scholarly journals Generalization of predator recognition: Velvet geckos display anti-predator behaviours in response to chemicals from non-dangerous elapid snakes

2010 ◽  
Vol 56 (3) ◽  
pp. 337-342 ◽  
Author(s):  
Jonathan K. Webb ◽  
Weiguo Du ◽  
David Pike ◽  
Richard Shine
Keyword(s):  
Chemical Cues ◽  
Prey Species ◽  
Predator Recognition ◽  
Risk Of Predation ◽  
Long Time ◽  
Time Periods

Abstract Many prey species detect chemical cues from predators and modify their behaviours in ways that reduce their risk of predation. Theory predicts that prey should modify their anti-predator responses according to the degree of threat posed by the predator. That is, prey should show the strongest responses to chemicals of highly dangerous prey, but should ignore or respond weakly to chemicals from non-dangerous predators. However, if anti-predator behaviours are not costly, and predators are rarely encountered, prey may exhibit generalised antipredator behaviours to dangerous and non-dangerous predators. In Australia, most elapid snakes eat lizards, and are therefore potentially dangerous to lizard prey. Recently, we found that the nocturnal velvet gecko Oedura lesueurii responds to chemicals from dangerous and non-dangerous elapid snakes, suggesting that it displays generalised anti-predator behaviours to chemicals from elapid snakes. To explore the generality of this result, we videotaped the behaviour of velvet geckos in the presence of chemical cues from two small elapid snakes that rarely consume geckos: the nocturnal golden-crowned snake Cacophis squamulosus and the diurnal marsh snake Hemiaspis signata. We also videotaped geckos in trials involving unscented cards (controls) and cologne-scented cards (pungency controls). In trials involving Cacophis and Hemiaspis chemicals, 50% and 63% of geckos spent long time periods (> 3 min) freezing whilst pressed flat against the substrate, respectively. Over half the geckos tested exhibited anti-predator behaviours (tail waving, tail vibration, running) in response to Cacophis (67%) or Hemiaspis (63%) chemicals. These behaviours were not observed in control or pungency control trials. Our results support the idea that the velvet gecko displays generalised anti-predator responses to chemical cues from elapid snakes. Generalised responses to predator chemicals may be common in prey species that co-occur with multiple, ecologically similar, dangerous predators.

The population dynamics of bite-sized predators: prey dependence, territoriality, and mobility

2018 ◽  
Author(s):  
Xavier Lambin
Keyword(s):  
Prey Species ◽  
Top Down ◽  
Predator Prey ◽  
Biological Barrier ◽  
Reciprocal Interactions ◽  
Demographic Rates ◽  
Risk Of Predation ◽  
Increased Risk ◽  
Rodent Prey ◽  
Small Mustelids

The dependency of mustelid demographic rates on prey abundance has the potential to cause a strong coupling between predator-prey populations. Data on mustelid dynamics show that such strong reciprocal interactions only materialise in some restricted conditions. Bite-size mustelid predators searching for scarce, depleted prey expose themselves to increased risk of predation by larger predators of small mammal that are themselves searching for similar prey species. As voles or muskrats become scarcer, weasels and mink searching for prey over larger areas become increasingly exposed to intra-guild predation, unless they operate in a habitat refuge such as the sub-nivean space. Where larger predators are sufficiently abundant or exert year-round predation pressure on small mustelids, their impact on mustelids may impose biological barrier to dispersal that are sufficient to weaken the coupling between small mustelids and their rodent prey, and thus impose a degree of top down limitation on mustelids.

Snowshoe hare feeding behavior responds to coyote and moose cues at diverse vegetation densities

2020 ◽  
Vol 101 (3) ◽  
pp. 710-717
Author(s):  
Zachary K Lankist ◽  
Christine R Maher
Keyword(s):  
Chemical Cues ◽  
Prey Species ◽  
Vegetation Density ◽  
Vegetative Cover ◽  
Feeding Sites ◽  
Risk Of Death ◽  
Lack Of Information ◽  
Snowshoe Hares ◽  
Number Of Visits ◽  
Indirect Cues

