scholarly journals Positive interactions support complex networks

2017 ◽  
Author(s):  
Gianalberto Losapio ◽  
Marcelino de la Cruz ◽  
Adrián Escudero ◽  
Bernhard Schmid ◽  
Christian Schöb
Keyword(s):  
Complex Networks ◽  
Network Architecture ◽  
Biotic Interactions ◽  
Positive Interactions ◽  
Plant Interactions ◽  
Network Analyses ◽  
Environmental Perturbations ◽  
Alpine Plant Communities ◽  
The Face ◽  
Living Organisms

Ecologists have recognised the effects of biotic interactions on the spatial distribution of living organisms. Yet, the spatial structure of plant interaction networks in real-world ecosystems has remained elusive so far. Using spatial pattern and network analyses, we found that alpine plant communities are organised in spatially variable and complex networks. Specifically, the cohesiveness of complex networks is promoted by short-distance positive plant interactions. At fine spatial scale, where positive mutual interactions prevailed, networks were characterised by a large connected component. With increasing scale, when negative interactions took over, network architecture became more hierarchical with many detached components that show a network collapse. This study highlights the crucial role of positive interactions for maintaining species diversity and the resistance of communities in the face of environmental perturbations.

scholarly journals Do interactions between plant and soil biota change with elevation? A study on Fagus sylvatica

2011 ◽  
Vol 7 (5) ◽  
pp. 699-701 ◽  
Author(s):  
Emmanuel Defossez ◽  
Benoît Courbaud ◽  
Benoît Marcais ◽  
Wilfried Thuiller ◽  
Elena Granda ◽  
...  
Keyword(s):  
Fagus Sylvatica ◽  
Elevation Gradient ◽  
Biotic Interactions ◽  
Theoretical Models ◽  
Tree Regeneration ◽  
Soil Biota ◽  
Positive Interactions ◽  
Plant Interactions ◽  
Tree Survival ◽  
Plant Plant

Theoretical models predict weakening of negative biotic interactions and strengthening of positive interactions with increasing abiotic stress. However, most empirical tests have been restricted to plant–plant interactions. No empirical study has examined theoretical predictions of interactions between plants and below-ground micro-organisms, although soil biota strongly regulates plant community composition and dynamics. We examined variability in soil biota effects on tree regeneration across an abiotic gradient. Our candidate tree species was European beech ( Fagus sylvatica L.), whose regeneration is extremely responsive to soil biota activity. In a greenhouse experiment, we measured tree survival in sterilized and non-sterilized soils collected across an elevation gradient in the French Alps. Negative effects of soil biota on tree survival decreased with elevation, similar to shifts observed in plant–plant interactions. Hence, soil biota effects must be included in theoretical models of plant biotic interactions to accurately represent and predict the effects of abiotic gradient on plant communities.

Nitric oxide signalling in plant interactions with pathogenic fungi and oomycetes

2020 ◽  
Author(s):  
Tereza Jedelská ◽  
Lenka Luhová ◽  
Marek Petřivalský
Keyword(s):  
Nitric Oxide ◽  
Current Knowledge ◽  
Biotic Interactions ◽  
Decisive Role ◽  
Pathogenic Fungi ◽  
Plant Colonization ◽  
No Production ◽  
Plant Interactions ◽  
Oriented Growth ◽  
Plant Pathogen Interactions

Abstract Nitric oxide (NO) and reactive nitrogen species have emerged as crucial signalling and regulatory molecules across all organisms. In plants, fungi and fungi-like oomycetes, NO is involved in the regulation of multiple processes during their growth, development, reproduction, responses to the external environment and biotic interactions. It has become evident that NO is produced and used as signalling and defence cues by both partners in multiple forms of plant interactions with their microbial counterparts, ranging from symbiotic to pathogenic modes. This review summarizes current knowledge on NO role in plant-pathogen interactions, focused on biotrophic, necrotrophic and hemibiotrophic fungi and oomycetes. Actual advances and gaps in the identification of NO sources and fate in plant and pathogen cells are discussed. We review the decisive role of time- and site-specific NO production in germination, oriented growth and active penetration of filamentous pathogens to the host tissues, as well in pathogen recognition, and defence activation in plants. Distinct functions of NO are highlighted on diverse interactions of host plants with fungal and oomycete pathogens of different lifestyles, where NO in interplay with reactive oxygen species govern successful plant colonization, cell death and resistance establishment.

