Interspecific Interactions II: Competition and Mutualism

Aquatic Environments ◽

Biotic Interaction ◽

Controlled Experiments ◽

Aquatic Communities ◽

Shared Resource ◽

Differential Reduction

Competition and mutualism are important forms of biotic interaction in aquatic communities. Quantification of the population and community-level effects of these interactions has historically been less common in fisheries analyses than predation. In part, this reflects the difficulties in conducting controlled experiments for larger-bodied organisms in aquatic environments. Documenting competition entails not only identifying patterns of shared resource use but evidence that these resources are limiting. Inferences concerning competitive interactions in non-experimental settings may be possible if histories of population change for putative competitors are available and quantifiable interventions involving the addition of a species (through deliberate or inadvertent introductions) or a differential reduction in abundance of the species through harvesting is undertaken. Care must be taken to account for other changes in the environment in these uncontrolled quasi-experiments. Mutualistic interactions are widely recognized in aquatic ecosystems but far less commonly quantified than competition.

Costs of intraspecific and interspecific host sharing in acanthocephalan cystacanths

Parasitology ◽

10.1017/s0031182001007454 ◽

2001 ◽

Vol 122 (4) ◽

pp. 483-489 ◽

Cited By ~ 40

Author(s):

B. S. DEZFULI ◽

L. GIARI ◽

R. POULIN

Keyword(s):

Intermediate Host ◽

Definitive Host ◽

Sympatric Species ◽

Host Size ◽

Intermediate Hosts ◽

Transmission Success ◽

Additional Costs ◽

Net Benefits

Larval helminths often share individual intermediate hosts with other larval worms of the same or different species. In the case of immature acanthocephalans capable of altering the phenotype of their intermediate hosts, the benefits or costs of host sharing can be evaluated in terms of increased or decreased probability of transmission to a suitable definitive host. Competitive interactions among the immature stages of acanthocephalans within the intermediate host could create additional costs of host sharing, however. The effects of intraspecific and interspecific interactions were measured in 3 sympatric species of acanthocephalans exploiting a population of the amphipod Echinogammarus stammeri in the River Brenta, Italy. The strength of interactions was assessed from differences in the size achieved by infective cystacanths in the intermediate host. The size of Pomphorhynchus laevis cystacanths was not correlated with host size, whereas the size of Acanthocephalus clavula and Polymorphus minutus cystacanths increased with host size. Reductions in cystacanth size caused by intraspecific competition were only detected in P. laevis, but may also occur in both A. clavula and P. minutus. When co-occurring in the same amphipod with cystacanths of A. clavula, cystacanths of P. laevis attained a smaller size than when they occurred on their own. This effect was not reciprocal, with the size of A. clavula cystacanths not being affected. This supports earlier suggestions that it is adaptive for A. clavula to associate with P. laevis in amphipod intermediate hosts, with both species going to the same fish definitive hosts. In contrast, cystacanths of P. laevis achieved their largest size when they co-occurred in an amphipod with a cystacanth of P. minutus, which has a different definitive host (i.e. birds). These findings suggest that the net benefits of sharing an intermediate host can only be estimated by taking into account both the effects on transmission success and the consequences for cystacanth development.

Context-dependent dynamics lead to the assembly of functionally distinct pitcher-plant microbiomes

10.1101/727701 ◽

2019 ◽

Author(s):

Leonora S. Bittleston ◽

Matti Gralka ◽

Gabriel E. Leventhal ◽

Itzhak Mizrahi ◽

Otto X. Cordero

Keyword(s):

Resource Use ◽

Bacterial Communities ◽

Niche Construction ◽

Sarracenia Purpurea ◽

Strongly Correlated ◽

Pitcher Plant ◽

Respiration Rates ◽

Active Debate ◽

And Function

AbstractNiche construction through interspecific interactions can condition future community states on past ones. However, the extent to which such history dependency can steer communities towards functionally different states remains a subject of active debate. Using bacterial communities collected from wild pitchers of the carnivorous pitcher plant, Sarracenia purpurea, we tested the effects of history on composition and function across communities assembled in synthetic pitcher plant microcosms. We found that the diversity of assembled communities was determined by the diversity of the system at early, pre-assembly stages. Species composition was also contingent on early community states, not only because of differences in the species pool, but also because the same species had different dynamics in different community contexts. Importantly, compositional differences were proportional to differences in function, as profiles of resource use were strongly correlated with composition, despite convergence in respiration rates. Early differences in community structure can thus propagate to mature communities, conditioning their functional repertoire.

