scholarly journals TOWARDS QUANTITATIVE FORECASTING OF SPECIES YIELDS WITH INCOMPLETE INFORMATION ON MODEL PARAMETERS

2021 ◽  
Author(s):  
Hugo Fort
Keyword(s):  
Incomplete Information ◽  
Relative Abundance ◽  
Environmental Science ◽  
Interspecific Interactions ◽  
Model Parameters ◽  
Generalized Equations ◽  
Ecological Communities ◽  
Incomplete Knowledge ◽  
The Absolute ◽  
Common Situation

Predicting both the absolute and the relative abundance of species in a spatial patch is of paramount interest in areas like, agriculture, ecology and environmental science. The linear Lotka-Volterra generalized equations (LLVGE) serve for describing the dynamics of communities of species connected by negative as well as positive interspecific interactions. Here we particularize these LLVGE to the case of single trophic ecological communities, like mixtures of plants, with S >2 species. Thus, by estimating the LLVGE parameters from the yields in monoculture and biculture experiments, the LLVGE are able to produce decently accurate predictions for species yields. However, a common situation we face is that we don't know all the parameters appearing in the LLVGE. Indeed, for large values of S, only a fraction of the experiments necessary for estimating the model parameters is commonly carried out. We then analyze which quantitative predictions are possible with an incomplete knowledge of the parameters.

scholarly journals Predicting The Yields Of Species Occupying A Single Trophic Level With Incomplete Information: Two Approximations Based On The Lotka-Volterra Generalized Equations

2021 ◽  
Author(s):  
Hugo Fort
Keyword(s):  
Trophic Level ◽  
Interspecific Interactions ◽  
Mean Field ◽  
Field Approximation ◽  
Mean Field Approximation ◽  
Model Parameters ◽  
Generalized Equations ◽  
Focal Species ◽  
The Mean ◽  
Common Situation

The linear Lotka-Volterra generalized equations (LLVGE) serve for describing the dynamics of communities of species connected by negative as well as positive interspecific interactions. Here we particularize these LLVGE to the case of a single trophic level community with S >2 species, either artificial or natural. In this case, by estimating the LLVGE parameters from the yields in monoculture and biculture experiments, the LLVGE are able to produce quite accurate predictions for species yields. However, a common situation we face is that we don't know all the parameters appearing in the LLVGE. Indeed, for large values of S, only a fraction of the experiments necessary for estimating the model parameters is commonly carried out. We then analyze which quantitative predictions are possible with an incomplete knowledge of the parameters. We discuss two approximations that allow using these LLVGE as a quantitative tool. First, when we only know a fraction of the model parameters, the mean field approximation allows making predictions on aggregate or average quantities. Second, for cases in which all the interaction parameters involving a particular species are available, we have the focal species approximation for predicting the yield of this focal species.

Climate-associated trends and variability in ichthyoplankton phenology from the longest continuous larval fish time series on the east coast of the United States

2020 ◽  
Vol 650 ◽  
pp. 269-287
Author(s):  
WC Thaxton ◽  
JC Taylor ◽  
RG Asch
Keyword(s):  
United States ◽  
Environmental Variability ◽  
Larval Fish ◽  
Interspecific Interactions ◽  
River Estuary ◽  
Atlantic Multidecadal Oscillation ◽  
The United States ◽  
Larval Survival ◽  
Ecological Communities ◽  
Northerly Wind

As the effects of climate change become more pronounced, variation in the direction and magnitude of shifts in species occurrence in space and time may disrupt interspecific interactions in ecological communities. In this study, we examined how the fall and winter ichthyoplankton community in the Newport River Estuary located inshore of Pamlico Sound in the southeastern United States has responded to environmental variability over the last 27 yr. We relate the timing of estuarine ingress of 10 larval fish species to changes in sea surface temperature (SST), the Atlantic Multidecadal Oscillation, the North Atlantic Oscillation, wind strength and phenology, and tidal height. We also examined whether any species exhibited trends in ingress phenology over the last 3 decades. Species varied in the magnitude of their responses to all of the environmental variables studied, but most shared a common direction of change. SST and northerly wind strength had the largest impact on estuarine ingress phenology, with most species ingressing earlier during warm years and delaying ingress during years with strong northerly winds. As SST warms in the coming decades, the average date of ingress of some species (Atlantic croaker Micropogonias undulatus, summer flounder Paralichthys dentatus, pinfish Lagodon rhomboides) is projected to advance on the order of weeks to months, assuming temperatures do not exceed a threshold at which species can no longer respond through changes in phenology. These shifts in ingress could affect larval survival and growth since environmental conditions in the estuarine and pelagic nursery habitats of fishes also vary seasonally.

