Abundance and dispersion of the invasive Mediterranean annual, Centaurea melitensis in its native and non-native ranges

Exploring the complex pre-adaptations of invasive plants to anthropogenic disturbance: a call for integration of archaeobotanical approaches

Pre-adaptation to anthropogenic disturbance is broadly considered key for plant invasion success. Nevertheless, empirical evidence remains scarce and fragmentary, given the multifaceted nature of anthropogenic disturbance itself and the complexity of other evolutionary forces shaping the (epi)-genomes of recent native and invasive plant populations. Here, we review and critically revisit the existing theory and empirical evidence in the field of evolutionary ecology and highlight novel integrative research avenues that work at the interface with archaeology to solve open questions. The approaches suggested so far focus on contemporary plant populations, although their genomes have rapidly changed since their initial introduction in response to numerous selective and stochastic forces. We elaborate that a role of pre-adaptation to anthropogenic disturbance in plant invasion success should thus additionally be validated based on the analyses of archaeobotanical remains. Such materials, in the light of detailed knowledge on past human societies could highlight fine-scale differences in the type and timing of past disturbances. We propose a combination of archaeobotanical, ancient DNA and morphometric analyses of plant macro- and microremains to assess past community composition, and species' functional traits to unravel the timing of adaptation processes, their drivers and their long-term consequences for invasive species. Although such methodologies have proven to be feasible for numerous crop plants, they have not been yet applied to wild invasive species, which opens a wide array of insights into their evolution.

Extraction and characterization of novel natural fiber from Centaurea melitensis plant

In this work a new cellulosic fibers extracted from Centaurea Melitensis plant to the prospect of employing them as a source of reinforcement in composite materials. In this investigation, morphological, chemical, physical and mechanical features of Centaurea Melitensis fibers are investigated. The morphological characteristics using anatomical technique and scanning electron microscopy revealed the presence of a large percentage of fibroblasts in the fibers that allow adhesion with the matrix when manufacturing of composite materials. The fiber density is 1.269 ± 0.018 g/cm3 and the diameter is 187.11 ± 60.41 μm depending on the physical properties. The chemical properties revealed that the Centaurea Melitensis fiber has a crystalline size of 16.92 nm and a crystallinity index of 47.69% using XRD. The results of FTIR analysis proved on major components such as cellulose, hemicelluloses and lignin, by TGA the thermal stability was found up to 210°C and the maximum temperature up to 317.86°C. The mechanical properties have shown that the value of the tensile strength of the fibers is 336.87 ± 59.94 MPa, Young’s modulus is 23.87 ± 5.21 GPa, and the strain at failure is 1.27 ± 0.36%, and the interfacial shear strength is 9.82 ± 2.35 MPa. The statistical approach, Weibull distribution was used with two and three parameters to examine the experimental data due to their dispersion. WEIBULL statistical analytical test was used with 2 and 3 parameters are used to examine the experimental data due to their dispersion. All the findings from this investigation reveal that Centaurea Melitensis fibers can be a qualified candidate to be used as reinforcement in low density composite materials.

The Neolithic Plant Invasion Hypothesis: the role of preadaptation and disturbance in grassland invasion

A long-standing hypothesis is that many European plants invade temperate grasslands globally because they are introduced simultaneously with pastoralism and cultivation, to which they are 'preadapted' after millennia of exposure dating to the Neolithic era ('Neolithic Plant Invasion Hypothesis' (NPIH)). These 'preadaptations' are predicted to maximize their performance relative to native species lacking this adaptive history. Here, we discuss the explanatory relevance of the NPIH, clarifying the importance of evolutionary context vs other mechanisms driving invasion. The NPIH makes intuitive sense given established connections between invasion and agricultural-based perturbation. However, tests are often incomplete given the need for performance contrasts between home and away ranges, while controlling for other mechanisms. We emphasize six NPIH-based predictions, centring on trait similarity of invaders between home vs away populations, and differing perturbation responses by invading and native plants. Although no research has integrated all six predictions, we highlight studies suggesting preadaptation influences on invasion. Given that many European grasslands are creations of human activity from the past, current invasions by these flora may represent the continuation of processes dating to the Neolithic. Ironically, European Neolithic-derived grasslands are becoming rarer, reflecting changes in management and illustrating the importance of human influences on these species.

Effect of light on the growth and photosynthesis of an invasive shrub in its native range

Invasive species success may depend on ecophysiological attributes present in their native area or derived from changes that took place in the invaded environment. We studied the growth and photosynthetic capacity of Berberis darwinii shrubs growing under different light conditions (gap, forest edge and below the canopy) in their native area of Patagonia, Argentina. Leaf photosynthesis results determined in the native area were discussed in relation to information provided by studies carried out under the same light conditions in an invaded area in New Zealand. Shoot elongation, leaf production, stem and leaf biomass per shoot and specific leaf area (SLA, cm2 g-1) were determined in five adult plants, randomly selected in each of three light conditions in two forest sites. Net photosynthesis as a function of PPFD (Photosynthetic Photon Flux Density), stomatal conductance (gs), maximum light-saturated photosynthesis rate (Pmax), Pmass (on mass bases) and water-use efficiency (WUEi) were determined in plants of one site. We predicted that functional traits would differ between populations of native and invasive ranges. In their native area, plants growing under the canopy produced the longest shoots and had the lowest values for shoot emergence and foliar biomass per shoot, while their SLA was higher than gap and forest edge plants. Leaf number and stem biomass per shoot were independent of light differences. Leaves of gap plants showed higher Pmax, Pmass and gs but lower WUEi than plants growing at the forest edge. In its native range B. darwinii grows under different light conditions by adjusting shoot and leaf morphology and physiology. Plants of B. darwinii growing under the same light conditions show similar physiology in native and invasive ranges. This means that for B. darwinii, intra-specific variation of the functional traits studied here do not condition successful spread in new areas.

Integrative invasion science: model systems, multi-site studies, focused meta-analysis and invasion syndromes

Invasion science is a very active subdiscipline of ecology. However, some scientists contend that theoretical integration has been limited and that predictive power remains weak. This paper, focusing on plants, proposes a new multi-pronged research strategy that builds on recent advances in invasion science. More intensive studies on particular model organisms and ecosystems are needed to improve our understanding of the full suite of interacting factors that influence invasions ('model system research'). At the same time, comparative studies across many study systems are essential for unravelling the context-dependencies of insights that emerge from particular studies ('multi-site studies'); and quantitative synthesis based on large datasets should be constrained to well-defined theoretical domains ('focused meta-analysis'). We also suggest ways for better integration of information about species biology and ecosystem characteristics ('invasion syndromes'). We expect that a resulting theory of invasions will need to be conceived as a somewhat heterogeneous conglomerate of elements of varying generality and predictive power: laws that apply to well-specified domains, general concepts and theoretical frameworks that can guide thinking in research and management, and in-depth knowledge about the drivers of particular invasions.