Perspectives in Plant Ecology Evolution and Systematics最新文献

The aim of this study was to determine physiological and molecular grounds for high adaptation potential of invasive populations of Rosa rubiginosa to soil drought. We assume that the invasive populations possess specific and effective adaptive mechanisms making them capable pioneer and nurse plants in dry environments. By colonizing the land, they limit its degradation and initiate revitalization of areas damaged by soil droughts. We analyzed plant water status, the photosynthetic apparatus activity, carbohydrate and phenolic content, the level of non-enzymatic antioxidants and RbcL protein associated with fixation of CO₂. The research involved native (Northern Hemisphere: Poland, Spain) and invasive (Southern Hemisphere: Argentine, New Zealand) populations. Contrary to the native population, the invasive one demonstrated soil drought induced specific responses aimed at maintaining high water potential in the leaves, greater content of soluble carbohydrates, and higher osmotic potential. In the invasive population, the accumulation of soluble carbohydrates prevailed over their consumption for the synthesis of phenolic compounds. The invasive plants also maintained high content of assimilation pigments and showed greater level of non-enzymatic antioxidants. Reduced activity of the photosynthetic apparatus was associated both with increased energy amount dissipated from PSII and the efficiency with which an electron can move from the reduced intersystem electron acceptors to the PSI end electron acceptors. The study results pave the path for further research on the genetic basis of sweet briar response to soil drought in the context of progressive steppe formation and desertification.

In Brazil, the country with the highest plant species richness in the world, biodiverse savannas and grasslands – i.e., grassy ecosystems, which occupy 27% of the country – have historically been neglected in conservation and scientific treatments. Reasons for this neglect include misconceptions about the characteristics and dynamics of these ecosystems, as well as inconsistent or regionally restricted terminology that impeded a more adequate communication about Brazil's savannas and grasslands, both within the country and internationally. Toward improved communication and recognition of Brazil’s diversity of ecosystems, we present the key drivers that control the main types of grassy ecosystems across Brazil (including in regions of the country where forests dominate). In doing so, we synthesize the main features of each grassy ecosystem in terms of physiognomy and ecological dynamics (e.g., relationships with herbivores and fire). We propose a terminology both for major grassland regions and for regionally relevant vegetation physiognomies. We also discuss terms associated with human land management and restoration of grassy ecosystems. Finally, we suggest key research needs to advance our understanding of the ecology and conservation values of Brazil’s grassy ecosystems. We expect that a common and shared terminology and understanding, as proposed here, will stimulate more integrative research that will be fundamental to developing improved conservation and restoration strategies.

Seed dispersal is an essential ecological process for plant (re)colonization, especially in intensively human-altered habitats such as old-fields (i.e. abandoned farmlands) where seed arrival is often limited. Assessment of spatial patterns of mammal-generated seed rain and their matching with the spatial distribution of adult plants provides essential information on the patterns and pace of the (re)colonization processes. For instance, increased seedling survival far from adult plants could indicate density-dependent mortality (Janzen-Connell) effects whereas increased survival close to adult plants could suggest facilitative effects. Here, we characterized during two dispersal seasons the spatial distribution of feces from four frugivorous mammals and quantified its spatial association with the distribution of adult plants of the pioneer Mediterranean dwarf palm (Chamaerops humilis) in two old-fields in southwestern Spain. We also estimated the dispersal kernels of both emerged and surviving seedlings and assessed potential evidence for Janzen-Connell and/or facilitative effects. Using a spatially explicit approach, we revealed strong differences between study sites in the strength and scale of spatial associations between mammal feces with C. humilis seeds and adult dwarf palms, being strongly positive at small scales in one site and slightly positive at larger scales in the other one. Further, we found some evidence of both Janzen-Connell and facilitative effects depending on the study site. Altogether, our results emphasize the central role as seed disperser of the Eurasian badger (Meles meles) in the natural (re)colonization of Mediterranean old-fields and the spatial variations of the underlying mechanisms and demographic consequences for plant populations.

Among the fascinating and highly specialized vascular plants in the hyperarid core of the Chilean and Peruvian Atacama Desert there are few Tillandsia species from the bromeliad family (Bromeliaceae). These grow epiarenically on bare sand without a functional root system, and in some rare cases they build up a monospecific and often the only landscape characterizing vegetation type, which is called Tillandsiales or Tillandsia loma. Tillandsia landbeckii is the dominating epiarenic species in Chile totally dependent on fog serving as the only water resource. Herein we elaborate on the hypothesis that migration and multiple colonization in concert with putative introgression from other Tillandsia species build up the present day phylogeographic distribution pattern and may contribute to the evolutionary dynamics and long-term success in hyperarid desert systems. Genomic analyses using GBS (genotyping-by-sequencing) data from the nuclear and plastid genome were conducted at the population level. A genome skimming approach was used to generate reference plastome data. The results indicate that both, multiple colonization and secondary contact of old gene pools and interspecies geneflow, contribute to present-day population genetic structure. Local-scale analysis also indicates that these past footprints of evolutionary history do contribute to present-day local adaptive potential of the species.

