scholarly journals The non-random structure of multi-trophic ecological interactions maximizes species coexistence within ecologically realistic constraints

2021 ◽  
Author(s):  
David Garcia-Callejas ◽  
Oscar Godoy ◽  
Lisa Buche ◽  
Maria Hurtado ◽  
Jose B. Lanuza ◽  
...  
Keyword(s):  
Species Coexistence ◽  
Random Network ◽  
Mean Field ◽  
Trophic Levels ◽  
Random Structure ◽  
Trophic Guilds ◽  
Ecological Communities ◽  
Ecological Interactions ◽  
Model Community ◽  
Structure Strength

Theory posits that the persistence of species in ecological communities is shaped by their interactions within and across trophic levels. However, we lack empirical evaluations of how the structure, strength and sign of these interactions drive the potential to coexist in diverse multi-trophic communities. Here we model community feasibility domains, a theoretically-informed measure of coexistence probability, from empirical data on communities comprising more than 50 species for three trophic guilds (plants, pollinators, and herbivores). Although feasibility domains vary depending on the number of trophic guilds considered, we show that higher network connectance leads to lower coexistence opportunities. Moreover, empirical estimations of the feasibility domains were higher with respect to random network structures but lower than a mean-field approach, suggesting that observed interaction structures tend to maximize coexistence within its imposed limits. Our results stress the importance of incorporating empirically-informed interaction structures within and across guilds to better understand how species coexist in diverse multi-trophic communities.

scholarly journals Symbiotic polydnavirus and venom reveal parasitoid to its hyperparasitoids

2018 ◽  
Vol 115 (20) ◽  
pp. 5205-5210 ◽  
Author(s):  
Feng Zhu ◽  
Antonino Cusumano ◽  
Janneke Bloem ◽  
Berhane T. Weldegergis ◽  
Alexandre Villela ◽  
...  
Keyword(s):  
Plant Volatiles ◽  
Trophic Levels ◽  
Plant Responses ◽  
Ecological Communities ◽  
Ecological Interactions ◽  
Host Immune Responses ◽  
Symbiotic Relationships ◽  
Key Drivers ◽  
Managed Ecosystems ◽  
Symbiotic Organisms

Symbiotic relationships may provide organisms with key innovations that aid in the establishment of new niches. For example, during oviposition, some species of parasitoid wasps, whose larvae develop inside the bodies of other insects, inject polydnaviruses into their hosts. These symbiotic viruses disrupt host immune responses, allowing the parasitoid’s progeny to survive. Here we show that symbiotic polydnaviruses also have a downside to the parasitoid’s progeny by initiating a multitrophic chain of interactions that reveals the parasitoid larvae to their enemies. These enemies are hyperparasitoids that use the parasitoid progeny as host for their own offspring. We found that the virus and venom injected by the parasitoid during oviposition, but not the parasitoid progeny itself, affected hyperparasitoid attraction toward plant volatiles induced by feeding of parasitized caterpillars. We identified activity of virus-related genes in the caterpillar salivary gland. Moreover, the virus affected the activity of elicitors of salivary origin that induce plant responses to caterpillar feeding. The changes in caterpillar saliva were critical in inducing plant volatiles that are used by hyperparasitoids to locate parasitized caterpillars. Our results show that symbiotic organisms may be key drivers of multitrophic ecological interactions. We anticipate that this phenomenon is widespread in nature, because of the abundance of symbiotic microorganisms across trophic levels in ecological communities. Their role should be more prominently integrated in community ecology to understand organization of natural and managed ecosystems, as well as adaptations of individual organisms that are part of these communities.

scholarly journals On the variability of Species Abundance Distributions with trophic guild and community structure

2018 ◽  
Author(s):  
David García-Callejas
Keyword(s):  
Trophic Level ◽  
Trophic Interactions ◽  
Species Abundance ◽  
Trophic Levels ◽  
Individual Species ◽  
Trophic Guilds ◽  
Ecological Communities ◽  
Trophic Guild ◽  
Marine Habitats ◽  
Species Abundance Distributions

