Non-native populations of an invasive tree outperform their native conspecifics

Introduced plants often face new environmental conditions in their non-native ranges. To become invasive, they need to overcome several biotic and abiotic filters that may trigger adaptive changes in life-history traits, like postgermination processes. Such early life cycle traits may play a crucial role in the colonization and establishment success of invasive plants. As a previous study revealed that seeds of non-native populations of the woody Siberian elm, Ulmus pumila, germinated faster than those of native populations, we expected growth performance of seedlings to mirror this finding. Here, we conducted a common garden greenhouse experiment using different temperature and watering treatments to compare the biomass production of U. pumila seedlings derived from 7 native and 13 populations from two non-native ranges. Our results showed that under all treatments, non-native populations were characterized by higher biomass production and enhanced resource allocation to aboveground biomass compared to the native populations. The observed enhanced growth performance of non-native populations might be one of the contributing factors for the invasion success of U. pumila due to competitive advantages during the colonization of new sites.Fil: Hirsch, Heidi. Stellenbosch University, Centre for Invasion Biology, Department of Botany and Zoology; Sudáfrica. Martin Luther University Halle-Wittenberg, Institute of Biology/Geobotany and Botanical Garden ; AlemaniaFil: Hensen, Isabell. Martin Luther University Halle-Wittenberg, Institute of Biology/Geobotany and Botanical Garden ; Alemania. German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig; AlemaniaFil: Wesche, Karsten. German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig; Alemania. Senckenberg Museum of Natural History Goerlitz; AlemaniaFil: Renison, Daniel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones Biológicas y Tecnológicas. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas, Físicas y Naturales. Instituto de Investigaciones Biológicas y Tecnológicas; ArgentinaFil: Wypior, Catherina. Martin Luther University Halle-Wittenberg, Institute of Biology/Geobotany and Botanical Garden ; AlemaniaFil: Hartmann, Matthias. Charles University in Prague, Herbarium PRC & Department of Botany; República ChecaFil: von Wehrden, Henrik. Leuphana University, Institute of Ecology/Faculty of Sustainability, Centre of Methods; Alemania. Research Institute of Wildlife Ecology; Austri

Sex morphs and invasiveness of a fleshy-fruited tree in natural grasslands from Argentina

Invasiveness has usually been studied as a species-level attribute; nevertheless, phenotypic differences between individuals in a population can lead to significant variations in colonization ability. In this paper, we analyse the potential effects of sex morphs of Prunus mahaleb, a gynodioecius fleshy-fruited tree, on its invasiveness in natural grasslands in the southern Argentine Pampas. We assessed the abundance of both hermaphrodite and female plants and compared their fecundity, propagule size and germination response. We found that the females were less abundant in the invasive populations studied, apparently since the beginning of the colonization. However, our results demonstrated that at the present time females do not show any fecundity reduction, which clearly shows that P. mahaleb has established an effective interaction with generalist pollinators which compensates for the apparent disadvantage of females. Fruit set showed a wider range of variability over time in the females than in the hermaphrodites, which could be the consequence of greater susceptibility to changes in the activity of pollinators. We found no evidence of a female benefit due to reallocation of resources or better outcrossed progeny considering propagule size and germination. We discuss the relative importance of sex morphs and interactions at different stages of the invasion process.Fil: Amodeo, Martín Raúl. Universidad Nacional del Sur. Departamento de Biología, Bioquímica y Farmacia. Grupo de Estudios en Conservación y Manejo; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Zalba, Sergio Martín. Universidad Nacional del Sur. Departamento de Biología, Bioquímica y Farmacia. Grupo de Estudios en Conservación y Manejo; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

A preliminary field trial to compare control techniques for invasive Berberis aquifolium in Belgian coastal dunes