scholarly journals Adaptation of turnip mosaic potyvirus to a specific niche reduces its genetic and environmental robustness

2020 ◽  
Vol 6 (2) ◽  
Author(s):  
Anamarija Butković ◽  
Rubén González ◽  
Inés Cobo ◽  
Santiago F Elena
Keyword(s):  
Mutation Rates ◽  
Permissive Temperature ◽  
Fitness Component ◽  
Temperature Conditions ◽  
Environmental Perturbations ◽  
Genetic Robustness ◽  
Congruence Theory ◽  
The Face ◽  
Environmental Robustness ◽  
Two Sides

Abstract Robustness is the preservation of the phenotype in the face of genetic and environmental perturbations. It has been argued that robustness must be an essential fitness component of RNA viruses owed to their small and compacted genomes, high mutation rates and living in ever-changing environmental conditions. Given that genetic robustness might hamper possible beneficial mutations, it has been suggested that genetic robustness can only evolve as a side-effect of the evolution of robustness mechanisms specific to cope with environmental perturbations, a theory known as plastogenetic congruence. However, empirical evidences from different viral systems are contradictory. To test how adaptation to a particular environment affects both environmental and genetic robustness, we have used two strains of turnip mosaic potyvirus (TuMV) that differ in their degree of adaptation to Arabidopsis thaliana at a permissive temperature. We show that the highly adapted strain is strongly sensitive to the effect of random mutations and to changes in temperature conditions. In contrast, the non-adapted strain shows more robustness against both the accumulation of random mutations and drastic changes in temperature conditions. Together, these results are consistent with the predictions of the plastogenetic congruence theory, suggesting that genetic and environmental robustnesses may be two sides of the same coin for TuMV.

scholarly journals Ant–plant interactions evolved through increasing interdependence

2018 ◽  
Vol 115 (48) ◽  
pp. 12253-12258 ◽  
Author(s):  
Matthew P. Nelsen ◽  
Richard H. Ree ◽  
Corrie S. Moreau
Keyword(s):  
Biotic Interactions ◽  
Extrafloral Nectaries ◽  
Food Sources ◽  
Intermediate Step ◽  
Plant Interactions ◽  
Dietary Transition ◽  
Ecological Dominance

Ant–plant interactions are diverse and abundant and include classic models in the study of mutualism and other biotic interactions. By estimating a time-scaled phylogeny of more than 1,700 ant species and a time-scaled phylogeny of more than 10,000 plant genera, we infer when and how interactions between ants and plants evolved and assess their macroevolutionary consequences. We estimate that ant–plant interactions originated in the Mesozoic, when predatory, ground-inhabiting ants first began foraging arboreally. This served as an evolutionary precursor to the use of plant-derived food sources, a dietary transition that likely preceded the evolution of extrafloral nectaries and elaiosomes. Transitions to a strict, plant-derived diet occurred in the Cenozoic, and optimal models of shifts between strict predation and herbivory include omnivory as an intermediate step. Arboreal nesting largely evolved from arboreally foraging lineages relying on a partially or entirely plant-based diet, and was initiated in the Mesozoic, preceding the evolution of domatia. Previous work has suggested enhanced diversification in plants with specialized ant-associated traits, but it appears that for ants, living and feeding on plants does not affect ant diversification. Together, the evidence suggests that ants and plants increasingly relied on one another and incrementally evolved more intricate associations with different macroevolutionary consequences as angiosperms increased their ecological dominance.

scholarly journals Phenotypic states become increasingly sensitive to perturbations near a bifurcation in a synthetic gene network

eLife ◽  
2015 ◽  
Vol 4 ◽  
Author(s):  
Kevin Axelrod ◽  
Alvaro Sanchez ◽  
Jeff Gore
Keyword(s):  
Gene Network ◽  
Environmental Variability ◽  
Synthetic Gene ◽  
Phenotypic Switching ◽  
Proper Function ◽  
Critical Transition ◽  
Environmental Perturbations ◽  
The Face ◽  
Synthetic Gene Network ◽  
Open Question

