Perspectives in Plant Ecology Evolution and Systematics最新文献

As global warming progresses, plants may be forced to adapt to drastically changing environmental conditions. Arctic-alpine plants have been among the first to experience the effects of climate change. As a result, cold acclimation and freezing tolerance may become increasingly crucial for the survival as winter warming events and earlier snowmelt will cause increased exposure to occasional frost. The tribe Cochlearieae in the mustard family (Brassicaceae) offers an instructive system for studying cold adaptation in evolutionary terms, as the two sister genera Ionopsidium and Cochlearia are distributed among different ecological habitats throughout the European continent and the far north into circumarctic regions. By applying an electrolyte leakage assay to leaves obtained from plants cultivated under controlled temperature regimes in growth chambers, the freezing tolerance of different Ionopsidium and Cochlearia species was assessed measuring lethal freezing temperature values (LT₅₀ and LT₁₀₀), thereby allowing for a comparison across different species and accessions in their responses to cold. We hypothesized that, owing to varying selection pressures, geographically distant species would differ in freezing tolerance. Despite Ionopsidium occurring under warm and dry Mediterranean conditions and Cochlearia species distributed often at cold habitats, all accessions exhibited similar cold responses. The results may indicate that physiological adaptations of primary metabolic pathways to different stressors, such as salinity and drought, may confer an additional tolerance to cold; this is because all these stressors induce osmotic challenges.

Efforts to understand the mechanisms explaining the relationship between abiotic stress tolerance and range size and filling have hitherto yielded contradictory results. Unlike previous studies that have focused on single stress factors, we here examine the extent to which range size and filling can be explained by tolerance of multiple abiotic stressors (cold, shade, drought and waterlogging). As range metrics, we used range size and filling (the ratio between actual and potential range) for 331 European and North American temperate woody plant species. Stress tolerance strategies were expressed as a multivariate axis reflecting a cold/waterlogging-drought tolerance trade-off. We used mixed models to evaluate the relationship between range size/filling and this multivariate stress tolerance axis, using latitude as a covariate, and phylogeny and plant functional type as random effects. Range size and stress tolerance were negatively correlated, mostly independently of latitude and continent. Thus, cold/wet-tolerant species had the largest range sizes and cold-sensitive/drought-tolerant species the smallest. In contrast, range filling mostly depended on latitude. Our results show that abiotic stress tolerance can explain interspecific differences in range size, and to a lesser extent range filling, which sets up predictions for range size variation in plants that go beyond latitude.

Dense and species-rich understory communities have been commonly found in old or abandoned stands of Eucalyptus plantations in the Cerrado domain presenting plant species and ecological niches that suggest a repository of the original biodiversity. This repository depends on the largely unknown effect of Eucalyptus plantations on their understories. We addressed this issue by testing if the effect of Eucalyptus trees on the assembly of Cerrado communities causes environmental filtering or competitive exclusion. For the test, 40 plots (20 inside stands and 20 outside) were allocated and all woody plants with a circumference at the ground level equal to or greater than 10 cm were sampled. Species richness, diversity indexes and species turnover were determined. The phylogenetic structure was evaluated at different scales using the values of Mean Pairwise Distance (MPD), the Mean Nearest Taxon Distance (MNTD), the Net Relatedness Index (NRI) and the Nearest Taxon Index (NTI), as well as phylobetadiversity indices. The metrics of alpha and beta phylogenetic diversity (NTI, MNTD, NRI and MPD, betaMPD and betaMNTD) fell within the random expectation in each plant community, suggesting a phylogenetic uniformity, but fewer plants of the Fabaceae family than expected by chance were detected outside Eucalyptus stands suggesting that this family is filtered in inside Eucalyptus stands. Species richness is lower inside than outside Eucalyptus stands. The pattern is congruent with simultaneous environmental filtering and competitive exclusion in a context of niche conservatism which means that functional traits are conserved within phylogenetic lineages.

