scholarly journals Species coexistence in resource-limited patterned ecosystems is facilitated by the interplay of spatial self-organisation and intraspecific competition

2020 ◽  
Author(s):  
Lukas Eigentler
Keyword(s):  
Intraspecific Competition ◽  
Species Coexistence ◽  
Stress Gradient ◽  
Woody Species ◽  
Vegetation Patterns ◽  
Functional Responses ◽  
Resource Limited ◽  
Wide Range ◽  
Self Organisation ◽  
Resource Input

The exploration of mechanisms that enable species coexistence under competition for a sole limiting resource is widespread across ecology. Two examples of such facilitative processes are intraspecific competition and spatial self-organisation. These processes determine the outcome of competitive dynamics in many resource-limited patterned ecosystems, classical examples of which include dryland vegetation patterns, intertidal mussel beds and Subalpine ribbon forests. Previous theoretical investigations have explained coexistence within patterned ecosystems by making strong assumptions on the differences between species (e.g. contrasting dispersal behaviours or different functional responses to resource availability). In this paper, I show that the interplay between the detrimental effects of intraspecific competition and the facilitative nature of self-organisation forms a coexistence mechanism that does not rely on species-specific assumptions and captures coexistence across a wide range of the environmental stress gradient. I use a theoretical model that captures the interactions of two generic consumer species with an explicitly modelled resource to show that coexistence relies on a balance between species' colonisation abilities and their local competitiveness, provided intraspecific competition is sufficiently strong. Crucially, the requirements on species' self-limitation for coexistence to occur differ on opposite ends of the resource input spectrum. For low resource levels, coexistence is facilitated by strong intraspecific dynamics of the species superior in its colonisation abilities, but for larger volumes of resource input, strong intraspecific competition of the locally superior species enables coexistence. Results presented in this paper also highlight the importance of hysteresis in understanding tipping points, in particular extinction events. Finally, the theoretical framework provides insights into spatial species distributions within single patches, supporting verbal hypotheses on coexistence of herbaceous and woody species in dryland vegetation patterns and suggesting potential empirical tests in the context of other patterned ecosystems.

scholarly journals Higher order interactions and coexistence theory

2019 ◽  
Author(s):  
Pragya Singh ◽  
Gaurav Baruah
Keyword(s):  
Intraspecific Competition ◽  
Species Coexistence ◽  
General Rule ◽  
Higher Order ◽  
Volterra Model ◽  
Ecological Communities ◽  
Coexistence Theory ◽  
Wide Range ◽  
Analytical Result ◽  
Underlying Mechanisms

AbstractHigher order interactions (HOIs) have been suggested to stabilize diverse ecological communities. However, their role in maintaining species coexistence from the perspective of modern coexistence theory is unknown. Here, using a three-species Lotka-Volterra model, we derive a general rule for species coexistence modulated by HOIs. We show that negative HOIs that intensify pairwise competition, can promote coexistence across a wide range of fitness differences, provided that HOIs strengthen intraspecific competition more than interspecific competition. In contrast, positive HOIs that alleviate pairwise competition can also stabilize coexistence across a wide range of fitness differences, irrespective of differences in strength of inter- and intraspecific competition. Furthermore, we extend our three-species analytical result to multispecies competitive community and show, using simulations, that feasible multispecies coexistence is possible provided that strength of negative intraspecific HOIs is higher than interspecific HOIs. In addition, multispecies communities, however, become unstable with positive HOIs as such higher-order interactions could lead to disproportionately infeasible growth rates. This work provides crucial insights on the underlying mechanisms that could maintain species diversity and links HOIs with modern coexistence theory.

scholarly journals Higher order interactions and species coexistence

2020 ◽  
Author(s):  
Pragya Singh ◽  
Gaurav Baruah
Keyword(s):  
Intraspecific Competition ◽  
Species Interactions ◽  
Species Coexistence ◽  
General Rule ◽  
Higher Order ◽  
Volterra Model ◽  
Ecological Communities ◽  
Wide Range ◽  
Analytical Result ◽  
Underlying Mechanisms

AbstractHigher order interactions (HOIs) have been suggested to stabilize diverse ecological communities. However, their role in maintaining species coexistence from the perspective of modern coexistence theory is not known. Here, using generalized Lotka-Volterra model, we derive a general rule for species coexistence modulated by HOIs. We show that where pairwise species interactions fail to promote species coexistence in regions of extreme fitness differences, negative HOIs that intensify pairwise competition, however, can promote coexistence provided that HOIs strengthen intraspecific competition more than interspecific competition. In contrast, positive HOIs that alleviate pairwise competition can stabilize coexistence across a wide range of fitness differences, irrespective of differences in strength of inter- and intraspecific competition. In addition, we extend our three-species analytical result to multispecies communities and show, using simulations, that multispecies coexistence is possible provided that strength of negative intraspecific HOIs is higher than interspecific HOIs. Our work sheds light on the underlying mechanisms through which HOIs can maintain species diversity.

scholarly journals Diagnostic Capabilities of a Smartphone- Based Low-Cost Microscope