Grime’s CSR classification of functional strategies in terms of competitors, stress-tolerators and ruderals provides a helpful framework for understanding and predicting vegetation responses to environmental changes. To evaluate the importance of alternative processes that structure plant communities, it is useful to disentangle the community functional variation into interspecific and intraspecific components and assess their degree of co-variation. Few efforts have been made to investigate the habitat filtering theory in all the interspecific and intraspecific components of a plant community. We hypothesized that under intense climatic conditions, such as drought and cold, functional diversity would decrease towards the dominance of stress tolerant strategies, and that such trends would be reinforced by similar variation at the intraspecific level. We investigated the effect of climatic variation on functional diversity and on community-weighted mean along an elevation gradient in central Italy that ranges from dry and warm climatic conditions at lower elevation to cold and moist ones at higher elevation. We ran regression models to disentangle the total community components for both functional diversity and community-weighted mean into interspecific effect, intraspecific effect and their covariation along the climatic gradient. Our observations were in line with the theory of habitat filtering: we found lower diversity of the Grime strategy for species at both warmer and colder climatic conditions, with dominance of the stress-tolerant strategy. Similarly, the intraspecific effect was lower in cold conditions but higher under drier conditions, which seems to indicate that different processes act at the level of individuals. Given the important intraspecific variability observed in this study, it can be proposed that investigations of vegetation communities should take the role of intraspecific variability into greater consideration.

The orchid genus Ophrys is a textbook example of a taxonomic controversy, with the number of species recognised in different classifications varying from around 10 to over 350, causing confusion among researchers and enthusiasts. Here, we illustrate that there are multiple drivers behind that disagreement, representing debates and discussions of various nature, and then reflect on strategies to mitigate confusion among the users of Ophrys taxonomies, reconciling legitimate taxonomic debates with demands for clarity among the broader biological community. First, we distil six possible factors explaining taxonomic disagreement from general literature on taxonomic difficulties, and assess the importance of each of them for the Ophrys controversy. We then explore two strategies to reduce confusion among the users of the taxonomies in question. On the one hand, we illustrate the possibility of constructing a consensus-based reference taxonomy for external users, despite the ongoing taxonomic disagreement, and on the other hand we explore a ‘pluralist’ alternative, in which different classifications are allowed to coexist, but in an orderly manner. Doing so, we build a case for the Ophrys systematics community to reflect collectively on which strategy to adopt.

Recently diverged species may hybridize in their contact zones if complete reproductive isolation has not yet emerged. Petunia inflata and P. interior are closely related species with a narrow geographic distribution in Argentina and southern Brazil. They share morphological features, genetic markers, pollinators, and occupy a transitional area between the Pampa grasslands and the Brazilian Atlantic Forest. Here, we used genomic data to verify species boundaries, identify putative hybrids, and shed light on their speciation process. We characterized 59 individuals from allopatric and contact zones using genotyping-by-sequencing technology, resulting in a final dataset with 21,759 neutral single nucleotide polymorphisms used to perform structure, demographic, and hybridization analyses. These species belong to distinct evolutionary lineages that hybridized after secondary contact. A combination of geographic distance, elevation, and climate explains the genetic divergence between species. Niche overlap analysis revealed that even though these species have overlapping distributions and similar habitat preferences, they are more distinct than expected by chance, rejecting the niche conservatism hypothesis. Demographic analysis suggested that the Pleistocene climatic changes led species to diverge but they came into secondary contact during the Holocene. The secondary contact led to limited gene flow between species and bidirectional introgression. The distribution expansion of these species’ ancestor to a transitional zone between biomes, associated with elevational ranges and habitat fragmentation promoted speciation and niche differentiation.