AbstractSpecies Abundance Distributions (SADs) are one of the most studied properties of ecological communities, and their variability has been studied mostly in the context of horizontal communities, i.e. sets of species from a particular trophic guild. However, virtually all ecological communities encompass several trophic guilds, and the trophic interactions between them are key for explaining the persistence and abundance of individual species. Here I ask whether trophic interactions are also important in shaping Species Abundance Distributions of the different guilds of a community. I analyze the variation in SAD shape across trophic guilds in model and empirical communities. For that, I use a theoretical model that allows tracking the variations in abundances across trophic levels. The relationship between SAD shape and (1) trophic level, and (2) degree of predator specialization is analyzed using mixed-effect models. I combine this approach with an analysis of 4676 empirical datasets spanning terrestrial, marine and freshwater habitats, for which the variation in SAD shape is related to (1) trophic guild, and (2) habitat type. The evenness of model SADs is positively correlated to the trophic level of the guild considered, and also to the number of prey species per predator. These findings are confirmed by the empirical data: there is a significant relationship between SAD evenness and trophic guild, whereby primary producers display the most uneven SADs and pure carnivores the most even ones. Furthermore, regardless of trophic guild, SADs from marine habitats are the most even ones, with terrestrial SADs being the most uneven.

scholarly journals Genetic diversity increases food-web persistence in the face of climate warming

2020 ◽  
Author(s):  
Matthew A. Barbour ◽  
Daniel J. Kliebenstein ◽  
Jordi Bascompte
Keyword(s):  
Genetic Diversity ◽  
Food Web ◽  
Allelic Variation ◽  
Chemical Defenses ◽  
Trophic Levels ◽  
Raw Material ◽  
Ecological Communities ◽  
Warming Scenario ◽  
The Face ◽  
Loss Of Genetic Diversity

Genetic diversity provides the raw material for species to adapt and persist in the face of climate change. Yet, the extent to which these genetic effects scale at the level of ecological communities remains unclear. Here we experimentally test the effect of plant genetic diversity on the persistence of an insect food web under a current and future warming scenario. We found that plant genetic diversity increased food-web persistence by increasing the intrinsic growth rates of species across multiple trophic levels. This positive effect was robust to a 3°C warming scenario and resulted from allelic variation at two genes that control the biosynthesis of chemical defenses. Our results suggest that the ongoing loss of genetic diversity may undermine the persistence and functioning of ecosystems in a changing world.One Sentence SummaryThe loss of genetic diversity accelerates the extinction of inter-connected species from an experimental food web.

How Does Nutrition Structure Ecosystems?

2012 ◽  
Author(s):  
Stephen J. Simpson ◽  
David Raubenheimer
Keyword(s):  
Evolutionary Ecology ◽  
Ecosystem Dynamics ◽  
Trophic Levels ◽  
Nutritional Requirements ◽  
Ecological Communities ◽  
Geometric Framework ◽  
Agent Based ◽  
Fundamental Niche ◽  
Biophysical Ecology ◽  
Ecology Of Nutrition

This chapter assesses the consequences of individual nutrition for populations and the assemblages of species that comprise ecological communities. However, the ecological consequences of nutrition are not restricted to the effects of diet on individual organisms but include as well the direct and indirect interactions occurring among individuals within populations and between species. Understanding the complex network of interactions that produce food webs and structure ecosystem dynamics requires the understanding of the participants' differing nutritional requirements, priorities, and regulatory capacities. Geometric Framework analyses have shown that these features differ between species and across trophic levels. Nutritional space is one part of the fundamental niche of an organism, and there is a need to integrate nutrition with the biophysical ecology of organisms. Evolutionary processes also need to be taken into account, and agent-based models offer promise toward development of a new understanding of the evolutionary ecology of nutrition.

scholarly journals Phylogenetic overdispersion of plant species in southern Brazilian savannas

2009 ◽  
Vol 69 (3) ◽  
pp. 843-849 ◽  
Author(s):  
IA. Silva ◽  
MA. Batalha
Keyword(s):  
Phylogenetic Relationships ◽  
Plant Traits ◽  
Environmental Filtering ◽  
Southeastern Brazil ◽  
Ecological Communities ◽  
Ecological Interactions ◽  
Ecological Processes ◽  
Phylogenetic Structure ◽  
History Of ◽  
Phylogenetic Overdispersion

