scholarly journals Compensatory foraging in Trinidadian guppies: Effects of acute and chronic predation threats

2014 ◽  
Vol 60 (3) ◽  
pp. 323-332 ◽  
Author(s):  
Chris K. Elvidge ◽  
Indar Ramnarine ◽  
Grant E. Brown
Keyword(s):  
Predation Risk ◽  
Predator Avoidance ◽  
Short Term ◽  
Graded Responses ◽  
Trade Offs ◽  
Behavioral Mechanism ◽  
Low Concentrations ◽  
High Predation ◽  
Threat Levels

Abstract In response to acute predation threats, prey may sacrifice foraging opportunities in favour of increased predator avoidance. Under conditions of high or frequent predation risk, such trade-offs may lead to reduced fitness. Here, we test the prediction that prey reduce the costs associated with lost opportunities following acute predation threats by exhibiting short-term compensatory foraging responses. Under semi-natural conditions, we exposed female guppies Poecilia reticulate from high and low predation risk sites to one of three levels of acute predation threat (high, intermediate or low concentrations of conspecific alarm cues). Our results confirm previous reports, demonstrating that guppies from a high predation site were consistently ‘bolder’ (shorter escape latencies) and exhibited graded threat-sensitive responses to different simulated threat levels while those from the low predation site were ‘shyer’ and exhibited non-graded responses. Most importantly, we found that when guppies from low predation sites resumed foraging, they did so at rates significantly lower than baseline rates. However, guppies from high predation sites resumed foraging either at rates equal to baseline (in response to low or intermediate risk stimuli) or significantly increased relative to baseline rates (in response to high risk stimuli). Together, these results highlight a complex compensatory behavioral mechanism that may allow prey to reduce the long-term costs associated with predator avoidance.

scholarly journals Is physiological glucocorticoid replacement important in children?

2016 ◽  
Vol 102 (2) ◽  
pp. 199-205 ◽  
Author(s):  
John Porter ◽  
Joanne Blair ◽  
Richard J Ross
Keyword(s):  
Circadian Rhythm ◽  
Adrenal Insufficiency ◽  
New Technologies ◽  
Poor Quality ◽  
Short Term ◽  
Once Daily ◽  
Low Concentrations ◽  
Diabetes And Obesity

Cortisol has a distinct circadian rhythm with low concentrations at night, rising in the early hours of the morning, peaking on waking and declining over the day to low concentrations in the evening. Loss of this circadian rhythm, as seen in jetlag and shift work, is associated with fatigue in the short term and diabetes and obesity in the medium to long term. Patients with adrenal insufficiency on current glucocorticoid replacement with hydrocortisone have unphysiological cortisol concentrations being low on waking and high after each dose of hydrocortisone. Patients with adrenal insufficiency complain of fatigue, a poor quality of life and there is evidence of poor health outcomes including obesity potentially related to glucocorticoid replacement. New technologies are being developed that deliver more physiological glucocorticoid replacement including hydrocortisone by subcutaneous pump, Plenadren, a once-daily modified-release hydrocortisone and Chronocort, a delayed and sustained absorption hydrocortisone formulation that replicates the overnight profile of cortisol. In this review, we summarise the evidence regarding physiological glucocorticoid replacement with a focus on relevance to paediatrics.

A decision-support tool to assist muscle-invasive bladder cancer patients choosing between radical cystectomy and chemoradiotherapy.

2018 ◽  
Vol 36 (6_suppl) ◽  
pp. 505-505
Author(s):  
Brian Christopher Baumann ◽  
Wei-Ting Hwang ◽  
Sharadha Srinivasan ◽  
Xingmei Wang ◽  
Ronac Mamtani ◽  
...  
Keyword(s):  
Bladder Cancer ◽  
Decision Support ◽  
Decision Support Tool ◽  
Short Term ◽  
Muscle Invasive Bladder Cancer ◽  
Support Tool ◽  
Trade Offs ◽  
Muscle Invasive ◽  
Break Even Point

