Perspectives in Plant Ecology Evolution and Systematics最新文献

Biotic interactions are widely accepted as an important driver of ecological and evolutionary patterns, contributing to the structure of systems as diverse as tropical tree seedlings, intertidal barnacles, and wildflower-pollinator networks. Species interactions within a trophic level, such as competition and facilitation, can drive patterns of community change over time, yielding both fundamental ecological theories of succession as well as insight vital to predicting biodiversity conservation priorities. One system in which biotic interactions are poorly explored is epiphytes, or structurally dependent, non-parasitic organisms. This is a topic of broad interest because epiphytes—including vascular plants, bryophytes, and lichens—exist in practically all terrestrial ecosystems throughout the world. From lichens acting as pollution-sensitive indicator species in urbanized landscapes, to the multimillion-dollar commercial market for horticultural bromeliads, to tropical orchids representing striking examples of rapid speciation, epiphytes make substantial contributions to theory, biodiversity, ecosystem services, and the global economy. This review is the first to broadly synthesize the underlying biotic interactions important to epiphyte ecology and evolution. We first draw from theory to discuss where and when biotic or abiotic processes are likely stronger drivers of epiphyte dynamics. We then systematically review the literature across the major interaction modes, highlighting areas where different groups of epiphytes (e.g., vascular versus nonvascular) and ecosystems have contrasting patterns or expectations. Throughout, we illustrate where research efforts have focused and where large gaps in knowledge exist. Our review is organized around the major biotic interactions, rather than the specific organisms interacting with the epiphytes, to highlight general processes and set epiphytism within the framework of ecological and evolutionary theory. Our review encompasses pollination and dispersal, intratrophic facilitation and competition, mycorrhizal mutualisms, epiphyte-host interactions, parasitism and pathogens, and herbivory, focusing on the impact of these interactions on the epiphyte. Finally, we provide a simple conceptual framework distilling open questions in the field, expand our findings to the community and ecosystem level, and summarize the biodiversity conservation implications of ignoring biotic interactions in epiphytes. Our synthesis brings together currently disparate literature from tropical and temperate systems on vascular and nonvascular plants and lichens. We hope our review stimulates further research and inspires cross-disciplinary collaboration.

The highly-demanded commercial citrus fruits of family Rutaceae arose primarily through sexual hybridization between the four ancestral taxa generating a range of nothospecies. The diversity of phenotypic traits in these cultivable groups was mainly due to somatic mutations fixed either by apomixis present in Citrus species or grafting for clonal propagation, leaving behind very scanty evidence to study the process of citrus domestication apart from its genealogy. Moreover, sexual compatibility between Citrus and its related genera is another broad area of controversy leading to a continuous reformulation of citrus taxonomy and phylogeny. Although advanced genomic studies to clarify the phylogenetic relationships of citrus are in progress, a detailed overview of citrus taxonomy, diversity, origin and domestication would enhance our knowledge not only to get an evolutionary framework of citrus phylogeny but also to unravel the history of citrus domestication. Therefore, the review has been presented comprehensively with recent studies emphasizing the identification of specific reproductive, sensory and morphological markers selected as traits during the course of domestication. Hence, studies on identifying genes related to polyembryony, self-incompatibility (SI) and anthocyanin production between wild and cultivated citrus have been discussed to provide new insights on citrus apomixis, SI and citric acid reduction. Further, the correlation of pummelo introgression with fruit size and palatability in cultivable mandarins has also been focused on understanding mandarin domestication.

Seasonally Dry Tropical Forest (SDTF) is one of the most threatened ecosystems worldwide and in Colombia it is considered critically endangered according to the national red list of ecosystems. Ongoing processes of fragmentation and degradation of SDTFs are expected to be accompanied by a loss of genetic diversity of the tree populations contained in it. Identifying remaining healthy tree populations is key for the implementation of conservation and restoration programs that embrace genetic diversity to enhance the capacity of populations to adapt to environmental changes. We studied the genetic diversity and structure of Astronium graveolens, one of the most ubiquitous species in Colombian SDTFs, across ten representative populations. We assess the relevance of the dry forest refugia hypothesis (DFRH) for explaining the observed genetic structures. We identified three genetic clusters which may have originated through prolonged isolation of populations. The most diverse cluster ranges from the Caribbean region to the Chicamocha river canyon which may reflect their connectedness during the last glacial period. A second cluster likely originated through isolation in a small area enclosed in the Caribbean region. The third cluster groups populations from the Cauca and Magdalena river valleys, suggesting cross-Andean expansion of populations at one point in time, thus corroborating similar findings for other species of SDTFs. Our results add to a growing number of studies providing support for the DFRH. All the populations sampled showed heterozygosity scores close to the Hardy-Weinberg expectations, suggesting populations might be relatively resistant to habitat fragmentation. However, our suitability modelling results suggest that climate change might imperil numerous areas in SDTFs where the species occurs today, including some that hold unique genetic diversity.