Ecological communities are the result of not only present ecological processes, such as competition among species and environmental filtering, but also past and continuing evolutionary processes. Based on these assumptions, we may infer mechanisms of contemporary coexistence from the phylogenetic relationships of the species in a community. We studied the phylogenetic structure of plant communities in four cerrado sites, in southeastern Brazil. We calculated two raw phylogenetic distances among the species sampled. We estimated the phylogenetic structure by comparing the observed phylogenetic distances to the distribution of phylogenetic distances in null communities. We obtained null communities by randomizing the phylogenetic relationships of the regional pool of species. We found a phylogenetic overdispersion of the cerrado species. Phylogenetic overdispersion has several explanations, depending on the phylogenetic history of traits and contemporary ecological interactions. However, based on coexistence models between grasses and trees, density-dependent ecological forces, and the evolutionary history of the cerrado flora, we argue that the phylogenetic overdispersion of cerrado species is predominantly due to competitive interactions, herbivores and pathogen attacks, and ecological speciation. Future studies will need to include information on the phylogenetic history of plant traits.

The Structure of Ecological Networks Across Levels of Organization

2020 ◽  
Vol 51 (1) ◽  
pp. 433-460 ◽  
Author(s):  
Paulo R. Guimarães
Keyword(s):  
Food Webs ◽  
Ecological Systems ◽  
Ecological Networks ◽  
Ecological Communities ◽  
Ecological Interactions ◽  
Biological Organization ◽  
Architectural Patterns ◽  
Fundamental Challenge ◽  
Spatiotemporal Scales ◽  
Multiple Levels

Interactions connect the units of ecological systems, forming networks. Individual-based networks characterize variation in niches among individuals within populations. These individual-based networks merge with each other, forming species-based networks and food webs that describe the architecture of ecological communities. Networks at broader spatiotemporal scales portray the structure of ecological interactions across landscapes and over macroevolutionary time. Here, I review the patterns observed in ecological networks across multiple levels of biological organization. A fundamental challenge is to understand the amount of interdependence as we move from individual-based networks to species-based networks and beyond. Despite the uneven distribution of studies, regularities in network structure emerge across scales due to the fundamental architectural patterns shared by complex networks and the interplay between traits and numerical effects. I illustrate the integration of these organizational scales by exploring the consequences of the emergence of highly connected species for network structures across scales.

scholarly journals A Perspective on Body Size and Abundance Relationships across Ecological Communities

Biology ◽  
2020 ◽  
Vol 9 (3) ◽  
pp. 42
Author(s):  
Vojsava Gjoni ◽  
Douglas Stewart Glazier
Keyword(s):  
Body Size ◽  
Ecological Factors ◽  
Trophic Levels ◽  
Marine Phytoplankton ◽  
Published Data ◽  
Scaling Exponent ◽  
Ecological Communities ◽  
Macroinvertebrate Communities ◽  
Power Functions ◽  
Phytoplankton Communities

Recently, several studies have reported relationships between the abundance of organisms in an ecological community and their mean body size (called cross-community scaling relationships: CCSRs) that can be described by simple power functions. A primary focus of these studies has been on the scaling exponent (slope) and whether it approximates −3/4, as predicted by Damuth’s rule and the metabolic theory in ecology. However, some CCSR studies have reported scaling exponents significantly different from the theoretical value of −3/4. Why this variation occurs is still largely unknown. The purpose of our commentary is to show the value of examining both the slopes and elevations of CCSRs and how various ecological factors may affect them. As a heuristic exercise, we reanalyzed three published data sets based on phytoplankton, rodent, and macroinvertebrate assemblages that we subdivided according to three distinctly different ecological factors (i.e., climate zone, season, and trophic level). Our analyses reveal significant variation in either or both the CCSR slopes and elevations for marine phytoplankton communities across climate zones, a desert rodent community across seasons, and saltwater lagoon macroinvertebrate communities across trophic levels. We conclude that achieving a comprehensive understanding of abundance-size relationships at the community level will require consideration of both slopes and elevations of these relationships and their possible variation in different ecological contexts.

scholarly journals Trait-mediated trophic cascade creates enemy-free space for nesting hummingbirds

