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.

scholarly journals The evolution of competitive ability for essential resources

2020 ◽  
Vol 375 (1798) ◽  
pp. 20190247 ◽  
Author(s):  
Joey R. Bernhardt ◽  
Pavel Kratina ◽  
Aaron Louis 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

Competition 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 that differed in resource supply ratios (including nitrogen, phosphorus and light limitation) and salt stress. We then grew the ancestors and descendants in a 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. This article is part of the theme issue ‘Conceptual challenges in microbial community ecology’.

scholarly journals Mixotrophy in nanoflagellates across environmental gradients in the ocean

2019 ◽  
Vol 116 (13) ◽  
pp. 6211-6220 ◽  
Author(s):  
Kyle F. Edwards
Keyword(s):  
Competitive Ability ◽  
Resource Competition ◽  
Environmental Gradients ◽  
Light Availability ◽  
Field Studies ◽  
Heterotrophic Nanoflagellates ◽  
Coastal Environments ◽  
Unicellular Eukaryotes ◽  
Theoretical Predictions ◽  
Trophic Strategy

Mixotrophy, the combination of autotrophic and heterotrophic nutrition, is a common trophic strategy among unicellular eukaryotes in the ocean. There are a number of hypotheses about the conditions that select for mixotrophy, and field studies have documented the prevalence of mixotrophy in a range of environments. However, there is currently little evidence for how mixotrophy varies across environmental gradients, and whether empirical patterns support theoretical predictions. Here I synthesize experiments that have quantified the abundance of phototrophic, mixotrophic, and heterotrophic nanoflagellates, to ask whether there are broad patterns in the prevalence of mixotrophy (relative to pure autotrophy and heterotrophy), and to ask whether observed patterns are consistent with a trait-based model of trophic strategies. The data suggest that mixotrophs increase in abundance at lower latitudes, while autotrophs and heterotrophs do not, and that this may be driven by increased light availability. Both mixotrophs and autotrophs increase greatly in productive coastal environments, while heterotrophs increase only slightly. These patterns are consistent with a model of resource competition in which nutrients and carbon can both limit growth and mixotrophs experience a trade-off in allocating biomass to phagotrophy vs. autotrophic functions. Importantly, mixotrophy is selected for under a range of conditions even when mixotrophs experience a penalty for using a generalist trophic strategy, due to the synergy between photosynthetically derived carbon and prey-derived nutrients. For this reason mixotrophy is favored relative to specialist strategies by increased irradiance, while at the same time increased nutrient supply increases the competitive ability of mixotrophs against heterotrophs.

scholarly journals Niche theory for mutualism: A graphical approach to plant-pollinator network dynamics

2020 ◽  
Author(s):  
Fernanda S. Valdovinos ◽  
Robert Marsland
Keyword(s):  
Community Dynamics ◽  
Species Coexistence ◽  
Resource Competition ◽  
Graphical Representation ◽  
Equilibrium Structure ◽  
Shared Environment ◽  
Niche Theory ◽  
Graphical Approach ◽  
Plant Pollinator ◽  
Consumer Resource

AbstractContemporary Niche Theory is a useful framework for understanding how organisms interact with each other and with their shared environment. Its graphical representation, popularized by Tilman’s Resource Ratio Hypothesis, facilitates the analysis of the equilibrium structure of complex dynamical models including species coexistence. This theory has been applied primarily to resource competition since its early beginnings. Here, we integrate mutualism into niche theory by expanding Tilman’s graphical representation to the analysis of consumer-resource dynamics of plant-pollinator networks. We graphically explain the qualitative phenomena previously found by numerical simulations, including the effects on community dynamics of nestedness, adaptive foraging, and pollinator invasions. Our graphical approach promotes the unification of niche and network theories, and deepens the synthesis of different types of interactions within a consumer-resource framework.Secondary AbstractTeoría de Nicho para Mutualismos: Una aproximación gráfica a la dinámica de redes planta-polinizadorLa Teoría Contemporánea de Nicho es un marco útil para entender cómo los organismos interactúan entre ellos y con su ambiente compartido. Su representatión gráfica, popularizada por la Hipótesis de Razón de Recursos de Tilman, facilita el análisis de la estructura de equilibrio de modelos dinámicos complejos, incluyendo la coexistencia de especies. Esta teoría ha sido aplicada primariamente a competencia por recursos desde sus inicios. Aquí, integramos el mutualismo dentro de la teoría de nicho al expandir la representatión gráfica de Tilman al análisis de la dinámica consumidor-recurso de las redes planta-polinizador. Explicamos gráficamente fenómenos cualitativos encontrados previamente mediante simulaciones numéricas, incluyendo los efectos sobre la dinámica comunitaria del anidamiento, forrajeo adaptativo y de las invasiones por polinizadores. Nuestra aproximación gráfica promueve la unificatión de las teorías de nicho y de redes, y profundiza la síntesis de diferentes tipos de interacciones dentro de un marco de consumidor-recurso.

