scholarly journals Species coexistence through simultaneous fluctuation-dependent mechanisms

2018 ◽  
Vol 115 (26) ◽  
pp. 6745-6750 ◽  
Author(s):  
Andrew D. Letten ◽  
Manpreet K. Dhami ◽  
Po-Ju Ke ◽  
Tadashi Fukami
Keyword(s):  
Species Coexistence ◽  
Resource Competition ◽  
Experimental Tests ◽  
Single Species ◽  
Storage Effect ◽  
Common Assumption ◽  
Relative Contribution ◽  
Coexistence Mechanisms ◽  
Plausible Mechanism ◽  
Relative Nonlinearity

Understanding the origins and maintenance of biodiversity remains one of biology’s grand challenges. From theory and observational evidence, we know that variability in environmental conditions through time is likely critical to the coexistence of competing species. Nevertheless, experimental tests of fluctuation-driven coexistence are rare and have typically focused on just one of two potential mechanisms, the temporal storage effect, to the neglect of the theoretically equally plausible mechanism known as relative nonlinearity of competition. We combined experiments and simulations in a system of nectar yeasts to quantify the relative contribution of the two mechanisms to coexistence. Resource competition models parameterized from single-species assays predicted the outcomes of mixed-culture competition experiments with 83% accuracy. Model simulations revealed that both mechanisms have measurable effects on coexistence and that relative nonlinearity can be equal or greater in magnitude to the temporal storage effect. In addition, we show that their effect on coexistence can be both antagonistic and complementary. These results falsify the common assumption that relative nonlinearity is of negligible importance, and in doing so reveal the importance of testing coexistence mechanisms in combination.

scholarly journals The relationship between species richness and ecosystem variability is shaped by the mechanism of coexistence

2017 ◽  
Author(s):  
Andrew T. Tredennick ◽  
Peter B. Adler ◽  
Frederick R. Adler
Keyword(s):  
Species Richness ◽  
Species Coexistence ◽  
Environmental Variability ◽  
Storage Effect ◽  
Natural Gradient ◽  
Species Pools ◽  
Coexistence Mechanisms ◽  
The Relationship ◽  
General Explanation ◽  
Consumer Resource

AbstractTheory relating species richness to ecosystem variability typically ignores the potential for environmental variability to promote species coexistence. Failure to account for fluctuation-dependent coexistence mechanisms may explain observed deviations from the expected negative diversity–ecosystem variability relationship, and limits our ability to predict the consequences of future increases in environmental variability. We use a consumer-resource model to explore how coexistence via the temporal storage effect and relative nonlinearity affects ecosystem variability. We show that a positive, rather than negative, diversity–ecosystem variability relationship is possible when ecosystem function is sampled across a natural gradient in environmental variability and diversity. We also show how fluctuation-dependent coexistence can buffer ecosystem functioning against increasing environmental variability by promoting species richness and portfolio effects. Our work provides a general explanation for variation in observed diversity–ecosystem variability relationships and highlights the importance of conserving regional species pools to help buffer ecosystems against predicted increases in environmental variability.

scholarly journals Assessing the Impacts of Competition and Dispersal on a Multiple Interactions Type Model

2021 ◽  
Vol 29 (3) ◽  
Author(s):  
Murtala Bello Aliyu ◽  
Mohd Hafiz Mohd ◽  
Mohd Salmi Md. Noorani
Keyword(s):  
Bifurcation Analysis ◽  
Species Coexistence ◽  
Real Life ◽  
Period Doubling ◽  
Type Model ◽  
Coexistence Mechanisms ◽  
Multiple Species ◽  
The Stability ◽  
Transcritical Bifurcations ◽  
Multiple Interactions

