scholarly journals Biotic predictors complement models of bat and bird responses to climate and tree diversity in European forests

2019 ◽  
Vol 286 (1894) ◽  
pp. 20182193 ◽  
Author(s):  
Luc Barbaro ◽  
Eric Allan ◽  
Evy Ampoorter ◽  
Bastien Castagneyrol ◽  
Yohan Charbonnier ◽  
...  
Keyword(s):  
Functional Diversity ◽  
Environmental Changes ◽  
Insect Herbivory ◽  
Biotic Interactions ◽  
Trophic Levels ◽  
Explained Variance ◽  
Spider Abundance ◽  
Insect Activity ◽  
Bat Diversity ◽  
Functional Evenness

Bats and birds are key providers of ecosystem services in forests. How climate and habitat jointly shape their communities is well studied, but whether biotic predictors from other trophic levels may improve bird and bat diversity models is less known, especially across large bioclimatic gradients. Here, we achieved multi-taxa surveys in 209 mature forests replicated in six European countries from Spain to Finland, to investigate the importance of biotic predictors (i.e. the abundance or activity of defoliating insects, spiders, earthworms and wild ungulates) for bat and bird taxonomic and functional diversity. We found that nine out of 12 bird and bat diversity metrics were best explained when biotic factors were added to models including climate and habitat variables, with a mean gain in explained variance of 38% for birds and 15% for bats. Tree functional diversity was the most important habitat predictor for birds, while bats responded more to understorey structure. The best biotic predictors for birds were spider abundance and defoliating insect activity, while only bat functional evenness responded positively to insect herbivory. Accounting for potential biotic interactions between bats, birds and other taxa of lower trophic levels will help to understand how environmental changes along large biogeographical gradients affect higher-level predator diversity in forest ecosystems.

Functional diversity alters the effects of a pulse perturbation on the dynamics of tritrophic food webs

2021 ◽  
Author(s):  
Ruben Ceulemans ◽  
Laurie Anne Myriam Wojcik ◽  
Ursula Gaedke
Keyword(s):  
Food Web ◽  
Food Webs ◽  
Functional Diversity ◽  
Feedback Loop ◽  
Environmental Changes ◽  
Biodiversity Loss ◽  
Trophic Levels ◽  
Nutrient Pulse ◽  
Trade Offs ◽  
Food Web Model

Biodiversity decline causes a loss of functional diversity, which threatens ecosystems through a dangerous feedback loop: this loss may hamper ecosystems' ability to buffer environmental changes, leading to further biodiversity losses. In this context, the increasing frequency of climate and human-induced excessive loading of nutrients causes major problems in aquatic systems. Previous studies investigating how functional diversity influences the response of food webs to disturbances have mainly considered systems with at most two functionally diverse trophic levels. Here, we investigate the effects of a nutrient pulse on the resistance, resilience and elasticity of a tritrophic---and thus more realistic---plankton food web model depending on its functional diversity. We compare a non-adaptive food chain with no diversity to a highly diverse food web with three adaptive trophic levels. The species fitness differences are balanced through trade-offs between defense/growth rate for prey and selectivity/half-saturation constant for predators. We showed that the resistance, resilience and elasticity of tritrophic food webs decreased with larger perturbation sizes and depended on the state of the system when the perturbation occured. Importantly, we found that a more diverse food web was generally more resistant, resilient, and elastic. Particularly, functional diversity dampened the probability of a regime shift towards a non-desirable alternative state. In addition, despite the complex influence of the shape and type of the dynamical attractors, the basal-intermediate interaction determined the robustness against a nutrient pulse. This relationship was strongly influenced by the diversity present and the third trophic level. Overall, using a food web model of realistic complexity, this study confirms the destructive potential of the positive feedback loop between biodiversity loss and robustness, by uncovering mechanisms leading to a decrease in resistance, resilience and elasticity as functional diversity declines.

scholarly journals Environmentally triggered evolutionary cascade across trophic levels in an experimental phage-bacteria-insect system

2019 ◽  
Author(s):  
Matthieu Bruneaux ◽  
Roghaieh Ashrafi ◽  
Ilkka Kronholm ◽  
Anni-Maria Örmälä-Odegrip ◽  
Juan A. Galarza ◽  
...  
Keyword(s):  
Environmental Effects ◽  
Large Scale ◽  
Environmental Changes ◽  
Galleria Mellonella ◽  
Biotic Interactions ◽  
Trophic Levels ◽  
Lytic Cycle ◽  
Biological Interactions ◽  
Insect Host ◽  
Cascading Effects

