scholarly journals Individual environmental niches in mobile organisms

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Ben S. Carlson ◽  
Shay Rotics ◽  
Ran Nathan ◽  
Martin Wikelski ◽  
Walter Jetz
Keyword(s):  
Individual Variation ◽  
Central Component ◽  
Environmental Niche ◽  
Ecological Processes ◽  
Movement Data ◽  
Niche Variation ◽  
Unknown Species ◽  
White Storks ◽  
Environmental Responses ◽  
Over Time

AbstractIndividual variation is increasingly recognized as a central component of ecological processes, but its role in structuring environmental niche associations remains largely unknown. Species’ responses to environmental conditions are ultimately determined by the niches of single individuals, yet environmental associations are typically captured only at the level of species. Here, we develop scenarios for how individual variation may combine to define the compound environmental niche of populations, use extensive movement data to document individual environmental niche variation, test associated hypotheses of niche configuration, and examine the consistency of individual niches over time. For 45 individual white storks (Ciconia ciconia; 116 individual-year combinations), we uncover high variability in individual environmental associations, consistency of individual niches over time, and moderate to strong niche specialization. Within populations, environmental niches follow a nested pattern, with individuals arranged along a specialist-to-generalist gradient. These results reject common assumptions of individual niche equivalency among conspecifics, as well as the separation of individual niches into disparate parts of environmental space. These findings underscore the need for a more thorough consideration of individualistic environmental responses in global change research.

The Negative Impact of Biological Variation in the Effect and Clearance of Warfarin on Methods for Prediction of Dose Requirements

1986 ◽  
Vol 56 (03) ◽  
pp. 371-375 ◽  
Author(s):  
Peretz Weiss ◽  
Hillel Halkin ◽  
Shlomo Almog
Keyword(s):  
Individual Variation ◽  
Negative Impact ◽  
Warfarin Dose ◽  
Empirical Therapy ◽  
Maintenance Phase ◽  
Individual Variability ◽  
Dose Prediction ◽  
Group I ◽  
Over Time ◽  
Variance Explained

SummaryWithin-individual variation over time in the clearance (Cl) and effect (PT%) of warfarin, was measured in 25 inpatients (group I) studied after standard single or individualized split loading doses and 1-3 times (n = 16) 8-16 weeks later during maintenance. Mean Cl (2.5 α 0.9 ml/min) was similar in both phases but significant changes occurred in 6/16 patients, exceeding those expected from within-individual variation alone (defined by its 95% tolerance limits -24% to +62%). Initial PT% (21 α 5) was unaffected by dosing schedule, total or free plasma warfarin, varying between patients by only 18-24%. Mean initial and maintenance dose-PT% ratios (8.2 mg/d: 21% and 4.1 mg/d: 40%) were similar but significant changes in sensitivity to warfarin occurred in 4/16 patients. In group I and 64 other outpatients on maintenance therapy, between-individual variability was 36-52% for Cl and 49-56% for effect. PT% correlated best (r = 0.56) with free and total plasma warfarin but poorly with dose (r = 0.29), with only 30% of PT% variance explained at best, due to high between patient variability.Warfarin dose prediction whether based on extrapolation from initial effects to the maintenance phase, or on iterative methods not allowing for between- or within-patient variation in warfarin clearance or effect which may occur independently over time, have not improved on empirical therapy. This, due to the elements of biological variability as well as the intricacy of the warfarin - prothrombin complex interaction not captured by any kinetic-dynamic model used for prediction to date.

scholarly journals Human immune system variation during one year

2020 ◽  
Author(s):  
Tadepally Lakshmikanth ◽  
Sayyed Auwn Muhammad ◽  
Axel Olin ◽  
Yang Chen ◽  
Jaromir Mikes ◽  
...  
Keyword(s):  
Immune System ◽  
Individual Variation ◽  
Immune Cell ◽  
Metabolic Health ◽  
Individual Feature ◽  
Human Immune System ◽  
Principal Curve ◽  
Human Immune ◽  
One Year ◽  
Over Time

SUMMARYThe human immune system varies extensively between individuals, but variation within individuals over time has not been well characterized. Systems-level analyses allow for simultaneous quantification of many interacting immune system components, and the inference of global regulatory principles. Here we present a longitudinal, systems-level analysis in 99 healthy adults, 50 to 65 years of age and sampled every 3rd month during one year. We describe the structure of inter-individual variation and characterize extreme phenotypes along a principal curve. From coordinated measurement fluctuations, we infer relationships between 115 immune cell populations and 750 plasma proteins constituting the blood immune system. While most individuals have stable immune systems, the degree of longitudinal variability is an individual feature. The most variable individuals, in the absence of overt infections, exhibited markers of poor metabolic health suggestive of a functional link between metabolic and immunologic homeostatic regulation.HIGHLIGHTSLongitudinal variation in immune cell composition during one yearInter-individual variation can be described along a principal curveImmune cell and protein relationships are inferredVariability over time is an individual feature correlating with markers of poor metabolic health