Multiple interactions (e.g., mutualist-resource-competitor-exploiter interactions) type models are known to exhibit oscillatory behaviour as a result of their complexity. This large-amplitude oscillation often de-stabilises multispecies communities and increases the chances of species extinction. What mechanisms help species in a complex ecological system to persist? Some studies show that dispersal can stabilise an ecological community and permit multi-species coexistence. However, previous empirical and theoretical studies often focused on one- or two-species systems, and in real life, we have more than two-species coexisting together in nature. Here, we employ a (four-species) multiple interactions type model to investigate how competition interacts with other biotic factors and dispersal to shape multi-species communities. Our results reveal that dispersal has (de-)stabilising effects on the formation of multi-species communities, and this phenomenon shapes coexistence mechanisms of interacting species. These contrasting effects of dispersal can best be illustrated through its combined influences with the competition. To do this, we employ numerical simulation and bifurcation analysis techniques to track the stable and unstable attractors of the system. Results show the presence of Hopf bifurcations, transcritical bifurcations, period-doubling bifurcations and limit point bifurcations of cycles as we vary the competitive strength in the system. Furthermore, our bifurcation analysis findings show that stable coexistence of multiple species is possible for some threshold values of ecologically-relevant parameters in this complex system. Overall, we discover that the stability and coexistence mechanisms of multiple species depend greatly on the interplay between competition, other biotic components and dispersal in multi-species ecological systems.

scholarly journals Gene by environmental interactions affecting oxidative phosphorylation and thermal sensitivity

2016 ◽  
Vol 311 (1) ◽  
pp. R157-R165 ◽  
Author(s):  
Tara Z. Baris ◽  
Pierre U. Blier ◽  
Nicolas Pichaud ◽  
Douglas L. Crawford ◽  
Marjorie F. Oleksiak
Keyword(s):  
Oxidative Phosphorylation ◽  
Complex I ◽  
Thermal Sensitivity ◽  
Single Species ◽  
Mitochondrial Haplotype ◽  
Acclimation Temperature ◽  
Atp Production ◽  
Acute Response ◽  
Relative Contribution ◽  
Mitochondrial Genotype

The oxidative phosphorylation (OxPhos) pathway is responsible for most aerobic ATP production and is the only metabolic pathway with proteins encoded by both nuclear and mitochondrial genomes. In studies examining mitonuclear interactions among distant populations within a species or across species, the interactions between these two genomes can affect metabolism, growth, and fitness, depending on the environment. However, there is little data on whether these interactions impact natural populations within a single species. In an admixed Fundulus heteroclitus population with northern and southern mitochondrial haplotypes, there are significant differences in allele frequencies associated with mitochondrial haplotype. In this study, we investigate how mitochondrial haplotype and any associated nuclear differences affect six OxPhos parameters within a population. The data demonstrate significant OxPhos functional differences between the two mitochondrial genotypes. These differences are most apparent when individuals are acclimated to high temperatures with the southern mitochondrial genotype having a large acute response and the northern mitochondrial genotype having little, if any acute response. Furthermore, acute temperature effects and the relative contribution of Complex I and II depend on acclimation temperature: when individuals are acclimated to 12°C, the relative contribution of Complex I increases with higher acute temperatures, whereas at 28°C acclimation, the relative contribution of Complex I is unaffected by acute temperature change. These data demonstrate a complex gene by environmental interaction affecting the OxPhos pathway.

Adaptive Diversification Due to Resource Competition in Asexual Models

2011 ◽  
Author(s):  
Michael Doebeli
Keyword(s):  
Resource Selection ◽  
Evolutionary Dynamics ◽  
Resource Competition ◽  
Single Species ◽  
Character Displacement ◽  
Adaptive Diversification ◽  
Ecological Character ◽  
Ecological Character Displacement ◽  
Phenotypic Diversification ◽  
Established Species

This chapter focuses on evolutionary branching in niche position due to frequency-dependent competition. When the majority phenotype of a population is competing for one type of resource, selection may favor minority phenotypes that consume different types of resources, which could result in phenotypic differentiation and divergence. The idea of divergence due to competition is also the basis for the well-known concept of ecological character displacement, although here the focus is not so much on the origin of diversity arising in a single species, but rather on the evolutionary dynamics of existing diversity between different and already established species. Ecological character displacement embodies the possibility that competition between species can drive divergence in characters determining resource use. However, there are alternative evolutionary scenarios for phenotypic diversification. In the context of resource competition, one such alternative is that individuals diversify their diet by evolving a wider niche.

