hybridization with mountain hares increases the functional allelic repertoire in brown hares

Brown hares (Lepus europaeus Pallas) are able to hybridize with mountain hares (L. timidus Linnaeus) and produce fertile offspring, which results in cross-species gene flow. However, not much is known about the functional significance of this genetic introgression. Using targeted sequencing of candidate loci combined with mtDNA genotyping, we found the ancestral genetic diversity in the Finnish brown hare to be small, likely due to founder effect and range expansion, while gene flow from mountain hares constitutes an important source of functional genetic variability. Some of this variability, such as the alleles of the mountain hare thermogenin (uncoupling protein 1, UCP1), might have adaptive advantage for brown hares, whereas immunity-related MHC alleles are reciprocally exchanged and maintained via balancing selection. Our study offers a rare example where an expanding species can increase its allelic variability through hybridization with a congeneric native species, offering a route to shortcut evolutionary adaptation to the local environmental conditions.

Clonal fragments of stoloniferous invasive plants benefit more from stolon storage than their congeneric native species

Plants with clonal growth may suffer from great fragmentation risk due to frequent disturbance. Meanwhile, storage capacity of clonal organs (stolon or rhizome) is important for survival and growth of clonal fragments. However, few studies have compared the difference in the regeneration capacity of clonal fragments between invasive clonal plants and congeneric native species. More studies between invasive plants and their congeneric native species are needed to provide insight into traits that contribute to invasiveness. Single-node fragments with stolon internode of different length were used to investigate the effects of stolon storage on survival and growth of three stoloniferous invasive plants (Wedelia trilobata, Alternanthera philoxeroides and Hydrocotyle vulgaris) and their congeneric native species (Wedelia chinensis, Alternanthera sessilis and Hydrocotyle sibthorpioides). Soluble sugar, starch and soluble protein contents of stolon internode per unit length were significantly greater in the three invasive plants than in their congeneric native species. During the experiment, regeneration of clonal fragments was not observed in A. sessilis. With increasing of stolon internode length, accumulative emergence rate of clonal fragments and biomass of their regenerated ramets significantly increased in the other five species. Accumulative emergence rate of clonal fragments and biomass of their regenerated ramets were significantly greater in invasive plant H. vulgaris than in its congeneric native species. A similar pattern was observed in the clonal fragments with stolon internode of long and medium length for Wedelia species pair. In the experiment, regeneration capacity of clonal fragments varied with species and stolon internode length. Clonal fragments of stoloniferous invasive plants benefit more from stolon storage than their congeneric native species. It is suggested that clonal storage may be an important trait for invasiveness of stoloniferous invasive plants. Therefore, intentional fragmentation should be carefully employed to manage stoloniferous invasive plants and avoid the dispersal of generative clonal fragments.

Invasive shrimp Cinetorhynchus erythrostictus (Decapoda: Caridea) misidentified in the marine aquarium trade: Niche overlap with a native congeneric species

An integrative taxonomic approach was adopted to confirm that the shrimp Cinetorhynchus erythrostictus was introduced into the Western Atlantic Ocean and it is for sale in the marine aquarium trade in Brazil, misidentified as C. rigens, a representative of the Atlantic fauna. The MaxEnt modeling technique was used to infer ecological niche models for Cinetorhynchus erythrostictus, an invasive (non-indigenous) species in the Atlantic Ocean, and C. rigens (native to the Atlantic Ocean). Subsequently, the hypothesis of niche conservatism over an evolutionary time scale was tested. The projection for C. erythrostictus suggested large areas of climatic suitability in the Atlantic Ocean. The background of the invasive species showed a similar range of environmental conditions to that of the native congeneric shrimp. The environmental niches of the native and invasive species overlap 26%, with significant equivalency and similarity between niches. Thus, these species can develop competitive interactions across environmental gradients. Importantly, we recommend that greater efforts should be made to identify the ornamental marine species that are currently traded, in order to minimize the risk of spread of invasive species and, consequently, of potential ecological damage to native biodiversity.

