scholarly journals Effects of niche overlap on coexistence, fixation and invasion in a population of two interacting species

2020 ◽  
Vol 7 (2) ◽  
pp. 192181
Author(s):  
Matthew Badali ◽  
Anton Zilman
Keyword(s):  
Resource Sharing ◽  
Specific Interaction ◽  
Niche Overlap ◽  
Mixed Population ◽  
Strong Interactions ◽  
Population Stability ◽  
Interacting Species ◽  
Experimental Systems ◽  
Competition Result ◽  
Antagonistic Interactions

Synergistic and antagonistic interactions in multi-species populations—such as resource sharing and competition—result in remarkably diverse behaviours in populations of interacting cells, such as in soil or human microbiomes, or clonal competition in cancer. The degree of inter- and intra-specific interaction can often be quantified through the notion of an ecological ‘niche’. Typically, weakly interacting species that occupy largely distinct niches result in stable mixed populations, while strong interactions and competition for the same niche result in rapid extinctions of some species and fixations of others. We investigate the transition of a deterministically stable mixed population to a stochasticity-induced fixation as a function of the niche overlap between the two species. We also investigate the effect of the niche overlap on the population stability with respect to external invasions. Our results have important implications for a number of experimental systems.

scholarly journals Eco-evolutionary feedbacks promote fluctuating selection and long-term stability of antagonistic networks

2018 ◽  
Vol 285 (1874) ◽  
pp. 20172596 ◽  
Author(s):  
Cecilia Siliansky de Andreazzi ◽  
Paulo R. Guimarães ◽  
Carlos J. Melián
Keyword(s):  
Temporal Variation ◽  
Evolutionary Dynamics ◽  
Species Interaction ◽  
Fluctuating Selection ◽  
Term Stability ◽  
Long Term Stability ◽  
Interacting Species ◽  
Species Abundances ◽  
Antagonistic Interactions

Studies have shown the potential for rapid adaptation in coevolving populations and that the structure of species interaction networks can modulate the vulnerability of ecological systems to perturbations. Although the feedback loop between population dynamics and coevolution of traits is crucial for understanding long-term stability in ecological assemblages, modelling eco-evolutionary dynamics in species-rich assemblages is still a challenge. We explore how eco-evolutionary feedbacks influence trait evolution and species abundances in 23 empirical antagonistic networks. We show that, if selection due to antagonistic interactions is stronger than other selective pressures, eco-evolutionary feedbacks lead to higher mean species abundances and lower temporal variation in abundances. By contrast, strong selection of antagonistic interactions leads to higher temporal variation of traits and on interaction strengths. Our results present a theoretical link between the study of the species persistence and coevolution in networks of interacting species, pointing out the ways by which coevolution may decrease the vulnerability of species within antagonistic networks to demographic fluctuation.

scholarly journals Antagonistic Interactions between Yeast [PSI+] and [URE3] Prions and Curing of [URE3] by Hsp70 Protein Chaperone Ssa1p but Not by Ssa2p

2002 ◽  
Vol 22 (11) ◽  
pp. 3590-3598 ◽  
Author(s):  
Christine Schwimmer ◽  
Daniel C. Masison
Keyword(s):  
De Novo ◽  
Prion Proteins ◽  
Specific Interaction ◽  
Positive Interactions ◽  
Genetic Elements ◽  
Hsp70 Protein ◽  
Elevated Expression ◽  
Constitutive Overexpression ◽  
Protein Chaperone ◽  
Antagonistic Interactions

ABSTRACT The yeast [PSI +], [URE3], and [PIN +] genetic elements are prion forms of Sup35p, Ure2p, and Rnq1p, respectively. Overexpression of Sup35p, Ure2p, or Rnq1p leads to increased de novo appearance of [PSI +], [URE3], and [PIN +], respectively. This inducible appearance of [PSI +] was shown to be dependent on the presence of [PIN +] or [URE3] or overexpression of other yeast proteins that have stretches of polar residues similar to the prion-determining domains of the known prion proteins. In a similar manner, [PSI +] and [URE3] facilitate the appearance of [PIN +]. In contrast to these positive interactions, here we find that in the presence of [PIN +], [PSI +] and [URE3] repressed each other's propagation and de novo appearance. Elevated expression of Hsp104 and Hsp70 (Ssa2p) had little effect on these interactions, ruling out competition between the two prions for limiting amounts of these protein chaperones. In contrast, we find that constitutive overexpression of SSA1 but not SSA2 cured cells of [URE3], uncovering a specific interaction between Ssa1p and [URE3] and a functional distinction between these nearly identical Hsp70 isoforms. We also find that Hsp104 abundance, which critically affects [PSI +] propagation, is elevated when [URE3] is present. Our results are consistent with the notion that proteins that have a propensity to form prions may interact with heterologous prions but, as we now show, in a negative manner. Our data also suggest that differences in how [PSI +] and [URE3] interact with Hsp104 and Hsp70 may contribute to their antagonistic interactions.

scholarly journals Microevolutionary Effects of Habitat Fragmentation on Plant-Animal Interactions

