Interference competition pressure predicts the number of avian predators that shifted their timing of activity

Being active at different times facilitates the coexistence of functionally similar species. Hence, time partitioning might be induced by competition. However, the relative importance of direct interference and indirect exploitation competition on time partitioning remains unclear. The aim of this study was to investigate the relative importance of these two forms of competition on the occurrence of time-shifting among avian predator species. As a measure of interference competition pressure, we used the species richness of day-active avian predator species or of night-active avian predator species (i.e. species of Accipitriformes, Falconiformes and Strigiformes) in a particular geographical area (assemblage). As an estimate of exploitation competition pressure, we used the total species richness of avian predators in each assemblage. Estimates of the intensity of interference competition robustly predicted the number of Accipitriformes species that became crepuscular and the number of Strigiformes species that became day-active or strictly crepuscular. Interference competition pressure may depend on body size and on the total duration of the typical active period (day or night length). Our results support—to some extent—that smaller species are more likely to become time-shifters. Day length did not have an effect on the number of time-shifter species in the Accipitriformes. Among the large Strigiformes, more time-shifter species occur in areas where nights are shorter (i.e. where less of the typical time resource is available). However, in the small Strigiformes, we found the opposite, counterintuitive effect: more time-shifters where nights are longer. Exploitation competition may have had an additional positive effect on the number of time-shifters, but only in Accipitriformes, and the effect was not as robust. Our results thus support the interference competition hypothesis, suggesting that animals may have shifted their time of activity, despite phylogenetic constraints on the ability to do so, to reduce the costs of direct interactions. Our findings also highlight the influence of body size as a surrogate of competitive ability during encounters on time partitioning, at least among avian predators.

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Behavioral Interactions and Body Size Differences in Competition for Food among Juvenile Brown Bullhead (Ictalurus nebulosus)

Canadian Journal of Fisheries and Aquatic Sciences ◽

10.1139/f82-043 ◽

1982 ◽

Vol 39 (2) ◽

pp. 316-320 ◽

Cited By ~ 6

Author(s):

W. Hubert Keen

Keyword(s):

Body Size ◽

Social Interactions ◽

Growth Rates ◽

Interference Competition ◽

Size Difference ◽

Food Level ◽

Brown Bullhead ◽

Exploitation Competition ◽

Behavioral Interactions ◽

Ictalurus Nebulosus

The effects of relative body size (larger or smaller fish), absolute body size differences, food level, and social interactions on the growth rates of juvenile brown bullhead (Ictalurus nebulosus) catfish were determined for pairs of fish. Overall growth rate of the larger fish was higher than for the smaller fish, although this difference did not depend on absolute body size difference within pairs. The reduced growth rates of both larger and smaller fish at limited food level was independent of both relative size difference and absolute body size difference within pairs. Both larger and smaller fish had highly variable growth rates. Size dominance and aggression were common within many pairs, yet this behavior was unrelated to food level and absolute body size difference. Aggression within pairs was not diminished by adding structural complexity to simple environments. It is suggested that the high variability in growth rates was due to differences in individuals within pairs with respect to the intensity of behavioral interactions. Social interactions within pairs offish were apparently unrelated to food level and were strong enough to mask both exploitative and interference mechanisms which may have been functional in competition for limited food.Key words: body size, dominance hierarchies, exploitation competition, food level, Ictalurus nebulosus, interference competition, behavioral interactions

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Trophic position scales positively with body size within but not among four species of rocky reef predators

Marine Ecology Progress Series ◽

10.3354/meps13275 ◽

2020 ◽

Vol 640 ◽

pp. 189-200 ◽

Cited By ~ 1

Author(s):

AM Olson ◽

A Frid ◽

JBQ dos Santos ◽

F Juanes

Keyword(s):

Body Size ◽

Trophic Position ◽

Stomach Contents ◽

Rocky Reef ◽

Morphometric Traits ◽

Predator Species ◽

Predatory Fishes ◽

Average Size ◽

Interspecific Comparisons ◽

Large Predators

Intra- and interspecifically, larger-bodied predators generally occupy higher trophic positions (TPs). With widespread declines in large predators, there is a need to understand their size-based trophic roles to predict ecosystem-level responses. In British Columbia, Canada, we examined size-based trophic interactions between predatory fishes—3 rockfish species (genus Sebastes) and lingcod Ophiodon elongatus—and their prey, converting predator δ15N signatures to TP and analyzing stomach contents. Intraspecifically, TP scaled positively with predator length and gape width, but the rates of change varied by species. Interspecifically, TP did not scale positively with the observed mean sizes or known maximum sizes of species. Lingcod TP was lower than that of yelloweye and quillback rockfishes, which were 51 and 37%, respectively, smaller than lingcod. Yellowtail rockfish had the smallest average size, yet their mean TP did not differ significantly from that of lingcod. Neither species differences in some morphometric traits known to influence body size-TP relationships nor phylogenetic history explained these results. Most prey consumed were <20% of the predator’s size, which might partially explain the lack of a size-based trophic hierarchy among species. Currently, large size classes of rockfishes are being lost due to fisheries and perhaps climate-driven changes. Our findings on intraspecific size-TP relationships indicate that fishery removals of large individuals may diminish trophic structures. Interspecific comparisons of TP suggest that, along with size, species remain an important factor in understanding trophic dynamics. In addition, smaller-bodied predator species may have significant ecological roles to be considered in ecosystem-based fisheries management.