New records for <i>Callithrix aurita</i> and <i>Callithrix </i>hybrids in the region of Viçosa, Minas Gerais, Brazil


 
 
 The genus Callithrix includes six species distributed across eastern Brazil in the Atlantic Rainforest, Caatinga, and Cerrado biomes. The buffy-tufted-ear marmoset (Callithrix aurita) is endemic to the Atlantic Rainforest and occurs in the states of Minas Gerais, Rio de Janeiro, and São Paulo. This species is considered ‘Endangered’ and listed among the world’s 25 most threatened primates. The release into the wild of marmosets kept as pets has led to numerous invasive populations in southeastern Brazil, which hybridize with native congeneric species. This, combined with habitat loss and fragmentation, has caused a dramatic decline in C. aurita populations, and threatens them with extinction. The city of Viçosa, in Minas Gerais, has an almost 50-year history of introduced Callithrix species. C. aurita, the native species, was last recorded in the region in 1995. With the aim of updating knowledge on the current situation of Callithrix in the region, we surveyed 43 fragments of the Atlantic Forest in Viçosa and nearby cities between 2017 and 2019. We recorded 22 groups of hybrid forms, three solitary individuals of hybrid marmosets, two mixed groups of C. aurita with hybrids, and a single group of C. aurita. This record of C. aurita was the first of a pure group of the species in the region in 20 years. These results highlight one of the most important threats to C. aurita, and management actions are urgently needed to control invasive and hybrid populations, to allow the endangered buffy-tufted-ear marmoset to recover
 
 

Latitudinal variation in soil nematode communities under climate warming-related range-expanding and native plants.

Current climate change has led to latitudinal and altitudinal range expansions of numerous species. During such range expansions, plant species are expected to experience changes in interactions with other organisms, especially with belowground biota that have a limited dispersal capacity. Nematodes form a key component of the belowground food web as they include bacterivores, fungivores, omnivores and root herbivores. However, their community composition under climate change‐driven intracontinental range‐expanding plants has been studied almost exclusively under controlled conditions, whereas little is known about actual patterns in the field. Here, we use novel molecular sequencing techniques combined with morphological quantification in order to examine nematode communities in the rhizospheres of four range‐expanding and four congeneric native species along a 2,000 km latitudinal transect from South‐Eastern to North‐Western Europe. We tested the hypotheses that latitudinal shifts in nematode community composition are stronger in range‐expanding plant species than in congeneric natives and that in their new range, range‐expanding plant species accumulate fewest root‐feeding nematodes. Our results show latitudinal variation in nematode community composition of both range expanders and native plant species, while operational taxonomic unit richness remained the same across ranges. Therefore, range‐expanding plant species face different nematode communities at higher latitudes, but this is also the case for widespread native plant species. Only one of the four range‐expanding plant species showed a stronger shift in nematode community composition than its congeneric native and accumulated fewer root‐feeding nematodes in its new range. We conclude that variation in nematode community composition with increasing latitude occurs for both range‐expanding and native plant species and that some range‐expanding plant species may become released from root‐feeding nematodes in the new range.

Range-expansion effects on the belowground plant microbiome.

Plant range expansion is occurring at a rapid pace, largely in response to human-induced climate warming. While the movement of plants along latitudinal and altitudinal gradients is well documented, effects on the belowground microbial communities remains largely unknown. Further, in range expansion not all plant species are equal: in a new range the relatedness between range-expanding plant species and native flora can influence plant-microbe interactions. Here we used a latitudinal gradient across Europe to examine bacterial and fungal communities in the rhizosphere and surrounding soils of range-expanding plant species. We selected range expanders with and without congeneric natives in the new range, and as a control, the congeneric natives, totaling 382 plant individuals collected across Europe. In general, a plant’s status as range expander was a weak predictor of bacterial and fungal community composition. However, microbial communities of range-expanding plant species became more similar to each other farther from their original range. Range expanders unrelated to the native community also experienced a decrease in the ratio of plant pathogens to symbionts, giving weak support to the enemy release hypothesis. Even at a continental scale the effects of plant range expansion on the belowground microbiome are detectable, though changes to specific taxa remain difficult to decipher.

