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The current understanding of multi-stress interplay assumes stresses occur in perfect synchrony, but this assumption is rarely met in the natural marine ecosystem. To understand the interplay between non-perfectly overlapped stresses in the ocean, we manipulated different temporal scenarios of acidification and assessed their effect on mercury toxicity in a marine copepod. We found that the scenario of past acidification aggravated mercury toxicity, but personal and persistent acidification mitigated the toxicity. This is because personal and persistent acidification initiated the energy compensation to enhance growth and mercury efflux. To explore how general temporal scenarios of acidification affected multi-stress interplay, we conducted a meta-analysis on marine animals and found that scenarios significantly changed the toxicity of several other metals. Our study thus demonstrates that time and duration of stresses modulate multi-stress interplay in the marine ecosystem, and suggests that future studies should move beyond the scenario of perfect synchrony.

International audience; Many insects metamorphose from antagonistic larvae into mutualistic adult pollinators, with reciprocal adaptation leading to specialized insect-plant associations. It remains unknown how such interactions are established at molecular level. Here we assemble high-quality genomes of a fig species, Ficus pumila var. pumila, and its specific pollinating wasp, Wiebesia pumilae. We combine multi-omics with validation experiments to reveal molecular mechanisms underlying this specialized interaction. In the plant, we identify the specific compound attracting pollinators and validate the function of several key genes regulating its biosynthesis. In the pollinator, we find a highly reduced number of odorant-binding protein genes and an odorant-binding protein mainly binding the attractant. During antagonistic interaction, we find similar chemical profiles and turnovers throughout the development of galled ovules and seeds, and a significant contraction of detoxification-related gene families in the pollinator. Our study identifies some key genes bridging coevolved mutualists, establishing expectations for more diffuse insect-pollinator systems.

Salt stress threatens plant growth, development and crop yields, and has become a critical global environmental issue. Increasing evidence has suggested that the epigenetic mechanism such as DNA methylation can mediate plant response to salt stress through transcriptional regulation and transposable element (TE) silencing. However, studies exploring genome-wide methylation dynamics under salt stress remain limited, in particular, for studies on multiple genotypes. Here, we adopted four natural accessions of the model species

The phenotypes of plants can be influenced by the environmental conditions experienced by their parents. In some cases, such parental effects have been found to be adaptive, which has led to much speculation about their ecological and evolutionary significance. However, there is still much uncertainty about how common and how predictable parental environmental effects really are. We carried out a comprehensive test for parental effects of different environmental stresses in the model plant Arabidopsis thaliana. We subjected plants of three Arabidopsis genotypes to a broad range of biotic or abiotic stresses, or combinations thereof, and compared their offspring phenotypes in a common environment. The majority of environmental stresses (16 out of 24 stress treatments) caused significant parental effects, in particular on plant biomass and reproduction, with positive or negative effects ranging from −35% to +38% changes in offspring fitness. The expression of parental effects was strongly genotype-dependent, with some effects only present in some genotypes but absent, or even in the opposite direction, in others. Parental effects of multiple environmental stresses were often non-additive, and their effects can thus not be predicted from what we know about the effects of individual stresses. Intriguingly, the direction and magnitude of parental effects were unrelated to the direct effects on the parents: some stresses did not affect the parents but caused substantial effects on offspring, while for others the situation was reversed. In summary, parental environmental effects are common and often strong in A. thaliana, but they are genotype-dependent and difficult to predict.SignificanceStress experienced by plants can alter the phenotypes of their offspring. To understand the ecological and evolutionary significance of such parental effects, we must know how common and how predictable they are. In a large experiment with Arabidopsis thaliana, we show that the majority of 24 environmental stresses cause significant, and often strong, positive or negative parental effects. However, we also find that parental effects are genotype-specific and unrelated to the direct effect of individual stresses, and that multiple stresses often act in non-additive ways across generations. Thus, parental effects appear to be common and strong, but difficult to predict. Our findings have important implications for the study of plant responses to environmental change, and the design of stress experiments.

Ecological character displacement (ECD) refers to a pattern of increased divergence at sites where species ranges overlap caused by competition for resources. Although ECD is believed to be common, there are few in-depth studies that clearly establish its existence, especially in plants. Thus, we have compared leaf traits in allopatric and sympatric populations of two East Asian deciduous oaks: Quercus dentata and Quercus aliena. In contrast to previous studies, we define sympatry and allopatry at a local scale, thereby comparing populations that can or cannot directly interact. Using genetic markers, we found greater genetic divergence between the two oak species growing in mixed stands and inferred that long-term gene flow has predominantly occurred asymmetrically from the cold-tolerant species (Q. dentata) to the warm-demanding later colonizing species (Q. aliena). Analysis of leaf traits revealed greater divergence in mixed than in pure oak stands. This was mostly due to the later colonizing species being characterized by more resource-conservative traits in the presence of the other species. Controlling for relevant environmental differences did not alter these conclusions. These results suggest that asymmetric trait divergence can take place where species coexist, possibly due to the imbalance in demographic history of species resulting in asymmetric inter-specific selection pressures.