Heteroploid Knautia sect. Trichera constitutes a taxonomically intricate assemblage of taxa with highly complex genetic architecture, which is mirrored in high morphological variability and blurred boundaries among the species. Here, we aim to disentangle the relationships among the xerophytic taxa from the Dinaric Mountains on the western Balkan Peninsula, which, based on relative genome size estimations, comprise di-, tetra- and hexaploid populations. Our analyses of amplified fragment length polymorphisms (AFLP) revealed a clear genetic differentiation among the diploid members, which are also morphologically clearly divergent. On the other hand, the phylogenetic structure among tetraploid and hexaploid populations as well as the ties with their diploid progenitors are complex, conferring unclear boundaries among species. Tetraploids were intermingled among the divergent diploid lineages, suggesting recurrent polyploidisation and/or extensive gene flow across sympatric lineages, whereas hexaploids clustered in two groups, pointing to two separate origins. In line with the genetic pattern, there is a high overlap in morphological characters across and within different ploidies. Nevertheless, comparisons of environmental niches showed differentiation among the ploidy levels, with the niche of hexaploids being most divergent. It is thus obvious that dynamic polyploid evolution, virtual lack of crossing barriers among polyploid cytotypes pertaining to different species, and exceedingly variable morphology along with the uniformity of reproductive characters preclude establishing a clear-cut taxonomic structure. Still, albeit generally corroborating previous observations for K. sect. Trichera as a whole, our study restricted to a limited geographic and taxonomic assemblage yielded constructive insights towards a workable taxonomic framework in this complex system. As a result, we propose a revised taxonomic treatment, including description of a new species, Knautia ehrendorferi, but we are aware that species identifications will remain challenging also in the future.

Data availability

Data will be made available on request.

Pollinator-transmitted pathogens typically hinder sexual reproduction of their hosts and affect pollen flow among remaining healthy individuals in a population. The extent to which a pathogen also influences host’s population growth depends on the importance of sexual reproduction for the host’s life cycle. Such pathogen impact cannot be traced by measuring only the vital rates directly affected by the pathogen, and thus a study of the host’s entire life cycle is necessary. In this study, we aimed to quantify the effects of the pollinator-transmitted anther smut pathogen Microbotryum carthusianorum on population growth rate in three populations of the long-lived perennial Dianthus carthusianorum. We followed plant individuals over three years and measured their size, disease state, and reproduction. We then constructed an Integral Projection Model (IPM). To evaluate the pathogen impact, we performed a stochastic analysis of the IPM for real diseased populations as well as for simulated populations without the pathogen. As the populations also hosted predispersal seed predators, the same approach was used to evaluate their impact. Stochastic population growth rates indicated two of the real populations to be increasing, and one to be declining. Comparison with the simulated healthy populations showed that the pathogen impact on the growth rate was negative and relatively strong, because the growth rate was highly sensitive to changes in sexual reproduction. However, the pathogen did not appear to cause the decline in the one decreasing population, since the growth rate there was impaired more substantially by high rates of predispersal seed predation and low germination rates than by the castration of diseased flowers. Overall, our study suggests that D. carthusianorum is highly vulnerable to biotic interactions affecting sexual reproduction pathway. Additionally, our study illustrated several complexities in disease dynamics (e.g., occurrence of partially or fully asymptomatic plants) that need to be incorporated into the assessment of the impact of pollinator-transmitted pathogens on long-lived perennials.