2014 ◽  
Vol 2014 ◽  
pp. 1-7 ◽  
Author(s):  
Francisco E. Fontúrbel ◽  
Maureen M. Murúa
Keyword(s):  
Habitat Fragmentation ◽  
Ecological Interactions ◽  
Fragmented Habitats ◽  
Interacting Species ◽  
Biodiversity Maintenance ◽  
Selective Forces ◽  
Plant Animal Interactions ◽  
New Interactions ◽  
Antagonistic Interactions

Plant-animal interactions are a key component for biodiversity maintenance, but they are currently threatened by human activities. Habitat fragmentation might alter ecological interactions due to demographic changes, spatial discontinuities, and edge effects. Also, there are less evident effects of habitat fragmentation that potentially alter selective forces and compromise the fitness of the interacting species. Changes in the mutualistic and antagonistic interactions in fragmented habitats could significantly influence the plant reproductive output and the fauna assemblage associated with. Fragmented habitats may trigger contemporary evolution processes and open new evolutionary opportunities. Interacting parties with a diffuse and asymmetric relationship are less susceptible to local extinction but more prone to evolve towards new interactions or autonomy. However, highly specialized mutualisms are likely to disappear. On the other hand, ecological interactions may mutually modulate their response in fragmented habitats, especially when antagonistic interactions disrupt mutualistic ones. Ecoevolutionary issues of habitat fragmentation have been little explored, but the empiric evidence available suggests that the complex modification of ecological interactions in fragmented habitats might lead to nonanalogous communities on the long term.

scholarly journals Evolutionary Ecology of Natural Comammox Nitrospira Populations

mSystems ◽  
2022 ◽  
Author(s):  
Alejandro Palomo ◽  
Arnaud Dechesne ◽  
Otto X. Cordero ◽  
Barth F. Smets
Keyword(s):  
Evolutionary Dynamics ◽  
Evolutionary Ecology ◽  
Single Species ◽  
Evolutionary Processes ◽  
Ecological Processes ◽  
Interacting Species ◽  
Microbial Species ◽  
Experimental Systems ◽  
Over Time

Microbial species interact with each other and their environment (ecological processes) and undergo changes in their genomic repertoire over time (evolutionary processes). How these two classes of processes interact is largely unknown, especially for complex communities, as most studies of microbial evolutionary dynamics consider single species in isolation or a few interacting species in simplified experimental systems.

scholarly journals FOOD RESOURCE SHARING AMONG BENTHIC AND NEKTONIC STREAM FISH SPECIES

2021 ◽  
Vol 47 ◽  
pp. e634
Author(s):  
Guilherme Raphael Camargo Arcanjo SILVA ◽  
Maurício CETRA
Keyword(s):  
Fish Species ◽  
Resource Sharing ◽  
Diet Composition ◽  
Food Resource ◽  
Niche Overlap ◽  
High Concentration ◽  
Insect Larvae ◽  
Significant Difference ◽  
Food Content ◽  
Water Ecosystems

Several tropical freshwater fish species are generally generalistic feeders, sometimes followed by a diet reduction during the period of decreased resource availability. This study aimed to analyze the dietary overlap between nektonic and benthic fish species. The stomachs of 82 obligatory nektonics and 52 benthic were removed. The diet composition for each individual was determined based on the analysis of the stomach content, and the contents were grouped into 11 categories. For the analysis of food items, the method of degree of food preference was used. To verify the niche overlap between benthic and nectonic, the Pianka index was applied. Benthic species consumed items across all 11 food categories and nektonic species consumed nine. The diet composition of species with nektonic and benthic habits showed a significant difference. Dietary overlapping suggests a supply of the same resources, as they are shared by both groups. The high concentration of water insect larvae in the food content of all sampled fish species, regardless of the position in the water column, shows the importance of insects in the water ecosystems. The composition of ecosystem diets is helpful towards understanding the community structure and can explain the coexistence between different fish’s groups where live in different micro-habitats and how tactics used to capture food which may minimize the effects of overlapping and competitive exclusion.

Macroecological patterns and niche structure in a new marine food web

2008 ◽  
Vol 3 (1) ◽  
pp. 91-103 ◽  
Author(s):  
Gabriel Yvon-Durocher ◽  
Jose Montoya ◽  
Mark Emmerson ◽  
Guy Woodward
Keyword(s):  
Food Web ◽  
Body Mass ◽  
Weak Interactions ◽  
Interaction Strength ◽  
Niche Overlap ◽  
Irish Sea ◽  
Strong Interactions ◽  
Predator Prey ◽  
Marine Food Web ◽  
Lough Hyne

AbstractThe integration of detailed information on feeding interactions with measures of abundance and body mass of individuals provides a powerful platform for understanding ecosystem organisation. Metabolism and, by proxy, body mass constrain the flux, turnover and storage of energy and biomass in food webs. Here, we present the first food web data for Lough Hyne, a species rich Irish Sea Lough. Through the application of individual-and size-based analysis of the abundance-body mass relationship, we tested predictions derived from the metabolic theory of ecology. We found that individual body mass constrained the flux of biomass and determined its distribution within the food web. Body mass was also an important determinant of diet width and niche overlap, and predator diets were nested hierarchically, such that diet width increased with body mass. We applied a novel measure of predator-prey biomass flux which revealed that most interactions in Lough Hyne were weak, whereas only a few were strong. Further, the patterning of interaction strength between prey sharing a common predator revealed that strong interactions were nearly always coupled with weak interactions. Our findings illustrate that important insights into the organisation, structure and stability of ecosystems can be achieved through the theoretical exploration of detailed empirical data.