Microorganisms often exhibit a history-dependent phenotypic response after exposure to a stimulus which can be imperative for proper function. However, cells frequently experience unexpected environmental perturbations that might induce phenotypic switching. How cells maintain phenotypic states in the face of environmental fluctuations remains an open question. Here, we use environmental perturbations to characterize the resilience of phenotypic states in a synthetic gene network near a critical transition. We find that far from the critical transition an environmental perturbation may induce little to no phenotypic switching, whereas close to the critical transition the same perturbation can cause many cells to switch phenotypic states. This loss of resilience was observed for perturbations that interact directly with the gene circuit as well as for a variety of generic perturbations-such as salt, ethanol, or temperature shocks-that alter the state of the cell more broadly. We obtain qualitatively similar findings in natural gene circuits, such as the yeast GAL network. Our findings illustrate how phenotypic memory can become destabilized by environmental variability near a critical transition.

scholarly journals MODELING THE SPATIAL DISTRIBUTION OF ESHNAN (SEIDLITZIA ROSMARINUS) SHRUBS TO EXPLORING THEIR ECOLOGICAL INTERACTIONS IN DRYLANDS OF CENTRAL IRAN

2015 ◽  
Vol XL-1-W5 ◽  
pp. 163-168 ◽  
Author(s):  
Y. Erfanifard ◽  
E. Khosravi
Keyword(s):  
Distribution Function ◽  
Spatial Distribution ◽  
Pair Correlation ◽  
Central Iran ◽  
Arid Ecosystems ◽  
Positive Interactions ◽  
Distribution Analysis ◽  
Summary Statistics ◽  
Plant Interactions ◽  
Intraspecific Interactions

Evaluating the interactions of woody plants has been a major research topic of ecological investigations in arid ecosystems. Plant-plant interactions can shift from positive (facilitation) to negative (competition) depending on levels of environmental stress and determine the spatial pattern of plants. The spatial distribution analysis of plants via different summary statistics can reveal the interactions of plants and how they influence one another. An aggregated distribution indicates facilitative interactions among plants, while dispersion of species reflects their competition for scarce resources. This study was aimed to explore the intraspecific interactions of eshnan (<i>Seidlitzia rosmarinus</i>) shrubs in arid lands, central Iran, using different summary statistics (i.e., pair correlation function g(<i>r</i>), O-ring function O(<i>r</i>), nearest neighbour distribution function D(<i>r</i>), spherical contact distribution function Hs(<i>r</i>)). The observed pattern of shrubs showed significant spatial heterogeneity as compared to inhomogeneous Poisson process (α=0.05). The results of g(<i>r</i>) and O(<i>r</i>) revealed the significant aggregation of eshnan shrubs up to scale of 3 m (α=0.05). The results of D(<i>r</i>) and Hs(<i>r</i>) also showed that maximum distance to nearest shrub was 6 m and the distribution of the sizes of gaps was significantly different from random distribution up to this spatial scale. In general, it was concluded that there were positive interactions between eshnan shrubs at small scales and they were aggregated due to their intraspecific facilitation effects in the study area.

scholarly journals The geographic scaling of biotic interactions

2013 ◽  
Author(s):  
Miguel B Araújo ◽  
Alejandro Rozenfeld
Keyword(s):  
Biotic Interactions ◽  
Species Distributions ◽  
Scale Dependence ◽  
Positive Interactions ◽  
Ample Evidence ◽  
Species Ranges ◽  
Central Tenet ◽  
Resource Interactions ◽  
Occurrence Patterns ◽  
Consumer Resource