Greenspaces represent an ark for urban biodiversity, but understanding their carrying capacity to sustain species remains challenging. Old greenspaces that were fragmented from natural habitats are now overcrowded, while revegetated new greenspaces remain vacant. This is because they have different processes leading towards biodiversity equilibrium, and conservation management needs to differentiate between fragmented and revegetated greenspaces.

Background Restoration through planting is the dominant strategy to conserve mangrove ecosystems. However, many of the plantations fail to survive. Site and seeding selection matters for planting. The process of afforestation, where individuals were planted in a novel environment, is essentially human-controlled transplanting events. Trying to deepen and expand the understanding of the effects of transplanting on plants, we have performed a seven-year-long reciprocal transplant experiment on Kandelia obovata along a latitudinal gradient. Results Combined phenotypic analyses and next-generation sequencing, we found phenotypic discrepancies among individuals from different populations in the common garden and genetic differentiation among populations. The central population with abundant genetic diversity and high phenotypic plasticity had a wide plantable range. But its biomass was reduced after being transferred to other latitudes. The suppressed expression of lignin biosynthesis genes revealed by RNA-seq was responsible for the biomass reduction. Moreover, using whole-genome bisulfite sequencing, we observed modification of DNA methylation in MADS-box genes that involved in the regulation of flowering time, which might contribute to the adaptation to new environments. Conclusions Taking advantage of classical ecological experiments as well as multi-omics analyses, our work observed morphology differences and genetic differentiation among different populations of K. obovata, offering scientific advice for the development of restoration strategy with long-term efficacy, also explored phenotypic, transcript, and epigenetic responses of plants to transplanting events between latitudes.

The adaptive value of transgenerational effects (the ancestor environmental effects on offspring) in changing environments has received much attention in recent years, but the related empirical evidence remains equivocal. Here, we conducted a meta-analysis summarising 139 experimental studies in plants and animals with 1170 effect sizes to investigate the generality of transgenerational effects across taxa, traits, and environmental contexts. It was found that transgenerational effects generally enhanced offspring performance in response to both stressful and benign conditions. The strongest effects are in annual plants and invertebrates, whereas vertebrates appear to benefit mostly under benign conditions, and perennial plants show hardly any transgenerational responses at all. These differences among taxonomic/life-history groups possibly reflect that vertebrates can avoid stressful conditions through their mobility, and longer-lived plants have alternative strategies. In addition to environmental contexts and taxonomic/life-history groups, transgenerational effects also varied among traits and developmental stages of ancestors and offspring, but the effects were similarly strong across three generations of offspring. By way of a more comprehensive data set and a different effect size, our results differ from those of a recent meta-analysis, suggesting that transgenerational effects are widespread, strong and persistent and can substantially impact the responses of plants and animals to changing environments.

Temperature is one of the climatic factors that shape the geographic distribution of plant populations. Mangroves are temperature-sensitive plants, and their distributions are severely limited by low temperatures. It is unknown, however, to what extent temperature contributes to their population differentiation and evolution.

The comment by Sanchez-Tojar et al. (2020, Ecol Lett) questioned the methodology, transparency, and conclusion of our study (Yin et al. 2019, Ecol Lett, 22, 1976). The comment has overlooked important evolutionary assumptions in their reanalysis, and the issues raised were in fact dealt with through the peer-review process. Far from being biased, the key conclusion of our meta-analysis still stands; transgenerational effects are largely adaptive.

Mangrove plants adapt to coastal tidal mudflats with specially evolved viviparity seed development. However, very little is known about the genetic and molecular mechanisms of mangrove viviparity. Here, we tested a hypothesis that plant hormone abscisic acid (ABA) plays a significant role in precocious germination of viviparous Kandelia obovata seeds by exogenous applications. Through transcriptome analysis of ABA treated seeds, it was found that ABA repressed mangrove fruit growth and development, and there were thousands of genes differentially expressed. As a result, dynamics of the pathways were dramatically altered. In particular, “Plant hormone signal transduction” and “MAPK signaling pathway” were represented significantly. Among differentially expressed genes, some key genes of ABA signal transduction were induced, while ABA biosynthesis genes were repressed. Take ABI1 and ABI2, key negative regulators in ABA signal pathway, as examples, homologous alignment and a phylogenetic tree in various species showed that ABI1 and ABI2 are highly conserved among various species. The functional similarity of these genes was confirmed by transgenic work in Arabidopsis. Taken together, ABA inhibited mangrove viviparity, but mangroves developed a mechanism to prevent accidently increase of ABA in the harsh environment for maintaining viviparous reproductive strategy.

