scholarly journals Metapopulations with habitat modification

2021 ◽  
Vol 118 (49) ◽  
pp. e2109896118
Author(s):  
Zachary R. Miller ◽  
Stefano Allesina
Keyword(s):  
Simple Model ◽  
Stability Condition ◽  
Positive Relationship ◽  
Conceptual Models ◽  
Local Environment ◽  
Habitat Modification ◽  
Metapopulation Model ◽  
Quantitative Stability ◽  
Number Of Species ◽  
Wide Range

Across the tree of life, organisms modify their local environment, rendering it more or less hospitable for other species. Despite the ubiquity of these processes, simple models that can be used to develop intuitions about the consequences of widespread habitat modification are lacking. Here, we extend the classic Levins metapopulation model to a setting where each of n species can colonize patches connected by dispersal, and when patches are vacated via local extinction, they retain a “memory” of the previous occupant—modeling habitat modification. While this model can exhibit a wide range of dynamics, we draw several overarching conclusions about the effects of modification and memory. In particular, we find that any number of species may potentially coexist, provided that each is at a disadvantage when colonizing patches vacated by a conspecific. This notion is made precise through a quantitative stability condition, which provides a way to unify and formalize existing conceptual models. We also show that when patch memory facilitates coexistence, it generically induces a positive relationship between diversity and robustness (tolerance of disturbance). Our simple model provides a portable, tractable framework for studying systems where species modify and react to a shared landscape.

scholarly journals Metapopulations with habitat modification

2021 ◽  
Author(s):  
Zachary R Miller ◽  
Stefano Allesina
Keyword(s):  
Simple Model ◽  
Stability Condition ◽  
Positive Relationship ◽  
Conceptual Models ◽  
Local Environment ◽  
Habitat Modification ◽  
Metapopulation Model ◽  
Quantitative Stability ◽  
Number Of Species ◽  
Wide Range

Across the tree of life, organisms modify their local environment, rendering it more or less hospitable for other species. Despite the ubiquity of these processes, simple models that can be used to develop intuitions about the consequences of widespread habitat modification are lacking. Here we extend the classic Levins' metapopulation model to a setting where each of n species can colonize patches connected by dispersal, and when patches are vacated via local extinction, they retain a "memory" of the previous occupant---modeling habitat modification. While this model can exhibit a wide range of dynamics, we draw several overarching conclusions about the effects of modification and memory. In particular, we find that any number of species may potentially coexist, provided that each is at a disadvantage when colonizing patches vacated by a conspecific. This notion is made precise through a quantitative stability condition, which provides a way to unify and formalize existing conceptual models. We also show that when patch memory facilitates coexistence, it generically induces a positive relationship between diversity and robustness (tolerance of disturbance). Our simple model provides a portable, tractable framework for studying systems where species modify and react to a shared landscape.

scholarly journals Chromosomal Locus That Affects Pathogenicity of Rhodococcus fascians

2002 ◽  
Vol 184 (4) ◽  
pp. 1112-1120 ◽  
Author(s):  
Danny Vereecke ◽  
Karen Cornelis ◽  
Wim Temmerman ◽  
Mondher Jaziri ◽  
Marc Van Montagu ◽  
...  
Keyword(s):  
Krebs Cycle ◽  
Malate Synthase ◽  
Habitat Modification ◽  
Signal Molecules ◽  
In Planta ◽  
Chromosomal Locus ◽  
Physiological Alterations ◽  
Rhodococcus Fascians ◽  
Wide Range ◽  
Symptomatic Tissue

ABSTRACT The gram-positive plant pathogen Rhodococcus fascians provokes leafy gall formation on a wide range of plants through secretion of signal molecules that interfere with the hormone balance of the host. Crucial virulence genes are located on a linear plasmid, and their expression is tightly controlled. A mutant with a mutation in a chromosomal locus that affected virulence was isolated. The mutation was located in gene vicA, which encodes a malate synthase and is functional in the glyoxylate shunt of the Krebs cycle. VicA is required for efficient in planta growth in symptomatic, but not in normal, plant tissue, indicating that the metabolic requirement of the bacteria or the nutritional environment in plants or both change during the interaction. We propose that induced hyperplasia on plants represents specific niches for the causative organisms as a result of physiological alterations in the symptomatic tissue. Hence, such interaction could be referred to as metabolic habitat modification.

