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Chapter 6 analyses the ecological mechanisms, and implications, of intraspecific trait variability (ITV) and some key approaches to take ITV properly into account in modern trait-based analyses. The different sources of ITV, genetic variation, epigenetic effects and phenotypic plasticity, are discussed and put in the context of species evolution, adaptation to environmental conditions, species distribution potential (including invasive species) and the effects of species on multiple ecosystem properties and trophic interactions. Different tools are provided to quantify how strong ITV affect ecological patterns. A comparison of within- vs between-species trait variability in a community is discussed. Tools showing how strong the effect of changes in species composition (turnover) compared to ITV along environmental gradients are provided. Finally, methods considering ITV to quantify trait differences between species, via trait overlap in trait probability distributions, are discussed in the light of modern tools measuring functional diversity across different scales
Strong competitive ability of introduced plant species has been frequently stated as a key factor promoting successful invasion. The dynamics of invasive species may depend on their abilities to compete for resources and exploit disturbances relative to native species. This study compares the growth performance of the invasive blackberry (Rubus niveus Thunb.) with four of the most common woody native species of the Scalesia forest in the Galapagos Islands. Using a series of greenhouse and field studies, the growth rate and biomass production of native species alone and in competition with R. niveus was compared under different water and light stress conditions. Rubus niveus showed a faster growth rate and biomass production than the native species as well as a broad tolerance to light and water stress conditions. Competitive ability was also assessed by looking at the seedbank and regeneration processes after herbicide control in the field. Although the number of R. niveus seedlings that germinated from the soil samples was considerably larger than that of native species, recruitment of the invasive on the experimental plots was limited. Overall, R. niveus showed superior competitive ability over native species with comparable growth forms, suggesting a possible mechanism that enables R. niveus to successfully invade a wide range of habitats in the Galapagos Islands. Implementing an integrated management strategy including biological control, seedbank reduction, and active revegetation, should improve the efficiency of R. niveus management, enabling the restoration of degraded vegetation in the Galapagos.
This chapter explores Trump’s language around immigration to determine how he manages to terrorize immigrants while arguing that immigrants should be the source of America’s terror. Drawing on conceptual metaphor theory and over 300 speeches and 6,000 tweets, the authors find that Trump’s primary metaphor represents America as a fortress that is under attack, its cities and towns overrun by polluting invaders. Trump characterizes Mexico as the enemy that sent unauthorized immigrants to wreak havoc, and represents himself as the only hero who can save the nation. Along the way, the chapter explores Trump’s misleading extension of MS-13, the notorious gang, to all Latino gangs and even all young Latinos, and Trump’s extension of the phrase “criminal alien” (immigrants who commit felonious crimes) to all unauthorized immigrants. The authors draw parallels to related conceptual metaphors to be found in the history of Western ethnic nationalism, including Nazi Germany.
How and when did Australia begin? One version of the country’s origins – a version taught to generations of school children and set down in literature and art, memorials and anniversaries – would have it that Australian history commenced at the end of the eighteenth century. By the end of the twentieth century it was no longer possible to maintain the fiction of Australia as terra nullius, a land that until its settlement in 1788 lacked human habitation, law, government or history. The growing recognition of this vastly extended Australian history spoke to late-twentieth-century sensibility. It revealed social organisation, ecological practices, languages, art forms and spiritual beliefs of great antiquity and richness. The second version of Australian history, the one that begins not at 1788 in the Western calendar but 50,000 years or more before the present, is at once more controversial, more rapidly changing and more compelling.
The publication of the RurLand (Rural Landscape in North-East Gaul) project has provided an opportunity to compare methodologies and results with those of The Rural Settlement of Roman Britain project. Two themes, which draw out the asymmetrical development of settlement in the two regions, are examined: the very different impacts of the Roman conquests of Gaul and of Britain on settlement numbers and settlement continuity, and the development of the agricultural economy and its relationship with the frontiers of Britain and Germany, as reflected in the growth and decline of villa estates in Britain and Gaul.
This chapter covers events in Europe from the summer of 1944 to the end of the war. Four invasions carried out on mainland Europe penetrate the outer defensive perimeter of the Third Reich: (1) the landing in Normandy in June, followed by the pursuit of the enemy to the western borders of the Reich; (2) the August 1944 invasion of southern France; (3) the offensive in Belarus in late June, Operation BAGRATION, followed by the retreat of the shattered Wehrmacht across the Baltic region and eastern Poland; (4) south of the Carpathian Mountains the Red Army advance across Hungary. The surrounded Nazi regime refuses to consider surrender and embarks on a policy of Total War. The December 1944 attempt by the Wehrmacht to mount counter-attacks, most famously the Ardennes offensive (the Battle of the Bulge). The Allies, meanwhile hold high-level conferences at Tehran and Yalta to discuss future strategy and post-war arrangements. The final defeat of Germany in five concentric campaigns: (1) western Poland and northeastern Germany; (2) the Rhineland; (3) western Germany and Bavaria; (4) Austria; and (5) the final battle for Berlin. The suicide of Hitler and the German surrender.
