scholarly journals Spatial ecology of territorial populations

2019 ◽  
Vol 116 (36) ◽  
pp. 17874-17879 ◽  
Author(s):  
Benjamin G. Weiner ◽  
Anna Posfai ◽  
Ned S. Wingreen
Keyword(s):  
Mixed Models ◽  
Spatial Ecology ◽  
Allee Effect ◽  
Spatial Organization ◽  
Resource Competition ◽  
Physical Space ◽  
Small Perturbations ◽  
Trade Offs ◽  
Nutrient Diffusion ◽  
Competition For Resources

Many ecosystems, from vegetation to biofilms, are composed of territorial populations that compete for both nutrients and physical space. What are the implications of such spatial organization for biodiversity? To address this question, we developed and analyzed a model of territorial resource competition. In the model, all species obey trade-offs inspired by biophysical constraints on metabolism; the species occupy nonoverlapping territories, while nutrients diffuse in space. We find that the nutrient diffusion time is an important control parameter for both biodiversity and the timescale of population dynamics. Interestingly, fast nutrient diffusion allows the populations of some species to fluctuate to zero, leading to extinctions. Moreover, territorial competition spontaneously gives rise to both multistability and the Allee effect (in which a minimum population is required for survival), so that small perturbations can have major ecological effects. While the assumption of trade-offs allows for the coexistence of more species than the number of nutrients—thus violating the principle of competitive exclusion—overall biodiversity is curbed by the domination of “oligotroph” species. Importantly, in contrast to well-mixed models, spatial structure renders diversity robust to inequalities in metabolic trade-offs. Our results suggest that territorial ecosystems can display high biodiversity and rich dynamics simply due to competition for resources in a spatial community.

scholarly journals Spatial Ecology of Territorial Populations

2019 ◽  
Author(s):  
Benjamin G. Weiner ◽  
Anna Posfai ◽  
Ned S. Wingreen
Keyword(s):  
Mixed Models ◽  
Spatial Ecology ◽  
Allee Effect ◽  
Spatial Organization ◽  
Resource Competition ◽  
Physical Space ◽  
Small Perturbations ◽  
Trade Offs ◽  
Nutrient Diffusion ◽  
Competition For Resources

Many ecosystems, from vegetation to biofilms, are composed of territorial populations that compete for both nutrients and physical space. What are the implications of such spatial organization for biodiversity? To address this question, we developed and analyzed a model of territorial resource competition. In the model, all species obey trade-offs inspired by biophysical constraints on metabolism; the species occupy non-overlapping territories while nutrients diffuse in space. We find that the nutrient diffusion time is an important control parameter for both biodiversity and the timescale of population dynamics. Interestingly, fast nutrient diffusion allows the populations of some species to fluctuate to zero, leading to extinctions. Moreover, territorial competition spontaneously gives rise to both multistability and the Allee effect (in which a minimum population is required for survival), so that small perturbations can have major ecological effects. While the assumption of trade-offs allows for the coexistence of more species than the number of nutrients – thus violating the principle of competitive exclusion – overall biodiversity is curbed by the domination of “oligotroph” species. Importantly, in contrast to well-mixed models, spatial structure renders diversity robust to inequalities in metabolic trade-offs. Our results suggest that territorial ecosystems can display high biodiversity and rich dynamics simply due to competition for resources in a spatial community.

scholarly journals Of Uberfleas and Krakens: Detecting Trade-offs Using Mixed Models

2017 ◽  
Vol 57 (2) ◽  
pp. 362-371 ◽  
Author(s):  
Vincent Careau ◽  
Robbie S. Wilson
Keyword(s):  
Mixed Models ◽  
Trade Offs

Structural organization in palm stems of Roystonea regia and Archontophoenix alexandrae

IAWA Journal ◽  
2020 ◽  
pp. 1-26
Author(s):  
Amy Ny Aina Aritsara ◽  
Kun-Fang Cao
Keyword(s):  
Water Transport ◽  
Structural Organization ◽  
Spatial Organization ◽  
Mechanical Support ◽  
Trade Off ◽  
Breast Height ◽  
Mechanical Constraints ◽  
Fiber Fraction ◽  
Trade Offs ◽  
Palm Species

