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Connors, B. M., M. Krkošek i L. M. Dill. "Sea lice escape predation on their host". Biology Letters 4, nr 5 (17.06.2008): 455–57. http://dx.doi.org/10.1098/rsbl.2008.0276.
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Parasites seldom have predators but often fall victim to those of their hosts. How parasites respond to host predation can have important consequences for both hosts and parasites, though empirical investigations are rare. The exposure of wild juvenile salmon to sea lice ( Lepeophtheirus salmonis ) from salmon farms allowed us to study a novel ecological interaction: the response of sea lice to predation on their juvenile pink and chum salmon hosts by two salmonid predators—coho smolts and cut-throat trout. In approximately 70% of trials in which a predator consumed a parasitized prey, lice escaped predation by swimming or moving directly onto the predator. This trophic transmission is strongly male biased, probably because behaviour and morphology constrain female movement and transmission. These findings highlight the potential for sea lice to be transmitted up marine food webs in areas of intensive salmon aquaculture, with implications for louse population dynamics and predatory salmonid health.
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Pal, Soumyadip, Fahad Al Basir i Santanu Ray. "Impact of Cooperation and Intra-Specific Competition of Prey on the Stability of Prey–Predator Models with Refuge". Mathematical and Computational Applications 28, nr 4 (28.07.2023): 88. http://dx.doi.org/10.3390/mca28040088.
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The main objective of this study is to find out the influences of cooperation and intra-specific competition in the prey population on escaping predation through refuge and the effect of the two intra-specific interactions on the dynamics of prey–predator systems. For this purpose, two mathematical models with Holling type II functional response functions were proposed and analyzed. The first model includes cooperation among prey populations, whereas the second one incorporates intra-specific competition. The existence conditions and stability of different equilibrium points for both models were analyzed to determine the qualitative behaviors of the systems. Refuge through intra-specific competition has a stabilizing role, whereas cooperation has a destabilizing role on the system dynamics. Periodic oscillations were observed in both systems through Hopf bifurcation. From the analytical and numerical findings, we conclude that intra-specific competition affects the prey population and continuously controls the refuge class under a critical value, and thus, it never becomes too large to cause predator extinction due to food scarcity. Conversely, cooperation leads the maximal number of individuals to escape predation through the refuge so that predators suffer from low predation success.
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Wilson, Robbie S., Theodore P. Pavlic, Rebecca Wheatley, Amanda C. Niehaus i Ofir Levy. "Modeling escape success in terrestrial predator–prey interactions". Integrative and Comparative Biology 60, nr 2 (22.06.2020): 497–508. http://dx.doi.org/10.1093/icb/icaa070.
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Synopsis Prey species often modify their foraging and reproductive behaviors to avoid encounters with predators; yet once they are detected, survival depends on out-running, out-maneuvering, or fighting off the predator. Though predation attempts involve at least two individuals—namely, a predator and its prey—studies of escape performance typically measure a single trait (e.g., sprint speed) in the prey species only. Here, we develop a theoretical model in which the likelihood of escape is determined by the prey animal’s tactics (i.e., path trajectory) and its acceleration, top speed, agility, and deceleration relative to the performance capabilities of a predator. The model shows that acceleration, top speed, and agility are all important determinants of escape performance, and because speed and agility are biomechanically related to size, smaller prey with higher agility should force larger predators to run along curved paths that do not allow them to use their superior speeds. Our simulations provide clear predictions for the path and speed a prey animal should choose when escaping from predators of different sizes (thus, biomechanical constraints) and could be used to explore the dynamics between predators and prey.
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Brinton, Brigette A., i Mary Carla Curran. "The effects of the parasite Probopyrus pandalicola (Packard, 1879) (Isopoda, Bopyridae) on the behavior, transparent camouflage, and predators of Palaemonetes pugio Holthuis, 1949 (Decapoda, Palaemonidae)". Crustaceana 88, nr 12-14 (2015): 1265–81. http://dx.doi.org/10.1163/15685403-00003501.
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The bopyrid isopod Probopyrus pandalicola (Packard, 1879) is a large, noticeable, hematophagous ectoparasite of palaemonid shrimps, including the daggerblade grass shrimp Palaemonetes pugio Holthuis, 1949. Bopyrids affect grass shrimp physiology and may also affect predator-prey dynamics. The purpose of this study was to determine whether the isopod affected the behavior and/or camouflage of grass shrimp, thereby altering the predation preferences of the mummichog Fundulus heteroclitus (Linnaeus, 1766). To determine whether the isopod affected predator preference through behavioral and/or camouflage alterations, paired combinations of unparasitized, parasitized, and marked shrimp were presented to mummichogs. One branchiostegite of some of the unparasitized shrimp was marked with black paint to mimic the bopyrid parasite. Mummichog predation preference and shrimp behavior immediately prior to predation events were recorded. All shrimp behavior was classified as motionless, walking, swimming, or backward thrusting. Immediately prior to predation, parasitized shrimp swam more () and backward thrusted less () than unparasitized shrimp. Mummichogs exhibited a preference for the more active shrimp (80.7% of shrimp; ), and also for the less camouflaged (parasitized or marked) shrimp (81.5% of shrimp; ) if there was no difference in shrimp behavior. Parasitized shrimp were preferentially consumed (51/85 shrimp) when paired with unparasitized shrimp (), but not with marked shrimp (). A 30-min activity budget was created for each type of shrimp both in the presence and absence of predators; neither the parasite nor marking affected their behavior over 30 min (). The major finding of this study was that P. pandalicola affected the predation preferences of F. heteroclitus by altering the behavior and/or camouflage of the grass shrimp. Parasitization alters predator-prey dynamics by decreasing the camouflage and the frequency of backward-thrusting behavior by the host when it is threatened by predation, which thereby decreases the ability of shrimp to escape from predators.
