Regional-scale impact of the weed biocontrol agent Mecinus janthinus on Dalmatian toadflax (Linaria dalmatica)

Dalmatian toadflax (Linaria dalmatica (L.) Mill.) is an important invasive plant on rangelands throughout western North America. In 1991, the stem-mining weevil, Mecinus janthinus Germar, was introduced into Canada from Europe as a classical biological control agent to reduce toadflax densities and improve rangelands, particularly in British Columbia. To determine if the program was a success at a regional level, this paper answers three key questions: (1) has M. janthinus spread throughout the study area, (2) is M. janthinus causing a decline in toadflax plant size or density at the regional scale, and (3) has the distribution of toadflax plants changed following M. janthinus introduction? These questions are answered by combining historical survey data and mensurative experimental data on plant and weevil densities across a 40,000 km² area in southern British Columbia. The results show that through a combination of intentional redistribution and natural dispersal weevils have spread throughout the study area. Stem densities at naturally colonized sites and historical release sites were equally low. Across weevil populations between 3 and 10 years old, weevil densities peaked in the eighth year, and there was a negative relationship between weevil density and stem length. Between 2000 and 2007, toadflax patches were found to both decrease in density and become more fragmented over time, with 15% of patches disappearing completely. These findings show that M. janthinus has had a significant negative impact on both the density and distribution of Dalmatian toadflax throughout a large part of its range in British Columbia.     

Polish Lebensraum: the colonial ambition to expand on racial terms

Lebensraum – the space a state believes is required for its natural expansion – has a pivotal role in the global expansion projects. Whenever this concept is discussed, it is almost exclusively reduced to the Imperial Russia’s domination of less-stately countries in Central and Eastern Europe; the British exploration and colonization of territories in Africa and Asia; the French settlements in parts of the Caribbean Islands and Africa; the German experimentation in South-West Africa, and the Dutch seaborne competing with the Spanish and Portuguese’s expansionism. Study related to Poland’s attempted acquisition of colonial territories outside Europe is rarely discussed. Drawing on the activities of the Polish Colonial Society, this article contends that the building blocks of colonization were not confined solely to European imperial powers. As colonization forged ahead in the twentieth century, Poland seemed to be the country where colonialism played a significant role in both national and transnational politics.     

Demographic history of european populations of Arabidopsis thaliana

The model plant species Arabidopsis thaliana is successful at colonizing land that has recently undergone human-mediated disturbance. To investigate the prehistoric spread of A. thaliana, we applied approximate Bayesian computation and explicit spatial modeling to 76 European accessions sequenced at 876 nuclear loci. We find evidence that a major migration wave occurred from east to west, affecting most of the sampled individuals. The longitudinal gradient appears to result from the plant having spread in Europe from the east ~10,000 years ago, with a rate of westward spread of ~0.9 km/year. This wave-of-advance model is consistent with a natural colonization from an eastern glacial refugium that overwhelmed ancient western lineages. However, the speed and time frame of the model also suggest that the migration of A. thaliana into Europe may have accompanied the spread of agriculture during the Neolithic transition.     

Genetic signature of a range expansion and leap‐frog event after the recent invasion of Europe by the grapevine downy mildew pathogen Plasmopara viticola

Biologic invasions can have important ecological, economic and social consequences, particularly when they involve the introduction and spread of plant invasive pathogens, as they can threaten natural ecosystems and jeopardize the production of human food. Examples include the grapevine downy mildew, caused by the oomycete Plasmopara viticola, an invasive species native to North America, introduced into Europe in the 1870s. We investigated the introduction and spread of this invasive pathogen, by analysing its genetic structure and diversity in a large sample from European vineyards. Populations of P. viticola across Europe displayed little genetic diversity, consistent with the occurrence of a bottleneck at the time of introduction. Bayesian coalescent analyses revealed a clear population expansion signal in the genetic data. We detected a weak, but significant, continental‐wide population structure, with two geographically and genetically distinct clusters in Western and Eastern European vineyards. Approximate Bayesian computation, analyses of clines of genetic diversity and of isolation‐by‐distance patterns provided evidence for a wave of colonization moving in an easterly direction across Europe. This is consistent with historical reports, first mentioning the introduction of the disease in Bordeaux vineyards (France) and sub‐sequently documenting its rapid spread across Europe. This initial introduction in the west was probably followed by a ‘leap‐frog’ event into Eastern Europe, leading to the formation of the two genetic clusters we detected. This study shows that recent population genetics methods within the Bayesian and coalescence frameworks are extremely powerful for increasing our understanding of pathogen population dynamics and invasion histories.     