Heterostyly is a polymorphism in which populations comprise two (distyly) or three (tristyly) floral morphs with reciprocal positioning of the height of the anthers and stigmas (reciprocal herkogamy). Such reciprocal herkogamy permits precise pollen placement on pollinators’ bodies and pollination success by promoting disassortative pollen transfer between floral morphs. Here, we aimed to understand how the different components of reciprocity relate to and differ from each other in distylous flowers, and whether factors, such as genus, morph-ratio variation, and corolla tube length influence the imprecisions in the sexual organs within populations. We gathered literature and original morphometrics data comprising 98 Palicourea and Psychotria populations from 44 species, the two largest distylous Rubiaceae genera, which differ in some floral features and pollination systems (hummingbirds vs. insects, respectively). We estimated reciprocity using new inaccuracy indices and standardization techniques, which allowed comparisons among a wide array of populations. Our results showed that maladaptive bias (i.e. departure from optimum reciprocity) of low organs was higher than the other decomposed inaccuracies indices tested. In addition, inaccuracy of low organs was higher than those of high organs. We did not find any relation of either genus, morph-ratio variation, or corolla tube length on general inaccuracy measurements. Apparently, pollinator-mediated selection on floral traits, imposed by different pollinators groups, did not differ markedly among the studied distylous Rubiaceae. This is the first study on inaccuracy components for such an ample array of populations and provides insights on the relative importance of morphological traits that optimize the functionality of distyly. We highlight the applicability of using standardized reciprocity indices for cross populational investigations, which may both support previous insights and reveal unknown patterns in distylous plants.

Marsilea quadrifolia L. is a leptosporangiate aquatic fern which has a played key role in the evolutionary history of plants. It is characterized by heterospory, the ancestral progressive trait that led to the evolution of seeds. The species has creeping, fleshy, adventitious roots containing multiple rhizomes. From the rhizomes a four-leaf clover grows above the water level with a long petiole, at the base of which the sporocarps containing spores are located. Its life cycle is characterized by alternation of generations; reproduction occurs either sexually or by vegetative propagation. The species grows in wet habitats containing shallow water. In the natural environment this includes lakes and small rivers; in agricultural areas it can be found in ditches and rice fields. The species can tolerate nutrient rich waters and because of its phytoremediation properties is capable of partially counteracting the negative effects induced by a moderate organic enrichment of sediments. It has been harvested for centuries in Asian countries as both a food source and for ethnobotanical use in Ayurvedic medicine. Supposed medicinal properties include antibacterial, diuretic, depurative, cytotoxic and antioxidant effects, but these require further investigation and testing.

M. quadrifolia has a widespread distribution, occurring throughout central-southern Europe and extending from Eurasia to tropical and temperate areas of eastern Asia and North America, where it is considered a non-native species. Despite its wide distribution, in its home range the species is threatened with extinction and has already been locally extirpated in several European countries. As a result, it is listed as “Vulnerable” in the European Union Red List due to its scattered distribution and declining population. Habitat loss and degradation, excessive water eutrophication, and agricultural practices such as the use of herbicides, mechanization and simplified rotation are the main threats to the species.

As it is listed in Appendix I of the Bern Convention and in Annexes II and IV of Directive 92/43/EEC as a strictly protected species, in situ and ex situ conservation activities have been conducted in most European countries. Reintroduction, cultivation in botanical gardens and in vitro propagation are the most commonly applied conservation methods.

Species-rich rocky outcrops and cliff vegetation in central Europe distributed outside alpine regions are typically associated with historical landscapes of interrelated natural and cultural features such as the Swabian Alb in Germany. Consequently, in these regions, biodiversity is highly threatened by various factors, such as land use change and increased land use intensity. In central Europe, the flagship species closely associated with these vegetation types is Cheddar Pink (Dianthus gratianopolitanus), whose total European population is declining. Herein, we exemplified a successful reintroduction experiment at two different sites at the species’ distribution center in Germany on the Swabian Alb. In total 549 individuals were reintroduced in 2017 and 2018 and monitored in the field until 2020. Using a subset of clonally replicated plants it was shown under controlled conditions in greenhouses during 2016–2019 that climate change and, in particular, increased temperature sum in late winter and during spring had a great effect on the phenology and population fitness of D. gratianopolitanus ex situ. It was demonstrated that these effects were independent of genetic variation and cultivation effects. Global climate change and increased temperature sums not only caused significant earlier flowering, but also significantly reduced number of flowers and seed set, thereby drastically affecting population viability in a negative way. We concluded that ecological micro-niches of the studied species are spatially shifting and that the germination and seedling phases will become increasingly crucial for its long-term population persistence. Our study has potential implications for future cliff management and successful long-term habitat protection strategies.