Abstract Heterospecific competitors can use chemical cues left by dominant species to avoid aggressive interactions. Similarly, prey avoid chemical cues from predators at feeding sites, presumably because risk of death outweighs the benefit of food. This study addressed the lack of information regarding mammals’ avoidance of direct cues from competitors and also examined how indirect cues, i.e., vegetative cover, affect foraging behavior. To test if chemical cues and vegetative cover alter the number of visits by prey species and time spent at feeding plots, we observed snowshoe hares (Lepus americanus) in plots containing coyote (Canis latrans; predator) and moose (Alces alces; competitor) urine across a spectrum of vegetation densities. Snowshoe hares significantly reduced number of visits to plots that contained coyote or moose urine. In plots treated with coyote urine, number of visits decreased significantly as plots became more densely vegetated. Neither chemical cues nor vegetation density affected time spent in plots. These results suggest that competition between snowshoe hares and moose has selected for an avoidance response. This study also reinforces the idea that an increase in vegetation density could prove disadvantageous to prey, perhaps because some predators use dense vegetation to their advantage.

scholarly journals Modeling and Simulation of Sky Survey

2021 ◽  
Vol 11 (16) ◽  
pp. 7584
Author(s):  
Kun Hu ◽  
Hongfei Wang ◽  
Wenzhao Zhang ◽  
Yuohua Xu ◽  
Shengmao He
Keyword(s):  
Modeling And Simulation ◽  
Scheduling Algorithm ◽  
Space Station ◽  
Scientific Output ◽  
Mission Planning ◽  
Design Algorithm ◽  
Sky Survey ◽  
Long Time ◽  
Time Periods ◽  
Design Ideas

Sky surveys with wide and deep field are the key direction of international astronomy research for the next decades. It is worthwhile to study how to design a sky survey algorithm to obtain the maximum scientific output in a limited period of observation. In this paper, the modeling and simulation of a wide and deep sky survey mission are presented using a Staged Design Algorithm (SDA), which takes into account the inefficient time periods and difficult-to-observe sky areas. In order to ensure the effective completion of the long-time survey observation tasks in large sky areas, a two-stage scheduling algorithm is designed. Firstly, the inefficient time periods and difficult observation areas are scheduled, and then the overall observation is carried out. The prearranged schedule is arranged when inefficient time periods or difficult areas are encountered during the overall arrangement. The simulation results are verified on the basic data of the China Space Station Telescope (CSST), and the obtained simulation result is three years ahead of the target of the telescope design to complete the wide and deep sky survey of 15,000 deg2. The design ideas in this paper not only have good results for sky survey observation but also can be extended to similar satellite Earth observation mission planning.

Spatial and temporal variation in abundance, group size and behaviour of bottlenose dolphins in the Florida coastal Everglades

2017 ◽  
Vol 98 (5) ◽  
pp. 1097-1107 ◽  
Author(s):  
Robin E. Sarabia ◽  
Michael R. Heithaus ◽  
Jeremy J. Kiszka
Keyword(s):  
Temporal Variation ◽  
Environmental Changes ◽  
Bottlenose Dolphins ◽  
Ecosystem Restoration ◽  
Spatial And Temporal Variation ◽  
Coastal Oceans ◽  
Inland Bays ◽  
Long Time ◽  
Time Periods ◽  
Ecological Importance

Bottlenose dolphins (Tursiops truncatus) are abundant in many coastal ecosystems, including the coastal Everglades. Understanding spatial and temporal variation in their abundance and group sizes is important for estimating their potential ecological importance and predicting how environmental changes (e.g. ecosystem restoration) might impact their populations. From August 2010 to June 2012, we completed a total of 67 belt transects covering a total of 2650 linear km and an area of 1232 km2. Dolphin densities varied spatially and temporally. The highest densities of dolphins were found in coastal oceans and inland bays and were lowest in rivers. Use of rivers, however, increased during the dry season while densities in other habitats remained similar across seasons. Dolphins appeared to prefer portions of bays close to mangrove-covered islands over open waters. A resighting rate of 63.6% of individuals across the 2-year study suggests that at least a portion of the population is probably resident within study regions over long time periods. The largest groups (mean 6.28, range 1–31) were found in open waters and bays despite apparently low predation pressure. Indeed, shark bite scars – likely the result of unsuccessful predation attempts – were conclusively observed on only 1% of individuals. Although further studies are warranted, the high densities of dolphins suggest that they are an important upper trophic level predator in the coastal Everglades, but their ecological importance probably varies in space and time.

scholarly journals Are stock returns an inflation hedge for the UK? Evidence from a wavelet analysis using over three centuries of data