scholarly journals MULTI-CLASS RESOURCE SHARING WITH BATCH ARRIVALS

2018 ◽  
Vol 33 (3) ◽  
pp. 348-366
Author(s):  
Paul Ezhilchelvan ◽  
Isi Mitrani
Keyword(s):  
Resource Sharing ◽  
Large Scale ◽  
Virtual Machines ◽  
Cloud Provider ◽  
Batch Arrivals ◽  
Large Scale Systems ◽  
Trade Offs ◽  
Resource Requirements ◽  
Partial Blocking ◽  
Fixed Point Iterations

A cloud provider hosts virtual machines (VMs) of different types, with different resource requirements. There are bounds on the total amounts of each kind of resource that are available. Requests arrive in batches of different sizes. Under the ‘complete blocking’ policy, a request is accepted only if all the VMs in its batch can be accommodated. The ‘partial blocking’ policy would accept a request if there is room for at least one of the VMs in the batch. Blocked requests are lost, with an associated loss of revenue. The trade-offs between costs and benefits are evaluated by means of appropriate models, for which novel solutions based on fixed-point iterations are proposed. The applicability of those solutions is extended, by means of simplifications, to very large-scale systems. Numerical examples and comparisons with simulations are presented.

scholarly journals Grazing resistance in phytoplankton

Hydrobiologia ◽  
2020 ◽  
Vol 848 (1) ◽  
pp. 237-249 ◽  
Author(s):  
Miquel Lürling
Keyword(s):  
Community Dynamics ◽  
Phytoplankton Community ◽  
Rapid Evolution ◽  
Variable Environment ◽  
Trade Off ◽  
Defense Strategies ◽  
Trade Offs ◽  
Grazing Resistance ◽  
Population And Community Dynamics

AbstractPhytoplankton is confronted with a variable assemblage of zooplankton grazers that create a strong selection pressure for traits that reduce mortality. Phytoplankton is, however, also challenged to remain suspended and to acquire sufficient resources for growth. Consequently, phytoplanktic organisms have evolved a variety of strategies to survive in a variable environment. An overview is presented of the various phytoplankton defense strategies, and costs and benefits of phytoplankton defenses with a zooming in on grazer-induced colony formation. The trade-off between phytoplankton competitive abilities and defenses against grazing favor adaptive trait changes—rapid evolution and phenotypic plasticity—that have the potential to influence population and community dynamics, as exemplified by controlled chemostat experiments. An interspecific defense–growth trade-off could explain seasonal shifts in the species composition of an in situ phytoplankton community yielding defense and growth rate as key traits of the phytoplankton. The importance of grazing and protection against grazing in shaping the phytoplankton community structure should not be underestimated. The trade-offs between nutrient acquisition, remaining suspended, and grazing resistance generate the dynamic phytoplankton community composition.

scholarly journals QTL × environment interactions underlie adaptive divergence in switchgrass across a large latitudinal gradient

2019 ◽  
Vol 116 (26) ◽  
pp. 12933-12941 ◽  
Author(s):  
David B. Lowry ◽  
John T. Lovell ◽  
Li Zhang ◽  
Jason Bonnette ◽  
Philip A. Fay ◽  
...  
Keyword(s):  
Local Adaptation ◽  
Panicum Virgatum ◽  
Environmental Gradients ◽  
Adaptive Divergence ◽  
Multiple Loci ◽  
Trade Offs ◽  
Locally Adaptive ◽  
Trait Locus ◽  
Benefits And Costs ◽  
Transplant Experiments