Landscape Heterogeneity and Dynamics

2019 ◽  
pp. 42-126
Author(s):  
Kimberly A. With
Keyword(s):  
Landscape Ecology ◽  
Spatial Heterogeneity ◽  
Landscape Structure ◽  
Landscape Heterogeneity ◽  
Spatial Scales ◽  
Anthropogenic Disturbances ◽  
Ecological Processes ◽  
Disturbance Dynamics ◽  
Wide Range ◽  
Over Time

Heterogeneity is a defining characteristic of landscapes and therefore central to the study of landscape ecology. Landscape ecology investigates what factors give rise to heterogeneity, how that heterogeneity is maintained or altered by natural and anthropogenic disturbances, and how heterogeneity ultimately influences ecological processes and flows across the landscape. Because heterogeneity is expressed across a wide range of spatial scales, the landscape perspective can be applied to address these sorts of questions at any level of ecological organization, and in aquatic and marine systems as well as terrestrial ones. Disturbances—both natural and anthropogenic—are a ubiquitous feature of any landscape, contributing to its structure and dynamics. Although the focus in landscape ecology is typically on spatial heterogeneity, disturbance dynamics produce changes in landscape structure over time as well as in space. Heterogeneity and disturbance dynamics are thus inextricably linked and are therefore covered together in this chapter.

COMPARISON OF OIL SPILL RATES IN DIFFERENT REGIONS OF THE UNITED STATES

1997 ◽  
Vol 1997 (1) ◽  
pp. 947-949
Author(s):  
Gary Yoshioka ◽  
Brad Kaiman ◽  
Eva Wong
Keyword(s):  
United States ◽  
Oil Spill ◽  
Coastal Area ◽  
East Coast ◽  
Oil Spills ◽  
Gulf Coast ◽  
The United States ◽  
Movement Data ◽  
Exposure Variable ◽  
Over Time

ABSTRACT Recent studies of oil spills of more than 10,000 gallons examined spill rates in certain East Coast and Gulf Coast regions of the United States. Using oil movement data as the exposure variable, these studies found similar spill rates among the regions and over time. This analysis expands upon these earlier studies by examining the California coastal area and by calculating new spill rates using refining capacity as the exposure variable.

scholarly journals Modelling the potential ecological niche of domesticated buckwheat in China: archaeological evidence, environmental constraints and climate change

2021 ◽  
Author(s):  
Marta Krzyzanska ◽  
Harriet V. Hunt ◽  
Enrico R. Crema ◽  
Martin K. Jones
Keyword(s):  
Ecological Niche ◽  
Species Distribution Model ◽  
Modern China ◽  
Distribution Model ◽  
Distribution Data ◽  
Environmental Niche ◽  
Dispersal Pattern ◽  
Present Distribution ◽  
Potential Area ◽  
Over Time

AbstractWe present a species distribution model (SDM) of Fagopyrum esculentum (buckwheat) in China using present distribution data and estimates for the past based on palaeoclimatic reconstructions. Our model estimates the potential area suitable for buckwheat cultivation over the last 8,000 years, with northeast China consistently showing the highest suitability, providing insights on the discrepancy between the location of the earliest archaeobotanical records in the area and its origins in southwest China based on biogeographic and genetic data. The model suggests little to no variation over time in the spatial extent of the potential area suitable for buckwheat cultivation. In the northern parts of China, the limits of the ecological niche largely fall within the borders of the study area, while to the west it never extends into the main Tibetan plateau, explaining the lack of fossil evidence from Central Asia. In the southwest, the niche overlaps with the borders of modern China, which supports this direction as a viable route of westward dispersal. The comparison between the prediction from the model and sites with archaeobotanical evidence for Fagopyrum indicates that the environmental niche it occupied remained stable over time. This may contrast with a dispersal pattern characterised by continuous adaptations to new environments facilitated by human activity, which may be suggested for other major and minor crops.

scholarly journals Modelling the spatial-temporal distributions and associated determining factors of a keystone pelagic fish

2020 ◽  
Author(s):  
Samantha Andrews ◽  
Shawn J. Leroux ◽  
Marie-Josée Fortin
Keyword(s):  
Species Distribution Model ◽  
Spatial Dynamics ◽  
Predictive Modelling ◽  
Distribution Model ◽  
Ecological Processes ◽  
Pelagic Species ◽  
The North ◽  
Determining Factors ◽  
The North Atlantic Oscillation ◽  
Over Time