Relative Growth Rate and Its Components in Invasive Species Heracleum sosnowskyi and Congeneric Native Species H. sibiricum

We studied the relative growth rate of seedlings and aboveground and underground organs, as well as functional traits of leaves and absorbing roots in the invasive species Heracleum sosnowskyi and congeneric native species H. sibiricum. The plants were grown in laboratory conditions and the functional plant traits of 21- and 35-day-old seedlings were analyzed. The relative growth rate (RGR) of H. sosnowskyi differed from that of H. sibiricum by 2.5 times, but the growth of plants in height and in area of leaves was similar. Plant biomass and total leaf area were twice as high in 35-day-old seedlings of invasive species. Structural features of the leaves in 35-day-old H. sosnowskyi seedlings were a lower leaf thickness and a higher leaf density. The invasive species had a lower root mass ratio, but the roots were more branched with a greater ratio of absorbing roots and a better development of the root hairs. As a result, H. sosnowskyi had a higher growth rate of absorbing roots (by 2 times) and a larger absorbing surface in relation to the total root surface. We concluded that the structural and functional traits of the leaves and roots provided a 2 times higher net assimilation rate (NAR) and 2.5 times larger RGR in the invasive species H. sosnowskyi.

The invasiveness of a non-native fungal forest pathogen is boosted by the presence of a congeneric native species

The invasiveness of a non-native fungal forest pathogen is boosted by the presence of a congeneric native species

Nematode community responses to range-expanding and native plant communities in original and new range soils.

Many plant species expand their range to higher latitudes in response to climate change. However, it is poorly understood how biotic interactions in the new range differ from interactions in the original range. Here, in a mesocosm experiment, we analyze nematode community responses in original and new range soils to plant communities with either (a) species native in both the original and new range, (b) range‐expanding species related to these natives (related range expanders), or (c) range expanders without native congeneric species in the new range (unrelated range expanders). We hypothesized that nematode community shifts between ranges are strongest for unrelated range expanders and minimal for plant species that are native in both ranges. As a part of these community shifts, we hypothesized that range expanders, but not natives, would accumulate fewer root‐feeding nematodes in their new range compared to their original range. Analyses of responses of nematodes from both original and new ranges and comparison between range expanders with and without close relatives have not been made before. Our study reveals that none of the plant communities experienced evident nematode community shifts between the original and new range. However, in soils from the new range, root‐feeding nematode communities of natives and related range expanders were more similar than in soils from the original range, whereas the nematode community of unrelated range expanders was distinct from the communities of natives and related range expanders in soils from both ranges. The abundances of root‐feeding nematodes were comparable between the original and new range for all plant communities. Unexpectedly, unrelated range expanders overall accumulated most root‐feeding nematodes, whereas related range expanders accumulated fewest. We conclude that nematode communities associated with native and range‐expanding plant species differ between the original and the new range, but that range‐expanding plant species do not accumulate fewer root‐feeding nematodes in their new than in their original range.

Grasses as appropriate targets in weed biocontrol: is the common reed, Phragmites australis, an anomaly?

Despite their importance as invasive species, there has been a hesitation to target grasses in classical biocontrol. This historic bias appears to be changing with multiple active research and release programs. Similarly, biocontrol workers appear to avoid targeting species with native congeners. These biases appear inappropriate as the ecological and entomological literature provide abundant evidence for sub-genus specificity for many herbivores, including those attacking grasses. The biocontrol program targeting Phragmites australis (Cav.) Trin. ex Steud (Poaceae) provides an informative example with endemic subspecies in North America and many sub-genus specific herbivores, including potential European control agents. Grasses and target weeds with congeneric native species require rigorous host range testing, similar to all other targets in current weed biological control programs. Furthermore, it appears prudent to ask petition reviewers and regulatory agencies to abandon their focus on results of no-choice studies and to distinguish between trivial feeding and demographic impacts.