An autonomous driving controller with heading adaptive calibration for agricultural robots

2020 ◽  
Vol 47 (3) ◽  
pp. 435-443
Author(s):  
Nan Qiao ◽  
Lihui Wang ◽  
Mingjie Liu
Keyword(s):  
Autonomous Driving ◽  
Steering System ◽  
Model Parameters ◽  
Content Type ◽  
Driving System ◽  
Adaptive Calibration ◽  
The Absolute ◽  
Lateral Error ◽  
Size Adjustment ◽  
Autonomous Driving System

Purpose This paper aims to propose a new autonomous driving controller to calibrate the absolute heading adaptively. Besides, the second purpose of this paper is to propose a new angle-track loop with a mass regulator to improve the adaptability of the autonomous driving system under different loads and road conditions. Design/methodology/approach In this paper, the error model of heading is built and a new autonomous driving controller with heading adaptive calibration is designed. The new controller calculates the average lateral error by the self-adjusting interval window and calibrates the absolute heading through the incremental proportional–integral–derivative (PID) controller. A window-size adjustment strategy, based on the current lateral error and the derivative of lateral error, is proposed to improve both the transient and the steady-state responses. An angle-tracking loop with mass regulator is proposed to improve the adaptability of autonomous steering system under different loads and road conditions. Findings The experiment results demonstrate that this method can compensate the heading installation error and restrain the off-track error from 13.8 to 1.30 cm. The standard error of new controller is smaller than fuzzy-PID calibration controller and the accuracy of autonomous driving system is improved. Originality/value The accuracy of heading calibrated by the new controller is not affected by external factors and the efficiency of calibration is improved. As the model parameters of steering system can be obtained manually, the new autonomous steering controller has more simple structure and is easy to implement. Mass regulator is adjusted according to the road conditions and the mass of harvester, which can improve the system adaptability.

scholarly journals The ecological consequences of temperament in spiders

2012 ◽  
Vol 58 (4) ◽  
pp. 589-596 ◽  
Author(s):  
Jonathan N. Pruitt ◽  
Susan E. Riechert
Keyword(s):  
Interspecific Interactions ◽  
Model Systems ◽  
Behavioral Syndromes ◽  
Ecological Communities ◽  
Ecological Consequences ◽  
Behavioral Trait ◽  
Trade Offs ◽  
Evolutionary Studies ◽  
Front Running ◽  
Trait Correlations

Abstract Ecological and evolutionary studies on spiders have been featured prominently throughout the contemporary behavioral syndromes movement. Here we review the behavioral syndromes literature devoted to spiders, and identify some ways in which behavioral syndromes can impact the function of spiders in ecological communities. We further highlight three general themes within the behavioral syndromes literature for which spiders have served as front running model systems: (1) how trait correlations beget performance trade-offs, (2) the influence that behavioral trait variants have on interspecific interactions and (3) mechanisms that aid in maintaining behavioral variation withinand among-populations. Research on behavioral syndromes continues to grow at an impressive rate, and we feel the success of behavioral syndromes studies in spiders bodes well for their continued prominence.

scholarly journals On the temporally flexible structure of plant-pollinator interaction networks

2020 ◽  
Author(s):  
Paul J. CaraDonna ◽  
Nickolas M. Waser
Keyword(s):  
Temporal Variation ◽  
Network Structure ◽  
Species Interactions ◽  
Interspecific Interactions ◽  
Activity Period ◽  
Individual Species ◽  
Ecological Communities ◽  
Short Term ◽  
Temporal Flexibility ◽  
Plant Pollinator

AbstractEcological communities consist of species that are joined in complex networks of interspecific interaction. The interactions that networks depict often form and dissolve rapidly, but this temporal variation is not well integrated into our understanding of the causes and consequences of network structure. If interspecific interactions exhibit temporal flexibility across time periods over which organisms co-occur, then the emergent structure of the corresponding network may also be temporally flexible, something that a temporally-static perspective would miss. Here, we use an empirical system to examine short-term flexibility in network structure (connectance, nestedness, and specialization), and in individual species interactions that contribute to that structure. We investigated weekly plant-pollinator networks in a subalpine ecosystem across three summer growing seasons. To link the interactions of individual species to properties of their networks, we examined weekly temporal variation in species’ contributions to network structure. As a test of the potential robustness of networks to perturbation, we also simulated the random loss of species from weekly networks. We then compared the properties of weekly networks to the properties of cumulative networks that aggregate field observations over each full season. A week-to-week view reveals considerable flexibility in the interactions of individual species and their contributions to network structure. For example, species that would be considered relatively generalized across their entire activity period may be much more specialized at certain times, and at no point as generalized as the cumulative network may suggest. Furthermore, a week-to-week view reveals corresponding temporal flexibility in network structure and potential robustness throughout each summer growing season. We conclude that short-term flexibility in species interactions leads to short-term variation in network properties, and that a season-long, cumulative perspective may miss important aspects of the way in which species interact, with implications for understanding their ecology, evolution, and conservation.

scholarly journals Interaction capacity underpins community diversity

2020 ◽  
Author(s):  
Masayuki Ushio
Keyword(s):  
Interspecific Interactions ◽  
Experimental Studies ◽  
Interaction Strength ◽  
Single Species ◽  
Species Interaction ◽  
Community Diversity ◽  
Ecological Communities ◽  
Total Dna ◽  
Mathematical Equations ◽  
The Mean