Remarks on the Taxonomy and nomenclature of theCarex bigelowii complex

Carex bigelowii complex is a group of taxa distributed over the whole Arctic region and in the mountains of the temperate zone. The species was described from the White Mountains in the eastern part of USA. The plants from Central Europe, the British Isles and Fennoscandinavian mountains differ from the plants of the typelocality in a number of characters, especially in the character of the inflorescence. On the basis of these differences the European plants represent a new taxon which is described asCarex bigelowii Torr. exSchweinitz subsp.nardeticola Holub, subsp. nova. Very closely related plants to the new taxon are known from Central Siberia and from the Arctic region.     

Genetic Variability of the Neogregarine Apicystis bombi,an Etiological Agent of an Emergent Bumblebee Disease

The worldwide spread of diseases is considered a major threat to biodiversity and a possible driver of the decline of pollinator populations, particularly when novel species or strains of parasites emerge. Previous studies have suggested that populations of introduced European honeybee (Apis mellifera) and bumblebee species (Bombus terrestris and Bombus ruderatus) in Argentina share the neogregarine parasite Apicystis bombi with the native bumblebee (Bombus dahlbomii). In this study we investigated whether A. bombi is acting as an emergent parasite in the non-native populations. Specifically, we asked whether A. bombi, recently identified in Argentina, was introduced by European, non-native bees. Using ITS1 and ITS2 to assess the parasite’s intraspecific genetic variation in bees from Argentina and Europe, we found a largely unstructured parasite population, with only 15% of the genetic variation being explained by geographic location. The most abundant haplotype in Argentina (found in all 9 specimens of non-native species) was identical to the most abundant haplotype in Europe (found in 6 out of 8 specimens). Similarly, there was no evidence of structuring by host species, with this factor explaining only 17% of the genetic variation. Interestingly, parasites in native Bombus ephippiatus from Mexico were genetically distant from the Argentine and European samples, suggesting that sufficient variability does exist in the ITS region to identify continent-level genetic structure in the parasite. Thus, the data suggest that A. bombi from Argentina and Europe share a common, relatively recent origin. Although our data did not provide information on the direction of transfer, the absence of genetic structure across space and host species suggests that A. bombi may be acting as an emergent infectious disease across bee taxa and continents.     

Reciprocal interactions between native and introduced populations of common milkweed,Asclepias syriaca,and the specialist aphid,Aphis nerii

Following its introduction into Europe (EU), the common milkweed (Asclepias syriaca) has been free of most specialist herbivores that are present in its native North American (NA) range, except for the oleander aphid Aphis nerii. We compared EU and NA populations of A. nerii on EU and NA milkweed populations to test the hypothesis that plant–insect interactions differ on the two continents. First, we tested if herbivore performance is higher on EU plants than on NA plants, because the former have escaped most of their herbivores and have perhaps been selected for lower defence levels following introduction. Second, we compared two A. nerii lines (one from each continent) to test whether genotypic differences in the herbivore may influence species interactions in plant–herbivore communities in the context of species introductions. The NA population of A. nerii developed faster, had higher fecundity and attained higher population growth rates than the EU population. There was no overall significant continental difference in aphid resistance between the plants. However, milkweed plants from EU supported higher population growth rates and faster development of the NA line of A. nerii than plants from NA. In contrast, EU aphids showed similar (low) performance across plant populations from both continents. In a second experiment, we examined how chewing herbivores indirectly mediate interactions between milkweeds and aphids, and induced A. syriaca plants from each continent by monarch caterpillars (Danaus plexippus) to compare the resulting changes in plant quality on EU aphid performance. As specialist chewing herbivores of A. syriaca are only present in NA, we expected that plants from the two continents may affect aphid growth in different ways when they are challenged by a specialist chewing herbivore. Caterpillar induction decreased aphid developmental times on NA plants, but not on EU plants, whereas fecundity and population growth rates were unaffected by induction on both plant populations. The results show that genetic variation in the plants as well as in the herbivores can determine the outcome of plant–herbivore interactions.     

