scholarly journals The evolution of size-dependent competitive interactions promotes species coexistence

2021 ◽  
Author(s):  
Jaime M Anaya-Rojas ◽  
Ronald D Bassar ◽  
Tomos Potter ◽  
Allison Blanchette ◽  
Shay Callahan ◽  
...  
Keyword(s):  
Body Size ◽  
Interspecific Competition ◽  
Poecilia Reticulata ◽  
Species Coexistence ◽  
Somatic Growth ◽  
Competitive Interactions ◽  
Growth Data ◽  
Sympatric Populations ◽  
Size Dependent ◽  
Niche Shifts

Theory indicates that competing species coexist in a community when intraspecific competition is stronger than interspecific competition. When body size determines the outcome of competitive interactions between individuals, coexistence depends also on how resource use and the ability to compete for these resources change with body size. Testing coexistence theory in size-structured communities, therefore, requires disentangling the effects of size-dependent competitive abilities and niche shifts. Here, we tested the hypothesis that the evolution of species and size-dependent competitive asymmetries increased the likelihood of coexistence between interacting species. We experimentally estimated the effects of size-dependent competitive interactions on somatic growth rates of two interacting fish species, Trinidadian guppies (Poecilia reticulata) and killifish (Rivulus hartii). We controlled for the effects of size-dependent changes in the niche at two competitive settings representing the early (allopatric) and late (sympatric) evolutionary stages of a killifish-guppy community. We fitted the growth data to a model that incorporates species and size-dependent competitive asymmetries to test whether changes in the competitive interactions across stages increased the likelihood of species coexistence from allopatry to sympatry. We found that guppies are competitively superior to killifish but were less so in sympatric populations. The decrease in the effects of interspecific competition on the fitness of killifish and increase in the interspecific effect on guppies` fitness increased the likelihood that sympatric guppies and killifish will coexist. However, while the competitive asymmetries between the species changed consistently between allopatry and sympatry between drainages, the size-dependent competitive asymmetries varied between drainages. These results demonstrate the importance of integrating evolution and trait-based interactions into the research of how species coexistence.

scholarly journals The evolution of size‐dependent competitive interactions promotes species coexistence

2021 ◽  
Author(s):  
Jaime M. Anaya‐Rojas ◽  
Ronald D. Bassar ◽  
Tomos Potter ◽  
Allison Blanchette ◽  
Shay Callahan ◽  
...  
Keyword(s):  
Species Coexistence ◽  
Competitive Interactions ◽  
Size Dependent

scholarly journals Character Displacement Through an Evolutionary Change in Ontogenetic Niche Shifts

2021 ◽  
Author(s):  
Jaime Anaya-Rojas ◽  
Ronald Bassar ◽  
Blake Matthews ◽  
Joshua Goldberg ◽  
David Reznick ◽  
...  
Keyword(s):  
Body Size ◽  
Poecilia Reticulata ◽  
Character Displacement ◽  
Trophic Niche ◽  
Niche Shift ◽  
Ontogenetic Niche Shifts ◽  
Ontogenetic Niche Shift ◽  
Significant Difference ◽  
Niche Shifts ◽  
Ontogenetic Niche

In communities structured by body size, coexistence can occur through combinations of ontogenetic changes in competitive ability and dietary niche. Using stable isotopes, we examined ontogenetic niche shifts in Trinidadian guppies (Poecilia reticulata) and killifish (Rivulus hartii) in three types of natural communities (both species with predators, KGP; both without predators, KG; killifish only, KO) and four experimental KG communities, initiated with KGP guppies and KO killifish between 13 and 45 years ago. In all communities, killifish occupied higher trophic positions and changed their diet (δ^13 C) with body size. Only KGP guppies displayed an ontogenetic niche shift. The KG guppies displayed a significant difference in trophic niche from KGP guppies, a character displacement that can facilitate coexistence with killifish. In the experimental communities, the guppy trophic niche was intermediate between those in KGP and KG communities, indicating that evolution has driven the niche shift in KG guppies.

scholarly journals Food Web Structure Informs Potential Causes of Bimodal Size Structure in a Top Predator

2018 ◽  
Vol 11 (1) ◽  
pp. 36-45 ◽  
Author(s):  
Peter C. Searle ◽  
Joshua A. Verde ◽  
Mark C. Belk
Keyword(s):  
Body Size ◽  
Yellow Perch ◽  
Lake Trout ◽  
Large Body ◽  
Somatic Growth ◽  
Salvelinus Namaycush ◽  
Trophic Niche ◽  
Competitive Interactions ◽  
Large Body Size ◽  
Small Lake