Latitudinal variation of life-history traits of an exotic and a native impatiens species in Europe

Understanding the responses of invasive and native populations to environmental change is crucial for reliable predictions of invasions in the face of global change. While comparisons of responses across invasive species with different life histories have been performed before, comparing functional traits of congeneric native and invasive species may help to reveal driving factors associated with invasion. Here we compared morphological functional trait patterns of an invasive species (Impatiens parviflora) with its congeneric native species (I. noli-tangere) along an approximately 1600 km European latitudinal gradient from France (49°34′N) to Norway (63°40′N). Soil nitrogen was recorded during six weeks of the growing season, and light, soil moisture, and nutrient availability were estimated for each sampled population using community weighted means of indicator values for co-occurring species. Temperature data were gathered from nearby weather stations.Both the native and invasive species are taller at higher latitudes and this response is strongest in the invasive species. Seed mass and number of seeds per capsule increase in I. noli-tangere but decrease in I. parviflora towards higher latitudes. Surprisingly, plant height in the invasive I. parviflora decreases with increasing soil nitrogen availability. The latitudinal pattern in seed mass is positively related to temperature in I. noli-tangere and negatively in I. parviflora. Leaf area of both species decreases with increasing Ellenberg indicator values for nitrogen and light but increases with increasing soil moisture. Soil nitrogen concentrations and Ellenberg indicator values for nitrogen have significant positive (I. noli-tangere) and negative (I. parviflora) effects on the number of seeds per capsule. Our results show that the native I. noli-tangere has efficient reproduction at its range edge while the invasive I. parviflora shows a marked decrease in seed size and seed number per capsule. These patterns are unrelated to the growth and obtained size of the plants: even low soil nitrogen availability in the north seemed not to limit plant growth and size. Our results suggest that the invasive I. parviflora tends to become more invasive at lower latitudes by producing heavier seeds and more seeds per capsule.

Post-release evaluation of non-target effects of Torymus sinensis, the biological control agent of Dryocosmus kuriphilus in Italy

A post-release study was performed to assess the impact of Torymus sinensis (Hymenoptera: Torymidae), the biological control agent of Dryocosmus kuriphilus (Hymenoptera: Cynipidae), on native cynipid gall inducers in Italy. In total, 14,512 non-target galls were collected, corresponding to seven genera: Andricus, Aphelonyx, Biorhiza, Cynips, Diplolepis, Neuroterus, and Synophrus, and 8708 chalcid parasitoids were recorded. The Torymidae family accounted for about 30%, and Bootanomyia (=Megastigmus) dorsalis, Torymus affinis and T. flavipes were the most represented species. A total of 116 T. sinensis emerged from 15 different oak galls, mainly Andricus curvator and A. inflator. In controlled conditions, oviposition was recorded on A. cydoniae, A. grossulariae and A. lucidus, while no mating with native congeneric species occurred. This paper confirms the realised host-range expansion by T. sinensis. Even if it were extremely difficult to evaluate its magnitude, the impact appears minimal, and an occasional feeding with no changes in the distribution or abundance of non-target hosts is expected.

Effects of Global Risks — Nitrogen Additions on Growth and Competitive Relations among Invasive and Native Congeneric Species —Bidens frondosa

ABSTRACT Human activity has greatly increased the amount of biologically available nitrogen entering the natural environment. Addition of N can affect growth of and competitive interactions between native and invasive plants, thus increasing or decreasing the risk of invasion by alien species. Bidens frondosa is an invasive weed native to North America that recently has begun to spread in China. The influence of soil nutrient content on B. frondosa invasion has not yet been reported. In a common garden experiment, we compared the growth and competitive effects between B. frondosa and its co-occurring native congeners — B. tripartita and B. biternata — under three N levels (0 g m-2, 1 g m-2, 5 g m-2) to assess whether increased levels of N modifies risk of B. frondosa invasion. Our results showed that while N additions increased both the growth and competitive advantage of B. frondosa as compared with that of the native congener species, results are particularly pronounced under high N levels. While growth...