505 Background: Patients with high-risk muscle-invasive bladder cancer (MIBC) who are borderline medically operable for radical cystectomy (RC) face a difficult decision between RC which has higher short-term treatment-related morbidity/mortality & chemoradiotherapy (CRT) which is better tolerated in the short-term but may have worse long-term cancer control outcomes. There are no existing decision support tools to assist patients & providers in understanding these trade-offs. Herein, we developed a visualization tool to inform patients & providers how the relative risks & benefits of RC & CRT vary over time with respect to overall survival (OS). Methods: We identified cT2-3 N0 M0 urothelial bladder cancer patients ≥65 y/o treated with RC +/- chemo (n = 5981) or definitive-dose CRT after TURBT (n = 793) in the National Cancer Database, 2003-2011. The database was split into a development & validation cohort. Multivariate Cox regression with time-varying hazard ratio was performed to assess pre-treatment factors associated with OS. The inverse probability of treatment weighting method using the propensity score was employed to reduce selection bias. External validation was performed. Visualization tool showing adjusted survival curves based on pre-op patient features was generated with input from patients & a multidisciplinary expert panel. Tool calculates median OS & the “break-even point,” where the short-term OS disadvantage of RC equals the long-term advantage of RC (i.e. the point where the restricted mean survival for RC & CRT are equal). Results: On MVA, significant predictors of OS were age, Charlson Deyo comorbidity index, & cT stage (p < 0.001 for all). Using these results, we iteratively developed a web application that utilizes clinical inputs to generate patient-specific survival curves that display estimated OS differences over time. Median OS, the break-even point, & percent alive at the break-even point are provided. Conclusions: This is the first decision-support tool developed to assist high-risk borderline operable MIBC patients & their providers in understanding the short-term & long-term trade-offs between RC & CRT. Additional testing is underway.

Habitat as a source of intrapopulational variation of ornament size in Galápagos lava lizards (Microlophus albemarlensis complex)

2008 ◽  
Vol 29 (2) ◽  
pp. 278-283 ◽  
Author(s):  
Mark Jordan ◽  
Howard Snell ◽  
Jennifer Hollis ◽  
Paul Stone
Keyword(s):  
Predation Risk ◽  
Body Mass ◽  
Predator Avoidance ◽  
Habitat Structure ◽  
Predation Pressure ◽  
Residual Body ◽  
Galápagos Islands ◽  
Vegetative Cover ◽  
High Predation ◽  
Intrapopulational Variation

Abstract Gradients in habitat structure are expected to influence the outcome of selection on traits that contribute to communicative display. Galápagos lava lizards (Microlophus albemarlensis complex) on Isla Plaza Sur in the Galápagos Islands occur across a gradient of vegetative cover. Previous work in this population has shown that traits associated with predator avoidance are magnified in habitats with low vegetative cover. This pattern suggests that predation pressure differs by habitat and thus, may act to select against the elaboration of ornamentation. We measured the size of the chin patch, an ornament known to be used in intraspecific signaling, to test this hypothesis. The area of the chin patch was dependent on both snout-vent length and residual body mass. In contrast to expectation, males had larger chin patches in the sparsely vegetated habitat suggested to have high predation risk. This result raises questions about the presumed survival cost of ornament elaboration.

PROGRESS AND REGRESS: UNDERSTANDING COMPLEX SOCIAL MEASURES AND THEIR TRADE-OFFS

2017 ◽  
Vol 34 (2) ◽  
pp. 164-189
Author(s):  
Daniel Austin Green ◽  
Roberta Q. Herzberg
Keyword(s):  
Income Inequality ◽  
Social Values ◽  
Scientific Progress ◽  
Well Being ◽  
Moral Progress ◽  
Short Term ◽  
Economic Progress ◽  
Trade Offs ◽  
Global And Local

Abstract:What is progress and what is not progress? We can talk about progress in lots of different arenas; we will focus primarily on economic and scientific progress, but also make brief reference to cultural and moral progress. In our discussion, we want to distinguish, especially, between overall, long-term progress and narrower, shorter-term progress or regress. We will refer to these as “global” and “local” progress, respectively. Of course, one can also regress; therefore, we will also look at instances where progress, along some dimension, slows or even moves backwards. Generally, such regress is local, and often still in a context of broader, global progress. In scientific progress, for example, there are many instances of short-term progress which, if not completely discarded or disproved, are at least substantially modified or fundamentally challenged. And yet, those research paths, even when later abandoned, still contributed to the overall progress of the field. In that sense, the regress (that is, rejection or modification of previous theories) is corrected by, but not in conflict with, the overall progress. In the case of economic progress, the concept of regress usually takes on a different form in which things that aren’t advancing progress don’t necessarily stop it, but are simply retarding progress — that is, making the rate of progress less efficient. The consequence, we suggest, is that when talking about economic progress, objections to certain consequences of economic progress (for instance, income inequality — a type of regress, in our terminology) should not be cordoned off and dealt with independently, but should be incorporated into the way we think about economic progress itself — as instances of local regress within a context of global progress. We explore the effects of these different relations between progress and regress to suggest some of the challenges those seeking to broaden the standard measure, GDP, to incorporate other social values of well-being will face moving forward.