Infraspecific variation and systematics of cultivatedSetaria italica,foxtail millet (Poaceae)

Foxtail millet (Setaria italica,) is grown as a cereal in southern Europe and in temperate, subtropical, and tropical Asia. Its closest wild relative isS. italica ssp.viridis (green foxtail). Green foxtail is native to temperate Eurasia, but was introduced and became widely established as a weed in temperate and warmer parts of the Americas. Spontaneous and cultivatedS. italica cross to produce fertile hybrids. Derivatives of such crosses, resembling foxtail millet in some inflorescence traits but with efficient natural seed dispersal, accompany the cereal across its range of cultivation. Giant green foxtail of Europe and the American corn belt is a weed of hybrid origin. Foxtail millet was domesticated in the highlands of central China; remains of cultivated foxtail millet are known from the Yang-shao culture period dating back some 5,000 yrs. Comparative morphology suggests that foxtail millet spread to Europe and India as a cereal soon after its domestication. Three cultivated races are recognized. Moharia, from Europe and southwestern Asia, includes cultivars with 5–52 culms, each bearing several, small, more or less erect inflorescences. Cultivars in race maxima are characterized by plants with 1–8 usually unbranched culms that bear large inflorescences; they occur in Transcaucasian Russia and the Far East. Race indica is intermediate in culm number (ave. 6.6) and inflorescence size between races moharia and maxima, and is cultivated in southern Asia.     

Postcolonial France: race,Islam, and the future of the republic

Abstract

The study explored feelings of European identity and attitudes towards Europe manifested in two groups within the British population: the indigenous white British population (N?=?58) and the South-Asian ethnic minority (N?=?44). A social survey approach was used with scales to evaluate British, European and ethnic identities and also attitudes towards Europe. Perceived compatibility of identities was also assessed using a visual representation of identities task. Previous research findings were confirmed with the indigenous white British respondents, who displayed a strong sense of national identity negatively correlated with European identity. In contrast, the South Asian respondents displayed positive feelings of identification on all three levels, and a British identity that correlated positively with European identification.     

The invasion history,distribution and colour pattern forms of the harlequin ladybird beetle Harmonia axyridis (Pall.) (Coleoptera,Coccinellidae) in Slovakia,Central Europe

The harlequin ladybird beetle Harmonia axyridis (Coleoptera, Coccinellidae) has invaded and established in Slovakia. Following unintentional introduction in 2008, the spread of the alien coccinellid was very fast. By the end of 2009, it was recorded across the whole country, and by the end of 2012 it was widely distributed and common in various habitats, particularly gardens, orchards and urban areas, where it was most frequent on trees. The rate of eastward spread was approximately 200 km year^-1, similar to the overall rate of spread in Europe. Between 2008 and 2012, the coccinellid was recorded in a total of 153 localities, in altitudes ranging from 98 to 1,250 m. Most records of this species were made in lowlands, hilly areas and valleys separating mountain ridges. However, it was only rarely documented in areas above 700 m a.s.l. The non-melanic colour form (f. succinea) was dominant along a longitudinal transect including eight urban areas across Slovakia, with the frequency of melanic forms (f. spectabilis and f. conspicua together) between 6.3 and 19.2% and a median equal to 10.5%. The invasion history and distribution of H. axyridis in Slovakia are discussed with regard to the time sequence of records, rate of spread, altitudinal distribution, anthropogenic dispersal, effective recording, proportion of melanic forms and other relevant aspects associated with the spread of this successful invader.     