2020 ◽  
Vol 6 (3) ◽  
pp. 522-525
Author(s):  
Dorina Hasselbeck ◽  
Max B. Schäfer ◽  
Kent W. Stewart ◽  
Peter P. Pott
Keyword(s):  
Low Cost ◽  
Field Of View ◽  
Parasitic Diseases ◽  
Optical Parameters ◽  
Trade Off ◽  
Resource Limited ◽  
Wide Range ◽  
Diagnostic Applications ◽  
Diagnostic Capabilities

AbstractMicroscopy enables fast and effective diagnostics. However, in resource-limited regions microscopy is not accessible to everyone. Smartphone-based low-cost microscopes could be a powerful tool for diagnostic and educational purposes. In this paper, the imaging quality of a smartphone-based microscope with four different optical parameters is presented and a systematic overview of the resulting diagnostic applications is given. With the chosen configuration, aiming for a reasonable trade-off, an average resolution of 1.23 μm and a field of view of 1.12 mm2 was achieved. This enables a wide range of diagnostic applications such as the diagnosis of Malaria and other parasitic diseases.

Use of Functional Response Modeling to Evaluate the Effect of Temperature on Predation of Amblyseius swirskii (Acari: Phytoseiidae) Adults Preying on Tetranychus urticae (Acari: Tetranychidae) Nymphs

2021 ◽  
Author(s):  
Azadeh Farazmand ◽  
Masood Amir-Maafi
Keyword(s):  
Functional Response ◽  
Tetranychus Urticae ◽  
Attack Rate ◽  
Handling Time ◽  
Effect Of Temperature ◽  
Coefficient Of Determination ◽  
Temperature Threshold ◽  
Amblyseius Swirskii ◽  
Functional Responses ◽  
Wide Range

Abstract In this research, functional responses of Amblyseius swirskii Athias-Henriot preying on different Tetranychus urticae Koch nymphal densities (2, 4, 8, 16, 32, 64, and 128) were studied at eight constant temperatures (15, 20, 25, 27.5, 30, 32.5, 35 and 37.5°C) in a circular Petri dish (3-cm diameter × 1-cm height) under lab conditions. At all temperatures, the logistic regression showed a type II functional response. A nonlinear relationship was found between temperature and attack rate and the reciprocal of handling time. The reciprocal of handling time decreased exponentially with increasing temperature. In contrast, the attack rate grew rapidly with increasing temperatures up to an optimum, showing a decreasing trend at higher temperatures. In order to quantify the functional response of A. swirskii over a broad range of temperatures and to gain a better estimation of attack rate and handling time, a temperature-settled functional response equation was suited to our data. Our model showed that the number of prey consumed increased with rising prey density. Also, the predation rates increased with increasing temperatures but decreased at extremely high temperatures. Based on our model, the predation rate begins at the lower temperature threshold (11.73°C) and reaches its peak at upper temperature threshold (29.43°C). The coefficient of determination (R2) of the random predator model was 0.99 for all temperatures. The capability of A. swirskii to search and consume T. urticae over a wide range of temperatures makes it a good agent for natural control of T. urticae in greenhouses.

scholarly journals Woody species do not differ in dormancy progression: differences in time to budbreak due to forcing and cold hardiness

2021 ◽  
Author(s):  
Al Kovaleski
Keyword(s):  
Maximum Rate ◽  
Path Length ◽  
Cold Hardiness ◽  
Woody Species ◽  
Two Dimensions ◽  
Spring Phenology ◽  
Wide Range ◽  
The Difference ◽  
Response To Temperature ◽  
Phenological Phases

AbstractBudbreak is one of the most observed and studied phenological phases in perennial plants. Two dimensions of exposure to temperature are generally used to model budbreak: accumulation of time spent at low temperatures (chilling); and accumulation of heat units (forcing). These two effects have a well-established negative correlation: the more chilling, the less forcing required for budbreak. Furthermore, temperate plant species are assumed to vary in amount of chilling required to complete endodormancy and begin the transition to breaking bud. Still, prediction of budbreak remains a challenge. The present work demonstrates across a wide range of species how bud cold hardiness must be accounted for to study dormancy and accurately predict time to budbreak. Cold hardiness defines the path length to budbreak, meaning the difference between the cold hardiness buds attain during the winter, and the cold hardiness at which deacclimated buds are predicted to open. This distance varies among species and throughout winter within a species. Increases in rate of cold hardiness loss (deacclimation) measured throughout winter show that chilling controls deacclimation potential – the proportion of the maximum rate response attained at high chill accumulation – which has a sigmoid relationship to chilling accumulation. For forcing, rates of deacclimation increase non-linearly in response to temperature. Comparisons of deacclimation potential show a dormancy progresses similarly for all species. This observation suggests that comparisons of physiologic and genetic control of dormancy requires an understanding of cold hardiness dynamics and the necessity for an update of the framework for studying dormancy and its effects on spring phenology.

scholarly journals Methylprednisolone-Responsive Leptospiral Acute Pulmonary Syndrome: A Case Report