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Correlates of Species Richness in Mammals: Body Size, Life History, and Ecology

The American Naturalist ◽

10.2307/3473390 ◽

2005 ◽

Vol 165 (5) ◽

pp. 600

Author(s):

Nick J. B. Isaac ◽

Jones ◽

Gittleman ◽

Purvis

Keyword(s):

Life History ◽

Species Richness ◽

Body Size

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Mechanisms Involved in Interspecific Communication between Wine Yeasts

Foods ◽

10.3390/foods10081734 ◽

2021 ◽

Vol 10 (8) ◽

pp. 1734

Author(s):

Ana Mencher ◽

Pilar Morales ◽

Jordi Tronchoni ◽

Ramon Gonzalez

Keyword(s):

Alcoholic Fermentation ◽

Yeast Species ◽

Interspecific Interactions ◽

Interference Competition ◽

Weighted Average ◽

Starter Cultures ◽

Simple Consequence ◽

Wine Yeasts ◽

Exploitation Competition ◽

Metabolic Intermediates

In parallel with the development of non-Saccharomyces starter cultures in oenology, a growing interest has developed around the interactions between the microorganisms involved in the transformation of grape must into wine. Nowadays, it is widely accepted that the outcome of a fermentation process involving two or more inoculated yeast species will be different from the weighted average of the corresponding individual cultures. Interspecific interactions between wine yeasts take place on several levels, including interference competition, exploitation competition, exchange of metabolic intermediates, and others. Some interactions could be a simple consequence of each yeast running its own metabolic programme in a context where metabolic intermediates and end products from other yeasts are present. However, there are clear indications, in some cases, of specific recognition between interacting yeasts. In this article we discuss the mechanisms that may be involved in the communication between wine yeasts during alcoholic fermentation.

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Disentangling the Ecological Determinants of Species and Functional Trait Diversity in Herb-Layer Plant Communities in European Temperate Forests

Forests ◽

10.3390/f12050552 ◽

2021 ◽

Vol 12 (5) ◽

pp. 552

Author(s):

Janez Kermavnar ◽

Lado Kutnar ◽

Aleksander Marinšek

Keyword(s):

Species Richness ◽

Species Composition ◽

Plant Communities ◽

Functional Trait ◽

Forest Stand ◽

Relative Importance ◽

Herb Layer ◽

Bud Bank ◽

Tree Species Composition ◽

Stand Characteristics

Forest herb-layer vegetation responds sensitively to environmental conditions. This paper compares drivers of both taxonomic, i.e., species richness, cover and evenness, and functional herb-layer diversity, i.e., the diversity of clonal, bud bank and leaf-height-seed plant traits. We investigated the dependence of herb-layer diversity on ecological determinants related to soil properties, climatic parameters, forest stand characteristics, and topographic and abiotic and biotic factors associated with forest floor structure. The study was conducted in different forest types in Slovenia, using vegetation and environmental data from 50 monitoring plots (400 m2 each) belonging to the ICP Forests Level I and II network. The main objective was to first identify significant ecological predictors and then quantify their relative importance. Species richness was strongly determined by forest stand characteristics, such as richness of the shrub layer, tree layer shade-casting ability as a proxy for light availability and tree species composition. It showed a clear positive relation to soil pH. Variation in herb-layer cover was also best explained by forest stand characteristics and, to a lesser extent, by structural factors such as moss cover. Species evenness was associated with tree species composition, shrub layer cover and soil pH. Various ecological determinants were decisive for the diversity of below-ground traits, i.e., clonal and bud bank traits. For these two trait groups we observed a substantial climatic signal that was completely absent for taxonomy-based measures of diversity. In contrast, above-ground leaf-height-seed (LHS) traits were driven exclusively by soil reaction and nitrogen availability. In synthesis, local stand characteristics and soil properties acted as the main controlling factors for both species and trait diversity in herb-layer communities across Slovenia, confirming many previous studies. Our findings suggest that the taxonomic and functional facets of herb-layer vegetation are mainly influenced by a similar set of ecological determinants. However, their relative importance varies among individual taxonomy- and functional trait-based diversity measures. Integrating multi-faceted approaches can provide complementary information on patterns of herb-layer diversity in European forest plant communities.