Responses of Percid Fishes and Their Habitats to Eutrophication

1977 ◽  
Vol 34 (10) ◽  
pp. 1964-1971 ◽  
Author(s):  
J. H. Leach ◽  
M. G. Johnson ◽  
J. R. M. Kelso ◽  
J. Hartmann ◽  
W. Nümann ◽  
...  
Keyword(s):  
Physicochemical Characteristics ◽  
Habitat Modification ◽  
Trophic Conditions ◽  
Relative Level ◽  
Cultural Eutrophication ◽  
Fish Yield ◽  
Species Dominance ◽  
Wide Range ◽  
Selective Mechanism ◽  
The Continuum

Percid fishes are found in lakes that cover a wide range of trophic conditions. The responses of percids and their habitats to progressive cultural eutrophication are predictable. Alterations in physicochemical characteristics of habitats precipitate changes in phytoplankton, macrophytes, zooplankton, and benthos that are ultimately deleterious. Enrichment can lead to favorable responses in percids, but somewhere in the continuum of trophic conditions the responses become unfavorable. The relative level at which the response becomes negative varies with the species according to tolerances to altered environment, adaptabilities to new habitat and forage base, and reproductive behavior. Progressive eutrophication acts as a selective mechanism that leads to a predictable sequence of fish species. Other perturbations, such as exploitation and habitat modification, can act synergistically with cultural eutrophication in accelerating the sequence. As eutrophication proceeds, the succession of species may not lead to increased fish yield because part of the nutrient load may be channeled through unharvestable food chains. Key words: Percidae, habitat, eutrophication, species dominance, food habits, parasitism, disease

Model and Infrastructure for Communications in Context-Aware Services

2011 ◽  
pp. 472-486
Author(s):  
Cristina Rodriguez-Sanchez ◽  
Susana Borromeo ◽  
Juan Hernandez-Tamames
Keyword(s):  
Mobile Communications ◽  
Local Environment ◽  
Local Context ◽  
Context Aware ◽  
The Novel ◽  
Novel Approach ◽  
Complex Process ◽  
Wide Range ◽  
Ambient Intelligent ◽  
New Type

The appearance of concepts such as “Ambient Intelligent”, “Ubiquitous Computing” and “Context-Awareness” is causing the development of a new type of services called “Context-Aware Services” that in turn may affect users of mobile communications. This technology revolution is a a complex process because of the heterogeneity of contents, devices, objects, technologies, resources and users that can coexist at the same local environment. The novel approach of our work is the development of a ”Local Infrastructure” in order to provide intelligent, transparent and adaptable services to the user as well as to solve the problem of local context control. Two contributions will be presented: conceptual model for developing a local infrastructure and an architecture design to control the service offered by the local infrastructure. This infrastructure proposed consists of an intelligent device network to link the personal portable device with the contextual services. The device design is modular, flexible, scalable, adaptable and reconfigurable remotely in order to tolerate new demanding services whenever are needed. Finally, the result suggests that we will be able to develop a wide range of new and useful applications, not conceived at origin.

scholarly journals Disentangling the Main Components of Hydromorphological Modifications at Reach Scale in Rivers of Greece

Hydrology ◽  
2020 ◽  
Vol 7 (2) ◽  
pp. 22
Author(s):  
Konstantinos Stefanidis ◽  
Anna Latsiou ◽  
Theodora Kouvarda ◽  
Anastasia Lampou ◽  
Nektarios Kalaitzakis ◽  
...  
Keyword(s):  
Habitat Modification ◽  
Ecological Quality ◽  
Cross Sectional ◽  
Habitat Features ◽  
Wide Range ◽  
Cross Sectional Profile ◽  
Sectional Profile ◽  
Main Components ◽  
The Individual ◽  
River Habitat Survey

The Water Framework Directive (WFD) requires from member states to monitor hydromorphological features of rivers in order to assess their ecological quality. Thus, numerous hydromorphological assessment methods have been developed with most of them focusing on the dynamics of hydrology, geomorphology and riparian zone extent. Within the scope of this study, we assessed the hydromorphological features of 106 river reaches distributed among thirteen WFD River Basin Districts (RBDs) to identify the main drivers of hydromorphological perturbation at a national scale. The studied reaches reflect a wide range of natural variability as they include various types of watercourses extending from lowlands to mid-altitude and mountainous systems. We employed the River Habitat Survey (RHS), and we recorded hydromorphological features and modifications in both banks and the channel bed along 500 m for each reach. Then, the Habitat Modification Score (HMS) and the individual sub-scores that indicate the extent of specific modifications (e.g., bridges, fords, weirs, bank reprofiling, bank reinforcement, etc.) were calculated in order to a) assess the severity of the total artificial modification and b) to highlight the most common and severe causes of overall alteration. The results showed that alterations such as reprofiling and reinforcement of banks contributed the most to the total HMS followed by the presence of fords and bridges. Particularly, the bank alterations indicate a serious deterioration of the longitudinal profile of the reaches, while the occurrence of many fords and bridges is the main cause for perturbations that affect locally the stream cross-sectional profile. Overall, these results compile a first nationwide assessment of the hydromorphological status of Greek rivers in line with the WFD and set the basis for further research that will focus on the diversity of stream habitat features as a measure for the overall ecological quality.

