Abstract Interactions between plants and animals are analyzed starting from the advantages gained by animals and proceeding to those
gained exclusively by plants. These interactions are essentially of five types: 1. predation of plants by animals; 2. benevolence
of plants towards certain animals to prevent or reduce predation; 3. predation by plants (carnivorous plants); 4. symbiosis
and mutualism; 5. seduction and deception of animals by plants for dispersal of plant reproductive structures. All types of
plants are preyed on by animals, though from as far back in evolution as algae, certain plant molecules reduce or prevent
predation. In the most primitive land plants, other types of interactions beneficial for plants are encountered. More evolved
land plants (angiosperms) show all facets of the five types of interaction, whereas in prokaryotic and eukaryotic algae there
is only predation and in some cases countermeasures to avoid it. An evolutionary path leading from predation, the original
condition, to seduction, deception and carnivory, is also postulated.
Keywords Plants, Animals, Predation, Benevolence, Symbiosis, Mutualism, Pollination, Seed dispersal
Subject codes: Animal Ecology, Plant Ecology, Evolutionary Biology 相似文献
Many recent studies show that plant–pollinator interaction webs exhibit consistent structural features such as long-tailed distributions of the degree of generalization, nestedness of interactions and asymmetric interaction dependencies. Recognition of these shared features has led to a variety of mechanistic attempts at explanation. Here it is hypothesized that beside size thresholds and species abundances, the frequency distribution of sizes (nectar depths and proboscis lengths) will play a key role in determining observed interaction patterns.
Methods
To test the influence of size distributions, a new network parameter is introduced: the degree of size matching between nectar depth and proboscis length. The observed degree of size matching in a Spanish plant–pollinator web was compared with the expected degree based on joint probability distributions, integrating size thresholds and abundance, and taking the sampling method into account.
Key Results
Nectar depths and proboscis lengths both exhibited right-skewed frequency distributions across species and individuals. Species-based size matching was equally close for plants, independent of nectar depth, but differed significantly for pollinators of dissimilar proboscis length. The observed patterns were predicted well by a model considering size distributions across species. Observed size matching was closer when relative abundances of species were included, especially for flowers with openly accessible nectar and pollinators with long proboscises, but was predicted somewhat less successfully by the model that included abundances.
Conclusions
The results suggest that in addition to size thresholds and species abundances, size distributions are important for understanding interaction patterns in plant–pollinator webs. It is likely that the understanding will be improved further by characterizing for entire communities how nectar production of flowers and energetic requirements of pollinators covary with size, and how sampling methods influence the observed interaction patterns.Key words: Plant–pollinator community, flower morphology, generalization, nectar, pollination network, body size, size matching, specialization相似文献
The continuing spread of exotic plants and increasing human land-use are two major drivers of global change threatening ecosystems, species and their interactions. Separate effects of these two drivers on plant–pollinator interactions have been thoroughly studied, but we still lack an understanding of combined and potential interactive effects. In a subtropical South African landscape, we studied 17 plant–pollinator networks along two gradients of relative abundance of exotics and land-use intensity. In general, pollinator visitation rates were lower on exotic plants than on native ones. Surprisingly, while visitation rates on native plants increased with relative abundance of exotics and land-use intensity, pollinator visitation on exotic plants decreased along the same gradients. There was a decrease in the specialization of plants on pollinators and vice versa with both drivers, regardless of plant origin. Decreases in pollinator specialization thereby seemed to be mediated by a species turnover towards habitat generalists. However, contrary to expectations, we detected no interactive effects between the two drivers. Our results suggest that exotic plants and land-use promote generalist plants and pollinators, while negatively affecting specialized plant–pollinator interactions. Weak integration and high specialization of exotic plants may have prevented interactive effects between exotic plants and land-use. Still, the additive effects of exotic plants and land-use on specialized plant–pollinator interactions would have been overlooked in a single-factor study. We therefore highlight the need to consider multiple drivers of global change in ecological research and conservation management. 相似文献