AbstractEnvironmental changes can cause strong cascading effects in species communities due to altered biological interactions between species (Zarnetske et al., 2012). Highly specialized interactions arising from the co-evolution of hosts and parasites, such as bacteria and phages, and short generation times of these species could rapidly lead to considerable evolutionary changes in their biotic interactions (Kerr, 2012; Buck and Ripple, 2017), with potential large-scale ramifications to other trophic levels. Here we report experimental evidence of cascading environmental effects across trophic levels in an experimental system where phage-bacteria coevolution in an abiotically altered environment cascaded on bacterial virulence in an insect host. We found that the lytic cycle of the temperate phage KPS20 induced at low temperatures led to selection in the bacterial host Serratia marcescens that tempered the likelihood of triggering the phage’s lytic cycle. These changes in S. marcescens concomitantly attenuated its virulence in an insect host, Galleria mellonella. In addition, our data suggests that this effect is mediated by mutations and epigenetic modifications of bacterial genes moderating the onset of the temperate phage’s lytic cycle. Given the abundance of temperate phages in bacterial genomes (Canchaya et al., 2003), the sensitivity of the onset of their lytic cycle to environmental conditions (Howard-Varona et al., 2017), and the predominance of environmental change due to climate change, our results warrants attention as a cautionary example of the dangers of predicting environmental effects on species without considering complex biotic interactions.

scholarly journals Identifying appropriate sampling and modelling approaches for analysing distributional patterns of Antarctic terrestrial arthropods along the Victoria Land latitudinal gradient

2010 ◽  
Vol 22 (6) ◽  
pp. 742-748 ◽  
Author(s):  
Tancredi Caruso ◽  
Ian D. Hogg ◽  
Roberto Bargagli
Keyword(s):  
Abiotic Factors ◽  
Relevant Literature ◽  
Biotic Interactions ◽  
Terrestrial Ecosystems ◽  
Climatic Conditions ◽  
Trophic Levels ◽  
Terrestrial Arthropods ◽  
Victoria Land ◽  
Dispersal Capability ◽  
Modelling Techniques

AbstractBiotic communities in Antarctic terrestrial ecosystems are relatively simple and often lack higher trophic levels (e.g. predators); thus, it is often assumed that species’ distributions are mainly affected by abiotic factors such as climatic conditions, which change with increasing latitude, altitude and/or distance from the coast. However, it is becoming increasingly apparent that factors other than geographical gradients affect the distribution of organisms with low dispersal capability such as the terrestrial arthropods. In Victoria Land (East Antarctica) the distribution of springtail (Collembola) and mite (Acari) species vary at scales that range from a few square centimetres to regional and continental. Different species show different scales of variation that relate to factors such as local geological and glaciological history, and biotic interactions, but only weakly with latitudinal/altitudinal gradients. Here, we review the relevant literature and outline more appropriate sampling designs as well as suitable modelling techniques (e.g. linear mixed models and eigenvector mapping), that will more adequately address and identify the range of factors responsible for the distribution of terrestrial arthropods in Antarctica.

scholarly journals Untargeted In Silico Compound Classification—A Novel Metabolomics Method to Assess the Chemodiversity in Bryophytes

2021 ◽  
Vol 22 (6) ◽  
pp. 3251
Author(s):  
Kristian Peters ◽  
Gerd Balcke ◽  
Niklas Kleinenkuhnen ◽  
Hendrik Treutler ◽  
Steffen Neumann
Keyword(s):  
In Silico ◽  
Structural Integrity ◽  
Environmental Changes ◽  
Light Availability ◽  
Biotic Interactions ◽  
Plant Ecology ◽  
Chemical Diversity ◽  
Classification Framework ◽  
Significant Difference ◽  
Compound Classification