The abnormal expression of lncRNAs and miRNAs has been found in the placentas of patients with preeclampsia (PE). Therefore, we determined the role of lncRNA FOXD2-AS1/miR-3127 in trophoblast cells. The expression of lncRNA FOXD2-AS1 was detected by qRT-PCR. The proliferation, migration and invasion ability of trophoblast cells were evaluated using CCK-8, wound healing and transwell assays. The target gene of lncRNA FOXD2-AS1 was determined by StarBase and luciferase reporter assays. Western blotting was used to analyze the expression of matrix metalloproteinase 2 (MMP2) and matrix metalloproteinase 9 (MMP9). The results showed that FOXD2-AS1 affected trophoblast cell viability in vitro, while the expression of miR-3127 was decreased. FOXD2-AS1 silencing decreased the promotion effects on trophoblast cell induced by miR-3127 inhibition. In addition, FOXD2-AS1 and miR-3127 presented the same effect on MMP2 and MMP9 levels. lncRNA FOXD2-AS1 modulated trophoblast cell proliferation, invasion and migration through downregulating miR-3127 expression. Therefore, lncRNA FOXD2-AS1 could act as a latent therapeutic marker in preeclampsia.
We consider an extension of the classical Fisher–Kolmogorov equation, called the “Fisher–Stefan” model, which is a moving boundary problem on
. A key property of the Fisher–Stefan model is the “spreading–vanishing dichotomy”, where solutions with
will eventually spread as
, whereas solutions where
will vanish as
. In one dimension it is well known that the critical length is
. In this work, we re-formulate the Fisher–Stefan model in higher dimensions and calculate
as a function of spatial dimensions in a radially symmetric coordinate system. Our results show how
depends upon the dimension of the problem, and numerical solutions of the governing partial differential equation are consistent with our calculations.
Apicomplexans, including species of Eimeria, pose a real threat to the health and wellbeing of animals and humans. Eimeria parasites do not infect humans but cause an important economic impact on livestock, in particular on the poultry industry. Despite its high prevalence and financial costs, little is known about the cell biology of these ‘cosmopolitan’ parasites found all over the world. In this review, we discuss different aspects of the life cycle and stages of Eimeria species, focusing on cellular structures and organelles typical of the coccidian family as well as genus-specific features, complementing some ‘unknowns’ with what is described in the closely related coccidian Toxoplasma gondii.
The first 30 years of conflict between the State of Israel and its Arab neighbours was focused chiefly on Egypt, Jordan and Syria. But Egypt made peace with Israel in 1978 and Jordan in 1994, after a long period of de facto peace between the two countries; and although there has been no peace between Israel and Syria, and Israel still occupies a large part of the Syrian Golan, the area itself was generally quiet from 1974 to 2006 (when this history ends) and beyond. Instead, after the 1973 War, there was increased conflict between Israel and the Palestinians in the occupied territories of Gaza and the West Bank, and vastly escalated conflict between Israel and its northern neighbour Lebanon. These conflicts were not unconnected, but this chapter looks in particular at the case of Lebanon.
Weed invasion is a prevailing problem in modestly managed lawns. Less attention has been given to the exploration of the role of arbuscular mycorrhizal fungi (AMF) under different invasion pressures from lawn weeds. We conducted a four-season investigation into a Zoysia tenuifolia Willd. ex Thiele (native turfgrass)–threeflower beggarweed [Desmodium triflorum (L.) DC.] (invasive weed) co-occurring lawn. The root mycorrhizal colonizations of the two plants, the soil AM fungal communities and the spore densities under five different coverage levels of D. triflorum were investigated. Desmodium triflorum showed significantly higher root hyphal and vesicular colonizations than those of Z. tenuifolia, while the root colonizations of both species varied significantly among seasons. The increased coverage of D. triflorum resulted in the following effects: (1) the spore density initially correlated with mycorrhizal colonizations of Z. tenuifolia but gradually correlated with those of D. triflorum. (2) Correlations among soil properties, spore densities, and mycorrhizal colonizations were more pronounced in the higher coverage levels. (3) Soil AMF community compositions and relative abundances of AMF operational taxonomic units changed markedly in response to the increased invasion pressure. The results provide strong evidence that D. triflorum possessed a more intense AMF infection than Z. tenuifolia, thus giving rise to the altered host contributions to sporulation, soil AMF communities, relations of soil properties, spore densities, and root colonizations of the two plants, all of which are pivotal for the successful invasion of D. triflorum in lawns.