Genetic admixture, the intraspecific hybridization among divergent introduced sources, can immediately facilitate colonization via hybrid vigor and profoundly enhance invasion via contributing novel genetic variation to adaption. As hybrid vigor is short-lived, provisioning adaptation is anticipated to be the dominant and long-term profit of genetic admixture, but the evidence for this is rare. We employed the 30 years' geographic-scale invasion of the salt marsh grass, Spartina alterniflora, as an evolutionary experiment and evaluated the consequences of genetic admixture by combining the reciprocal transplant experiment with quantitative and population genetic surveys. Consistent with the documentation, we found that the invasive populations in China had multiple origins from the southern Atlantic coast and the Gulf of Mexico in the US. Interbreeding among these multiple sources generated a "hybrid swarm" that spread throughout the coast of China. In the northern and mid-latitude China, natural selection greatly enhanced fecundity, plant height and shoot regeneration compared to the native populations. Furthermore, genetic admixture appeared to have broken the negative correlation between plant height and shoot regeneration, which was genetically-based in the native range, and have facilitated the evolution of super competitive genotypes in the invasive range. In contrast to the evolved northern and mid-latitude populations, the southern invasive populations showed slight increase of plant height and shoot regeneration compared to the native populations, possibly reflecting the heterotic effect of the intraspecific hybridization. Therefore, our study suggests a critical role of genetic admixture in accelerating the geographic invasion via provisioning rapid adaptive evolution.

Increasing evidence for epigenetic variation within and among natural plant populations has led to much speculation about its role in the evolution of plant phenotypes. However, we still have a very limited understanding of the evolutionary potential of epigenetic variation, in particular in comparison to DNA sequence-based variation. To address this question, we compared the magnitudes of heritable phenotypic variation in epigenetic recombinant inbred lines (epiRILs) of Arabidopsis thaliana—lines that mainly differ in DNA methylation but only very little in DNA sequence—with other types of A. thaliana lines that differ strongly also in DNA sequence. We grew subsets of two epiRIL populations with subsets of two genetic RIL populations, of natural ecotype collections, and of lines from a natural population in a common environment and assessed their heritable variation in growth, phenology, and fitness. Among-line phenotypic variation and broad-sense heritabilities tended to be largest in natural ecotypes, but for some traits the variation among epiRILs was comparable to that among RILs and natural ecotypes. Within-line phenotypic variation was generally similar in epiRILs, RILs, and ecotypes. Provided that phenotypic variation in epiRILs is mainly caused by epigenetic differences, whereas in RILs and natural lines it is largely driven by sequence variation, our results indicate that epigenetic variation has the potential to create phenotypic variation that is stable and substantial, and thus of evolutionary significance.

Land-use intensification is a key driver of biodiversity change. However, little is known about how it alters relationships between the diversities of different taxonomic groups, which are often correlated due to shared environmental drivers and trophic interactions. Using data from 150 grassland sites, we examined how land-use intensification (increased fertilization, higher livestock densities, and increased mowing frequency) altered correlations between the species richness of 15 plant, invertebrate, and vertebrate taxa. We found that 54% of pairwise correlations between taxonomic groups were significant and positive among all grasslands, while only one was negative. Higher land-use intensity substantially weakened these correlations (35% decrease in r and 43% fewer significant pairwise correlations at high intensity), a pattern which may emerge as a result of biodiversity declines and the breakdown of specialized relationships in these conditions. Nevertheless, some groups (Coleoptera, Heteroptera, Hymenoptera and Orthoptera) were consistently correlated with multidiversity, an aggregate measure of total biodiversity comprised of the standardized diversities of multiple taxa, at both high and low land-use intensity. The form of intensification was also important; increased fertilization and mowing frequency typically weakened plant–plant and plant–primary consumer correlations, whereas grazing intensification did not. This may reflect decreased habitat heterogeneity under mowing and fertilization and increased habitat heterogeneity under grazing. While these results urge caution in using certain taxonomic groups to monitor impacts of agricultural management on biodiversity, they also suggest that the diversities of some groups are reasonably robust indicators of total biodiversity across a range of conditions. Read More: http://www.esajournals.org/doi/10.1890/14-1307.1