In plant ecology, biochemical analyses of bryophytes and vascular plants are often conducted on dried herbarium specimen as species typically grow in distant and inaccessible locations. Here, we present an automated in silico compound classification framework to annotate metabolites using an untargeted data independent acquisition (DIA)–LC/MS–QToF-sequential windowed acquisition of all theoretical fragment ion mass spectra (SWATH) ecometabolomics analytical method. We perform a comparative investigation of the chemical diversity at the global level and the composition of metabolite families in ten different species of bryophytes using fresh samples collected on-site and dried specimen stored in a herbarium for half a year. Shannon and Pielou’s diversity indices, hierarchical clustering analysis (HCA), sparse partial least squares discriminant analysis (sPLS-DA), distance-based redundancy analysis (dbRDA), ANOVA with post-hoc Tukey honestly significant difference (HSD) test, and the Fisher’s exact test were used to determine differences in the richness and composition of metabolite families, with regard to herbarium conditions, ecological characteristics, and species. We functionally annotated metabolite families to biochemical processes related to the structural integrity of membranes and cell walls (proto-lignin, glycerophospholipids, carbohydrates), chemical defense (polyphenols, steroids), reactive oxygen species (ROS) protection (alkaloids, amino acids, flavonoids), nutrition (nitrogen- and phosphate-containing glycerophospholipids), and photosynthesis. Changes in the composition of metabolite families also explained variance related to ecological functioning like physiological adaptations of bryophytes to dry environments (proteins, peptides, flavonoids, terpenes), light availability (flavonoids, terpenes, carbohydrates), temperature (flavonoids), and biotic interactions (steroids, terpenes). The results from this study allow to construct chemical traits that can be attributed to biogeochemistry, habitat conditions, environmental changes and biotic interactions. Our classification framework accelerates the complex annotation process in metabolomics and can be used to simplify biochemical patterns. We show that compound classification is a powerful tool that allows to explore relationships in both molecular biology by “zooming in” and in ecology by “zooming out”. The insights revealed by our framework allow to construct new research hypotheses and to enable detailed follow-up studies.

scholarly journals Context-dependency in biodiversity-multifunctionality relationships is driven by nitrogen availability and plant functional composition

2020 ◽  
Author(s):  
Noémie A. Pichon ◽  
Seraina L. Cappelli ◽  
Santiago Soliveres ◽  
Tosca Mannall ◽  
Thu Zar Nwe ◽  
...  
Keyword(s):  
Species Richness ◽  
Plant Species ◽  
Functional Diversity ◽  
Experimental Studies ◽  
Plant Species Richness ◽  
Trophic Levels ◽  
Context Dependency ◽  
Composition Gradient ◽  
Nitrogen Enrichment ◽  
Functional Composition

SummaryThe ability of an ecosystem to deliver multiple functions at high levels (multifunctionality) typically increases with biodiversity but there is substantial variation in the strength and direction of biodiversity effects, suggesting context-dependency. However, the drivers of this context dependency have not been identified and understood in comparative meta-analyses or experimental studies. To determine how different factors modulate the effect of diversity on multifunctionality, we conducted a large grassland experiment with 216 communities, crossing a manipulation of plant species richness (1-20 species) with manipulations of resource availability (nitrogen enrichment), plant functional composition (gradient in mean specific leaf area [SLA] to manipulate abundances of fast vs. slow species), plant functional diversity (variance in SLA) and enemy abundance (fungal pathogen removal). We measured ten functions, above and belowground, related to productivity, nutrient cycling and energy transfer between trophic levels, and calculated multifunctionality. Plant species richness and functional diversity both increased multifunctionality, but their effects were context dependent. Species richness increased multifunctionality, but only when communities were assembled with fast growing (high SLA) species. This was because slow species were more redundant in their functional effects, whereas fast species tended to promote different functions. Functional diversity also increased multifunctionality but this effect was dampened by nitrogen enrichment, however, unfertilised, functionally diverse communities still delivered more functions than low diversity, fertilised communities. Our study suggests that a shift towards exploitative communities will not only alter ecosystem functioning but also the strength of biodiversity-functioning relationships, which highlights the potentially complex effects of global change on multifunctionality.

scholarly journals Epichloë Endophyte-Promoted Seed Pathogen Increases Host Grass Resistance Against Insect Herbivory

2022 ◽  
Vol 12 ◽  
Author(s):  
Miika Laihonen ◽  
Kari Saikkonen ◽  
Marjo Helander ◽  
Beatriz R. Vázquez de Aldana ◽  
Iñigo Zabalgogeazcoa ◽  
...  
Keyword(s):  
Pathogenic Fungus ◽  
Insect Herbivory ◽  
Common Garden ◽  
Trophic Levels ◽  
Context Dependency ◽  
Research Station ◽  
Natural Setting ◽  
Plant Seed ◽  
Aphid Infestation ◽  
Red Fescue

Plants host taxonomically and functionally complex communities of microbes. However, ecological studies on plant–microbe interactions rarely address the role of multiple co-occurring plant-associated microbes. Here, we contend that plant-associated microbes interact with each other and can have joint consequences for higher trophic levels. In this study we recorded the occurrence of the plant seed pathogenic fungus Claviceps purpurea and aphids (Sitobion sp.) on an established field experiment with red fescue (Festuca rubra) plants symbiotic to a seed transmitted endophytic fungus Epichloë festucae (E+) or non-symbiotic (E–). Both fungi are known to produce animal-toxic alkaloids. The study was conducted in a semi-natural setting, where E+ and E– plants from different origins (Spain and Northern Finland) were planted in a randomized design in a fenced common garden at Kevo Subarctic Research Station in Northern Finland. The results reveal that 45% of E+ plants were infected with Claviceps compared to 31% of E– plants. Uninfected plants had 4.5 times more aphids than Claviceps infected plants. By contrast, aphid infestation was unaffected by Epichloë symbiosis. Claviceps alkaloid concentrations correlated with a decrease in aphid numbers, which indicates their insect deterring features. These results show that plant mutualistic fungi can increase the infection probability of a pathogenic fungus, which then becomes beneficial to the plant by controlling herbivorous insects. Our study highlights the complexity and context dependency of species–species and multi-trophic interactions, thus challenging the labeling of species as plant mutualists or pathogens.