Allozymic variation in the widespread and cultivated Viola odorata (Violaceae) in western Eurasia

Viola odorata has been cultivated for cosmetics and medicine in Europe since antiquity. The spread by humans has expanded its distribution considerably beyond its original range in parts of the Mediterranean region, south‐western Europe, and western Asia. One hundred and sixty‐five plants of V. odorata from 52 collection sites from throughout most of its native range were analysed for seven isoenzyme systems. Twenty‐eight allozymic markers were obtained, twenty‐five of which were geographically variable. A profound east–west differentiation separating Anatolian and Caucasian populations from European populations was detected, with Greek and Sicilian populations somewhat intermediate. Western European populations were rather homogeneous, suggesting a common origin, which also included the Canarian var. maderensis and the naturalized Scandinavian (and British?) populations. Cretan and Cypriot populations were apparently recruited from more westward stations. The possibility that the two allozymic groups of V. odorata reflect isolated Pleistocene refugia is discussed. V. odorata appears to possess more geographically structured variation than has been found in other cultivated and human‐spread species in southern Europe. © 2006 The Linnean Society of London, Botanical Journal of the Linnean Society, 2006, 151 , 563–571.     

New insights on postglacial colonization in western Europe: the phylogeography of the Leisler's bat (Nyctalus leisleri)

Despite recent advances in the understanding of the interplay between a dynamic physical environment and phylogeography in Europe, the origins of contemporary Irish biota remain uncertain. Current thinking is that Ireland was colonized post-glacially from southern European refugia, following the end of the last glacial maximum (LGM), some 20 000 years BP. The Leisler''s bat (Nyctalus leisleri), one of the few native Irish mammal species, is widely distributed throughout Europe but, with the exception of Ireland, is generally rare and considered vulnerable. We investigate the origins and phylogeographic relationships of Irish populations in relation to those across Europe, including the closely related species N. azoreum. We use a combination of approaches, including mitochondrial and nuclear DNA markers, in addition to approximate Bayesian computation and palaeo-climatic species distribution modelling. Molecular analyses revealed two distinct and diverse European mitochondrial DNA lineages, which probably diverged in separate glacial refugia. A western lineage, restricted to Ireland, Britain and the Azores, comprises Irish and British N. leisleri and N. azoreum specimens; an eastern lineage is distributed throughout mainland Europe. Palaeo-climatic projections indicate suitable habitats during the LGM, including known glacial refugia, in addition to potential novel cryptic refugia along the western fringe of Europe. These results may be applicable to populations of many species.     

Changes in the population structure and sporulation behaviour of <Emphasis Type="Italic">Phytophthora ramorum</Emphasis> associated with the epidemic on <Emphasis Type="Italic">Larix</Emphasis> (larch) in Britain

During a decade of invasion, the exotic pathogen Phytophthora ramorum has undergone an unexpected change in behaviour during spread into the woodlands and forests of Great Britain. From 2002 to 2008 most outbreaks centred on nurseries and managed gardens with affected hosts almost exclusively broadleaf shrubs and trees. However 2009 saw a major shift as larch tree plantations (Larix) were affected by widespread infection and mortality incited by P. ramorum. To understand the processes underlying the host jump to larch, isolates of the EU1 lineage of P. ramorum collected from 2002 to 2012 were investigated using seven polymorphic microsatellite markers. Analysis of 347 isolates resolved 51 multilocus genotypes (MLGs) which partitioned into two distinct clusters. One comprised MLGs unique to Britain and unknown elsewhere in Europe, the other cluster was primarily of MLGs already known in other European countries but dominated by one genotype, EU1MG1. Pre-2009 isolates were predominantly of the unique British cluster with only a few typical of the European cluster. This reversed after 2009 with European MLGs, especially EU1MG1, becoming increasingly common as the larch epidemic expanded. We hypothesise that the growing dominance of EU1MLG1 has been an important driver in the emergence of the epidemic on larch, aided by its ability to sporulate more abundantly compared with the dominant unique British MLG. European MLGs appear closely associated with the distribution of larch along the west coast of Britain whereas unique British MLGs tend to be concentrated in south west England. The two population clusters suggest at least two separate introductions of the EU1 lineage into Britain with subsequent diversification.     