The Ecology and Evolution of Model Microbial Mutualisms

Annual Review of Ecology Evolution and Systematics ◽

10.1146/annurev-ecolsys-012121-091753 ◽

2021 ◽

Vol 52 (1) ◽

Author(s):

Jeremy M. Chacón ◽

Sarah P. Hammarlund ◽

Jonathan N.V. Martinson ◽

Leno B. Smith ◽

William R. Harcombe

Keyword(s):

Future Study ◽

Evolutionary Dynamics ◽

Natural World ◽

Annual Review ◽

Publication Date ◽

Controlled Experiments ◽

Evolutionary Origins ◽

Ecological Features ◽

Open Questions

Mutually beneficial interspecific interactions are abundant throughout the natural world, including between microbes. Mutualisms between microbes are critical for everything from human health to global nutrient cycling. Studying model microbial mutualisms in the laboratory enables highly controlled experiments for developing and testing evolutionary and ecological hypotheses. In this review, we begin by describing the tools available for studying model microbial mutualisms. We then outline recent insights that laboratory systems have shed on the evolutionary origins, evolutionary dynamics, and ecological features of microbial mutualism. We touch on gaps in our current understanding of microbial mutualisms, note connections to mutualism in nonmicrobial systems, and call attention to open questions ripe for future study. Expected final online publication date for the Annual Review of Ecology, Evolution, and Systematics, Volume 52 is November 2021. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

Proximity to wastewater effluent alters behaviour in bluegill sunfish (Lepomis machrochirus)

Behaviour ◽

10.1163/1568539x-00003576 ◽

2019 ◽

Vol 156 (15) ◽

pp. 1495-1517 ◽

Cited By ~ 2

Author(s):

Adrienne R. McLean ◽

Sherry N.N. Du ◽

Jasmine A. Choi ◽

Brett M. Culbert ◽

Erin S. McCallum ◽

...

Keyword(s):

Predator Avoidance ◽

Reference Site ◽

Lepomis Macrochirus ◽

Treatment Plant ◽

Wastewater Effluent ◽

Aquatic Environments ◽

Bluegill Sunfish ◽

Aquatic Communities ◽

Risk Of Predation ◽

Negative Impacts

Abstract Wastewater from municipal, agricultural and industrial sources is a pervasive contaminant of aquatic environments worldwide. Most studies that have investigated the negative impacts of wastewater on organisms have taken place in a laboratory. Here, we tested whether fish behaviour is altered by exposure to environmentally relevant concentrations of wastewater effluent in the field. We caged bluegill sunfish (Lepomis macrochirus) for 28 days at two sites downstream (adjacent to and 870 m) from a wastewater treatment plant and at a reference site without wastewater inputs. We found that exposed fish had a dampened response to simulated predation compared to unexposed fish, suggesting that fish may be at greater risk of predation after exposure to wastewater effluent. Fish held at the different sites did not differ in activity and exploration. Our results suggest that predator avoidance may be impaired in fish exposed to wastewater effluent, which could have detrimental implications for aquatic communities.

Productivity, resource use, and competitive interactions of Fra×inus uhdei in Hawaii uplands

Canadian Journal of Forest Research ◽

10.1139/cjfr-31-1-132 ◽

2001 ◽

Vol 31 (1) ◽

pp. 132-142 ◽

Cited By ~ 1

Author(s):

Adrián Ares ◽

James H. Fownes

Keyword(s):

Resource Use ◽

Competitive Interactions

Competitive interactions and distributional dynamics in two Malagasy frogs

Journal of Tropical Ecology ◽

10.1017/s0266467405002580 ◽

2005 ◽

Vol 21 (5) ◽

pp. 569-576 ◽

Cited By ~ 5

Author(s):

Richard M. Lehtinen

Keyword(s):