Conservatism in species interaction, meaning that related species tend to interact with similar partners, is an important feature of ecological interactions. Studies at community scale highlight variations in conservatism strength depending on the characteristics of the ecological interaction studied. However, the heterogeneity of datasets and methods used prevent to compare results between mutualistic and antagonistic networks. Here we perform such a comparison by taking plant–insect communities as a study case, with data on plant–herbivore and plant–pollinator networks. Our analysis reveals that plants acting as resources for herbivores exhibit the strongest conservatism in species interaction among the four interacting groups. Conservatism levels are similar for insect pollinators, insect herbivores and plants as interacting partners of pollinators, although insect pollinators tend to have a slightly higher conservatism than the two others. Our results thus clearly support the current view that within antagonistic networks, conservatism is stronger for species as resources than for species as consumer. Although the pattern tends to be opposite for plant–pollinator networks, our results suggest that asymmetry in conservatism is much less pronounced between the pollinators and the plant they interact with. We discuss these differences in conservatism strength in relation with the processes structuring plant–insect communities. 相似文献
An understanding of the diversity spatial organization in plant communities provides essential information for management and conservation planning. In this study we investigated, using a multi-species approach, how plant–plant interactions determine the local structure and composition of diversity in a set of Mediterranean plant communities, ranging from semi-arid to subalpine habitats. Specifically, we evaluated the spatial pattern of diversity (i.e., diversity aggregation or segregation) in the local neighborhood of perennial plant species using the ISAR (individual species–area relationship) method. We also assessed the local pattern of beta-diversity (i.e., the spatial heterogeneity in species composition among local assemblages), including the contribution of species turnover (i.e., species replacement) and nestedness (i.e., differences in species richness) to the overall local beta-diversity. Our results showed that local diversity segregation decreased in the less productive plant communities. Also, we found that graminoids largely acted as diversity segregators, while forbs showed more diverse neighborhoods than expected in less productive study sites. Interestingly, not all shrub and dwarf shrub species aggregated diversity in their surroundings. Finally, an increase in nestedness was associated with less segregated diversity patterns in the local neighborhood of shrub species, underlining their role in creating diversity islands in less productive environmental conditions. Our results provide further insights into the effect of plant–plant interactions in shaping the structure and composition of diversity in Mediterranean plant communities, and highlight the species and groups of species that management and conservation strategies should focus on in order to prevent a loss of biodiversity.
The biodiversity of tropical reefs is typified by the interaction between fishes and corals. Despite the importance of this ecological association, coevolutionary patterns between these two animal groups have yet to be critically evaluated. After compiling a large dataset on the prevalence of fish–coral interactions, we found that only a minority of fish species associate strongly with live corals (~5%). Furthermore, we reveal an evolutionary decoupling between fish and coral lineage trajectories. While fish lineages expanded in the Miocene, the bulk of coral diversification occurred in the Pliocene/Pleistocene. Most importantly, we found that coral association did not drive major differences in fish diversification. These results suggest that the Miocene fish diversification is more likely related to the development of novel, wave-resistant reef structures and their associated ecological opportunities. Macroevolutionary patterns in reef fishes are thus more strongly correlated with the expansion of reefs than with the corals themselves. 相似文献
Plants display a wide range of traits that allow them to use animals for vital tasks. To attract and reward aggressive ants that protect developing leaves and flowers from consumers, many plants bear extrafloral nectaries (EFNs). EFNs are exceptionally diverse in morphology and locations on a plant. In this study the evolution of EFN diversity is explored by focusing on the legume genus Senna, in which EFNs underwent remarkable morphological diversification and occur in over 80 % of the approx. 350 species.
Methods
EFN diversity in location, morphology and plant ontogeny was characterized in wild and cultivated plants, using scanning electron microscopy and microtome sectioning. From these data EFN evolution was reconstructed in a phylogenetic framework comprising 83 Senna species.
Key Results
Two distinct kinds of EFNs exist in two unrelated clades within Senna. ‘Individualized’ EFNs (iEFNs), located on the compound leaves and sometimes at the base of pedicels, display a conspicuous, gland-like nectary structure, are highly diverse in shape and characterize the species-rich EFN clade. Previously overlooked ‘non-individualized’ EFNs (non-iEFNs) embedded within stipules, bracts, and sepals are cryptic and may represent a new synapomorphy for clade II. Leaves bear EFNs consistently throughout plant ontogeny. In one species, however, early seedlings develop iEFNs between the first pair of leaflets, but later leaves produce them at the leaf base. This ontogenetic shift reflects our inferred diversification history of iEFN location: ancestral leaves bore EFNs between the first pair of leaflets, while leaves derived from them bore EFNs either between multiple pairs of leaflets or at the leaf base.