Background: Assemblages of fishes in lakes and reservoirs in the western USA are dominated by non-native, large-bodied, piscivorous fishes that lack a shared evolutionary history. Top predators in these crowded systems are often characterized by unstable population dynamics and poor somatic growth rates. One such assemblage is in Fish Lake, located in southern Utah, USA, in which introduced lake trout (Salvelinus namaycush, Walbaum) exhibit a bimodal growth pattern. A few lake trout in Fish Lake grow rapidly to large size typical of the species; whereas, most never grow beyond 600 mm total length. Objective: To inform competitive interactions in this evolutionarily novel fish assemblage that might cause the low recruitment to large body size in lake trout, we characterized trophic niche (from stable isotope analysis of C and N) of all fishes in the lake. Methods: We used a Bayesian mixing model to describe the trophic niche and infer diet of lake trout and their potential prey, and we used Bayesian ellipse analysis to identify potential areas of high competition within the food web. Large lake trout feed mostly on small lake trout and splake (Salvelinus namaycush, Walbaum x Salvelinus fontinalis, Mitchill) despite availability of abundant yellow perch. (Perca flavescens, Mitchill). Small lake trout and splake feed mostly on zooplankton and exhibit substantial overlap of their trophic niche implying competition for food. Yellow perch and Utah chub (Gila atraria, Girard; formerly an important food item for lake trout in Fish Lake) exhibit extreme overlap of their trophic niche implying strong competitive interactions. Results: Our data suggest that lack of recruitment to large body size in lake trout may result from a reduction in availability of Utah chub resulting from competitive interactions with yellow perch, and increased competition from introduced splake for available prey. Conclusion: Management actions that may help ameliorate the poor somatic growth rates of most lake trout include efforts to reduce perch populations or increase vulnerability of perch to predation by lake trout, and removal of splake as a competitor of small lake trout.

scholarly journals Character Displacement Through and Evolutionary Change in Ontogenetic niche shifts

2021 ◽  
Author(s):  
Jaime Anaya-Rojas ◽  
Ronald Bassar ◽  
Blake Matthews ◽  
Joshua Goldberg ◽  
David Reznick ◽  
...  
Keyword(s):  
Body Size ◽  
Poecilia Reticulata ◽  
Character Displacement ◽  
Trophic Niche ◽  
Niche Shift ◽  
Ontogenetic Niche Shifts ◽  
Ontogenetic Niche Shift ◽  
Significant Difference ◽  
Niche Shifts ◽  
Ontogenetic Niche

In communities structured by body size, coexistence can occur through combinations of ontogenetic changes in competitive ability and dietary niche. Using stable isotopes, we examined ontogenetic niche shifts in Trinidadian guppies (Poecilia reticulata) and killifish (Rivulus hartii) in three types of natural communities (both species with predators, KGP; both without predators, KG; killifish only, KO) and four experimental KG communities, initiated with KGP guppies and KO killifish between 13 and 45 years ago. In all communities, killifish occupied higher trophic positions and changed their diet (δ^13 C) with body size. Only KGP guppies displayed an ontogenetic niche shift. The KG guppies displayed a significant difference in trophic niche from KGP guppies, a character displacement that can facilitate coexistence with killifish. In the experimental communities, the guppy trophic niche was intermediate between those in KGP and KG communities, indicating that evolution has driven the niche shift in KG guppies.

scholarly journals Predicting Coexistence in Species with Continuous Ontogenetic Niche Shifts and Competitive Asymmetry

2017 ◽  
Author(s):  
Ronald D. Bassar ◽  
Joseph Travis ◽  
Tim Coulson
Keyword(s):  
Body Size ◽  
Competitive Ability ◽  
Species Coexistence ◽  
Stable State ◽  
Life Cycles ◽  
Niche Separation ◽  
Ontogenetic Changes ◽  
Alternative Stable State ◽  
Niche Shifts ◽  
Body Sizes

ABSTRACTA longstanding problem in ecology is whether structured life cycles impede or facilitate coexistence between species. Theory based on populations with two discrete stages in the life-cycle indicates that coexistence requires at least one species to shift its niche between stages and that each species is a better competitor in one of the niches. However, in many cases, niche shifts are associated with changes in an underlying continuous trait like organism size and we have few predictions for how the conditions for coexistence are affected by this type of ontogenetic dynamics. Here we develop a framework for analyzing species coexistence based on Integral Projection Models (IPMs) that incorporates continuous ontogenetic changes in both the resource niche and competitive ability. We parameterize the model using experimental data from Trinidadian guppies and make predictions about how niche shifts and competitive symmetries allow or prevent species coexistence. Overall, our results show that the effects of competition on fitness depend upon trait-mediated niche-separation, trait-mediated competitive asymmetry in the part of the niche that is shared across body sizes, and the sensitivity of fitness to body size. When all three conditions are considered, we find multiple ecological and evolutionary routes to coexistence. When both species can shift their niche with increasing body size and competition for resources among the species and sizes is symmetric, then the species that shifts its niche to a greater degree with ontogeny will competitively exclude the other species. When competitive ability increases with increasing body size, then the two species can coexist when the better competitor shifts its niche with body size to a lesser degree than the weaker competitior. This region of coexistence shrinks as the better competitor increasingly shifts its niche with increasing size. When both species shift their niches with size, but each is a better competitor on resources used by smaller or larger individuals, then the model predicts an alternative stable state over some range of niche shifts. We discuss how our results provide new insights into species coexistence and the evolutionary consequences of size-structured interspecific competition.

