Ontogenetic variation in antipredator behavior of Iberian rock lizards (Lacerta monticola): effects of body-size-dependent thermal-exchange rates and costs of refuge use

2003 ◽  
Vol 81 (7) ◽  
pp. 1131-1137 ◽  
Author(s):  
José Martín ◽  
Pilar López
Keyword(s):  
Body Size ◽  
Exchange Rates ◽  
Antipredator Behavior ◽  
Physical Property ◽  
Theory Approach ◽  
Ontogenetic Changes ◽  
Refuge Use ◽  
Thermal Exchange ◽  
Escape Theory ◽  
Heating And Cooling

In lizards, ontogenetic changes in body size affect thermal-exchange rates. This simple physical property may have consequences for thermoregulation, and also for antipredator behavior. We examined how ontogenetic changes in body mass affect rates of heating and cooling of the lizard Lacerta monticola, confirming the general result obtained for other lizards. We further analyzed the differences between juveniles and adults in approach distances to a simulated predator and in time to emerge from refuges. Juvenile lizards have a lower absolute running speed, making them more vulnerable to predation. However, in contrast to results expected from optimal-escape theory, approach distances were shorter for juveniles than for adults. Juveniles may be confident in their small size and only flee when the probability of being detected is high. On the other hand, differences in thermal properties might affect costs of refuge use. Thus, juveniles might delay fleeing because their costs of hiding are higher, as they cool faster than adults. Differences in thermal costs may also explain the juveniles' shorter times of emergence from refuges. Because of the behavioral adjustments involved in antipredator behavior, the physiological costs of reaching a low body temperature in refuges probably do not differ between age classes.

scholarly journals Calorimetric glass transition in a mean-field theory approach

2015 ◽  
Vol 112 (8) ◽  
pp. 2361-2366 ◽  
Author(s):  
Manuel Sebastian Mariani ◽  
Giorgio Parisi ◽  
Corrado Rainone
Keyword(s):  
Mean Field Theory ◽  
Mean Field ◽  
Supercooled Liquid ◽  
Analytic Solutions ◽  
Theory Approach ◽  
Mean Field Model ◽  
Thermalization Time ◽  
Glass Forming ◽  
Heating And Cooling ◽  
Spatial Dimensions

The study of the properties of glass-forming liquids is difficult for many reasons. Analytic solutions of mean-field models are usually available only for systems embedded in a space with an unphysically high number of spatial dimensions; on the experimental and numerical side, the study of the properties of metastable glassy states requires thermalizing the system in the supercooled liquid phase, where the thermalization time may be extremely large. We consider here a hard-sphere mean-field model that is solvable in any number of spatial dimensions; moreover, we easily obtain thermalized configurations even in the glass phase. We study the 3D version of this model and we perform Monte Carlo simulations that mimic heating and cooling experiments performed on ultrastable glasses. The numerical findings are in good agreement with the analytical results and qualitatively capture the features of ultrastable glasses observed in experiments.

Compensatory changes in escape and refuge use following autotomy in the lizard Sceloporus virgatus

2007 ◽  
Vol 85 (1) ◽  
pp. 99-107 ◽  
Author(s):  
W.E. Cooper, Jr.
Keyword(s):  
Body Part ◽  
Control Group ◽  
Flight Initiation Distance ◽  
Refuge Use ◽  
Predator Prey ◽  
Escape Theory ◽  
Antipredatory Strategies ◽  
Sceloporus Virgatus ◽  
Flight Initiation ◽  
Predator Effects

Following autotomy of a body part to escape from a predator, prey may alter antipredatory strategies to compensate for the inability to use autotomy and impaired escape ability. Because prey that have been captured may increase their assessment of risk posed by a predator, effects of capture may have been attributed to autotomy. I conducted an experiment using three groups of striped plateau lizards ( Sceloporus virgatus Smith, 1938): control, captured, and autotomized. Captured and autotomized lizards were less active on the day after autotomy than controls. Flight initiation distance and distance fled were greater in both experimental groups than in the control group, but did not differ between experimental groups. Flight initiation distance was greater in autotomized than in captured lizards only in males. No sex difference occurred for distance fled. Autotomized lizards entered refuges more than other groups. Escape strategy changed after autotomy to increased reliance on refuge and, in males, to increased flight initiation distance; behaviours that are appropriate to compensate for impaired escape ability. Decreased activity and increased distance fled might erroneously have been considered effects of autotomy, had effects of capture not been assessed. Predictions of escape theory that flight initiation distance and distance fled increase with predation risk were supported.