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Differences in abundance, species richness, and body size of ground beetles (Coleoptera: Carabidae) between beech (Fagus sylvatica L.) forests on Podzol and Cambisol

Forest Ecology and Management ◽

10.1016/j.foreco.2008.08.006 ◽

2008 ◽

Vol 256 (12) ◽

pp. 2154-2159 ◽

Cited By ~ 9

Author(s):

Germund Tyler

Keyword(s):

Species Richness ◽

Body Size ◽

Fagus Sylvatica ◽

Ground Beetles ◽

Fagus Sylvatica L

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Body size, reef area and temperature predict global reef-fish species richness across spatial scales

Global Ecology and Biogeography ◽

10.1111/geb.12851 ◽

2018 ◽

Vol 28 (3) ◽

pp. 315-327 ◽

Cited By ~ 8

Author(s):

D. R. Barneche ◽

E. L. Rezende ◽

V. Parravicini ◽

E. Maire ◽

G. J. Edgar ◽

...

Keyword(s):

Species Richness ◽

Body Size ◽

Reef Fish ◽

Fish Species ◽

Spatial Scales ◽

Reef Area ◽

Reef Fish Species

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Competition among Nasal Bacteria Suggests a Role for Siderophore-Mediated Interactions in Shaping the Human Nasal Microbiota

Applied and Environmental Microbiology ◽

10.1128/aem.02406-18 ◽

2018 ◽

Vol 85 (10) ◽

Cited By ~ 11

Author(s):

Reed M. Stubbendieck ◽

Daniel S. May ◽

Marc G. Chevrette ◽

Mia I. Temkin ◽

Evelyn Wendt-Pienkowski ◽

...

Keyword(s):

Nasal Cavity ◽

Iron Acquisition ◽

Interference Competition ◽

Human Microbiome ◽

Human Microbiome Project ◽

Siderophore Production ◽

Coagulase Negative Staphylococci ◽

Exploitation Competition ◽

Content Type

ABSTRACTResources available in the human nasal cavity are limited. Therefore, to successfully colonize the nasal cavity, bacteria must compete for scarce nutrients. Competition may occur directly through interference (e.g., antibiotics) or indirectly by nutrient sequestration. To investigate the nature of nasal bacterial competition, we performed coculture inhibition assays between nasalActinobacteriaandStaphylococcusspp. We found that isolates of coagulase-negative staphylococci (CoNS) were sensitive to growth inhibition byActinobacteriabut thatStaphylococcus aureusisolates were resistant to inhibition. AmongActinobacteria, we observed thatCorynebacteriumspp. were variable in their ability to inhibit CoNS. We sequenced the genomes of 10Corynebacteriumspecies isolates, including 3Corynebacterium propinquumisolates that strongly inhibited CoNS and 7 otherCorynebacteriumspecies isolates that only weakly inhibited CoNS. Using a comparative genomics approach, we found that theC. propinquumgenomes were enriched in genes for iron acquisition and harbored a biosynthetic gene cluster (BGC) for siderophore production, absent in the noninhibitoryCorynebacteriumspecies genomes. Using a chrome azurol S assay, we confirmed thatC. propinquumproduced siderophores. We demonstrated that iron supplementation rescued CoNS from inhibition byC. propinquum, suggesting that inhibition was due to iron restriction through siderophore production. Through comparative metabolomics and molecular networking, we identified the siderophore produced byC. propinquumas dehydroxynocardamine. Finally, we confirmed that the dehydroxynocardamine BGC is expressedin vivoby analyzing human nasal metatranscriptomes from the NIH Human Microbiome Project. Together, our results suggest that bacteria produce siderophores to compete for limited available iron in the nasal cavity and improve their fitness.IMPORTANCEWithin the nasal cavity, interference competition through antimicrobial production is prevalent. For instance, nasalStaphylococcusspecies strains can inhibit the growth of other bacteria through the production of nonribosomal peptides and ribosomally synthesized and posttranslationally modified peptides. In contrast, bacteria engaging in exploitation competition modify the external environment to prevent competitors from growing, usually by hindering access to or depleting essential nutrients. As the nasal cavity is a nutrient-limited environment, we hypothesized that exploitation competition occurs in this system. We determined thatCorynebacterium propinquumproduces an iron-chelating siderophore, and this iron-sequestering molecule correlates with the ability to inhibit the growth of coagulase-negative staphylococci. Furthermore, we found that the genes required for siderophore production are expressedin vivo. Thus, although siderophore production by bacteria is often considered a virulence trait, our work indicates that bacteria may produce siderophores to compete for limited iron in the human nasal cavity.

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