2015 ◽  
Vol 3 (3) ◽  
pp. 159-162
Author(s):  
Iman D. Johan-Arief, ◽  
Shen H. Lee ◽  
Xin Y. Er ◽  
Ganesh Kasinathan ◽  
Naganathan Pillai
Keyword(s):  
Chest Radiograph ◽  
Early Recognition ◽  
Pulmonary Hemorrhage ◽  
Immunoglobulin M ◽  
Enzyme Linked Immunosorbent Assay ◽  
Resource Limited ◽  
High Fatality Rate ◽  
Intravenous Antibiotics ◽  
Wide Range ◽  
History Of

Background: Leptospirosis is an infectious disease caused by the spirochete of the genus leptospira. It is thought to be the most common zoonosis globally and has a wide range of clinical presentations with pulmonary hemorrhage being one of its most severe manifestations. This entity known as acute pulmonary syndrome carries a high fatality rate. However, it can be effectively managed with methylprednisolone therapy. Case: We report a case of leptospirosis in a 26-year-old Bangladeshi male who was otherwise healthy. He presented with a 7-day history of fever with chills and rigors, and hemoptysis for a duration of 2 days. Physical examination revealed a febrile and lethargic man. Respiratory examination exhibited bilateral generalized crepitations over the lung fields. A chest radiograph performed showed bilateral alveolar shadowing. The diagnosis of leptospirosis was made based on positive Immunoglobulin M enzyme-linked immunosorbent assay serology, which was then confirmed by the microscopic agglutination test for leptospirosis. The patient was commenced on intravenous antibiotics and methylprednisolone at this time. He responded well clinically with resolution of fever and hemoptysis and a marked decrease in crepitations upon auscultation. This correlated with radiological improvement evidence by an obvious reduction in alveolar shadowing on subsequent chest radiograph 2 days later. Conclusion: This case is highly pertinent to the medical field as leptospirosis is an ever-growing problem and acute pulmonary syndrome is an emerging manifestation of it. Therefore, early recognition and intervention is required as this can be effectively treated with methylprednisolone therapy even in resource-limited settings

Sciences of complexity and language origins: an alternative to natural selection

2001 ◽  
Vol 30 (1) ◽  
pp. 1-17 ◽  
Author(s):  
Víctor M Longa
Keyword(s):  
Natural Selection ◽  
Specific Property ◽  
Dynamic Interaction ◽  
Human Beings ◽  
Internal Factors ◽  
Language Origins ◽  
Complex Design ◽  
Wide Range ◽  
Self Organisation ◽  
Sciences Of Complexity

AbstractNatural selection is claimed to be the only way to explain complex design. The same assumption has also been held for language. However, sciences of complexity have shown, from a wide range of domains, the existence of a clear alternative: self-organisation, spontaneous patterns of order arising from chaos. According to this view, design derives from internal factors (dynamic interaction of the elements within the system) rather than from adaptation to the environment by means of selection. This paper aims to apply sciences of complexity to language origins; it shows that preexisting and well established ideas can be rethought according to such a view. The main objective of the paper is to illustrate the new and promising horizons that complexity could open as regards the origins of the most specific property of human beings.

scholarly journals Black Soldier Fly Larvae Adapt to Different Food Substrates through Morphological and Functional Responses of the Midgut

2020 ◽  
Vol 21 (14) ◽  
pp. 4955
Author(s):  
Marco Bonelli ◽  
Daniele Bruno ◽  
Matteo Brilli ◽  
Novella Gianfranceschi ◽  
Ling Tian ◽  
...  
Keyword(s):  
Larval Growth ◽  
Nutrient Content ◽  
Functional Responses ◽  
Black Soldier Fly ◽  
Poor Diet ◽  
Balanced Diet ◽  
Long Term Storage ◽  
Wide Range ◽  
Extreme Variability ◽  
Adaptation Processes

Modulation of nutrient digestion and absorption is one of the post-ingestion mechanisms that guarantees the best exploitation of food resources, even when they are nutritionally poor or unbalanced, and plays a pivotal role in generalist feeders, which experience an extreme variability in diet composition. Among insects, the larvae of black soldier fly (BSF), Hermetia illucens, can grow on a wide range of feeding substrates with different nutrient content, suggesting that they can set in motion post-ingestion processes to match their nutritional requirements. In the present study we address this issue by investigating how the BSF larval midgut adapts to diets with different nutrient content. Two rearing substrates were compared: a nutritionally balanced diet for dipteran larvae and a nutritionally poor diet that mimics fruit and vegetable waste. Our data show that larval growth performance is only moderately affected by the nutritionally poor diet, while differences in the activity of digestive enzymes, midgut cell morphology, and accumulation of long-term storage molecules can be observed, indicating that diet-dependent adaptation processes in the midgut ensure the exploitation of poor substrates. Midgut transcriptome analysis of larvae reared on the two substrates showed that genes with important functions in digestion and absorption are differentially expressed, confirming the adaptability of this organ.

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