Perspectives in Plant Ecology Evolution and Systematics最新文献

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.

Cannabis is among the oldest human domesticates and has been subjected to intensive artificial (human-mediated) selection throughout history to create a wide array of varieties and biotypes for diverse uses, including fiber, food, biofuel, medicine and drugs. This paper briefly reviews the available literature on the taxonomy, evolutionary origin and domestication of this plant, as well as its worldwide dispersal, in both its wild and cultivated forms. Emphasis is placed on Europe and especially on the Iberian Peninsula. Today, it is accepted that Cannabis is a monospecific genus with two subspecies, C. sativa subsp. sativa and C. sativa subsp. indica, originating in Europe and Asia, respectively, by allopatric differentiation after geographic isolation fostered by Pleistocene glacial-interglacial cycles. Palynological and phylogeographic evidence situates the Cannabis ancestor on the NE Tibetan Plateau during the mid-Oligocene. The timing and place of domestication is still a matter of debate between contrasting views that defend single or multiple Neolithic domestication centers situated in different parts of the Eurasian supercontinent, notably central/southeastern China and the Caucasus region. Recent meta-analyses have suggested that wild Cannabis may have already been spread across Europe in the Pleistocene, and its domestication could have occurred during the European Copper/Bronze ages. According to the available reviews and meta-analyses, pre-anthropic dispersal of Cannabis into the Iberian Peninsula seems to have occurred only in postglacial times, and the earlier signs of cultivation date to the Early Medieval Ages. However, the palynological and archeological evidence used to date is insufficient for a sound assessment, and the development of thorough Iberian databases to address further meta-analysis is essential for more robust conclusions. Some clues are provided for these achievements to be fulfilled.

The effects of wild game feeding on the local environment have been widely investigated in northern European countries but have received little consideration in Central Europe. Bait sites, that is, places where food is set out to entice wild boar for hunting are becoming ever more widespread, and they are having an increasing impact on surrounding vegetation. The aim of the present study was to assess the extent of weed invasion at different bait types. 3 bait sites located in forests, 3 baits in clearings and 3 baits on unpaved forest roads in the Central European lower montane zone, in Hungary. The field work was conducted in May and August. Four transects were laid out (at right angles to each other) from the centre of each bait, and consisted of 22 one meter square quadrats, in which vegetation survey were conducted. The application of multivariate statistical methods (PCA) and UPGMA analysis to the data collected revealed substantial differences between the bait types. The baits in the forest were the least degraded, with a sparse understory cover in both surveys. Road baits displayed a notable difference, as they varied depending on canopy closure, accessibility and exposure. Sites in clearings proved to be the most infected. Furthermore, there was a significant difference between the vegetation of the periods examined, arable weeds dominated in August. A stress gradient was detected along the transects, with the proportion of weeds decreasing from the centre, while the natural components of the vegetation increased. The effect was more noticeable in clearings, probably due to their greater openness. Invasion is typically limited to the immediate environment of the bait sites, but valuable patches of habitat can also be destroyed, and bait sites may serve as bridgeheads for biological invasions.

Leaf nutrient composition and stoichiometry reflect complex interactions of the plant with its environment and are useful traits to explore ecological processes and relationships. In the present study, the foliar elemental compositions of two common Mediterranean woody species, the evergreen broad-leaved Quercus ilex and the coniferous Pinus pinaster growing in an area of Central Italy known for geochemical and geothermal anomalies, were investigated. To assess the site-specific and age-dependent pattern of foliar composition and stoichiometry, macronutrients (C, N, P, K, Mg, S) and trace elements (Al, As, Ba, Cd, Cr, Cu, Fe, Hg, Ni, Pb, Sb, V, Zn) were determined in leaves and needles of three different ages (6-, 12- and 24-month-old) collected from metalliferous (geothermal, mining) and rural areas. Leaves of Q. ilex showed comparatively high concentrations of micronutrients (i.e., Cu, Fe and Zn), while needles of P. pinaster accumulated significantly high concentrations of potentially toxic elements (i.e., As, Pb and S). No significant trend was found in elemental concentrations in relation to the age of leaves and needles. Multi-element stoichiometry of P. pinaster was driven by the geochemical heterogeneity of the sites, suggesting plastic adaptation at the sites with the most selective edaphoclimatic conditions (i.e., patches with nutrient poor and metalliferous soils). On the other hand, the content of both nutrients and potentially toxic elements in Q. ilex leaves varied little across the study area, reflecting stoichiometric stability; this is consistent with the ecophysiological features of Q. ilex as a late-successional species with a dominant role in the ecosystems of the Mediterranean area. Our findings demonstrate the value of foliar stoichiometric traits for understanding plant adaptation in a heterogeneous environment and also the consequences of biotic interactions during succession.

Polyploidisation is an important evolutionary force in land plants. Due to its recurrent incidence, many plant species retain individuals of two or more different ploidy levels. However, particular ecological and evolutionary mechanisms facilitating intraspecific cytotype coexistence have been identified for just a handful of species and cannot yet be generalised. Our pilot data have revealed a unique complex of mixed diploid-triploid populations of the marshland perennial Butomus umbellatus in the Eastern Slovak Lowland (eastern Central Europe). Intensive flow-cytometric ploidy screening of 1,230 individuals sampled from 72 populations was conducted at both regional and local (within-population) scales to assess cytotype distribution patterns. Vegetation assessments along with phenotypic comparisons of cytotypes directly in the field and later under common garden cultivation served to provide insight into mechanisms of cytotype coexistence. Altogether 42 % of the sampled populations were mixed-ploidy, pointing to unexpectedly high rates of diploid-triploid coexistence. While the cytotype distribution was random at the regional scale, significant spatial clustering occurred at the local scale. No ecological niche differences between the cytotypes were detected. Triploids attained greater values of several morphological characters both in the field and under cultivation, differences in the shape of inner tepals even show potential for cytotype discrimination. Both cytotypes exhibited high and comparable investments into clonal traits, reproductive assurance provided by asexual reproduction likely plays a key role in cytotype coexistence and triploid predominance. The common cytotype coexistence in this region seems to be also facilitated by periodical seasonal floods promoting transport of vegetative propagules among populations (i.e. metapopulation dynamics) and providing long-term continuity of favourable sites by recurrent disturbances.

Chondrilla chondrilloides (Asteraceae) is a rare and endangered early-successional plant species endemic to the Eastern European Alps. Its distribution is restricted to near-natural braided rivers and to alluvial fans. The species was common along Alpine gravel rivers, but has declined markedly due to river regulation and degradation in the 19th and 20th century, while some recent restoration projects benefit the plant. Its population declines were caused by habitat fragmentation and destruction as a consequence of extensive hydro-engineering. This paper summarises the published material on taxonomy, morphology, habitat requirements and distribution of the species. The review is complemented by own research data and a phylogenetic assessment of extant and extinct populations within the infrageneric context. A summary on location, size and structure of the remaining populations in the north-eastern and south-eastern Alps is combined with data on seed germination and the habitat niche of the species, with a particular focus on differences between northern and southern populations. Chondrilla chondrilloides forms meta-populations on consolidated gravel bars and older terraces, with extinction and recolonisation due to floodplain dynamics; small populations quickly recover from few founder individuals. Populations in the southern parts of the species’ range are larger with bigger plants and more reproduction, while germination is very high in all populations. Thus, C. chondrilloides has characteristics that allow it to respond rapidly to degradation and restoration of its habitats along gravel rivers in the Eastern Alps.