Growth Rates ◽

Field Data ◽

Community Dynamics ◽

Larval Growth ◽

Frog Species ◽

Distributional Dynamics ◽

Population And Community Dynamics ◽

Forest Plants

Ecological theory predicts that interspecific interactions can affect population and community dynamics. Two experiments were conducted on Mantidactylus bicalcaratus and M. punctatus, two sympatric frog species from Madagascar that live and breed in rain-forest plants (Pandanus spp.), to test for interspecific competition. The first experiment examined larval growth rates and survivorship with and without conspecifics. While survivorship did not differ among treatments, mean growth rates for M. bicalcaratus were significantly reduced in the presence of M. punctatus larvae. The second experiment manipulated the presence and density of adults in Pandanus plants. Emigration from and immigration to experimental plants tended to be higher and lower, respectively, for M. bicalcaratus in the presence of M. punctatus, but these differences were not significant. These results demonstrate asymmetric competition (at least as larvae) and indicate that M. punctatus is the superior competitor. Field data showed that M. bicalcaratus was found significantly more frequently in the absence of M. punctatus. Also, M. bicalcaratus populations were significantly more likely to go locally extinct in the presence of M. punctatus. These data suggest that asymmetric competitive interactions are important influences on the dynamics of these populations.

Forest dynamics of a subtropical monsoon forest in Dinghushan, China: recruitment, mortality and the pace of community change

Journal of Tropical Ecology ◽

10.1017/s0266467413000059 ◽

2013 ◽

Vol 29 (2) ◽

pp. 131-145 ◽

Cited By ~ 23

Author(s):

Yong Shen ◽

Louis S. Santiago ◽

Lei Ma ◽

Guo-Jun Lin ◽

Ju-Yu Lian ◽

...

Keyword(s):

Tropical Forests ◽

Forest Dynamics ◽

Tree Mortality ◽

Population Change ◽

Community Change ◽

Subtropical Forest ◽

Size Class ◽

Forest Plot ◽

Monsoon Forest

Abstract:Structure and demographics in many tropical forests is changing, but the causes of these changes remain unclear. We studied 5 y (2005–2010) of species turnover, recruitment, mortality and population change data from a 20-ha subtropical forest plot in Dinghushan, China, to identify trends in forest change, and to test whether tree mortality is associated with intraspecific or interspecific competition. We found the Dinghushan forest to be more dynamic than one temperate and two tropical forests in a comparison of large, long-term forest dynamics plots. Within Dinghushan, size-class distributions were bell-shaped only for the three most dominant species and reverse J-shaped for other species. Bell-shaped population distributions can indicate a population in decline, but our data suggest that these large and long-lived species are not in decline because the pattern is driven by increasing probabilities of transition to larger size class with increasing size and fast growth in saplings. Spatially aggregated tree species distributions were common for surviving and dead individuals. Competitive associations were more frequently intraspecific than interspecific. The competition that induced tree mortality was more associated with intraspecific than interspecific interactions. Intraspecific competitive exclusion and density-dependence appear to play important roles in tree mortality in this subtropical forest.

Inducible competitors and adaptive diversification

Current Zoology ◽

10.1093/czoolo/59.4.537 ◽

2013 ◽

Vol 59 (4) ◽

pp. 537-552 ◽

Cited By ~ 9

Author(s):

Beren W. Robinson ◽

David W. Pfennig

Keyword(s):

Phenotypic Plasticity ◽

Resource Use ◽

Evolutionary Biology ◽

The Other ◽

Adaptive Plasticity ◽

Evolutionary Divergence ◽

Phenotypic Differences ◽

Adaptive Diversification ◽

Divergent Natural Selection

Abstract Identifying the causes of diversification is central to evolutionary biology. The ecological theory of adaptive diversification holds that the evolution of phenotypic differences between populations and species—and the formation of new species—stems from divergent natural selection, often arising from competitive interactions. Although increasing evidence suggests that phenotypic plasticity can facilitate this process, it is not generally appreciated that competitively mediated selection often also provides ideal conditions for phenotypic plasticity to evolve in the first place. Here, we discuss how competition plays at least two key roles in adaptive diversification depending on its pattern. First, heterogenous competition initially generates heterogeneity in resource use that favors adaptive plasticity in the form of “inducible competitors”. Second, once such competitively induced plasticity evolves, its capacity to rapidly generate phenotypic variation and expose phenotypes to alternate selective regimes allows populations to respond readily to selection favoring diversification, as may occur when competition generates steady diversifying selection that permanently drives the evolutionary divergence of populations that use different resources. Thus, competition plays two important roles in adaptive diversification—one well-known and the other only now emerging—mediated through its effect on the evolution of phenotypic plasticity.