Conclusions
EFNs are more diverse than previously thought. EFN-bearing plant parts provide different opportunities for EFN presentation (i.e. location) and individualization (i.e. morphology), with implications for EFN morphological evolution, EFN–ant protective mutualisms and the evolutionary role of EFNs in plant diversification. 相似文献
Previous syntheses on the effects of environmental conditions on the outcome of plant–plant interactions summarize results from pairwise studies. However, the upscaling to the community-level of such studies is problematic because of the existence of multiple species assemblages and species-specific responses to both the environmental conditions and the presence of neighbors. We conducted the first global synthesis of community-level studies from harsh environments, which included data from 71 alpine and 137 dryland communities to: (i) test how important are facilitative interactions as a driver of community structure, (ii) evaluate whether we can predict the frequency of positive plant–plant interactions across differing environmental conditions and habitats, and (iii) assess whether thresholds in the response of plant–plant interactions to environmental gradients exists between “moderate” and “extreme” environments. We also used those community-level studies performed across gradients of at least three points to evaluate how the average environmental conditions, the length of the gradient studied, and the number of points sampled across such gradient affect the form and strength of the facilitation-environmental conditions relationship. Over 25% of the species present were more spatially associated to nurse plants than expected by chance in both alpine and dryland areas, illustrating the high importance of positive plant–plant interactions for the maintenance of plant diversity in these environments. Facilitative interactions were more frequent, and more related to environmental conditions, in alpine than in dryland areas, perhaps because drylands are generally characterized by a larger variety of environmental stress factors and plant functional traits. The frequency of facilitative interactions in alpine communities peaked at 1000 mm of annual rainfall, and globally decreased with elevation. The frequency of positive interactions in dryland communities decreased globally with water scarcity or temperature annual range. Positive facilitation-drought stress relationships are more likely in shorter regional gradients, but these relationships are obscured in regions with a greater species turnover or with complex environmental gradients. By showing the different climatic drivers and behaviors of plant–plant interactions in dryland and alpine areas, our results will improve predictions regarding the effect of facilitation on the assembly of plant communities and their response to changes in environmental conditions. 相似文献
Defence against abiotic and biotic stresses is crucial for the fitness and survival of plants under adverse or suboptimal
growth conditions. The phytohormone abscisic acid (ABA) is not only important for mediating abiotic stress responses, but
also plays a multifaceted and pivotal role in plant immunity. This review presents examples demonstrating the importance of
crosstalk between ABA and the key biotic stress phytohormone salicylic acid in determining the outcome of plant–pathogen interactions.
We then provide an overview of how ABA influences plant defence responses against various phytopathogens with particular emphasis
on the Arabidopsis–Pseudomonas syringae model pathosystem. Lastly, we discuss future directions for studies of ABA in plant immunity with emphasis on, its role in
the crosstalk between biotic and abiotic stress responses, the importance of distinguishing direct and indirect effects of
ABA, as well as the prospect of utilizing the recently elucidated core ABA signaling network to gain further insights into
the roles of ABA in plant immunity. 相似文献
Two pot experiments were conducted to examine three-level interactions between host plants, mycorrhizal fungi and parasitic
plants. In a greenhouse experiment, Poa annua plants were grown in the presence or absence of an AM fungus (either Glomus lamellosum V43a or G. mosseae BEG29) and in the presence or absence of a root hemiparasitic plant (Odontites vulgaris). In a laboratory experiment, mycorrhizal infection (Glomus claroideum BEG31) of Trifolium pratense host plants (mycorrhizal versus non-mycorrhizal) was combined with hemiparasite infection (Rhinanthus serotinus) of the host (parasitized versus non-parasitized). Infection with the two species of Glomus had no significant effect on the growth of P. annua, while hemiparasite infection caused a significant reduction in host biomass. Mycorrhizal status of P. annua hosts (i.e. presence/absence of AM fungus) affected neither the biomass nor the number of flowers produced by the attached O. vulgaris plants. Infection with G. claroideum BEG31 greatly increased the biomass of T. pratense, but hemiparasite infection had no effect. The hemiparasitic R. serotinus plants attached to mycorrhizal hosts had higher biomass and produced more flowers than plants growing with non-mycorrhizal
hosts. Roots of T. pratense were colonized by the AM fungus to an extent independent of the presence or absence of the hemiparasite. Our results confirm
earlier findings that the mycorrhizal status of a host plant can affect the performance of an attached root hemiparasite.