Overlap and resource sharing in coteries of fruit-eating birds

2013 ◽  
Vol 29 (5) ◽  
pp. 409-416 ◽  
Author(s):  
Adriano Marcos da Silva ◽  
Celine de Melo
Keyword(s):  
Plant Species ◽  
Resource Sharing ◽  
Relative Proportion ◽  
Bird Species ◽  
Niche Overlap ◽  
Mean Value ◽  
Null Models ◽  
Savanna Woodland ◽  
The Mean ◽  
Focal Observation

Abstract:A range of species eating the same fruit suggests that niche overlap can occur, along with potential competition among them. To test if the overlap in the coterie of fruit-eating birds is larger than would be expected by chance, we performed a comparison with coteries generated from the use of null models. The study was carried out in an area of savanna woodland of 127 ha in Uberlândia city, Brazil. Four individuals of five zoochorous plant species were selected and 60 h of focal observation was performed on each species. We recorded species of birds that consumed fruits and the quantity of fruit removed. We used an index of Proportional Similarity (PS) between each pair of plant species, using the relative proportion of fruit taken by each bird species of each plant. The mean value of observed PS was compared with the mean PS generated from randomizations. Thirty-six bird species were recorded eating fruits in the selected plant species. The mean overlap observed (PS = 0.183) was significantly higher (P = 0.032) than the mean overlap generated by the null models (PS = 0.123). This pattern suggests that competition is not an important factor in the formation of the coteries and there is sharing of resources. The abundance of fruits offered, especially in the rainy season, and the relatively low number of frugivorous species may be factors explaining the low influence of interactions and therefore the overlap between coteries.

scholarly journals The T4 RI Antiholin Has an N-Terminal Signal Anchor Release Domain That Targets It for Degradation by DegP

2007 ◽  
Vol 189 (21) ◽  
pp. 7618-7625 ◽  
Author(s):  
Tram Anh T. Tran ◽  
Douglas K. Struck ◽  
Ry Young
Keyword(s):  
Signal Sequence ◽  
Secondary Infection ◽  
Specific Interaction ◽  
Proteolytic Processing ◽  
Hydrophobic Domain ◽  
Experimental Systems ◽  
Lysis Inhibition ◽  
Infected Cells ◽  
Signal Anchor ◽  
Hydrophilic Domain

ABSTRACT Lysis inhibition (LIN) of T4-infected cells was one of the foundational experimental systems for modern molecular genetics. In LIN, secondary infection of T4-infected cells results in a dramatically protracted infection cycle in which intracellular phage and endolysin accumulation can continue for hours. At the molecular level, this is due to the inhibition of the holin, T, by the antiholin, RI. RI is only 97 residues and contains an N-terminal hydrophobic domain and a C-terminal hydrophilic domain; expression of the latter domain fused to a secretory signal sequence is sufficient to impose LIN, due to its specific interaction with the periplasmic domain of the T holin. Here we show that the N-terminal sequence comprises a signal anchor release (SAR) domain, which causes the secretion of RI in a membrane-tethered form and then its subsequent release into the periplasm, without proteolytic processing. Moreover, the SAR domain confers both functional lability and DegP-mediated proteolytic instability on the released form of RI, although LIN is not affected in a degP host. These results are discussed in terms of a model for the activation of RI in the establishment of the LIN state.

The Cellular Origin in Atheromatous Lesion

1970 ◽  
Vol 28 ◽  
pp. 202-203
Author(s):  
T. M. Murad ◽  
H. A. I. Newman ◽  
K. F. Kern
Keyword(s):  
Smooth Muscle ◽  
Smooth Muscle Cells ◽  
Rabbit Aorta ◽  
Mixed Population ◽  
The Other ◽  
Cellular Origin ◽  
Ultrastructural Studies ◽  
Atherosclerotic Lesions ◽  
Show Evidence ◽  
Early Lesion

The origin of lipid containing cells in atheromatous lesion has been disputed. Geer in his study on atheromatous lesions of rabbit aorta, suggested that the early lesion is composed mainly of lipid-laden macrophages and the later lesion has a mixed population of macrophages and smooth muscle cells. Parker on the other hand, was able to show evidence that the rabbit lesion is primarily composed of lipid-laden cells of smooth muscle origin. The above studies and many others were done on an intact lesion without any attempt of cellular isolation previous to their ultrastructural studies. Cell isolation procedures have been established for atherosclerotic lesions through collagenase and elastase digestion Therefore this procedure can be utilized to identify the cells involved in rabbit atheroma.

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