Summary: A new mechanistic model of the photosynthesis–light response is developed based on photosynthetic electron transport via photosystem II (PSII) to specifically describe light‐harvesting characteristics and associated biophysical parameters of photosynthetic pigment molecules. This model parameterizes ‘core’ characteristics not only of the light response but also of difficult to measure physical parameters of photosynthetic pigment molecules in plants. Application of the model to two C₃ and two C₄ species grown under the same conditions demonstrated that the model reproduced extremely well (r² > 0.992) the light response trends of both electron transport and CO₂ uptake. In all cases, the effective absorption cross‐section of photosynthetic pigment molecules decreased with increasing light intensity, demonstrating novel operation of a key mechanism for plants to avoid high light damage. In parameterizing these previously difficult to measure characteristics of light harvesting in higher plants, the model provides a new means to understand the mechanistic processes underpinning variability of CO₂ uptake, for example, photosynthetic down‐regulation or reversible photoinhibition induced by high light and photoprotection. However, an important next step is validating this parameterization, possibly through application to less structurally complex organisms such as single‐celled algae.

Invasion biology aims to identify traits and mechanisms that contribute to successful invasions, while also providing general insights into the mechanisms underlying population expansion and adaptation to rapid climate and habitat changes. Certain phenotypic attributes have been linked to successful invasions, and the role of genetics has been critical in understanding adaptation of invasive species. Nevertheless, a comprehensive summary evaluating the most common evolutionary mechanisms associated with successful invasions across species and environments is still lacking. Here we present a systematic review of studies since 2015 that have applied genomic tools to investigate mechanisms of successful invasions across different organisms. We examine demographic patterns such as changes in genomic diversity at the population level, the presence of genetic bottlenecks and gene flow in the invasive range. We review mechanisms of adaptation such as selection from standing genetic variation and de novo mutations, hybridisation and introgression, all of which can have an impact on invasion success. This comprehensive review of recent articles on the genomic diversity of invasive species led to the creation of a searchable database to provide researchers with an accessible resource. Analysis of this database allowed quantitative assessment of demographic and adaptive mechanisms acting in invasive species. A predominant role of admixture in increasing levels of genetic diversity enabling molecular adaptation in novel habitats is the most important finding of our study. The “genetic paradox” of invasive species was not validated in genomic data across species and ecosystems. Even though the presence of genetic drift and bottlenecks is commonly reported upon invasion, a large reduction in genomic diversity is rarely observed. Any decrease in genetic diversity is often relatively mild and almost always restored via gene flow between different invasive populations. The fact that loci under selection are frequently detected suggests that adaptation to novel habitats on a molecular level is not hindered. The above findings are confirmed herein for the first time in a semi‐quantitative manner by molecular data. We also point to gaps and potential improvements in the design of studies of mechanisms driving rapid molecular adaptation in invasive populations. These include the scarcity of comprehensive studies that include sampling from multiple native and invasive populations, identification of invasion sources, longitudinal population sampling, and the integration of fitness measures into genomic analyses. We also note that the potential of whole genome studies is often not exploited fully in predicting invasive potential. Comparative genomic studies identifying genome features promoting invasions are underrepresented despite their potential for use as a tool in invasive species control.

Leaves developing in different irradiances undergo structural and functional acclimation, although the extent of trait plasticity is species specific. We tested the hypothesis that irradiance-induced plasticity of photosynthetic and anatomical traits is lower in highly shade-tolerant species than in moderately shade-tolerant species. Seedlings of two evergreen conifers, shade-tolerant Abies alba Mill. and moderately shade-tolerant Picea abies Karst., and two deciduous angiosperm species, highly shade-tolerant Fagus sylvatica L. and moderately shade-tolerant Acer pseudoplatanus L., were grown in deep shade (LL, 5% of full irradiance) or in full solar irradiance (HL) during 2003 and 2004. Steady state responses of quantum yield of PSII (φ_PSII), apparent electron transport rate (ETR), nonphotochemical quenching (NPQ) and photochemical quenching (qP) were generally modified by the light environment, with slower declines in φ_PSII and qP and greater maximal ETR and NPQ values in HL plants in at least one season; however, no link between quantitative measures of plasticity of these traits and shade tolerance was found. Plasticity of nine anatomical traits (including palisade cell length, which was reduced in LL) showed no relationship with shade tolerance, but was less in conifers than in deciduous trees, suggesting that leaf life span may be a significant correlate of plasticity. When LL-acclimated plants were exposed to HL conditions, the degree and duration of photoinhibition (measured as a decline in maximum quantum yield) was greatest in F. sylvatica, much lower in P. abies and A. alba, and lowest in A. pseudoplatanus. Thus, as with the other traits studied, vulnerability to photoinhibition showed no relationship with shade tolerance.