scholarly journals OPTIMAL CLIMATE POLICY IN 3D: MITIGATION, CARBON REMOVAL, AND SOLAR GEOENGINEERING

2021 ◽  
pp. 2150008
Author(s):  
MARIIA BELAIA ◽  
JUAN B. MORENO-CRUZ ◽  
DAVID W. KEITH
Keyword(s):  
Climate Model ◽  
Integrated Assessment Model ◽  
Assessment Model ◽  
Short Term ◽  
Trade Offs ◽  
Solar Geoengineering ◽  
Optimal Climate Policy ◽  
The Cost ◽  
Far Future

We introduce solar geoengineering (SG) and carbon dioxide removal (CDR) into an integrated assessment model to analyze the trade-offs between mitigation, SG, and CDR. We propose a novel empirical parameterization of SG that disentangles its efficacy, calibrated with climate model results, from its direct impacts. We use a simple parameterization of CDR that decouples it from the scale of baseline emissions. We find that (a) SG optimally delays mitigation and lowers the use of CDR, which is distinct from moral hazard; (b) SG is deployed prior to CDR while CDR drives the phasing out of SG in the far future; (c) SG deployment in the short term is relatively independent of discounting and of the long-term trade-off between SG and CDR over time; (d) small amounts of SG sharply reduce the cost of meeting a [Formula: see text]C target and the costs of climate change, even with a conservative calibration for the efficacy of SG.

scholarly journals Energetics and fear of humans constrain the spatial ecology of pumas

2021 ◽  
Vol 118 (5) ◽  
pp. e2004592118
Author(s):  
Barry A. Nickel ◽  
Justin P. Suraci ◽  
Anna C. Nisi ◽  
Christopher C. Wilmers
Keyword(s):  
Predation Risk ◽  
Spatial Ecology ◽  
Puma Concolor ◽  
Space Use ◽  
High Energy ◽  
Primary Role ◽  
Accelerometer Data ◽  
Short Term ◽  
Energetic Costs

Energetic demands and fear of predators are considered primary factors shaping animal behavior, and both are likely drivers of movement decisions that ultimately determine the spatial ecology of wildlife. Yet energetic constraints on movement imposed by the physical landscape have only been considered separately from those imposed by risk avoidance, limiting our understanding of how short-term movement decisions scale up to affect long-term space use. Here, we integrate the costs of both physical terrain and predation risk into a common currency, energy, and then quantify their effects on the short-term movement and long-term spatial ecology of a large carnivore living in a human-dominated landscape. Using high-resolution GPS and accelerometer data from collared pumas (Puma concolor), we calculated the short-term (i.e., 5-min) energetic costs of navigating both rugged physical terrain and a landscape of risk from humans (major sources of both mortality and fear for our study population). Both the physical and risk landscapes affected puma short-term movement costs, with risk having a relatively greater impact by inducing high-energy but low-efficiency movement behavior. The cumulative effects of short-term movement costs led to reductions of 29% to 68% in daily travel distances and total home range area. For male pumas, long-term patterns of space use were predominantly driven by the energetic costs of human-induced risk. This work demonstrates that, along with physical terrain, predation risk plays a primary role in shaping an animal’s “energy landscape” and suggests that fear of humans may be a major factor affecting wildlife movements worldwide.

scholarly journals Fear of predators as an ecosystem service

2016 ◽  
Author(s):  
Liana Y Zanette ◽  
Michael Clinchy
Keyword(s):  
Public Policy ◽  
Predation Risk ◽  
Crop Protection ◽  
Management Tool ◽  
Large Carnivores ◽  
Natural Experiments ◽  
Short Term ◽  
Fear Effects ◽  
Perceived Predation Risk