Elevation gradients of mountains serve as ideal settings to test the impact of pollinators on plant community assemblages. A shift from bird to insect-mediated pollination is expected with an increase in elevation, and such biotic shifts become more prominent in transition zones or ecotones. This shift in pollinator communities may influence plant communities if pollinators select plants with a specific set of floral traits and flowering phenology to maximize their floral resource (nectar) acquisition. However, empirical studies that examine the relative role of pollinator interactions (such as facilitation and competition) in the assembly of plant communities along elevation gradients are limited. Here we use an integrative framework combining floral traits, pollinators, flowering phenology and community phylogenetic data to reveal the relative role of facilitative and competitive interactions in the assembly of Rhododendron communities along elevation gradients in the Sikkim Himalaya. We find evidence that at lower elevations the Rhododendron community is structured by both facilitation and competition. In contrast, communities in the transition zone and at higher elevations are structured by competition alone. In lower elevations, corolla length, followed by the start of flowering phenology and nectar volume, showed significant phenotypic clustering and supported the facilitation while all other traits were overdispersed, suggesting the role of competition. Furthermore, a clustered phylogenetic structure was predominately observed at lower-elevation Rhododendron communities. In comparison, a dispersed and random phylogenetic structure was observed in the transition zone and at higher elevations. We observed greater overlap in flowering phenology and less pollinator similarity in lower elevation communities, compared to those in higher reaches.

We suggest that in the Himalaya, even at small spatial scales, indirect biotic interactions may significantly contribute to the assembly of interdependent alpine plant communities. Overall, our findings highlight the importance of considering plant-pollinator interactions as important drivers when evaluating plant community assembly processes.

Allelochemicals involved in plant-plant interaction (Allelopathy) are a potential source for alternative agrochemicals to solve the negative effects caused by synthetic herbicides. The present study is focused on the prediction and evaluation of allelopathic plants species in Saharan ecosystem from the Souf region in the southeastern of Algeria. The study was articulated through three steps of investigation: (1) a floristic survey, including a general inventory with notation of abundance and sociability scores for each species to understand the floristic composition of the study area, (2) Species co-occurrence analysis, using a presence/absence of data species in restricted sampling plots, which allowed to identify eight negatively associated species pairs with only one positive association and (3) allelopathic bioassays were performed with the aqueous extracts of the three species negatively associated species. The results showed a significant effect of aqueous extracts of Halocnemum strobilaceum (Pall.) M. Bieb, Retama raetam Forssk. Webb and Limoniastrum guyonianum Boiss on seed germination or seedling growth of target species (Lactuca sativa L., Daucus carota L., Triticum durum Desf. and Zea mays L.) at concentrations of 10 % and 15 %. H.strobilaceum showed the highest phytotoxic activity with 0% germination rate of all target species at concentration of 15 %, followed by R. raetam and L. guyonianum, and D. carota was the most sensitive target species with total inhibition of germination in most of treatments. Besides, plumule length was most affected then radicle length. It was conducted that some of these extracts may be represent a promising alternative bioherbicides from Saharan plants in agricultural and environmental management.

Forest age is a major predictor of secondary forest functional properties and through the chronosequence approach continues to be a principal focus in local, landscape, and regional-scale studies of secondary succession. Recent work has shown that patterns of temporal change in functional properties differ markedly between wet and seasonally dry lowland forests, suggesting that decreasing light and increasing water availability, respectively, are the main drivers of successional change. Meanwhile, however, the potentially marked effects of anthropogenic factors (especially fire), soils, climate, and dispersal limitation on the variation of forest characteristics over landscapes remain poorly understood. We studied the functional properties of seasonally dry secondary forests 5–35 years after pasture abandonment on the Nicoya Peninsula, Costa Rica. We measured 11 functional traits for 63 dominant tree and palm species in 52 plots of 0.12 ha. We used linear regression and variation partitioning to determine the relative importance of soil, climate, site use, fire history, spatial factors, and forest age in the determination of community weighted mean (CWM) trait values. CWM leaf trait and stem trait spectra of the 52 plots were orthogonal in a PCA ordination. Our seasonal forest hypothesis, that forest functional properties become more acquisitive with age as suggested by other authors, was not supported, perhaps because our chronosequence was relatively short. Our fire tolerance hypothesis was that bark thickness, wood specific gravity and resprouting capacity would increase with time of exposure to fires. This hypothesis was not supported for bark thickness. Rather, our results suggest that wood specific gravity and resprouting capacity are better predictors of fire tolerance. Also, our results suggest that >10 years of exposure to fire generates changes in forest fire tolerance strategies from high CWM bark thickness to high wood specific gravity. Finally, we tested our dispersal limitation hypothesis, that spatial variables, expressed as principal coordinates of neighbor matrices (PCNM) eigenfunctions, predict variation in forest functional properties, using variation partitioning analysis with matrices of climate, soil, anthropogenic and spatial variables. The results (overall model R² = 0.46) indicated that spatial variables, followed by soil (acidity, depth, and extractable Mn), are the best overall predictors of forest functional traits values, supporting this hypothesis. Overall, fire, dispersal limitation and soil characteristics explain the functional properties of these secondary forests, with no effect of age in the 5–35 years range. This indicates a critical need for sampling designs and analytical approaches that take into account all these factors to advance understanding of tropical seasonal forest recovery at the landscape scale.

Myricaria germanica (German tamarisk or false tamarisk), Tamaricaceae, is a pioneer shrub species native to the Eurasian temperate zone where it colonises gravel bars in braided rivers. Over the past 150 years, human alterations of rivers have caused its dramatic decline in Europe. This paper reviews the current state of knowledge on the taxonomy, morphology, genetics, distribution, habitat, life cycle, uses, conservation and management of this riparian species.