Some of the world's most successful invasive plants have spread across large geographic areas while retaining little or no genetic diversity. Because of this lack of heritable variation evolutionary hypotheses are usually not invoked when attempting to explain the success of these species. However heritable trait variation within and among invasive populations could also be created through epigenetic or other nongenetic processes particularly in clonal invaders where somatic changes can potentially persist indefinitely. We tested this possibility in a collection of 83 genetically identical clones of the invasive Japanese knotweed Fallopia japonica collected across Central Europe and propagated in a common environment for several years. Using regular as well as methylation sensitive amplified fragment length polymorphism (AFLP) markers we found that all clones indeed belonged to the same genotype but to 27 different epigenotypes. The different knotweed clones were also phenotypically differentiated. Path analysis indicated that among clone phenotypic variation is partly correlated with epigenetic variation as well as both directly and indirectly (through epigenetic variation) with climates of origin. Our results thus suggest a potential role of epigenetic variation in the geographic spread and invasion success of Japanese knotweed. More generally our study highlights the need to incorporate large scale epigenetic screens in studies of genetically uniform clonal invaders.

Heritable variation in plant phenotypes, and thus potential for evolutionary change, can in principle not only be caused by variation in DNA sequence, but also by underlying epigenetic variation. However, the potential scope of such phenotypic effects and their evolutionary significance are largely unexplored. Here, we conducted a glasshouse experiment in which we tested the response of a large number of epigenetic recombinant inbred lines (epiRILs) of Arabidopsis thaliana--lines that are nearly isogenic but highly variable at the level of DNA methylation--to drought and increased nutrient conditions. We found significant heritable variation among epiRILs both in the means of several ecologically important plant traits and in their plasticities to drought and nutrients. Significant selection gradients, that is, fitness correlations, of several mean traits and plasticities suggest that selection could act on this epigenetically based phenotypic variation. Our study provides evidence that variation in DNA methylation can cause substantial heritable variation of ecologically important plant traits, including root allocation, drought tolerance and nutrient plasticity, and that rapid evolution based on epigenetic variation alone should thus be possible.

Aquatic plant invasions are often associated with long-distance dispersal of vegetative propagules and prolific clonal reproduction. These reproductive features combined with genetic bottlenecks have the potential to severely limit genetic diversity in invasive populations. To investigate this question we conducted a global scale population genetic survey using amplified fragment length polymorphism markers of the world's most successful aquatic plant invader -Eichhornia crassipes (water hyacinth). We sampled 1140 ramets from 54 populations from the native (South America) and introduced range (Asia, Africa, Europe, North America, Central America and the Caribbean). Although we detected 49 clones, introduced populations exhibited very low genetic diversity and little differentiation compared with those from the native range, and approximately 80% of introduced populations were composed of a single clone. A widespread clone ('W') detected in two Peruvian populations accounted for 70.9% of the individuals sampled and dominated in 74.5% of the introduced populations. However, samples from Bangladesh and Indonesia were composed of different genotypes, implicating multiple introductions to the introduced range. Nine of 47 introduced populations contained clonal diversity suggesting that sexual recruitment occurs in some invasive sites where environmental conditions favour seedling establishment. The global patterns of genetic diversity in E. crassipes likely result from severe genetic bottlenecks during colonization and prolific clonal propagation. The prevalence of the 'W' genotype throughout the invasive range may be explained by stochastic sampling, or possibly because of pre-adaptation of the 'W' genotype to tolerate low temperatures.

Until a few years ago, epigenetics was a field of research that had nothing to do with ecology and that virtually no ecologist had ever heard of. This is now changing, as more and more ecologists learn about epigenetic processes and their potential ecological and evolutionary relevance, and a new research field of ecological epigenetics is beginning to take shape. One question that is particularly intriguing ecologists is to what extent epigenetic variation is an additional, and hitherto overlooked, source of natural variation in ecologically important traits. In this issue of Molecular Ecology, Herrera & Bazaga (2011) provide one of the first attempts to truly address this question in an ecological setting. They study variation of DNA methylation in a wild population of the rare, long-lived violet Viola cazorlensis, and they use these data to explore interrelations between environmental, genetic and epigenetic variation, and in particular the extent to which these factors are related to long-term differences in herbivore damage among plants. They find substantial epigenetic variation among plant individuals. Interestingly, this epigenetic variation is significantly correlated with long-term differences in herbivory, but only weakly with herbivory-related DNA sequence variation, which suggests that besides habitat, substrate and genetic variation, epigenetic variation may be an additional, and at least partly independent, factor influencing plant–herbivore interactions in the field. Although the study by Herrera & Bazaga (2011) raises at least as many new questions as it answers, it is a pioneering example of how epigenetics can be incorporated into ecological field studies, and it illustrates the value and potential novel insights to be gained from such efforts.