However, improvement of the performance of the parasitic plant following attachment to a mycorrhizal host depends on the extent
to which the AM fungi is able to enhance the growth of the host.
Accepted: 23 February 2001 相似文献
The 104 kb genome of cold-active bacteriophage 9A, which replicates in the marine psychrophilic gamma-proteobacterium Colwellia psychrerythraea strain 34H (between ?12 and 8 °C), was sequenced and analyzed to investigate elements of molecular adaptation to low temperature and phage?Chost interactions in the cold. Most characterized ORFs indicated closest similarity to gamma-proteobacteria and their phages, though no single module provided definitive phylogenetic grouping. A subset of primary structural features linked to psychrophily suggested that the majority of annotated phage proteins were not psychrophilic; those that were, primarily serve phage-specific functions and may also contribute to 9A??s restricted temperature range for replication as compared to host. Comparative analyses suggest ribonucleotide reductase genes were acquired laterally from host. Neither restriction modification nor the CRISPR-Cas system appeared to be the predominant phage defense mechanism of Cp34H or other cold-adapted bacteria; we hypothesize that psychrophilic hosts rely more on the use of extracellular polymeric material to block cell surface receptors recognized by phages. The relative dearth of evidence for genome-specific defenses, genetic transfer events or auxiliary metabolic genes suggest that the 9A-Cp34H system may be less tightly coupled than are other genomically characterized marine phage?Chost systems, with possible implications for phage specificity under different environmental conditions. 相似文献
<正>Plants have to overcome different types of environment stress including various insect and pathogen attacks during their life cycle. With long-term evolution, plants have developed sophisticated systems to recognize different biotic attacks and initiate an integrated defense network for survival. On the other hand, pathogens and insects have devised multiple strategies to adapt to their host plants. In the past 相似文献
When the chimpanzee genome sequence was released, human deleterious alleles associated with simple mendelian diseases were observed as wild-type alleles in six genes (AIRE, MKKS, MLH1, MYOC, OTC and PRSS1). The absence of recognizable phenotypic effects in chimpanzee, contrary to the clinical effect observed in humans, is attributed to epistatic interactions (compensation) between potentially deleterious and compensatory alleles. In this report we investigate the possible evolutionary histories by which substitution of alternative variants in these six genes either ameliorates or avoids pathological consequences. 相似文献
Spatial patterns of plant species are determined by an array of ecologica factors including biotic and abiotic environmental constraints and intrinsic species traits. Thus, an observed aggregated pattern may be the result of short‐distance dispersal, the presence of habitat heterogeneity, plant–plant interactions or a combination of the above. Here, we studied the spatial pattern of Mediterranean alpine plant Silene ciliata (Caryophyllaceae) in five populations and assessed the contribution of dispersal, habitat heterogeneity and conspecific plant interactions to observed patterns. For this purpose, we used spatial point pattern analysis combined with specific a priori hypotheses linked to spatial pattern creation. The spatial pattern of S. ciliata recruits was not homogeneous and showed small‐scale aggregation. This is consistent with the species’ short‐distance seed dispersal and the heterogeneous distribution of suitable sites for germination and establishment. Furthermore, the spatial pattern of recruits was independent of the spatial pattern of adults. This suggests a low relevance of adult‐recruits interactions in the spatial pattern creation. The difference in aggregation between recruits and adults suggests that once established, recruits are subjected to self‐thinning. However, seedling mortality did not erase the spatial pattern generated by seed dispersal, as S. ciliata adults were still aggregated. Thus, the spatial aggregation of adults is probably due to seed dispersal limitation and the heterogeneous distribution of suitable sites at seedling establishment rather than the presence of positive plant–plant interactions at the adult stage. In fact, a negative density‐dependent effect of the conspecific neighbourhood was found on adult reproductive performance. Overall, results provide empirical evidence of the lack of a simple and direct relationship between the spatial structure of plant populations and the sign of plant–plant interactions and outline the importance of considering dispersal and habitat heterogeneity when performing spatial analysis assessments. 相似文献