Non-native Berberis aquifolium is an invasive species in Belgian coastal dunes. With its strong clonal growth through suckers, this evergreen shrub outcompetes native species and affects dune succession. To prevent further secondary spread and mitigate its impact, there was an urgent need for knowledge on the effectiveness of control measures, both at the plant and habitat level. Here, we report on a first control experiment. Individual B. aquifolium clones were subjected to one of four treatments (manual uprooting, foliar herbicide application, stem cutting followed by herbicide or salt application), with regrowth being measured up to one year after treatment. We analyzed the relationship between kill rate, treatment, dune area, plant volume and number of plant stems using a generalized linear model. Berberis aquifolium plants proved most susceptible to foliar herbicide application (5% glyphosate solution), resulting in 88% (64%-97%) of the clones dying after treatment. The predicted kill rate decreased with an increasing number of stems under all treatments. We discuss the limitations of our experiment and the potential for actual field application of the different treatments. We present some guidelines for future control that may become further refined as experience builds up and we provide some recommendations for tackling invasive alien species in Atlantic dune ecosystems

The ecosystem and evolutionary contexts of allelopathy

Plants can release chemicals into the environment that suppress the growth and establishment of other plants in their vicinity, a process known as ‘allelopathy’. However, chemicals with allelopathic functions have other ecological roles, such as plant defense, nutrient chelation, and regulation of soil biota in ways that affect decomposition and soil fertility. These ecosystem-scale roles of allelopathic chemicals can augment, attenuate or modify their community-scale functions. In this review we explore allelopathy in the context of ecosystem properties, and through its role in exotic invasions consider how evolution might affect the intensity and importance of allelopathic interactions

Kohalike ja invasiivsete röövtoiduliste suurselgrootute elupaigakasutus ja toitumissuhted Läänemere põhjaosas

Väitekirja elektrooniline versioon ei sisalda publikatsiooneRöövtoidulised suurselgrootud, peamiselt vähilaadsed, on rannikumere toitumisvõrgustikes oluliseks lüliks põhjaelustiku ja kalade vahel ning ühtlasi nad reguleerivad väiksemate selgrootute arvukust. Läänemere põhjaosas elas selle rühma esindajaid seni ainult kaks liiki – läänemere krevett (Palaemon adspersus) ja põhjamere garneel (Crangon crangon). Hiljuti lisandusid neile kohalikele liikidele kaks võõrliiki – elegantne krevett (Palaemon elegans) ja rändkrabi (Rhithropanopeus harrisii). Kohalike ja võõrliikidest röövtoiduliste suurselgrootute leviku, elupaigaeelistuste ja toitumise uurimiseks kasutati olemasolevaid põhjaelustiku leviku andmeid, spetsiaalselt uuritavatele liikidele suunatud proovide kogumist loodusest ja laborikatseid, kus rakendati muuhulgas loomade raadiomärgistamist. Võõrliigist kreveti levik oli ulatuslikum kui kohalike krevettide levik. Võõrliik oli kohalike krevettidega võrreldes enam seotud elupaikadega, millele on iseloomulikud etrofeerumise tunnused (kõrge toitainete kontsentratsioon, lühiealiste niitjate vetikate suur hulk). Krevettide toitumisuuringud näitasid, et uuritud Palaemon liikide toitumisintensiivsus ja toidu kooseis ei erinenud. Seega on kohaliku ja võõrkreveti roll rannikumere toiduvõrkudes sarnane, ent võõrliik võib troofilisi suhteid ümber kujundada piirkondades, kus kohalikud krevetid puuduvad. Kõige kitsama elupaigakasutusega oli põhjamere garneel ja Palaemon liikidest oli võõrliigi P. elegans spetsialiseerumise tase mõnevõrra kõrgem kui kohalikul liigil. R. harrisii eelistas põisadruga (Fucus vesiculosus) elupaika mis viitab sellele, et põisadruga elupaik pakub krabile aastaringset stabiilset elupaika ja et mitmekesine põhjakooslus võib saada seetõttu krabidest oluliselt mõjutatud. Doktoritöö tulemused näitasid, et elupaikade iseloom ja seisund mõjutab kohalike ja võõrliikide levikumustreid ning võõrliikidest selgrootute kiskjate saabumine ja kiire levila laienemine Läänemere põhjaosas toovad kaasa täiesti uue ökoloogilise funktsiooni (suuremõõtmeline kiskja) või juba varem regionaalselt esinenud funktsiooni leviku piirkondadesse, kus see varem puudus.Decapod crustaceans, such as crabs and shrimps play an important role in coastal ecosystems as they prey on small benthic invertebrates and at the same time they are an important food item for fishes. Until recently, this group of macroinvertebrates consisted of only a few species in the northern Baltic Sea, including only two species of native shrimps – Crangon crangon and Palaemon adspersus. However, very recently two non-native crustacean predators arrived – the shrimp Palaemon elegans and the crab Rhithropanopeus harrisii. Data from available databases were used together with field sampling and laboratory experiments (incl. radio frequency positioning technology) to describe the geographical distribution, habitat selection, and feeding of native and invasive predatory crustaceans in the coastal areas of the northern Baltic Sea. The distribution of the non-native P. elegans was wider than that of native species. P. elegans was associated with lower salinity, higher concentrations of nutrients and higher proportions of ephemeral filamentous algae, relative to P. adspersus. According to results of the experiment on feeding activity, P. elegans performs a similar role in the coastal food web as the native congener, although it may rearrange trophic interactions and introduce new ecological function in the most eutrophicated areas previously lacking any native shrimp. Among the studied shrimps, C. crangon had the highest habitat specialization. The non-native P. elegans showed slightly higher habitat specialization compared to the native P. adspersus. The invasive crab R. harrisii preferred habitats with bladder wrack where the diverse native community may become heavily impacted by this novel large-bodied predator. This thesis showed that the successful establishment of non-native predatory invertebrates can introduce new ecological functions (large-bodied predators) or considerably strengthen already existed ones, while the heterogeneity of habitats has varying effects on the distribution patterns of native and invasive species