Abstract Having a high stature subjects palms to the same constraints as trees, but the lack of cambial growth urges them to adopt a different strategy. We aimed to characterize the spatial organization of xylem tissues and their potential functions in two palm stems: a 30 cm diameter at breast height (DBH) royal palm (Roystonea regia) and a 12 cm DBH Alexandra king palm (Archontophoenix alexandrae). Macroscopic and microscopic anatomical characteristics were assessed at five vertical locations and 5–6 radial locations at each height. Over 9600 vessels across the two stems were drawn manually and measured based on histological sections. Vertically, a hydraulic bottleneck was identified at the first meter, and both stems showed conduit tapering from 4 m to the top. Radially, most water transport and mechanical support were achieved within 2–5 cm below the bark. The larger stem diameter of royal palm may have improved its water transport, storage, and potential for mechanical support compared to king palm. There was a strong trade-off between ground parenchyma and the fiber fraction. However, the correlation between theoretical hydraulic conductivity (Kt) and the ground parenchyma fraction, and between Kt and the fiber fraction, shifted from positive or non-significant below the bark, to strongly negative close to the center. These changes reflect the functional sectoriality of the palm stems, which may reduce the constraint of trade-offs between water transport, storage, and mechanical support. To conclude, functional sectoriality may have helped both palm species to withstand the hydraulic and mechanical constraints due to high stature.

Sexuality and the Spatial Dynamics of Capitalism

1992 ◽  
Vol 10 (6) ◽  
pp. 651-669 ◽  
Author(s):  
L Knopp
Keyword(s):  
Social Relations ◽  
Spatial Organization ◽  
Spatial Dynamics ◽  
Physical Space ◽  
Social Categories ◽  
Symbolic Space ◽  
Physical Mobility ◽  
Recent Developments ◽  
The Usa ◽  
Gender Based

Sexuality, gender, and class (with race, ethnicity, physical mobility, and other social categories related to power) are deeply implicated in the constitution of each other as social relations. Spatial structures and conflicts that are constitutive of class relations are therefore also constitutive of sexuality. An examination of recent developments in feminist, lesbian and gay, and radical social theory, and certain elements of the historical geography of capitalism, reveals specific ways in which this is so. Urban spatial designs in Britain and the USA in the 19th and 20th centuries, for example, implicate hegemonic constructions of sexuality in gender-based and class-based spatial divisions of labor. Similarly, struggles over the social definitions of sexuality have involved individuals and groups recoding spaces that have been devalued by the market in potentially counterhegemonic ways. Thus, struggles over sexuality manifest themselves as struggles over sexual representations of, and sexual symbols in, space as well as over spatial organization. Indeed, these sorts of struggles may actually be more important in the contemporary era than those concerning the spatial organization of sexuality. This is because the sociospatial construction of otherness, which has as much to do with representational and symbolic space as with physical space, has become key to the survival of capitalism.

scholarly journals Competition and the origins of novelty: experimental evolution of niche-width expansion in a virus

2013 ◽  
Vol 9 (1) ◽  
pp. 20120616 ◽  
Author(s):  
Lisa M. Bono ◽  
Catharine L. Gensel ◽  
David W. Pfennig ◽  
Christina L. Burch
Keyword(s):  
Host Range ◽  
Resource Use ◽  
Intraspecific Competition ◽  
Experimental Evolution ◽  
Resource Competition ◽  
Experimental Tests ◽  
Model System ◽  
Standard Laboratory ◽  
Narrow Host Range ◽  
Competition For Resources

Competition for resources has long been viewed as a key agent of divergent selection. Theory holds that populations facing severe intraspecific competition will tend to use a wider range of resources, possibly even using entirely novel resources that are less in demand. Yet, there have been few experimental tests of these ideas. Using the bacterial virus (bacteriophage) ϕ 6 as a model system, we examined whether competition for host resources promotes the evolution of novel resource use. In the laboratory, ϕ 6 exhibits a narrow host range but readily produces mutants capable of infecting novel bacterial hosts. Here, we show that when ϕ 6 populations were subjected to intense intraspecific competition for their standard laboratory host, they rapidly evolved new generalist morphs that infect novel hosts . Our results therefore suggest that competition for host resources may drive the evolution of host range expansion in viruses. More generally, our findings demonstrate that intraspecific resource competition can indeed promote the evolution of novel resource-use phenotypes.