AbstractMobile pelagic species habitat is structured around dynamic oceanographic and ecological processes which operate and interact horizontally and vertically throughout the water column and change over time. However, pelagic species movements and distributions are often poorly understood. We use the Maxent species distribution model to assess how changes in the relative importance of modelled oceanographic (e.g., temperature) and climatic variables (e.g., the North Atlantic Oscillation) over 17-years affect the monthly average horizontal and vertical distribution of a keystone pelagic forage species, Atlantic Canadian capelin (Mallotus villosus). We show the range and distribution of capelin occurrence probabilities vary across horizontal and vertical axes over time, with binary presence/absence predictions indicating capelin occupy between 0.72% (April) and 3.45% (November) of the total modelled space. Furthermore, our analysis reveals that the importance of modelled oceanographic variables, such as temperature, vary between months (44% permutation importance in August to 2% in May). By capturing the spatial dynamics of capelin over horizontal, vertical, and temporal axes, our analysis builds on work that improves our understanding and predictive modelling ability of pelagic species distributions under current and future conditions for pro-active ecosystem-based management.

scholarly journals Degree of urbanization and predation pressure on artificial lepidopteran caterpillars in Cali, Colombia

2018 ◽  
Author(s):  
Jefferson Cupitra-Rodríguez ◽  
Lorena Cruz-Bernate ◽  
James Montoya-Lerma
Keyword(s):  
Urban Expansion ◽  
Urban Environments ◽  
Predation Pressure ◽  
Ecological Processes ◽  
Successional Stage ◽  
Trophic Networks ◽  
Lepidopteran Larvae ◽  
The City ◽  
Over Time ◽  
Predator Community

Growing urban expansion results in the alteration of ecological processes (i.e. predation) within trophic networks. Predation on herbivores is known to vary with the size of the area covered in vegetation, successional stage, altitude, and the structure of the predator community, but there are gaps in information regarding how this occurs in urban and suburban environments. The purpose of this study was to determine whether the predation pressure on artificial models of lepidopteran larvae varied with degree of urbanization, type of substrate, and group of predators (birds or arthropods) in Cali, Colombia. Five hundred and eighteen artificial larvae were placed in two areas of the city (urban vs. suburban) and in two types of substrate (leaf vs. stem) for 30 continuous days and with two replications over time. Total predation was measured as the number of models with evidence of attack by predators. The overall incidence of predation was 24.13%, and was significantly higher in the urban area (63.20%) when compared to the suburban area (36.80%). The leaf substrate was attacked significantly more than the stem (60% vs. 40%). The proportion of attacks carried out by birds was significantly higher (74.40%) than that carried out by arthropods (24.80%). Together, these results suggest that the incidence of predation varies with the disturbance caused by urbanization and by the type of substrate in which prey organisms are found. In addition, the study confirms that birds are the main controllers of herbivorous insects in urban environments.

scholarly journals Understanding the Importance of Dynamic Landscape Connectivity

Land ◽  
2020 ◽  
Vol 9 (9) ◽  
pp. 303
Author(s):  
Katherine Zeller ◽  
Rebecca Lewsion ◽  
Robert Fletcher ◽  
Mirela Tulbure ◽  
Megan Jennings
Keyword(s):  
Landscape Connectivity ◽  
Conservation Strategy ◽  
Dynamic Processes ◽  
Negative Effects ◽  
Ecological Processes ◽  
Movement Data ◽  
Dynamic Landscape ◽  
Spatiotemporal Scales ◽  
Intrinsic Component ◽  
Dynamic Connectivity

Landscape connectivity is increasingly promoted as a conservation tool to combat the negative effects of habitat loss, fragmentation, and climate change. Given its importance as a key conservation strategy, connectivity science is a rapidly growing discipline. However, most landscape connectivity models consider connectivity for only a single snapshot in time, despite the widespread recognition that landscapes and ecological processes are dynamic. In this paper, we discuss the emergence of dynamic connectivity and the importance of including dynamism in connectivity models and assessments. We outline dynamic processes for both structural and functional connectivity at multiple spatiotemporal scales and provide examples of modeling approaches at each of these scales. We highlight the unique challenges that accompany the adoption of dynamic connectivity for conservation management and planning in the context of traditional conservation prioritization approaches. With the increased availability of time series and species movement data, computational capacity, and an expanding number of empirical examples in the literature, incorporating dynamic processes into connectivity models is more feasible than ever. Here, we articulate how dynamism is an intrinsic component of connectivity and integral to the future of connectivity science.

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