Flight initiation distance is differentially sensitive to the costs of staying and leaving food patches in a small-mammal prey

2009 ◽  
Vol 87 (11) ◽  
pp. 1016-1023 ◽  
Author(s):  
Patricio A. Lagos ◽  
Andrea Meier ◽  
Liliana Ortiz Tolhuysen ◽  
Rodrigo A. Castro ◽  
Francisco Bozinovic ◽  
...  
Keyword(s):  
Small Mammal ◽  
Antipredator Behavior ◽  
Interactive Effect ◽  
Flight Initiation Distance ◽  
Food Patch ◽  
Supplementary Food ◽  
Escape Theory ◽  
Risk Of Predation ◽  
The Cost ◽  
Flight Initiation

Escape theory predicts that a prey should flee from an approaching predator at a point in which the cost of staying equals the cost of escape. We manipulated the cost of fleeing upon approaching human predators by providing the small mammal Octodon degus (Molina, 1782) with varying amounts of supplementary food likely to disappear while the animals are not in the food patch (e.g., hidden in their burrows). Simultaneously, we manipulated the risk of remaining in the patch by providing supplementary food at varying distances from the nearest burrow. Degus fled at a shorter distance to approaching predators when foraging in patches closer to the nearest burrow and supplied with relatively high abundance of food, but only when these rodents were foraging socially. Also, degus fled at a greater distance to approaching predators when foraging in patches far from the nearest burrow. Thus, functions linked to the loss of feeding opportunities and the risk of predation interact to influence flight initiation distance after a simulated attack. This study represented one of the few demonstrations of an interactive effect between cost and risks on antipredator behavior in a small, social prey mammal.

Opposite companion effect on flight initiation distance in sympatric species: plateau pika (Ochotona curzoniae) and White-rumped Snowfinch (Onychostruthus taczanowskii)

2016 ◽  
Vol 94 (2) ◽  
pp. 109-114 ◽  
Author(s):  
He Zhang ◽  
Wenjing Li ◽  
Yanping Hu ◽  
Yanming Zhang
Keyword(s):  
Linear Models ◽  
Antipredator Behavior ◽  
Sympatric Species ◽  
Flight Initiation Distance ◽  
Plateau Pika ◽  
Escape Theory ◽  
Ochotona Curzoniae ◽  
Positive Correlations ◽  
Escape Decision ◽  
Flight Initiation

There are many factors influencing prey’s risk perception and escape decision during predator–prey encounters. The distance at which animals move away from perceived danger (often quantified as flight initiation distance or FID) has been used by behavioral ecologists to understand the economics of antipredator behavior. Using general linear models, we investigated escape decision-making processes in plateau pika (Ochotona curzoniae (Hodgson, 1858)) and White-rumped Snowfinch (Onychostruthus taczanowskii (Prjevalsky, 1876), formerly known as Montifringilla taczanowskii Przewalski, 1876) together and we found that (i) there are significant positive correlations between starting distance and FID in both species; (ii) pika escapes at a longer distance from an approaching intruder when it is far from its burrow; (iii) foraging animals tolerate closer distances than watching ones, both in pikas and in Snowfinches; (iv) conspecifics seem to have no effect on pikas’ escaping behavior, while the appearance of Snowfinches dramatically decreases the FID of pikas. On the contrary, conspecifics significantly decrease the FID of Snowfinches, while the presence of pikas has no effects. These findings provide new evidence, which are consistent with optimal escape theory. These novel results in multispecies interactions prompt us to pay attention to the potential relationship between pikas and Snowfinches, as well as the “bird–pika in one hole” phenomenon.

scholarly journals Numerical Investigation of the Physical Properties Effect on the Thermal Performance of a Vertical Geothermal Heat Exchanger

2018 ◽  
Vol 8 (2) ◽  
pp. 2715-2723
Author(s):  
M. Benyoub ◽  
B. Aour ◽  
B. Bouhacina ◽  
K. Sadek
Keyword(s):  
Heat Exchanger ◽  
Construction Materials ◽  
Green Energy ◽  
Filling Material ◽  
Geothermal Heat ◽  
Thermal Exchange ◽  
Heating And Cooling ◽  
Knowing That ◽  
Shaped Tube ◽  
Geothermal Heat Exchanger

Low-temperature geothermal energy is a promising technique for heating and cooling residential and commercial premises, especially since it is one of the green energy solutions that respect the environment. The principle of this technique is based on thermal exchange between the heat pump and the basement using a vertically buried heat exchanger. This is usually made of a U-shaped tube inserted vertically in a borehole made in the ground and filled with a filler material. The purpose of the present study is to vary the different construction materials of the U-tube, the filling material and the soil, in order to obtain the most energy-efficient parameters. The evolution of temperature and heat flux as a function of time has been highlighted for different combinations. Knowing that an experimental study requires a considerable monetary fund, the present model has been validated using previously literature results. Recommendations on the choice of different materials of the geothermal heat exchanger are proclaimed at the end of this work.