Natural resource use conflicts in a changing climate: The case of the wetlands of Kilombero and Kilosa districts in Tanzania.

2020 ◽  
pp. 153-168
Author(s):  
Emma T. Liwenga ◽  
Florian Silangwa
Keyword(s):  
Conflict Resolution ◽  
Natural Resource ◽  
Land Use Planning ◽  
Resource Competition ◽  
Climatic Factors ◽  
Household Survey ◽  
Land Conflicts ◽  
Changing Climate ◽  
Relative Contribution ◽  
Challenges And Opportunities

Abstract In Tanzania studies on conflicts between subsistence farmers and agropastoralists/pastoralists as well communities versus conservationists have been frequently reported. These include studies on water use conflicts in the Pangan River Basin. Agropastoralists have also been evicted as a result of these conflicts. The overriding tendency has thus been centered on discussion about what keeps pastoralists and crop cultivators apart rather than what keeps them together. Although conflicts occur mainly as a result of resource competition, some conflicts constitute only one aspect of a much more complex interaction between the two groups. Little has been documented in examining the relative contribution of climatic and non-climatic factors in aggravating these conflicts and how this triggers various dimensions of conflicts among livelihood groups. This study examined the relative contribution of climatic and non-climatic factors as causes of natural resource conflict, based on a study conducted in Kilosa and Kilombero districts in south-central Tanzania. The study further examined conflict resolution mechanisms in terms of adaptive capacity to address these issues in a changing climate and in particular explored the roles of institutions in conflict resolution, and the associated challenges and opportunities involved. The study was conducted through a household survey, focus group discussions and expert interviews with Kilosa and Kilombero district land planning officers. The aim was to understand the challenges of land use planning and how those transformed into conflicts between users. The results of the interviews in the two districts revealed that there were land conflicts related to boundary disputes between and among villages, investors against villages or communities, and government agencies versus villages or investors. Unlike Kilosa, Kilombero District had more land conflicts involving villages and government institutions. There is a complicated land conflict in 25 villages against the Ramsar site area.

scholarly journals Resource competition and species coexistence in a two-patch metaecosystem model

2019 ◽  
Vol 13 (2) ◽  
pp. 209-221
Author(s):  
Ioannis Tsakalakis ◽  
Bernd Blasius ◽  
Alexey Ryabov
Keyword(s):  
Species Coexistence ◽  
Resource Competition

scholarly journals Competition and the origins of novelty: experimental evolution of niche-width expansion in a virus

2013 ◽  
Vol 9 (1) ◽  
pp. 20120616 ◽  
Author(s):  
Lisa M. Bono ◽  
Catharine L. Gensel ◽  
David W. Pfennig ◽  
Christina L. Burch
Keyword(s):  
Host Range ◽  
Resource Use ◽  
Intraspecific Competition ◽  
Experimental Evolution ◽  
Resource Competition ◽  
Experimental Tests ◽  
Model System ◽  
Standard Laboratory ◽  
Narrow Host Range ◽  
Competition For Resources

Competition for resources has long been viewed as a key agent of divergent selection. Theory holds that populations facing severe intraspecific competition will tend to use a wider range of resources, possibly even using entirely novel resources that are less in demand. Yet, there have been few experimental tests of these ideas. Using the bacterial virus (bacteriophage) ϕ 6 as a model system, we examined whether competition for host resources promotes the evolution of novel resource use. In the laboratory, ϕ 6 exhibits a narrow host range but readily produces mutants capable of infecting novel bacterial hosts. Here, we show that when ϕ 6 populations were subjected to intense intraspecific competition for their standard laboratory host, they rapidly evolved new generalist morphs that infect novel hosts . Our results therefore suggest that competition for host resources may drive the evolution of host range expansion in viruses. More generally, our findings demonstrate that intraspecific resource competition can indeed promote the evolution of novel resource-use phenotypes.