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 Trade-offs and design principles in the spatial organization of catalytic particles

2021 ◽  
Author(s):  
Florian Hinzpeter ◽  
Filipe Tostevin ◽  
Alexander Buchner ◽  
Ulrich Gerland
Keyword(s):  
Spatial Organization ◽  
Design Principles ◽  
Trade Offs ◽  
Catalytic Particles

Spatial valuation of California marine fisheries as an ecosystem service

2017 ◽  
Vol 74 (11) ◽  
pp. 1732-1748 ◽  
Author(s):  
Rebecca R. Miller ◽  
John C. Field ◽  
Jarrod A. Santora ◽  
Melissa H. Monk ◽  
Rosemary Kosaka ◽  
...  
Keyword(s):  
Ecosystem Services ◽  
Spatial Organization ◽  
Economic Value ◽  
Spatially Explicit ◽  
Marine Spatial Planning ◽  
Marine Fisheries ◽  
Trade Offs ◽  
Stock Assessments ◽  
Proportional Value ◽  
Taxonomic Groups

Quantifying spatiotemporal dynamics of ecosystem services is an emerging approach for informing and managing trade-offs among cumulative or competing activities in marine environments. As one proxy for ecosystem services and benefits, we quantified and mapped catch and economic value of California commercial fisheries removals using a 75-year spatially explicit time series. From 1931 to 2005, approximately 88% of the catch was attributed to finfish. However, there has been an increasing reliance of proportional value from invertebrates over the last 25 years. The spatial organization of historical catches suggests species composition varies substantially by depth and latitude, and an evaluation of changes in the spatial distribution of catches in three different time periods suggests that spatial shifts in catch locations have occurred for some taxonomic groups over time. A spatial assessment of historical catches and value benefits marine spatial planning, informs stock assessments, provides a quantification of ecosystem services, and facilitates ecosystem-based approaches to marine fisheries management.

scholarly journals Spatial organization of the pale fox in the Termit Massif of east Niger

2016 ◽  
Vol 97 (2) ◽  
pp. 526-532 ◽  
Author(s):  
Claudio Sillero-Zubiri ◽  
Susana Rostro-García ◽  
Dylan Burruss
Keyword(s):  
Spatial Ecology ◽  
Spatial Organization ◽  
Home Range Size ◽  
Density Estimator ◽  
Body Measurements ◽  
Minimum Convex Polygon ◽  
Semiarid Environments ◽  
Adult Body Mass ◽  
Adult Body ◽  
Core Areas

Abstract Pale foxes ( Vulpes pallida ) have a widespread distribution across the Saharan-Sahel in northern Africa, but little is known about their ecology and natural history. Here, we provide the 1st ecological information on the species. We captured and radio-collared 10 pale foxes in the Termit & Tin Toumma National Nature and Cultural Reserve of east Niger. The adult body mass (1.20 ± SD 0.18kg, n = 6) was about half of what was previously reported, confirming this species as one of the smallest canids in the world. Body measurements were relatively similar between sexes, suggesting little if any sexual dimorphism. Mean ± SD home range size ( n = 6) was 6.79±3.58 km 2 using 100% minimum convex polygon and 5.62±3.11 km 2 using 95% fixed kernel density estimator. Overlap between adjacent pale fox ranges was generally low (mean overlap index = 0.11±0.22), with nearly exclusive core areas (mean overlap index = 0.02±0.06), suggesting pale foxes are territorial. Overall, the spatial ecology of pale foxes showed similar characteristics to other Vulpes species, especially those inhabiting arid and semiarid environments.

Demystifying asynchronous I/O Interference in HPC applications

2021 ◽  
pp. 109434202110165
Author(s):  
Shu-Mei Tseng ◽  
Bogdan Nicolae ◽  
Franck Cappello ◽  
Aparna Chandramowlishwaran
Keyword(s):  
Data Management ◽  
Resource Sharing ◽  
Memory Bandwidth ◽  
Parallel File System ◽  
Network Bandwidth ◽  
Application Behavior ◽  
Trade Offs ◽  
Depth Study ◽  
Memory Network ◽  
Competition For Resources

With increasing complexity of HPC workflows, data management services need to perform expensive I/O operations asynchronously in the background, aiming to overlap the I/O with the application runtime. However, this may cause interference due to competition for resources: CPU, memory/network bandwidth. The advent of multi-core architectures has exacerbated this problem, as many I/O operations are issued concurrently, thereby competing not only with the application but also among themselves. Furthermore, the interference patterns can dynamically change as a response to variations in application behavior and I/O subsystems (e.g. multiple users sharing a parallel file system). Without a thorough understanding, I/O operations may perform suboptimally, potentially even worse than in the blocking case. To fill this gap, this paper investigates the causes and consequences of interference due to asynchronous I/O on HPC systems. Specifically, we focus on multi-core CPUs and memory bandwidth, isolating the interference due to each resource. Then, we perform an in-depth study to explain the interplay and contention in a variety of resource sharing scenarios such as varying priority and number of background I/O threads and different I/O strategies: sendfile, read/write, mmap/write underlining trade-offs. The insights from this study are important both to enable guided optimizations of existing background I/O, as well as to open new opportunities to design advanced asynchronous I/O strategies.

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