The chapter identifies warnings within the EU foreign policy system related to the Russian annexation of Crimea and the destabilisation of Eastern Ukraine in 2014 and examines the reasons for the differentiated impact among EU decision-makers. The Ukraine case was a strategic surprise to the overwhelming majority of EU policy-makers and posed significant diagnostic problems, but senior ministers within the system were warning their peers on the basis of previous cases, historical analogies, expert knowledge and recent indications of changed Russian intent. However, the persuasiveness of the few and late warnings suffered, first of all, from distraction by external crises coupled with limited bandwidth in the EU, shortages in relevant and reliable intelligence, high resistance against divergent policy predispositions of the warning and, finally, significant suspicions of national biases against key warning sources. The supranational part of the system was almost completely blindsided to geopolitical risk, while the newly established EEAS was partly unable and partly unwilling to persuade the Commission. It is fair to say that the system as a whole acted as an impediment to having a holistic discussion of warning as part of foreign policy discourse.
Many invasive species managers state that their objective is to “control” an invader. However, the appropriate choice of a management option requires a more explicit statement of management objectives, in terms of both the relevant time horizon and spatial scale. Using data from a 2-yr mowing experiment, we show that the most effective management strategy for controlling an invasive thistle depends fundamentally on the management goals. We integrate field data from a two-cohort experiment with modeling to assess 14 mowing treatments (differing in intensity, frequency, and timing, and thus also in their required logistical effort) based on their effectiveness in (1) reducing population density of the existing cohort, (2) decreasing projected long-term population growth, and (3) limiting projected population spread of an invasive thistle, musk thistle (Carduus nutans L.). The treatment with high intensity and a single late mow caused the largest reduction in plant survival (and density of existing adult plants); the treatment with high intensity and an early mow in addition to a late mow was most effective at reducing population growth rate and population spread. Against expectation and conventional wisdom, the most frequent mowing treatment did not provide the most effective management outcome for any stated objective. This study highlights the necessity of clearly defined management aims; the term “control” is too vague to be truly useful. The results also provide important insights for the management of this invasive species.
Organic cropping systems are characterized by soil-disturbance events that can be diversified over years through crop rotations and within seasons by varying planting dates. The Farming Systems Project at Beltsville, MD, USA, is a long-term experiment that includes three organic rotations, corn (Zea mays L.)–soybean [Glycine max (L.) Merr.], corn–soybean–wheat (Triticum aestivum L.), and corn–soybean–wheat–alfalfa (Medicago sativa L.). Analysis of weed presence and cover over the first 18 yr of this experiment revealed that the tall, erect annual broadleaf weeds smooth pigweed (Amaranthus hybridus L.), common lambsquarters (Chenopodium album L.), horseweed (Erigeron canadensis L.), jimsonweed (Datura stramonium L.), and/or velvetleaf (Abutilon theophrasti Medik.) were most prominent in corn and soybean. Generally, these species exhibited traits adapted to the disturbance regimes, nutrient availability, crop environment and duration, and local meteorological conditions associated with the summer annual corn and soybean crops. Abundance of A. hybridus, D. stramonium, and A. theophrasti were controlled primarily by rotation diversity, whereby presence and cover of these species were highest in the short corn–soybean rotation and lowest in the longer rotations that had more diverse seasonal soil-disturbance regimes. Early-season temperature was the primary factor controlling C. album presence and cover, which were higher at lower temperatures associated with earlier planting dates. Higher early-season precipitation was the primary factor associated with higher presence of annual grass species. The relative abundance of species in organic corn and soybean was determined primarily by the diversity of crops and disturbance operations in rotation, the timing of spring tillage and planting, and annual meteorological conditions driving emergence periodicity.
Junglerice [Echinochloa colona (L.) Link] is a problematic weed in the northern grain region of Australia. Two pot experiments (Experiment 1 and Experiment 2) were conducted in a screen house to evaluate the growth and reproductive behavior of two biotypes (A, collected from a cotton (Gossypium hirsutum L.)–fallow; B, collected from a fence near a water channel) of E. colona in response to water stress (100%, 75%, 50%, and 25% water holding capacity [WHC]). Averaged across both biotypes, the plant height, biomass, and seed production of E. colona were reduced at 25% WHC compared with 100% WHC. However, E. colona still produced a considerable amount of seeds at 25% WHC (at least 365 seeds plant−1). Biotype A produced more seeds in the second experiment, while biotype B produced more seeds in the first experiment. In Experiment 2, at 100% WHC, biotype A produced more seeds (17,618 seeds plant−1) than biotype B (4,378 seeds plant−1), and similar observations were noticed for root biomass. Growth and seed production of E. colona at all moisture levels and environmental conditions ensure survival in an unpredictable environment and contribute to the weedy nature of this species. Results indicate that biotype A is more invasive than biotype B under favorable environmental conditions (100% WHC). This study suggests an enhanced competitive ability of some biotypes of E. colona in response to a range of environmental and soil moisture conditions in Australia. Under favorable environmental conditions, biotype A could be more problematic, as it has higher seed production than biotype B. Therefore, it is important to implement sustainable weed control methods for such biotypes in the early stages of crop growth to prevent loss of stored moisture.