AbstractHow patterns in community diversity emerge is a long-standing question in ecology. Theories and experimental studies suggested that community diversity and interspecific interactions are interdependent. However, evidence from multitaxonomic, high-diversity ecological communities is lacking because of practical challenges in characterizing speciose communities and their interactions. Here, I analyzed time-varying causal interaction networks that were reconstructed using 1197 species, DNA-based ecological time series taken from experimental rice plots and empirical dynamic modeling, and show that species interaction capacity, namely, the sum of interaction strength that a single species gives and receives, underpins community diversity. As community diversity increases, the number of interactions increases exponentially but the mean species interaction capacity of a community becomes saturated, weakening interaction among species. These patterns are explicitly modeled with simple mathematical equations, based on which I propose the “interaction capacity hypothesis”, namely, that species interaction capacity and network connectance are proximate drivers of community diversity. Furthermore, I show that total DNA concentrations and temperature influence species interaction capacity and connectance nonlinearly, explaining a large proportion of diversity patterns observed in various systems. The interaction capacity hypothesis enables mechanistic explanations of community diversity, and how species interaction capacity is determined is a key question in ecology.

scholarly journals A Holling Functional Response Model for Mapping QTLs Governing Interspecific Interactions

2021 ◽  
Vol 12 ◽  
Author(s):  
Xiao-Yu Zhang ◽  
Huiying Gong ◽  
Qing Fang ◽  
Xuli Zhu ◽  
Libo Jiang ◽  
...  
Keyword(s):  
Functional Response ◽  
Species Interactions ◽  
Community Dynamics ◽  
Interspecific Interactions ◽  
Microbial Interactions ◽  
Ecological Communities ◽  
Response Model ◽  
Ecological Interactions ◽  
Dynamic Complexity ◽  
Genome Level

Genes play an important role in community ecology and evolution, but how to identify the genes that affect community dynamics at the whole genome level is very challenging. Here, we develop a Holling type II functional response model for mapping quantitative trait loci (QTLs) that govern interspecific interactions. The model, integrated with generalized Lotka-Volterra differential dynamic equations, shows a better capacity to reveal the dynamic complexity of inter-species interactions than classic competition models. By applying the new model to a published mapping data from a competition experiment of two microbial species, we identify a set of previously uncharacterized QTLs that are specifically responsible for microbial cooperation and competition. The model can not only characterize how these QTLs affect microbial interactions, but also address how change in ecological interactions activates the genetic effects of the QTLs. This model provides a quantitative means of predicting the genetic architecture that shapes the dynamic behavior of ecological communities.

scholarly journals Extracting Backbones from Weighted Complex Networks with Incomplete Information

2015 ◽  
Vol 2015 ◽  
pp. 1-11 ◽  
Author(s):  
Liqiang Qian ◽  
Zhan Bu ◽  
Mei Lu ◽  
Jie Cao ◽  
Zhiang Wu
Keyword(s):  
Local Search ◽  
Complex Networks ◽  
Incomplete Information ◽  
Real Life ◽  
Extraction Methods ◽  
Filter Method ◽  
Search Model ◽  
Or Efficiency ◽  
Incomplete Knowledge ◽  
Global View

The backbone is the natural abstraction of a complex network, which can help people understand a networked system in a more simplified form. Traditional backbone extraction methods tend to include many outliers into the backbone. What is more, they often suffer from the computational inefficiency—the exhaustive search of all nodes or edges is often prohibitively expensive. In this paper, we propose a backbone extraction heuristic with incomplete information (BEHwII) to find the backbone in a complex weighted network. First, a strict filtering rule is carefully designed to determine edges to be preserved or discarded. Second, we present a local search model to examine part of edges in an iterative way, which only relies on the local/incomplete knowledge rather than the global view of the network. Experimental results on four real-life networks demonstrate the advantage of BEHwII over the classic disparity filter method by either effectiveness or efficiency validity.

Ethics of Caring in Environmental Ethics

2016 ◽  
Author(s):  
Kyle Powys Whyte ◽  
Chris Cuomo
Keyword(s):  
Environmental Ethics ◽  
Environmental Science ◽  
Care Ethics ◽  
Ecological Communities ◽  
Environmental Care ◽  
Environmental Decision Making ◽  
The Social ◽  
Ethics Of Caring ◽  
Feminist Movements ◽  
Mother Earth

Indigenous ethics and feminist care ethics offer a range of related ideas and tools for environmental ethics. These ethics delve into deep connections and moral commitments between nonhumans and humans to guide ethical forms of environmental decision making and environmental science. Indigenous and feminist movements such as the Mother Earth Water Walk and the Green Belt Movement are ongoing examples of the effectiveness of on-the-ground environmental care ethics. Indigenous ethics highlight attentive caring for the intertwined needs of humans and nonhumans within interdependent communities. Feminist environmental care ethics emphasize the importance of empowering communities to care for themselves and the social and ecological communities in which their lives and interests are interwoven. The gendered, feminist, historical, and anticolonial dimensions of care ethics, indigenous ethics, and other related approaches provide rich ground for rethinking and reclaiming the nature and depth of diverse relationships as the fabric of social and ecological being.

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