scholarly journals Unconventional Myosins: How Regulation Meets Function

2019 ◽  
Vol 21 (1) ◽  
pp. 67 ◽  
Author(s):  
Natalia Fili ◽  
Christopher P. Toseland
Keyword(s):  
Molecular Motors ◽  
Current Knowledge ◽  
Local Environment ◽  
Structural Features ◽  
Regulatory Mechanisms ◽  
Tight Control ◽  
Cellular Processes ◽  
Binding Partners ◽  
Wide Range ◽  
Multiple Levels

Unconventional myosins are multi-potent molecular motors that are assigned important roles in fundamental cellular processes. Depending on their mechano-enzymatic properties and structural features, myosins fulfil their roles by acting as cargo transporters along the actin cytoskeleton, molecular anchors or tension sensors. In order to perform such a wide range of roles and modes of action, myosins need to be under tight regulation in time and space. This is achieved at multiple levels through diverse regulatory mechanisms: the alternative splicing of various isoforms, the interaction with their binding partners, their phosphorylation, their applied load and the composition of their local environment, such as ions and lipids. This review summarizes our current knowledge of how unconventional myosins are regulated, how these regulatory mechanisms can adapt to the specific features of a myosin and how they can converge with each other in order to ensure the required tight control of their function.

Revison of the Tasmanian genus of freshwater crayfish Astacopsis Huxley (Decapoda : Parastacidae)

1982 ◽  
Vol 33 (4) ◽  
pp. 699 ◽  
Author(s):  
R Swain ◽  
AMM Richardson ◽  
M Hortle
Keyword(s):  
Geographical Distribution ◽  
Morphological Characters ◽  
Species Boundaries ◽  
Freshwater Crayfish ◽  
Separate Species ◽  
Drainage Systems ◽  
Number Of Species ◽  
Wide Range ◽  
Animal Size

Astacopsis Huxley is revised by examination of a wide range of morphological characters. The number of species is reduced from four to two by synonymy. Variation in spination is examined in A. franklinii in relation to geographical distribution (based upon the major drainage systems in Tasmania), animal size and habitat; spininess is found to relate predominantly to animal size. The distribution of Astacopsis within Tasmania is greatly extended and previous reports of geographically separate species' boundaries, indicating limited distributions. can no longer be accepted. Synonymies and diagnoses are provided for A. franklinii and A. gouldi, and a key to their identification is presented.

Toward Endografting of the Ascending Aorta: Insight into Dynamics Using Dynamic Cine-CTA

2007 ◽  
Vol 14 (4) ◽  
pp. 551-560 ◽  
Author(s):  
Joffrey van Prehn ◽  
Koen L. Vincken ◽  
Bart E. Muhs ◽  
Gijsbrecht K. W. Barwegen ◽  
Lambertus W. Bartels ◽  
...  
Keyword(s):  
Thoracic Aorta ◽  
Coronary Arteries ◽  
Cardiac Cycle ◽  
Clinical Success ◽  
Innominate Artery ◽  
Local Environment ◽  
Ascending Aorta ◽  
Maximum Diameter ◽  
Anatomical Landmarks ◽  
Wide Range