Biomass development and CO2 gas exchange of Ambrosia artemisiifolia L. under different soil moisture conditions

Ambrosia artemisiifolia L. is an annual plant species whose pollen is produced in high quantities and may cause allergies and asthma. Originating from North America, it has become established in several European countries. This leads to increasing costs in the public health sector of these countries. The aim of our study was to characterize aspects of the species’ growth and ecophysiology, to assess the probability of a further spread and widespread establishment in Central Europe.For this purpose Ambrosia seedlings were cultivated under different soil moisture conditions. Growth, root and stem tissue porosity, leaf chlorophyll contents and biomass allocation were measured. Additionally, gas-exchange measurements at leaf level were conducted.Ambrosia grew best and had the highest net photosynthesis rates under moist soil conditions. Under dry or waterlogged soil conditions the plants remained smaller, produced less seeds, and had lower assimilation rates. However, even under waterlogged soil conditions Ambrosia was able to survive over months and finally to produce seeds. Under such conditions root porosity increased 2.5 times as compared with plants from dry soil. This reasonably improved the O₂ transport within the waterlogged plant. The measured gas exchange rates were comparable to those reported from the species’ native range of occurrence. Light saturation of CO₂ uptake was reached at 300 μmol photons m⁻² s⁻¹.The results suggest that a further spread in Central Europe is very probable because of the broad hydrological amplitude of the species and its generalist character concerning irradiation. Thus, control measures should be started, respectively intensified, timely.     

Population History and Pathways of Spread of the Plant Pathogen Phytophthora plurivora

Human activity has been shown to considerably affect the spread of dangerous pests and pathogens worldwide. Therefore, strict regulations of international trade exist for particularly harmful pathogenic organisms. Phytophthora plurivora, which is not subject to regulations, is a plant pathogen frequently found on a broad range of host species, both in natural and artificial environments. It is supposed to be native to Europe while resident populations are also present in the US. We characterized a hierarchical sample of isolates from Europe and the US and conducted coalescent-, migration, and population genetic analysis of sequence and microsatellite data, to determine the pathways of spread and the demographic history of this pathogen. We found P. plurivora populations to be moderately diverse but not geographically structured. High levels of gene flow were observed within Europe and unidirectional from Europe to the US. Coalescent analyses revealed a signal of a recent expansion of the global P. plurivora population. Our study shows that P. plurivora has most likely been spread around the world by nursery trade of diseased plant material. In particular, P. plurivora was introduced into the US from Europe. International trade has allowed the pathogen to colonize new environments and/or hosts, resulting in population growth.     

The giant bird Gastornis in Asia: A revision of Zhongyuanus xichuanensis Hou, 1980, from the Early Eocene of China

The type specimen of the gastornithid Zhongyuanus xichuanensis Hou, 1980, from the Early Eocene of Henan (central China) is redescribed and compared with European and North American representatives of Gastornis. Differences between the Chinese specimen (the distal end of tibiotarsus) and its European and North American counterparts are of a minor nature, and it is concluded that it can be referred to as Gastornis xichuanensis (Hou, 1980). Stratigraphic evidence suggests that Gastornis originated in Europe, where it is known as early as the Paleocene. Whether the Asian Gastornis dispersed from North America via the Bering land bridge, or directly from Europe across the Turgai Strait, remains uncertain.     