Body size of ectotherms constrains thermal requirements for reproductive activity in seasonal environments

2020 ◽  
Vol 98 (10) ◽  
pp. 651-659
Author(s):  
Jared W.H. Connoy ◽  
Jessica A. Leivesley ◽  
Ronald J. Brooks ◽  
Jacqueline D. Litzgus ◽  
Njal Rollinson
Keyword(s):  
Body Size ◽  
Thermal Inertia ◽  
Reproductive Activity ◽  
Time Of Day ◽  
Thermal Requirements ◽  
Heating And Cooling ◽  
Painted Turtles ◽  
Snapping Turtles ◽  
Nesting Behaviour ◽  
Preferred Body Temperature

Body size may influence ectotherm behaviour by influencing heating and cooling rates, thereby constraining the time of day that some individuals can be active. The time of day at which turtles nest, for instance, is hypothesized to vary with body size at both inter- and intra-specific levels because large individuals have greater thermal inertia, retaining preferred body temperatures for a longer period of time. We use decades of data on thousands of individual nests from Algonquin Park, Ontario, Canada, to explore how body size is associated with nesting behaviour in Painted Turtles (Chrysemys picta (Schneider, 1783); small bodied) and Snapping Turtles (Chelydra serpentina (Linnaeus, 1758); large bodied). We found that (i) between species, Painted Turtles nest earlier in the evening and at higher mean temperatures than Snapping Turtles, and (ii) within species, relatively large individuals of both species nest at cooler temperatures and that relatively larger Painted Turtles nest later in the evening compared with smaller Painted Turtles. Our data support the thermal inertia hypothesis and may help explain why turtles in general exhibit geographic clines in body size: northern environments experience more daily variation in temperature, and larger size may evolve, in part, for retention of preferred body temperature during terrestrial forays.

Refuge use in a killifish: influence of body size and nutritional state

2002 ◽  
Vol 80 (4) ◽  
pp. 782-788 ◽  
Author(s):  
Lisa M Dowling ◽  
Jean-Guy J Godin
Keyword(s):  
Body Size ◽  
Risk Taking ◽  
Control Model ◽  
Nutritional State ◽  
Refuge Use ◽  
Individual Fitness ◽  
Threatening Stimulus ◽  
Energetic State ◽  
Predator Model ◽  
Individual Body

Refuge use by animals provides greater safety from predation. A refuging animal continuously must decide whether to stay in the refuge or to emerge into open habitat. This decision may depend on its energetic state and vulnerability to predation, both of which can vary with individual body size. We experimentally tested the concurrent effects of body size and nutritional (hunger) state on refuge use in the banded killifish (Fundulus diaphanus). Individual killifish were "attacked" in an open laboratory habitat (containing food) by either a trout predator model or a control model that did not resemble a trout. Frightened fish typically fled into a foodless refuge nearby. The amount of time that killifish spent in the refuge before emerging increased significantly with body length, but was not affected by their current nutritional state or the threatening stimulus (type of model). Smaller killifish were thus more risk-prone than larger conspecifics irrespective of their current nutritional state. Such size-mediated risk-taking behaviour has important consequences for individual fitness and implications for population and community composition and dynamics in nature.

Beyond optimal escape theory: microhabitats as well as predation risk affect escape and refuge use by the phrynosomatid lizard Sceloporus virgatus

Behaviour ◽  
2007 ◽  
Vol 144 (10) ◽  
pp. 1235-1254 ◽  
Author(s):  
Dawn Wilson ◽  
William Cooper
Keyword(s):  
Risk Factors ◽  
Individual Differences ◽  
Predation Risk ◽  
Flight Initiation Distance ◽  
Refuge Use ◽  
Escape Theory ◽  
Sceloporus Virgatus ◽  
Flight Initiation

AbstractEscape studies often focus on one variable, but tactics and refuge use vary with microhabitats, exposure, distance to refuge, and temperature. We studied these effects and effects of microhabitats and risk factors (distance from refuge, temperature) on flight initiation distance (FID, distance between predator and prey when escape begins) and distance fled (DF) in the lizard Sceloporus virgatus. FID increased as distance to refuge increased and temperature decreased. DF increased as FID increased, supporting the hypothesis that individual differences in boldness are consistent among encounter phases. Refuges were rock crevices, trees, logs, and grass clumps. Interhabitat differences in FID and DF matched those in distance to refuge. FID was longer for lizards on rocks and ground than trees due to proximity to and use of refuge. Lizards on trees rarely changed microhabitats, moving to the far side and unpredictably up or down. Lizards on slopes fled long distances up slopes. Most lizards on rocks entered crevices or switched microhabitats. Lizards on ground usually changed microhabitats. Optimal escape theory accurately predicted effects of risk on FID, but initial microhabitats and final microhabitats and refuges affected tactics, FID and DF. DF was affected by risk, being longer when lizards remained visible.

Sign in / Sign up

Export Citation Format

Share Document