It has been established by research on plant invasions that soil biota and availability of nutrients affect the processes of alien species establishment and spread. So far, attention was mainly on alien invaders, although some native species (expansive), vigorously spread in human-influenced landscapes and also transform the habitats they colonize. Based on indirect gradient ordination analysis of vegetation relevés dominated by five native (Calamagrostis epigejos, Filipendula ulmaria, Phalaris arundinacea, Rubus idaeus, Urtica dioica) and five alien taxa (Impatiens glandulifera, Lupinus polyphyllus, Telekia speciosa, Reynoutria sp., Solidago canadensis agg.) in the Czech Republic, Central Europe, we identified pairs of species differing by origin (native vs alien) and growing in similar habitats. In the resulting 10 pairs, we tested the net effect of species origin on the following soil characteristics: (i) physical properties, (ii) nutrient availability, and (iii) biological activity. We found that the impact of alien invasive and native expansive species on soil cannot be explained simply by species’ origin as a factor. Regardless of the origin, a statistically significant effect was recorded only for factors expressing nitrogen supply at the peak of the vegetation season and soil biological activity. Differences in impacts attributable to origin were only verified for individual pairs, being most pronounced between the alien Lupinus and its native counterparts Calamagrostis and Filipendula, and least between Solidago vs Calamagrostis, and Telekia vs Rubus. Both invasive alien and expansive native dominant plants can alter the rate of decomposition by changing the litter quality and availability of nutrients, mainly inorganic nitrogen. Therefore, management actions to preserve or restore diversity and mitigate the negative impacts of dominant species should be focused both on native and alien species.

The Hyrcanian forests positioned along the southern and south-western shores of the Caspian Sea and the Euxine-Colchic forests along the southern and eastern shores of the Black Sea (western Asia) are renowned as hotspots of biodiversity and represent major refugia of Eurasian Tertiary relict forest species. One of them was considered to be Euphorbia amygdaloides (Euphorbia sect. Patellares), a forest species with wide distribution from northern Africa across Europe to western Asia. Using nuclear ribosomal ITS and plastid ndhF–trnL sequences we here show that the western Asian populations previously treated as E. amygdaloides are clearly divergent from European E. amygdaloides and actually pertain to two new species, which are also morphologically different. The newly described E. sylvicola is widespread in the Hyrcanian and Euxine-Colchic forests and is morphologically most similar to E. amygdaloides, with which it also shares its genome size. On the other hand, E. caspica is endemic to the Hyrcanian forests in Iran and is most closely related to another western Asian species, E. macroceras, with which it partly overlaps in distribution. Both species have also similar genome size, slightly lower from that of E. amygdaloides and E. sylvicola, but morphologically E. caspica resembles more E. amygdaloides than E. macroceras. Our study uncovered cryptic diversity in the forests of western Asia that had remained hidden due to slow rates of morphological evolution, i.e. morphological stasis, commonly observed in other Tertiary forest relict species, and highlights the Euxine-Colchic and especially the Hyrcanian forests as important centres of biodiversity and endemism.

In non-fire prone ecosystems, like some subtropical humid forests, fire produces habitat destruction and intensifies land degradation by inducing changes in native species composition, soil properties and erosive processes. Bryophytes are key components of the Macaronesian laurel forests playing an important role in regulating water cycling and microclimate. Ecological and taxonomical bryophytes groups have distinct ecological and physiological requirements and may respond in a different way to the same fire events. Therefore, analysing post fire recovery of bryophyte communities represents a key step towards a better understanding of forest fire drivers and post fire management. We investigated how species richness and composition of different ecological and taxonomical bryophyte groups varied in 1158 samples within a fire chronosequence from 5 to 57 years in the best-preserved laurel forest from Canary Islands (Garajonay National Park) analysing communities in terms of differences with comparable surrounding old growth unburnt stands. Epiphyte, terricolous and saxicolous bryophytes were sampled at each plot and the influence of the time since fire was analyzed together with environmental variables (temperature, precipitation, mist precipitation and elevation) and forest structure variables. Our results indicate that there is no general pattern of post fire recolonization, as recolonization varies depending on the ecological and phylogenetic groups considered. Climate and forest structure play an important role in post-fire recolonization, such that time since fire is not the most important variable influencing richness and composition. The results increase the understanding of the processes that shape compositional patterns in groups with high dispersal capacities and high microclimate dependence, such as mosses and liverworts.