Purpose: To evaluate pulsatility and movement along the ascending thoracic aorta using dynamic electrocardiographically-gated 64-slice cine computed tomographic angiography (CTA). Methods: Diameter and area change and center of mass (COM) movement of the ascending thoracic aorta was determined per cardiac cycle in 15 patients at surgically relevant anatomical levels: (A) 5 mm distal to the coronary arteries, (B) 5 mm proximal to the innominate artery, and (C) halfway up the ascending aorta. Additionally, COM movement was determined 1 cm (level P) and 2 cm (level Q) distal from the origins of the innominate, left carotid, and left subclavian arteries. Eight gated datasets covering the cardiac cycle were used to reconstruct images at each level perpendicular to the aortic lumen. The distance between important anatomical landmarks was determined. Results: All levels showed significant cardiac cycle—induced diameter and area changes (p<0.001), with the largest pulsatility 5 mm distal to the coronary arteries. Mean maximum diameter changes were (A) 17.4%±4.8% (range 7.5%–27.5%), (B) 13.9%±3.5% (range 10.6%–25.0%), and (C) 12.9%±3.4% (8.3%–19.6%). Mean area changes were (A) 12.7%±5.5% (range 4.3%–21.8%), (B) 7.5%±2.0% (range 4.1%–11.0%), and (C) 5.6%±2.2% (range 1.9%–11.4%). Mean maximum COM movements were (A) 6.1±2.0 mm (range 2.7–9.0), (B) 2.3±1.1 mm (range 1.1–5.6), and (C) 3.6±1.5 mm (range 1.4–6.5). Mean COM movements of the innominate, left carotid, and left subclavian arteries, respectively, were (P) 1.960.7 mm (range 0.9–3.7), 2.4±0.6 mm (range 1.4–3.3), and 1.9±0.6 mm (range 0.8–2.8), and (Q) 1.8±0.7 mm (range 0.8–3.5), 1.8±0.6 mm (range 0.8–2.7), 1.9±0.6 mm (range 1.1–3.4). Conclusion: The dynamics of the ascending thoracic aorta and the arch vessels are impressive, showing a wide range of 3-dimensional motions. Future ascending arch branched and fenestrated thoracic endograft designs must consider this active local environment, as it may have implications for durability, sealing, and ultimate clinical success.

scholarly journals Synthesis of Some New 2-Methyl -1,4-benzothiazine-3(1H)- one Derivatives as Potential Vasodilators

2004 ◽  
Vol 1 (4) ◽  
pp. 206-210 ◽  
Author(s):  
M. B. Deshmukh ◽  
A. R. Mulik ◽  
Savita Dhongade-Desai
Keyword(s):  
Blood Flow ◽  
Biological Activities ◽  
Local Environment ◽  
Internal Diameter ◽  
Fresh Blood ◽  
Software Application ◽  
Wide Range ◽  
Normal Metabolism ◽  
Cardiac Disorders ◽  
The Relationship

The increase in the internal diameter of a blood vessel that results from relaxation of smooth muscle within the wall of the vessel is vasodilation. This causes an increase in blood flow and a decrease in systemic vascular resistance. Some substances produced by tissue deprived of fresh blood seem to be responsible for the dilation. Many products of metabolism bring about the action, CO2and acids are among them. Dilation of vessels is necessary to restore local environment of tissues and normal metabolism. It may prove to be potential in the treatment of different cardiac disorders like atherosclerosis, where, the blood vessels are narrowed due to deposition of plaque of substances like cholesterol etc. 1,4-benzothiazines have been reported to possess wide range of pharmacological and biological activities. Here, we report the synthesis and biological activity of some new arylidenehydrazino-(1H)-1,4-benzothiazines. The synthesized compounds were subjected to a prediction of biological activities. A software application (PASS) was used for this purpose. The relationship between structure and different biological activities was studied and it was found that the arylidenehydrazino-(1H)-1,4-benzothiazines are expected to be potential vasodilators.

BEYOND INFORMATION SILOS — AN OMNIPRESENT APPROACH TO SOFTWARE EVOLUTION

2008 ◽  
Vol 02 (04) ◽  
pp. 431-468 ◽  
Author(s):  
JUERGEN RILLING ◽  
RENÉ WITTE ◽  
PHILIPP SCHUEGERL ◽  
PHILIPPE CHARLAND
Keyword(s):  
Software Development ◽  
Software Maintenance ◽  
Conceptual Models ◽  
Software Evolution ◽  
Specific Information ◽  
Historical Knowledge ◽  
Knowledge Based ◽  
Distributed Processes ◽  
Wide Range ◽  
Abstraction Levels

Nowadays, software development and maintenance are highly distributed processes that involve a multitude of supporting tools and resources. Knowledge relevant for a particular software maintenance task is typically dispersed over a wide range of artifacts in different representational formats and at different abstraction levels, resulting in isolated 'information silos'. An increasing number of task-specific software tools aim to support developers, but this often results in additional challenges, as not every project member can be familiar with every tool and its applicability for a given problem. Furthermore, historical knowledge about successfully performed modifications is lost, since only the result is recorded in versioning systems, but not how a developer arrived at the solution. In this research, we introduce conceptual models for the software domain that go beyond existing program and tool models, by including maintenance processes and their constituents. The models are supported by a pro-active, ambient, knowledge-based environment that integrates users, tasks, tools, and resources, as well as processes and history-specific information. Given this ambient environment, we demonstrate how maintainers can be supported with contextual guidance during typical maintenance tasks through the use of ontology queries and reasoning services.

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