2018 ◽  
Vol 23 (3) ◽  
Author(s):  
Aviral Kumar Tiwari ◽  
Juncal Cunado ◽  
Rangan Gupta ◽  
Mark E. Wohar
Keyword(s):  
South Africa ◽  
Wavelet Analysis ◽  
Stock Returns ◽  
Time Period ◽  
Inflation Rates ◽  
The Us ◽  
Long Time ◽  
Time Periods ◽  
The Uk ◽  
The Relationship

Abstract This paper analyzes the relationship between stock returns and the inflation rates for the UK over a long time period (February 1790–February 2017) and at different frequencies, by employing a wavelet analysis. We also compare the results for the UK economy with those for the US and two developing countries (India and South Africa). Overall, our results tend to suggest that, while the relationship between stock returns and inflation rates varies across frequencies and time periods, there is no evidence of stock returns acting as an inflation hedge, irrespective of whether we look at the two developed or the two developing markets in our sample.

Introduction

2019 ◽  
pp. 1-22
Author(s):  
Rachel Kahn Best
Keyword(s):  
Public Policy ◽  
Social Movements ◽  
Interest Groups ◽  
Agenda Setting ◽  
Social Problems ◽  
Contentious Politics ◽  
Long Time ◽  
Time Periods ◽  
Time Changes ◽  
Or Organization

For more than a century, disease campaigns have been the causes Americans ask their neighbors to donate to and the issues that inspire them to march and volunteer. Studies of social movements, interest groups, agenda setting, and social problems tend to focus on contentious politics and study one movement or organization at a time. But these approaches cannot reveal why disease campaigns are the battles Americans can agree to fight, why some diseases attract more attention than others, and how fighting one disease at a time changes charity and public policy. Understanding the causes and effects of disease campaigns, requires studying consensus politics and collecting data on fields of organizations over long time periods.

Description of My Model

2019 ◽  
pp. 56-59
Author(s):  
Andrew Smithers
Keyword(s):  
Capital Stock ◽  
Full Employment ◽  
Quality Improvements ◽  
The Poor ◽  
The Us ◽  
Long Time ◽  
Civilian Employment ◽  
Time Periods ◽  
The Uk ◽  
Employment Quality

The volume of the capital stock is defined as the original cost at constant prices of all tangible capital that has not been scrapped. Due to the poor data available for the UK my calculations and testing have had to be limited to the US. The volume of labour is defined as civilian employment. Quality improvements for both labour and capital are defined as being part of TFP. TFP is under conditions of full employment and must therefore be measured over long time periods. All growth comes from TFP, changes in labour and NTVs. The change in the volume of capital less the change in the volume of labour equals the change in NTVs and the balance is that from changes in technology (TFP). NTV is exogenous in aggregate. The value of the capital stock, but not its volume, is mean-reverting.

scholarly journals Knowing the Enemy: Inducible Defences in Freshwater Zooplankton

Diversity ◽  
2020 ◽  
Vol 12 (4) ◽  
pp. 147 ◽  
Author(s):  
Patricia Diel ◽  
Marvin Kiene ◽  
Dominik Martin-Creuzburg ◽  
Christian Laforsch
Keyword(s):  
Life History ◽  
Chemical Cues ◽  
Prey Species ◽  
Inducible Defences ◽  
Animal Kingdom ◽  
Predator Species ◽  
Freshwater Zooplankton ◽  
Taxonomic Range ◽  
Set Up ◽  
Made In

Phenotypic plasticity in defensive traits is an appropriate mechanism to cope with the variable hazard of a frequently changing predator spectrum. In the animal kingdom these so-called inducible defences cover the entire taxonomic range from protozoans to vertebrates. The inducible defensive traits range from behaviour, morphology, and life-history adaptations to the activation of specific immune systems in vertebrates. Inducible defences in prey species play important roles in the dynamics and functioning of food webs. Freshwater zooplankton show the most prominent examples of inducible defences triggered by chemical cues, so-called kairomones, released by predatory invertebrates and fish. The objective of this review is to highlight recent progress in research on inducible defences in freshwater zooplankton concerning behaviour, morphology, and life-history, as well as difficulties of studies conducted in a multipredator set up. Furthermore, we outline costs associated with the defences and discuss difficulties as well as the progress made in characterizing defence-inducing cues. Finally, we aim to indicate further possible routes in this field of research and provide a comprehensive table of inducible defences with respect to both prey and predator species.

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