The fear that predators instill in prey induces short-term anti-predator behaviours across every animal taxa that are beneficial in avoiding immediate death, but carry costs; one of the most well-established being that scared prey eat less. These findings, that animals stop eating to avoid being eaten under perceived predation risk, are not controversial. What is controversial is whether such fear effects can be long-term and powerful enough to affect wildlife prey populations and generate trophic cascades. For example, some have suggested that the restoration of wolves to Yellowstone National Park also restored the fear of predators, reducing elk foraging and in turn the pregnancy rate, contributing to rapidly declining elk numbers. Other Yellowstone researchers have suggested that the restoration of fear has generated a trophic cascade whereby scared elk eat less, increasing the food that elk eat. The prospect that fear can help restore populations and ecosystems has critical management implications, but to implement a management plan fear effects must be quantified. Indeed, the enormous amount of often acrimonious debate centred on whether fear can affect populations and ecosystems lingers in both the scientific and public policy domains because studies have largely been based on natural experiments. Manipulations that establish whether fear effects actually do exist for wildlife can help resolve management debates, and are critical for conservation and management on a global scale because the status of large carnivores world-wide is quite dismal with 77 % of species in decline. Public policy would also benefit because if restoring large carnivores also restores fear such that degraded ecosystems can become healthy again, then this has real implications for human lives and livelihoods. We present research from our lab and others, in which perceived predation risk has been experimentally manipulated in free-living wildlife. The results to date definitively demonstrate that fear effects do exist. Fear alters prey foraging behaviour, and fearful prey in turn produce 50 % fewer offspring; fear permanently impairs the reproduction of surviving offspring; and restoring the fear of large carnivores generates cascading effects down at least four tiers in the food chain. Given the enormous effects that fear has in nature, we elaborate on how manipulating fear using sound can be a particularly useful management tool for diagnosing and treating environmental ills. We describe a new system we have designed (Automated Behavioural Response systems-ABRs) that allows any researcher working on any wildlife species to conduct manipulations that quantify fear effects. We conclude that fear has its uses. Fear is good for the environment and as such, management may sometimes need to inject fear artificially for short-term goals (e.g. crop protection) but in many cases, the best and cheapest long-term solution might be to restore native predators where lost.

Negotiation in Foreign Policy

2017 ◽  
Author(s):  
Kristopher Ramsay
Keyword(s):  
Foreign Policy ◽  
International Relations ◽  
Armed Conflict ◽  
International Politics ◽  
The Political ◽  
Short Term ◽  
Trade Offs ◽  
Alternative Means

Foreign policy often involves two or more countries finding a path from contested interests to a peaceful agreement that incorporates the political and security desires of the relevant parties. In almost every case, the possibility of armed conflict as an alternative means of settling disagreements casts its shadow. Recent research on foreign policy can be well understood as following the view, first articulated by Thomas C. Schelling, that all international relations is really about negotiations and bargaining. This worldview brings a number of aspects of international politics into a natural and coherent framework. We can understand what leads countries to fail to reach peaceful solutions when disagreements arise, how the issues on the agenda influence the content and success of negotiations, and how domestic constituencies shape the ability of leaders to make agreements. Equally important, we can understand the trade-offs between short-term negotiating advantages and long-term issues of reputation.

The effect of low concentrations of sodium on potassium uptake and growth of wheat

2000 ◽  
Vol 27 (2) ◽  
pp. 175 ◽  
Author(s):  
Sally Box ◽  
Daniel P. Schachtman
Keyword(s):  
Plant Biomass ◽  
Wheat Root ◽  
Terrestrial Plants ◽  
Short Term ◽  
Root Cells ◽  
Light Levels ◽  
Low Concentrations ◽  
Na Uptake

Sodium is a beneficial mineral for some plant species when external concentrations are low. The role of Na+ in energising K+ acquisition in terrestrial plants has recently been suggested because of evidence demonstrating that wheat root cells express a high-affinity Na+-energised K+ symporter. To determine whether low concentrations of Na+ improve the K+ nutrition and growth of wheat, long-term growth and short-term tracer flux experiments were conducted. Long-term growth experiments were conducted over a range of K+ concentrations, at acidic and alkaline pH, with and without 500 µM NaCl. Plant biomass and tissue Na+ and K+ content was measured. Short-term experi-ments were conducted using tracers to determine whether low concentrations of Na+ or K+ stimulate Rb+ or Na+ uptake, respectively. Sodium stimulated the growth of wheat only at low (20 µM) external K+ in one of the long-term experiments, but not in two other experiments. Na+ did not stimulate Rb+ uptake, but K+ stimulated Na+ uptake in short-term tracer flux experiments. The results suggest that low concentrations of Na+ do not increase K+ uptake to a large extent, and only when light levels are low does Na+ have a beneficial effect on the growth of wheat.

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