Body size-dependent Cd accumulation in the zebra mussel Dreissena polymorpha from different routes

Chemosphere ◽  
2017 ◽  
Vol 168 ◽  
pp. 825-831 ◽  
Author(s):  
Wen-Li Tang ◽  
Douglas Evans ◽  
Lisa Kraemer ◽  
Huan Zhong
Keyword(s):  
Body Size ◽  
Zebra Mussel ◽  
Dreissena Polymorpha ◽  
Cd Accumulation ◽  
Size Dependent

An ecological explanation for hyperallometric scaling of reproduction

2021 ◽  
Author(s):  
Tomos Potter ◽  
Anja Felmy
Keyword(s):  
Body Size ◽  
Reproductive Output ◽  
Resource Competition ◽  
Natural Populations ◽  
Scaling Exponent ◽  
Wild Populations ◽  
Wet Season ◽  
Size Dependent ◽  
In The Wild ◽  
The Relationship

AbstractIn wild populations, large individuals have disproportionately higher reproductive output than smaller individuals. We suggest an ecological explanation for this observation: asymmetry within populations in rates of resource assimilation, where greater assimilation causes both increased reproduction and body size. We assessed how the relationship between size and reproduction differs between wild and lab-reared Trinidadian guppies. We show that (i) reproduction increased disproportionately with body size in the wild but not in the lab, where effects of resource competition were eliminated; (ii) in the wild, the scaling exponent was greatest during the wet season, when resource competition is strongest; and (iii) detection of hyperallometric scaling of reproduction is inevitable if individual differences in assimilation are ignored. We propose that variation among individuals in assimilation – caused by size-dependent resource competition, niche expansion, and chance – can explain patterns of hyperallometric scaling of reproduction in natural populations.

scholarly journals Guppies prefer to follow large (robot) leaders irrespective of own size

2018 ◽  
Author(s):  
David Bierbach ◽  
Hauke J. Mönck ◽  
Juliane Lukas ◽  
Marie Habedank ◽  
Pawel Romanczuk ◽  
...  
Keyword(s):  
Body Size ◽  
Risk Taking ◽  
Poecilia Reticulata ◽  
Direct Evidence ◽  
Behavioral Patterns ◽  
Behavioral Differences ◽  
Leaders And Followers ◽  
Biomimetic Robotic Fish ◽  
Risk Taking Behavior ◽  
Swimming Capacity

AbstractBody size is often assumed to determine how successful an individual can lead others with larger individuals being more likely to lead than smaller ones. However, direct evidence for such a relation is scarce. Furthermore, even if larger individuals are more likely to lead, body size correlates often with specific behavioral patterns (e.g., swimming capacity) and it is thus unclear whether larger individuals are more often followed than smaller ones because they are larger or because they behave in a certain way. To control for behavioral differences among differentially-sized leaders, we used biomimetic robotic fish – Robofish – of different sizes. Robofish is accepted as a conspecific by live guppies (Poecilia reticulata) and provides standardized behaviors irrespective of its size. We specifically asked whether larger leaders are preferentially followed when behavior is controlled for and whether the preferences of followers depend on their own body size or their risk taking behavior (‘boldness’). We found that live guppies followed larger Robofish leaders closer than smaller ones and this pattern was independent of the followers’ own body size as well as risk-taking behavior. This is the first study that shows a ‘bigger is better’ pattern in leadership in shoaling fish that is fully independent of behavioral differences between differentially-sized leaders and followers’ own size and personality.

scholarly journals Metabolic Symbiosis Facilitates Species Coexistence and Generates Light-Dependent Priority Effects

2021 ◽  
Vol 8 ◽  
Author(s):  
Veronica Hsu ◽  
Holly V. Moeller
Keyword(s):  
Carbon Source ◽  
Community Composition ◽  
Green Algae ◽  
Species Interactions ◽  
Species Coexistence ◽  
Priority Effects ◽  
Competitive Interactions ◽  
Paramecium Bursaria ◽  
Mutual Benefit ◽  
Cascading Effects

Metabolic symbiosis is a form of symbiosis in which organisms exchange metabolites, typically for mutual benefit. For example, acquired phototrophs like Paramecium bursaria obtain photosynthate from endosymbiotic green algae called Chlorella. In addition to facilitating the persistence of P. bursaria by providing a carbon source that supplements P. bursaria’s heterotrophic digestion of bacteria, symbiotic Chlorella may impact competitive interactions between P. bursaria and other bacterivores, with cascading effects on community composition and overall diversity. Here, we tested the effects of metabolic symbiosis on coexistence by assessing the impacts of acquired phototrophy on priority effects, or the effect of species arrival order on species interactions, between P. bursaria and its competitor Colpidium. Our results suggest light-dependent priority effects. The acquired phototroph benefited from metabolic symbiosis during sequential arrival of each organism in competition, and led to increased growth of late-arriving Colpidium. These findings demonstrate that understanding the consequences of priority effects for species coexistence requires consideration of metabolic symbiosis.

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