domingo, 13 de junio de 2021

Reinterpreting the relationship between number of species and number of links connects community structure and stability  

Carpentier et al., 2021

For 50 years, ecologists have examined how the number of interactions (links) scales with the number of species in ecological networks. Here, we show that the way the number of links varies when species are sequentially removed from a community is fully defined by a single parameter identifiable from empirical data. We mathematically demonstrate that this parameter is network-specific and connects local stability and robustness, establishing a formal connection between community structure and two prime stability concepts. Importantly, this connection highlights a local stability–robustness trade-off, which is stronger in mutualistic than in trophic networks. Analysis of 435 empirical networks confirmed these results. We finally show how our network-specific approach relates to the classical across-network approach found in literature. Taken together, our results elucidate one of the intricate relationships between network structure and stability in community networks.


lunes, 7 de junio de 2021

Plant holobiont interactions mediated by the type VI secretion system and the membrane vesicles: promising tools for a greener agriculture 

José Manuel Borrero de Acuña Patricia Bernal, 2021

A deeper understanding of the complex relationship between plants and their microbiota is allowing researchers to appreciate a plethora of possibilities to improve crops using chemical‐free alternatives based on beneficial microorganisms. An increase in crop yield from the promotion of plant growth or even simultaneous protection of the plants from the attack of phytopathogens can be achieved in the presence of different plant‐associated microorganisms known as plant‐growth‐promoting rhizobacteria (PGPR) and biocontrol agents (BCAs), respectively. Thus, the study of the great diversity of plant‐microbe and microbe‐microbe interactions is an attention‐grabbing topic covering studies of interactions since the plant seed and through all developmental stages, from root to shoot. The intricate communication systems that plant holobionts co‐evolved has resulted in many different strategies and interplays between these organisms shaping the bacterial communities and the plant fitness simultaneously. Herein, we emphasize two understudied delivery systems existing in plant‐associated bacteria: the type VI secretion system (T6SS) and the membrane vesicles with a huge potential to boost a highly demanded and necessary green agriculture. 


martes, 1 de junio de 2021

Coordination of microbe–host homeostasis by crosstalk with plant innate immunity     

Ma et al., 2021.

Plants grown in natural soil are colonized by phylogenetically structured communities of microbes known as the microbiota. Individual microbes can activate microbe-associated molecular pattern (MAMP)-triggered immunity (MTI), which limits pathogen proliferation but curtails plant growth, a phenomenon known as the growth–defence trade-off. Here, we report that, in monoassociations, 41% (62 out of 151) of taxonomically diverse root bacterial commensals suppress Arabidopsis thaliana root growth inhibition (RGI) triggered by immune-stimulating MAMPs or damage-associated molecular patterns. Amplicon sequencing of bacterial 16S rRNA genes reveals that immune activation alters the profile of synthetic communities (SynComs) comprising RGI-non-suppressive strains, whereas the presence of RGI-suppressive strains attenuates this effect. Root colonization by SynComs with different complexities and RGI-suppressive activities alters the expression of 174 core host genes, with functions related to root development and nutrient transport. Furthermore, RGI-suppressive SynComs specifically downregulate a subset of immune-related genes. Precolonization of plants with RGI-suppressive SynComs, or mutation of one commensal-downregulated transcription factor, MYB15, renders the plants more susceptible to opportunistic Pseudomonas pathogens. Our results suggest that RGI-non-suppressive and RGI-suppressive root commensals modulate host susceptibility to pathogens by either eliciting or dampening MTI responses, respectively. This interplay buffers the plant immune system against pathogen perturbation and defence-associated growth inhibition, ultimately leading to commensal–host homeostasis.


jueves, 27 de mayo de 2021


«Dime lo que comes y te diré lo que eres»

[Dis-moi ce que tu manges, je te dirai ce que tu es] Jean Anthelme Brillat-Savarin (1755-1826)


miércoles, 26 de mayo de 2021

Landscape complexity and US crop production  

Katherine S. Nelson & Emily K. Burchfield, 2021.