A central tenet of ecology and biogeography is that the broad outlines of species ranges are determined by climate, whereas the effects of biotic interactions are manifested at local scales. While the first proposition is supported by ample evidence, the second is still a matter of controversy. To address this question, we develop a mathematical model that predicts the spatial overlap, i.e., co-occurrence, between pairs of species subject to all possible types of interactions. We then identify the scale in which predicted range overlaps are lost. We found that co-occurrence arising from positive interactions, such as mutualism (+/+) and commensalism (+/0), are manifested across scales of resolution. Negative interactions, such as competition (-/-) and amensalism (-/0), generate checkerboard-type co-occurrence patterns that are discernible at finer resolutions. Scale dependence in consumer-resource interactions (+/-) depends on the strength of positive dependencies between species. Our results challenge the widely held view that climate alone is sufficient to characterize species distributions at broad scales, but also demonstrate that the spatial signature of competition is unlikely to be discernible beyond local and regional scales.

Beneficial interactions in communities: mutualism and facilitation

2019 ◽  
pp. 158-176
Author(s):  
Gary G. Mittelbach ◽  
Brian J. McGill
Keyword(s):  
Mycorrhizal Fungi ◽  
Population Growth Rate ◽  
Context Dependency ◽  
Positive Interactions ◽  
Costs And Benefits ◽  
Negative Effects ◽  
Biological Markets ◽  
The Face ◽  
Community Theory ◽  
Competition For Resources

The consequences of beneficial interactions for the diversity and functioning of communities remain poorly understood, but this is changing. This chapter examines how mutualism may evolve in the face of cheating, using the concept of biological markets where members of each species exchange resources and services, with associated costs and benefits. Understanding the evolution and maintenance of positive interactions in communities requires that we consider the broader web of interactions and abiotic conditions in which mutualisms are embedded—their context dependency. Ant-plant mutualisms, plant-Rhizobium mutualisms, and plant-mycorrhizal fungi mutualisms are discussed as examples of shifting costs and benefits based on context dependency. Recent advances at incorporating positive interactions into community theory allow species to have both positive and negative effects on each other’s population growth rate. For example, the presence of a neighboring plant may enhance survival in a harsh environment, but may reduce plant growth due to competition for resources.

scholarly journals Biotic rescaling reveals importance of species interactions for variation in biodiversity responses to climate change

2020 ◽  
Vol 117 (37) ◽  
pp. 22858-22865 ◽  
Author(s):  
Vigdis Vandvik ◽  
Olav Skarpaas ◽  
Kari Klanderud ◽  
Richard J. Telford ◽  
Aud H. Halbritter ◽  
...  
Keyword(s):  
Climate Change ◽  
Species Interactions ◽  
Community Dynamics ◽  
Biotic Interactions ◽  
Plant Interactions ◽  
Climate Gradients ◽  
Climate Change Responses ◽  
Local Extinctions ◽  
Future Work ◽  
Underlying Processes

Generality in understanding biodiversity responses to climate change has been hampered by substantial variation in the rates and even directions of response to a given change in climate. We propose that such context dependencies can be clarified by rescaling climate gradients in terms of the underlying biological processes, with biotic interactions as a particularly important process. We tested this rescaling approach in a replicated field experiment where entire montane grassland communities were transplanted in the direction of expected temperature and/or precipitation change. In line with earlier work, we found considerable variation across sites in community dynamics in response to climate change. However, these complex context dependencies could be substantially reduced or eliminated by rescaling climate drivers in terms of proxies of plant−plant interactions. Specifically, bryophytes limited colonization by new species into local communities, whereas the cover of those colonists, along with bryophytes, were the primary drivers of local extinctions. These specific interactions are relatively understudied, suggesting important directions for future work in similar systems. More generally, the success of our approach in explaining and simplifying landscape-level variation in climate change responses suggests that developing and testing proxies for relevant underlying processes could be a fruitful direction for building more general models of biodiversity response to climate change.

Biotic Interactions in the Face of Climate Change

2012 ◽  
pp. 321-349 ◽  
Author(s):  
Ellen Gellesch ◽  
Roman Hein ◽  
Anja Jaeschke ◽  
Carl Beierkuhnlein ◽  
Anke Jentsch
Keyword(s):  
Climate Change ◽  
Biotic Interactions ◽  
The Face
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