Community structure of acorn weevils (Curculio): inferences from multispecies occupancy models

2015 ◽  
Vol 93 (1) ◽  
pp. 31-39 ◽  
Author(s):  
Byju N. Govindan ◽  
Robert K. Swihart
Keyword(s):  
Community Structure ◽  
Tree Species ◽  
Resource Competition ◽  
Host Tree ◽  
Parameter Estimates ◽  
Storage Effect ◽  
Primary Host ◽  
Host Trees ◽  
Host Tree Species ◽  
Mast Production

We tested whether community structure of insect seed predators is influenced by spatiotemporal variation in mast availability on host-tree species. Specifically, mast production and acorn weevil (Curculio L., 1758) occupancy were estimated annually from 2006 to 2008 for individual host trees in a sample of 74 northern red oaks (Quercus rubra L.), 100 white oaks (Quercus alba L.), and 81 shagbark hickories (Carya ovata (Mill.) K. Koch) in west-central Indiana, USA. Occupancy and vital rates of nine Curculio species on their primary host-tree species were derived using multispecies, multiseason (MSMS) models within a Bayesian framework, accounting for imperfect detection. Mast production of host trees had a strong positive effect on community-level occupancy and survival of Curculio. Mast production varied considerably between years and generally was spatially autocorrelated only at distances <2 km, which likely reduced interspecific resource competition. Derived estimates of mean weevil species richness per tree and community similarity were highest in 2007 when mast production on all host-tree species was in phase. Generalist species compensated for lower survival rate on secondary hosts with higher colonization rates on these hosts during a year of mast failure in the primary host. We hypothesize that differential suitability of hosts as resources for Curculio created a spatial storage effect that, when coupled with a temporal storage effect induced by prolonged diapause common among Curculio, facilitated species coexistence. Methodologically, increased precision of parameter estimates from MSMS models makes it generally more useful than single-species models in studies of community dynamics.

scholarly journals The evolution of competitive ability for essential resources

2019 ◽  
Author(s):  
Joey R. Bernhardt ◽  
Pavel Kratina ◽  
Aaron Pereira ◽  
Manu Tamminen ◽  
Mridul K. Thomas ◽  
...  
Keyword(s):  
Competitive Ability ◽  
Community Dynamics ◽  
Species Coexistence ◽  
Resource Competition ◽  
Environmental Gradients ◽  
Light Limitation ◽  
Major Question ◽  
Trade Offs ◽  
Resource Requirements ◽  
Competitive Abilities

AbstractCompetition for limiting resources is among the most fundamental ecological interactions and has long been considered a key driver of species coexistence and biodiversity. Species’ minimum resource requirements, their R*s, are key traits that link individual physiological demands to the outcome of competition. However, a major question remains unanswered - to what extent are species’ competitive traits able to evolve in response to resource limitation? To address this knowledge gap, we performed an evolution experiment in which we exposed Chlamydomonas reinhardtii for approximately 285 generations to seven environments in chemostats which differed in resource supply ratios (including nitrogen, phosphorus and light limitation) and salt stress. We then grew the ancestors and descendants in common garden and quantified their competitive abilities for essential resources. We investigated constraints on trait evolution by testing whether changes in resource requirements for different resources were correlated. Competitive abilities for phosphorus improved in all populations, while competitive abilities for nitrogen and light increased in some populations and decreased in others. In contrast to the common assumption that there are trade-offs between competitive abilities for different resources, we found that improvements in competitive ability for a resource came at no detectable cost. Instead, improvements in competitive ability for multiple resources were either positively correlated or not significantly correlated. Using resource competition theory, we then demonstrated that rapid adaptation in competitive traits altered the predicted outcomes of competition. These results highlight the need to incorporate contemporary evolutionary change into predictions of competitive community dynamics over environmental gradients.

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