Callery pear (Pyrus calleryana Decne.) was introduced to North America as an ornamental tree in the early 1900s. Due to widespread planting, P. calleryana has become common throughout the eastern United States and has invaded natural areas, especially disturbed areas. Prescribed fire is a common management technique in prairie ecosystems to mimic natural disturbances. We tested the effectiveness of prescribed fire as a control technique for P. calleryana in a managed prairie system. Fire top-killed all established P. calleryana individuals. However, these individuals responded to fire with 3 to 4 epicormic sprouts each. Similar sprouting behavior occurred in 2-yr-old seedlings. Exposed seeds, fruits, and 1-yr-old seedlings were killed by fire. Established P. calleryana were single-stemmed individuals before exposure to fire. After the prescribed fire, they all were multistemmed, which increased the potential flower-bearing stems within the prairie. We conclude that fire alone is not a suitable technique for managing P. calleryana invasion. Cut and herbicide application methods are labor-intensive. However, combining cut and spray methods with prescribed fire may be effective. Fire removes standing grass and forb biomass, leaving exposed P. calleryana stems, which would make locating individuals and directly applying herbicides easier.
An effective management plan for invasive herb populations must consider the potential for regeneration from the soil seedbank. To test this potential, we examined two species, Japanese stiltgrass and garlic mustard, at deciduous forest sites in southeastern Ohio. Seeds were buried in nylon mesh bags and recovered at regular intervals over 24 mo. Recovered seeds were tested for germination and viability. Burial was replicated on north- and south-facing slopes to test for environmental control of dormancy state. Stiltgrass seeds experienced severe mortality in the soil, rarely surviving the full 24 mo. Stiltgrass showed fractional germination in the lab ranging from 86% to 89% of viable seeds in late spring (the season of natural seedling emergence) to complete nongermination in winter. Most garlic mustard seeds survived through the experimental period (82% and 88% survival across 24 mo) with consistently low mortality (0% to 13%) unrelated to season. Slope aspect had no significant effect on survival or dormancy state in either species. Extrapolation of garlic mustard mortality implies that reproduction would need to be suppressed for a substantial period (perhaps >10 yr) to ensure eradication of a population. In stiltgrass, rapid seed mortality suggests that control can be achieved in 2 to 4 yr.
Multiple introductions of an exotic species can facilitate invasion success by allowing for a wider range of expressed trait values in the adventive range. Schinus terebinthifolius (Brazilian peppertree) is an invasive shrub that was introduced into Florida in two separate introductions and has subsequently hybridized, resulting in three distinct lineages (eastern, western, and hybrid). To determine whether allocation of aboveground biomass differed by introduction history, we destructively sampled 257 stems from each of six populations with differing introduction histories. The proportion of aboveground biomass allocated to fruit, wood, and leaves differed among the three populations. To determine whether the relationship between stem size and several dependent variables that measure plant performance (total dry weight, wood dry weight, number of fruits, fruit dry weight, leaf dry weight, and number of leaves) differed quantitatively by introduction history, we performed analyses of covariance. Slopes of these relationships (dependent variable vs. stem size) varied by lineage. Hybrid populations had the steepest slopes for one set of dependent variables (total dry weight, wood dry weight, and leaf dry weight), while western populations had the steepest slopes for a different set of dependent variables (number of fruits, fruit dry weight, and number of leaves). The parameterized regression equations for each dependent variable and lineage were used to nondestructively estimate different kinds of production by individuals that are part of long-term longitudinal studies to understand the demographic consequences of these different biomass allocation strategies for the performance of S. terebinthifolius individuals across the invaded range in Florida.
The grass species Spartina alterniflora (smooth cordgrass) is an invasive ecosystem engineer with serious ecological consequences to intertidal mudflats and saltmarshes. The largest infestation in North America was in Willapa Bay, WA, where it occupied ~3,600 solid ha, covering ~27,000 ha of intertidal habitat. An extensive effort by land managers to eradicate S. alterniflora has been in place for over two decades. This article discusses (1) the success of the control and issues that will need to be resolved in order to achieve eradication; (2) post-control succession of affected tidelands to native marsh species, and (3) the impact that S. alterniflora removal has had on shorebird usage of affected tidelands.