Dominant Role of Nucleotide Substitution in the Diversification of Serotype 3 Pneumococci over Decades and during a Single Infection

Streptococcus pneumoniae of serotype 3 possess a mucoid capsule and cause disease associated with high mortality rates relative to other pneumococci. Phylogenetic analysis of a complete reference genome and 81 draft sequences from clonal complex 180, the predominant serotype 3 clone in much of the world, found most sampled isolates belonged to a clade affected by few diversifying recombinations. However, other isolates indicate significant genetic variation has accumulated over the clonal complex’s entire history. Two closely related genomes, one from the blood and another from the cerebrospinal fluid, were obtained from a patient with meningitis. The pair differed in their behaviour in a mouse model of disease and in their susceptibility to antimicrobials, with at least some of these changes attributable to a mutation that upregulated the patAB efflux pump. This indicates clinically important phenotypic variation can accumulate rapidly through small alterations to the genotype

Differences in genotype and virulence among four multidrug-resistant <i>Streptococcus pneumoniae</i> isolates belonging to the PMEN1 clone

We report on the comparative genomics and characterization of the virulence phenotypes of four &lt;i&gt;S. pneumoniae&lt;/i&gt; strains that belong to the multidrug resistant clone PMEN1 (Spain&lt;sup&gt;23F&lt;/sup&gt; ST81). Strains SV35-T23 and SV36-T3 were recovered in 1996 from the nasopharynx of patients at an AIDS hospice in New York. Strain SV36-T3 expressed capsule type 3 which is unusual for this clone and represents the product of an in vivo capsular switch event. A third PMEN1 isolate - PN4595-T23 - was recovered in 1996 from the nasopharynx of a child attending day care in Portugal, and a fourth strain - ATCC700669 - was originally isolated from a patient with pneumococcal disease in Spain in 1984. We compared the genomes among four PMEN1 strains and 47 previously sequenced pneumococcal isolates for gene possession differences and allelic variations within core genes. In contrast to the 47 strains - representing a variety of clonal types - the four PMEN1 strains grouped closely together, demonstrating high genomic conservation within this lineage relative to the rest of the species. In the four PMEN1 strains allelic and gene possession differences were clustered into 18 genomic regions including the capsule, the blp bacteriocins, erythromycin resistance, the MM1-2008 prophage and multiple cell wall anchored proteins. In spite of their genomic similarity, the high resolution chinchilla model was able to detect variations in virulence properties of the PMEN1 strains highlighting how small genic or allelic variation can lead to significant changes in pathogenicity and making this set of strains ideal for the identification of novel virulence determinant