Endophytic beauveria bassiana (balsamo) vuillemin in corn: The influence of the plant growth stage and ostrinia nubilalis (hübner)

A conidial suspension of the entomopathogenic fungus Beauveria bassiana (Balsamo) Vuillemin, was injected into corn plants at anthesis to suppress populations of the European corn borer Ostrinia nubilalis (Hübner) (Lepidoptera: Pyralidae). The fungus colonized the plants and moved, primarily upward, within the pith, possibly along with plant photosyn‐thates. Beauveria bassiana injected into the corn plants significantly reduced the amount of European corn borer tunneling. Colonization of corn plants by B. bassiana was independent of European corn borer infestation. The impact of environmental conditions on the movement and colonization of the plants by B. bassiana is discussed.     

When selection deceives phylogeographic interpretation: the case of the Mediterranean house gecko, Hemidactylus turcicus (Linnaeus, 1758)

A previous study on Hemidactylus turcicus based on mtDNA makers indicated that this gecko has a Middle-East origin, and that the current phylogeographic pattern is the result of a very rapid spread from the east to the west of the species’ range. The same study identified two distinct mitochondrial lineages with low differentiation and genetic diversity. Since H. turcicus is known to be closely associated to humanized environments, its present distribution range and phylogeography is frequently interpreted to be the result of recurrent human-mediated introductions. These conclusions used to be the same as those used to interpret the results obtained for the European populations of another gecko, Tarentola mauritanica. However, a recent study has revealed that the phylogeographic pattern of T. mauritanica is not solely the result of a recent colonization, but also of a mitochondrial selective sweep. Could the same be occurring in H. turcicus? To answer this question, two mitochondrial (12S rRNA and cytochrome b) and two nuclear genes (ACM4 and Rag2) were used in this study. From the mtDNA data we confirmed the existence of two distinct phylogeographic lineages; one occurring exclusively in the northern Mediterranean (Clade A), and another one more widespread that is the only lineage present in North Africa (Clade B). In light of these results, we could hypothesize that H. turcicus had its origin in Turkey, and from there Clade A moved to Europe and Clade B to North Africa spreading latter into Europe. However, Clade A presents significantly higher nucleotide diversity for the nuclear DNA compared to the mtDNA, and neutrality tests gave significant results for the mitochondrial data. These results suggest that the lack of mtDNA genetic diversity and structure in the European population of H. turcicus could also be due to a selective sweep, and not only because of a recent colonization. Together with the situation reported in T. mauritanica, the identification of a hitch-hiking process occurring in H. turcicus, represents two unprecedented cases of a selective sweep taking place in the same geographic area shaping the phylogeographic patterns of two unrelated genera of geckos.     

Reproductive Plasticity in Freshwater Invader: From Long-Term Sperm Storage to Parthenogenesis

Orconectes limosus, a North American crayfish species, is one of the most important aquatic invaders in European inland waters. Despite more than 120 years occurrence in Europe and intense research, there are still gaps in knowledge of its life history and ecology. Investigation into O. limosus invasive success requires identifying the mechanisms that enabled them to establish dense and widespread populations from small initial numbers without observable limitation by an introduction bottleneck. In part, O. limosus success may lie in its ability to reproduce by facultative parthenogenesis. Moreover, there are possible other mating scenarios, because of two mating seasons (autumn and spring) in O. limosus. This work investigated the effect of four reproductive scenarios (autumn mating only, spring mating only, autumn and spring mating, and without mating) on the reproductive success of O. limosus. Females successfully reproduced in all tested mating regimes using parthenogenesis as well as log term sperm storage. This reproductive plasticity likely facilitates the overwhelming success of O. limosus spread and establishment in new localities. It can explain the spread of O. limosus from the initial introduction of 90 specimens to most of continental Europe and Great Britain. These conclusions imply a serious threat, not only for autochthonous European astacofauna, but for other aquatic organisms as well as entire ecosystems.