Agricultural expansion and intensification have simplified Earth’s landscapes, thereby adversely affecting the biodiversity and ecosystem services that support agricultural production. Field-scale research suggests that increased landcover complexity can improve crop productivity, but less is known about how complexity and crop productivity interact at broader landscape scales. This study evaluates the relationship between landscape complexity and crop yields for counties in the conterminous United States from 2008 to 2018. Our results suggest that the number and quantity of landcover categories on a landscape has a stronger influence on yields than how these landcover categories are arranged on the landscape. Specifically, increased landcover diversity is associated with yield increases for corn and wheat of more than 10%—an effect strength similar to the impact of seasonal precipitation and soil suitability. Notably, landscape configurations that are both moderately complex and also highly diverse are associated with yield increases of more than 20% for corn and wheat. Our findings suggest that increasing the complexity of landcover may provide a way to improve crop productivity in the United States without further extensification or intensification of agriculture.


sábado, 22 de mayo de 2021

lunes, 17 de mayo de 2021

Individual‐based plant‐pollinator networks are structured by phenotypic and microsite plant traits 

Arroyo‐Correa et al., 2021

  1. The biotic and abiotic context of individual plants within animal‐pollinated plant populations can influence pollinator foraging behavior. Pollinator movements regulate pollen flow among plant individuals, and ultimately determine individual plant reproductive success. Yet the underlying drivers of this context‐dependency of interactions at the population level and their functional consequences for individuals remain poorly known.
  2. Here we used a well‐characterised population of Halimium halimifolium (Cistaceae), a Mediterranean shrub species, in combination with exponential random graph models (ERGMs) to evaluate how the intrapopulation variation in plant attributes configures individual‐based plant‐pollinator networks and determines their reproductive outcomes. Specifically, we assessed (i) how the intrinsic (i.e., phenotype and phenology) and extrinsic (i.e., microsite) plant attributes influenced the emerging configuration of the bipartite plant‐pollinator network and the unipartite plant‐plant network derived from pollinator sharing, and (ii) how these plant attributes combined with the network topological position of individual plants affect their female fitness, measured as the total seed weight per plant.
  3. We found that both intrinsic and extrinsic plant attributes contributed substantially to explain the configuration of both the bipartite and the unipartite pollination network. Besides the effects of plant attributes, the functional group to which pollinator species belonged was also important to determine the variance in plant‐pollinator interaction odds, while the probability of plants to share more pollinator species was additionally influenced by the spatial distance between those plants. Further, our results showed that these influences of plant attributes on network structure can be translated into functional outcomes at the plant individual level, with direct consequences for intrapopulation fitness variation.
  4. Synthesis. This study builds towards a better understanding of the multiple drivers underlying the context‐dependency of plant‐pollinator interactions and how they mediate the reproductive outputs for individual plants within a population. The application of our analytical framework allows a conceptual shift from descriptive to predictive research on the evolutionary and ecological processes that give rise to complex ecological networks at the population level. 


miércoles, 12 de mayo de 2021

May Flower

Emily Dickinson 

Pink, small, and punctual,

Aromatic, low,

Covert in April,

Candid in May,

Dear to the moss,

Known by the knoll,

Next to the robin

In every human soul.

Bold little beauty,

Bedecked with thee,

Nature forswears


sábado, 8 de mayo de 2021

Network motifs involving both competition and facilitation predict biodiversity in alpine plant communities 

Losapio et al., 2021

Biological diversity depends on multiple, cooccurring ecological interactions. However, most studies focus on one interaction type at a time, leaving community ecologists unsure of how positive and negative associations among species combine to influence biodiversity patterns. Using surveys of plant populations in alpine communities worldwide, we explore patterns of positive and negative associations among triads of species (modules) and their relationship to local biodiversity. Three modules, each incorporating both positive and negative associations, were overrepresented, thus acting as "network motifs." Furthermore, the overrepresentation of these network motifs is positively linked to species diversity globally. A theoretical model illustrates that these network motifs, based on competition between facilitated species or facilitation between inferior competitors, increase local persistence. Our findings suggest that the interplay of competition and facilitation is crucial for maintaining biodiversity.


Global map of alpine plant networks studied here. Red dots on the map indicate the spatial location of the networks, with a few networks plotted for reference. In the networks, green dots represent plant species, and blue and red arrows represent negative- and positive species associations, respectively. Dot size is proportional to species abundance. The four network modules analyzed here are represented at the bottom of the figure, from left to right: intransitive competition, facilitation-driven competition, and competition-driven facilitation 1 and 2.