The predominantly allogamous Broad-leaved Helleborines (Epipactis helleborine) and the predominantly autogamous Narrow-lipped Helleborines (Epipactis leptochila) represent two taxonomically complex groups with great morphological diversity and close genetic relationships at the subspecies level. They are influenced by environment, clinal variability, hybridization between allogamous taxa, and in particularly by speciation through transitions from allogamy to autogamy. We analysed floral traits, genome size and performed molecular analyses (Internal transcribed spacer region, ITS; Amplified Fragment Length Polymorphism, AFLP) of several individuals of E. helleborine and E. leptochila aggregate from different geographical regions in Slovenia, focusing on intermediate traits of E. helleborine subsp. moratoria, E. helleborine subsp. leutei and E. leptochila subsp. neglecta. In order to successfully distinguish studied taxa, the main attention should be paid to the shape of the epichil and the ovary, as well as to the size ratio of sepals and petals. Among the microfloral characters, the shape and size of the lower margin of the stigma and staminodes are found to be supportive. E. neglecta clearly shows intermediate floral characteristics between E. leptochila and E. leutei, suggesting that the transition to autogamy evolved E. neglecta as an intermediate stage in the speciation process, coinciding with the colonisation of forest sites with lower light intensity. Analysis of genome size revealed significant differences, with E. neglecta having the greatest value. Using molecular markers, we were able to determine two main ribotype clusters within the E. helleborine group, which were also determined by AFLP analyses. E. leutei and E. neglecta formed two clearly defined subclusters within the E. leptochila lineage. The results of the presented study suggest that combining molecular markers and genome size with information on how variation in floral morphology is distributed, using multivariate analyses, is the most reliable way to gain improved insight into the relationships among the taxa analysed.

Members of Polygala sections Clinclinia and Monninopsis, from the New World Clade (NWC), inhabit arid to humid habitats along the American continent. Although knowledge of these sections is currently incomplete, it is crucial for understanding evolutionary and diversification patterns in Polygalaceae. Here, we sample new species from the Polygala NWC with emphasis on these two sections, providing a comprehensive molecular phylogeny based on DNA sequence data from one nuclear (ITS) and three chloroplast (trnL-F intergenic spacer, rbcL, and partial matK-trnK) loci. Furthermore, we conducted comparisons for the main clades in the environmental and geographic spaces using climatic and elevation data processed by ordination and species distribution modelling (SDM) techniques. In addition, an ancestral state reconstruction for the morphological flower traits "violet spots on lateral petals" and "style shape" was carried out. The ancestral flower of the Polygala NWC was reconstructed as not having violet spots on the lateral petals and with a style with superior appendages. Within Polygala sect. Monninopsis, we found three distinct lineages. The North American clade A1 showed a potential distribution found along the Andes, from southern United States to Argentina. The South American P. argentinensis was predicted to be found from central Mexico to Argentina. The Patagonian P. darwiniana was also predicted to be found in northern North America and in the Lower California Peninsula in Mexico. Within Polygala sect. Clinclinia, we also found three distinct lineages. Clade B1 in addition to its empirical distribution found in Chile and Argentina, also showed a potential distribution found in Colombia. Clade B2 in addition to its empirical distribution found in north and central Argentina, southern Bolivia, Paraguay, Uruguay, and southern Brazil, also showed a potential distribution in southern Chile, southern Argentina, and the South Atlantic Islands. Finally, the Argentinian clade B3 was also predicted to be found in central Chile and southern Bolivia. An updated synonymic list of the Polygala sects. Clinclinia and Monninopsis as treated in this study is also provided.

Pollinator specialisation is one of the major drivers of angiosperm diversification in the Greater Cape Floristic Region (GCFR) of South Africa. Conophytum (Aizoaceae) is a flagship genus for the underexplored arid regions of the GCFR (ca. 108 spp.) with 83.9% of its species endemic to this region and has a floral structure that is unique within the rapidly diversified Ruschieae (Aizoaceae). Floral traits, together with leaf characters divide the genus into 16 sections. We present here the first phylogenetic hypothesis for Conophytum, based on molecular data. The combined phylogenetic data for six plastid regions (matK, rpl16, rps16, trnL-F, trnQ-rps16 and trnS-trnG) were analysed using Bayesian inference, maximum likelihood and maximum parsimony to test the evolution of this floral diversity and current sectional classification. Conophytum was recovered as monophyletic including the three small genera Berrisfordia L.Bolus, Herreanthus Schwantes and Ophthalmophyllum Dinter & Schwantes. Six strongly supported clades were recovered within Conophytum: while several of the sections were broadly retrieved within these clades, the more morphologically variable sections such as Minuscula and Wettsteinia were not supported by our data. The distributions of the six clades largely overlap and are generally confined to the arid parts of the GCFR within South Africa, with only one clade extending into the southern wetter parts. Ancestral character reconstructions showed that floral traits evolved multiple times with low phylogenetic signal recovered for autumn- and winter-flowering and flower type, while the other traits indicated no phylogenetic signal. This lack of phylogenetic signal suggests that drivers of diversity in Conophytum are possibly linked to adaptation to pollinators, with a high rate of inferred pollination shifts observed, i.e. 1.7 shifts per species, mirroring that of Lapeirousia (Iridacaeae) in the GCFR. The evolution of unique tubular flowers and shift to autumn-flowering were recovered as traits indicating strong phylogenetic signal and may have enabled Conophytum to exploit a range of pollinators through diversification in floral morphologies.