Multiple feedbacks due to biotic interactions across trophic levels can lead to persistent novel conditions that hinder restoration.

2020 ◽  
pp. 402-420
Author(s):  
Stephanie G. Yelenik ◽  
Carla M. D'Antonio ◽  
Evan M. Rehm ◽  
Iain R. Caldwell
Keyword(s):  
Species Interactions ◽  
Native Species ◽  
Biotic Interactions ◽  
Terrestrial Ecosystems ◽  
Trophic Levels ◽  
Native Grasses ◽  
Positive Feedbacks ◽  
Mesic Forest ◽  
Management Context ◽  
Multiple Challenges

Abstract Unlike traditional successional theory, Alternate Stable Equilibrium (ASE) theory posits that more than one community state is possible in a single environment, depending on the order that species arrive. ASE theory is often invoked in management situations where initial stressors have been removed, but native-dominated communities are not returning to degraded areas. Fundamental to this theory is the assumption that equilibria are maintained by positive feedbacks between colonizers and their environment. While ASE has been relatively well studied in aquatic ecosystems, more complex terrestrial systems offer multiple challenges, including species interactions across trophic levels that can lead to multiple feedbacks. Here, we discuss ASE theory as it applies to terrestrial, invaded ecosystems, and detail a case study from Hawai'i that exemplifies how species interactions can favour the persistence of invaders, and how an understanding of interactions and feedbacks can be used to guide management. Our system includes intact native-dominated mesic forest and areas cleared for pasture, planted with non-native grasses, and later planted with a monoculture of a native nitrogen-fixing tree in an effort to restore forests. We discuss interactions between birds, understorey fruiting native species, understorey non-native grasses, soils and bryophytes in separate feedback mechanisms, and explain our efforts to identify which of these feedbacks is most important to address in a management context. Finally, we suggest that using models can help overcome some of the challenges that terrestrial ecosystems pose when studying ASE.

How does fish functional diversity respond to environmental changes in two large shallow lakes?

2021 ◽  
Vol 753 ◽  
pp. 142158
Author(s):  
Zhigang Mao ◽  
Xiaohong Gu ◽  
Yong Cao ◽  
Juhua Luo ◽  
Qingfei Zeng ◽  
...  
Keyword(s):  
Functional Diversity ◽  
Shallow Lakes ◽  
Environmental Changes

scholarly journals Loss of top-down biotic interactions changes the relative benefits for obligate mutualists

2019 ◽  
Vol 286 (1897) ◽  
pp. 20182501 ◽  
Author(s):  
Rong Wang ◽  
Xiao-Yong Chen ◽  
Yan Chen ◽  
Gang Wang ◽  
Derek W. Dunn ◽  
...  
Keyword(s):  
Biotic Interactions ◽  
Trophic Levels ◽  
Fig Wasp ◽  
Negative Effects ◽  
Top Down ◽  
Top Predators ◽  
Natural Range ◽  
Obligate Mutualism ◽  
The Stability ◽  
Food Web Complexity

The collapse of mutualisms owing to anthropogenic changes is contributing to losses of biodiversity. Top predators can regulate biotic interactions between species at lower trophic levels and may contribute to the stability of such mutualisms, but they are particularly likely to be lost after disturbance of communities. We focused on the mutualism between the fig tree Ficus microcarpa and its host-specific pollinator fig wasp and compared the benefits accrued by the mutualists in natural and translocated areas of distribution. Parasitoids of the pollinator were rare or absent outside the natural range of the mutualists, where the relative benefits the mutualists gained from their interaction were changed significantly away from the plant's natural range owing to reduced seed production rather than increased numbers of pollinator offspring. Furthermore, in the absence of the negative effects of its parasitoids, we detected an oviposition range expansion by the pollinator, with the use of a wider range of ovules that could otherwise have generated seeds. Loss of top-down control has therefore resulted in a change in the balance of reciprocal benefits that underpins this obligate mutualism, emphasizing the value of maintaining food web complexity in the Anthropocene.

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