2015 ◽  
Vol 1 (8) ◽  
pp. e1500310 ◽  
Author(s):  
Harold F. Greeney ◽  
M. Rocio Meneses ◽  
Chris E. Hamilton ◽  
Eli Lichter-Marck ◽  
R. William Mannan ◽  
...  
Keyword(s):  
Climate Change ◽  
Habitat Fragmentation ◽  
Breeding Success ◽  
Indirect Effects ◽  
Trophic Cascade ◽  
Terrestrial Ecosystems ◽  
Trophic Levels ◽  
Ecological Communities ◽  
Top Predators ◽  
Enemy Free Space

The indirect effects of predators on nonadjacent trophic levels, mediated through traits of intervening species, are collectively known as trait-mediated trophic cascades. Although birds are important predators in terrestrial ecosystems, clear examples of trait-mediated indirect effects involving bird predators have almost never been documented. Such indirect effects are important for structuring ecological communities and are likely to be negatively impacted by habitat fragmentation, climate change, and other factors that reduce abundance of top predators. We demonstrate that hummingbirds in Arizona realize increased breeding success when nesting in association with hawks. An enemy-free nesting space is created when jays, an important source of mortality for hummingbird nests, alter their foraging behavior in the presence of their hawk predators.

scholarly journals Pleistocene megafaunal interaction networks became more vulnerable after human arrival

2015 ◽  
Vol 282 (1814) ◽  
pp. 20151367 ◽  
Author(s):  
Mathias M. Pires ◽  
Paul L. Koch ◽  
Richard A. Fariña ◽  
Marcus A. M. de Aguiar ◽  
Sérgio F. dos Reis ◽  
...  
Keyword(s):  
Structural Changes ◽  
Ecological Communities ◽  
Ecological Interactions ◽  
Ecological Data ◽  
The Past ◽  
As Species ◽  
Extinction Events ◽  
Almost All ◽  
The Impact ◽  
Unstable Dynamics

The end of the Pleistocene was marked by the extinction of almost all large land mammals worldwide except in Africa. Although the debate on Pleistocene extinctions has focused on the roles of climate change and humans, the impact of perturbations depends on properties of ecological communities, such as species composition and the organization of ecological interactions. Here, we combined palaeoecological and ecological data, food-web models and community stability analysis to investigate if differences between Pleistocene and modern mammalian assemblages help us understand why the megafauna died out in the Americas while persisting in Africa. We show Pleistocene and modern assemblages share similar network topology, but differences in richness and body size distributions made Pleistocene communities significantly more vulnerable to the effects of human arrival. The structural changes promoted by humans in Pleistocene networks would have increased the likelihood of unstable dynamics, which may favour extinction cascades in communities facing extrinsic perturbations. Our findings suggest that the basic aspects of the organization of ecological communities may have played an important role in major extinction events in the past. Knowledge of community-level properties and their consequences to dynamics may be critical to understand past and future extinctions.

scholarly journals Vulnerable species interactions are important for the stability of mutualistic networks

2019 ◽  
Author(s):  
Benno I. Simmons ◽  
Hannah S. Wauchope ◽  
Tatsuya Amano ◽  
Lynn V. Dicks ◽  
William J. Sutherland ◽  
...  
Keyword(s):  
Species Interactions ◽  
Species Coexistence ◽  
Species Interaction ◽  
Interaction Networks ◽  
Ecological Communities ◽  
Ecological Context ◽  
Intrinsic Properties ◽  
Network Stability ◽  
Starting Point ◽  
The Stability

AbstractSpecies are central to ecology and conservation. However, it is the interactions between species that generate the functions on which ecosystems and humans depend. Despite the importance of interactions, we lack an understanding of the risk that their loss poses to ecological communities. Here, we quantify risk as a function of the vulnerability (likelihood of loss) and importance (contribution to network stability in terms of species coexistence) of 4330 mutualistic interactions from 41 empirical pollination and seed dispersal networks across six continents. Remarkably, we find that more vulnerable interactions are also more important: the interactions that contribute most to network stability are those that are most likely to be lost. Furthermore, most interactions tend to have more similar vulnerability and importance across networks than expected by chance, suggesting that vulnerability and importance may be intrinsic properties of interactions, rather than only a function of ecological context. These results provide a starting point for prioritising interactions for conservation in species interaction networks and, in areas lacking network data, could allow interaction properties to be inferred from taxonomy alone.

Sign in / Sign up

Export Citation Format

Share Document