Local adaptation is the process by which natural selection drives adaptive phenotypic divergence across environmental gradients. Theory suggests that local adaptation results from genetic trade-offs at individual genetic loci, where adaptation to one set of environmental conditions results in a cost to fitness in alternative environments. However, the degree to which there are costs associated with local adaptation is poorly understood because most of these experiments rely on two-site reciprocal transplant experiments. Here, we quantify the benefits and costs of locally adaptive loci across 17° of latitude in a four-grandparent outbred mapping population in outcrossing switchgrass (Panicum virgatumL.), an emerging biofuel crop and dominant tallgrass species. We conducted quantitative trait locus (QTL) mapping across 10 sites, ranging from Texas to South Dakota. This analysis revealed that beneficial biomass (fitness) QTL generally incur minimal costs when transplanted to other field sites distributed over a large climatic gradient over the 2 y of our study. Therefore, locally advantageous alleles could potentially be combined across multiple loci through breeding to create high-yielding regionally adapted cultivars.

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 My niche: individual spatial niche specialization affects within- and between-species interactions

2020 ◽  
Vol 287 (1918) ◽  
pp. 20192211 ◽  
Author(s):  
Annika Schirmer ◽  
Julia Hoffmann ◽  
Jana A. Eccard ◽  
Melanie Dammhahn
Keyword(s):  
Species Interactions ◽  
Community Dynamics ◽  
Species Coexistence ◽  
Myodes Glareolus ◽  
Ecological Niches ◽  
Species Variation ◽  
Interaction Patterns ◽  
Spatial Interactions ◽  
Interindividual Differences ◽  
Niche Specialization

Intraspecific trait variation is an important determinant of fundamental ecological interactions. Many of these interactions are mediated by behaviour. Therefore, interindividual differences in behaviour should contribute to individual niche specialization. Comparable with variation in morphological traits, behavioural differentiation between individuals should limit similarity among competitors and thus act as a mechanism maintaining within-species variation in ecological niches and facilitating species coexistence. Here, we aimed to test whether interindividual differences in boldness covary with spatial interactions within and between two ecologically similar, co-occurring rodent species ( Myodes glareolus , Apodemus agrarius ). In five subpopulations in northeast Germany, we quantified individual differences in boldness via repeated standardized tests and spatial interaction patterns via capture–mark–recapture ( n = 126) and automated VHF telemetry ( n = 36). We found that boldness varied with space use in both species. Individuals of the same population occupied different spatial niches, which resulted in non-random patterns of within- and between-species spatial interactions. Behavioural types mainly differed in the relative importance of intra- versus interspecific competition. Within-species variation along this competition gradient could contribute to maintaining individual niche specialization. Moreover, behavioural differentiation between individuals limits similarity among competitors, which might facilitate the coexistence of functionally equivalent species and, thus, affect community dynamics and local biodiversity.

scholarly journals Below-ground plant–fungus network topology is not congruent with above-ground plant–animal network topology

2015 ◽  
Vol 1 (9) ◽  
pp. e1500291 ◽  
Author(s):  
Hirokazu Toju ◽  
Paulo R. Guimarães ◽  
Jens M. Olesen ◽  
John N. Thompson
Keyword(s):  
Network Topology ◽  
Network Architecture ◽  
Community Dynamics ◽  
Species Coexistence ◽  
Interspecific Interactions ◽  
Fungal Species ◽  
Sequencing Data ◽  
Phylogenetic Groups ◽  
Form Complex ◽  
Below Ground

In nature, plants and their pollinating and/or seed-dispersing animals form complex interaction networks. The commonly observed pattern of links between specialists and generalists in these networks has been predicted to promote species coexistence. Plants also build highly species-rich mutualistic networks below ground with root-associated fungi, and the structure of these plant–fungus networks may also affect terrestrial community processes. By compiling high-throughput DNA sequencing data sets of the symbiosis of plants and their root-associated fungi from three localities along a latitudinal gradient, we uncovered the entire network architecture of these interactions under contrasting environmental conditions. Each network included more than 30 plant species and hundreds of mycorrhizal and endophytic fungi belonging to diverse phylogenetic groups. The results were consistent with the notion that processes shaping host-plant specialization of fungal species generate a unique linkage pattern that strongly contrasts with the pattern of above-ground plant–partner networks. Specifically, plant–fungus networks lacked a “nested” architecture, which has been considered to promote species coexistence in plant–partner networks. Rather, the below-ground networks had a conspicuous “antinested” topology. Our findings lead to the working hypothesis that terrestrial plant community dynamics are likely determined by the balance between above-ground and below-ground webs of interspecific interactions.

Sign in / Sign up

Export Citation Format

Share Document