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Willis, Anthony J., Richard H. Groves i Julian E. Ash. "Seed Ecology of Hypericum gramineum, an Australian Forb". Australian Journal of Botany 45, nr 6 (1997): 1009. http://dx.doi.org/10.1071/bt96074.
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Aspects of the seed ecology of Hypericum gramineum Forster, a perennial forb that is native to Australia, were examined in several germination and seed predation experiments. Fresh seeds were innately dormant. Highest germination of non-dormant seeds occurred in the light at a temperature regime of approximately 35/25˚C. The results of field experiments indicated that there was no strongly seasonal effect on germination. Predators, such as ants, removed < 20% seeds, thereby suggesting that post-dispersal seed predation is relatively unimportant in the dynamics of H. gramineum populations. Seeds that escape predation and that fail to germinate after dispersal may be incorporated into a persistent soil seed bank.
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Warren, Donald T., Jennifer M. Donelson i Mark I. McCormick. "Extended exposure to elevated temperature affects escape response behaviour in coral reef fishes". PeerJ 5 (18.08.2017): e3652. http://dx.doi.org/10.7717/peerj.3652.
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The threat of predation, and the prey’s response, are important drivers of community dynamics. Yet environmental temperature can have a significant effect on predation avoidance techniques such as fast-start performance observed in marine fishes. While it is known that temperature increases can influence performance and behaviour in the short-term, little is known about how species respond to extended exposure during development. We produced a startle response in two species of damselfish, the lemon damselPomacentrus moluccensis,and the Ambon damselfishPomacentrus amboinensis,by the repeated use of a drop stimulus. We show that the length of thermal exposure of juveniles to elevated temperature significantly affects this escape responses.Short-term (4d) exposure to warmer temperature affected directionality and responsiveness for both species. After long-term (90d) exposure, onlyP. moluccensisshowed beneficial plasticity, with directionality returning to control levels. Responsiveness also decreased in both species, possibly to compensate for higher temperatures. There was no effect of temperature or length of exposure on latency to react, maximum swimming speed, or escape distance suggesting that the physical ability to escape was maintained. Evidence suggests that elevated temperature may impact some fish species through its effect on the behavioural responses while under threat rather than having a direct influence on their physical ability to perform an effective escape response.
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Free, Brian A., Matthew J. McHenry i Derek A. Paley. "Probabilistic analytical modelling of predator–prey interactions in fishes". Journal of The Royal Society Interface 16, nr 150 (styczeń 2019): 20180873. http://dx.doi.org/10.1098/rsif.2018.0873.
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Predation is a fundamental interaction between species, yet it is largely unclear what tactics are successful for the survival or capture of prey. One challenge in this area comes with how to test theoretical ideas about strategy with experimental measurements of features such as speed, flush distance and escape angles. Tactics may be articulated with an analytical model that predicts the motion of predator or prey as they interact. However, it may be difficult to recognize how the predictions of such models relate to behavioural measurements that are inherently variable. Here, we present an alternative approach for modelling predator–prey interactions that uses deterministic dynamics, yet incorporates experimental kinematic measurements of natural variation to predict the outcome of biological events. This technique, called probabilistic analytical modelling (PAM), is illustrated by the interactions between predator and prey fish in two case studies that draw on recent experiments. In the first case, we use PAM to model the tactics of predatory bluefish ( Pomatomus saltatrix ) as they prey upon smaller fish ( Fundulus heteroclitus ). We find that bluefish perform deviated pure pursuit with a variable pursuit angle that is suboptimal for the time to capture. In the second case, we model the escape tactics of zebrafish larvae ( Danio rerio ) when approached by adult predators of the same species. Our model successfully predicts the measured patterns of survivorship using measured probability density functions as parameters. As these results demonstrate, PAM is a data-driven modelling approach that can be predictive, offers analytical transparency, and does not require numerical simulations of system dynamics. Though predator–prey interactions demonstrate the use of this technique, PAM is not limited to studying biological systems and has broad utility that may be applied towards understanding a wide variety of natural and engineered dynamical systems where data-driven modelling is beneficial.
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Morris, Cynthia L., i Matthew S. Lattanzio. "Intraspecific variation in tree lizard escape behaviour in relation to habitat and temperature". Behaviour 157, nr 2 (6.02.2020): 185–204. http://dx.doi.org/10.1163/1568539x-00003586.
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Abstract Optimal escape theory has proven useful for understanding the dynamics of antipredator behaviour in animals; however, approaches are often limited to single-population studies. We studied how the escape behaviour of tree lizards (Urosaurus ornatus) varied across a disturbance gradient. We also considered how sex, body temperature, and perch temperature affected their escape decisions. Both sexes exhibited similar response patterns; however, lizards in the most-disturbed habitat, as well as cooler (body or perch temperature) lizards, initiated escape earlier (but did not flee further) than other animals. Increased wariness as indicated by earlier escape suggests that frequently-disturbed, more-open localities may be stressful habitats for species like U. ornatus. In addition, because cooler temperatures limit locomotor performance capacity, escape decisions should also depend on a species’ thermal ecology. Overall, we stress the importance of multi-population approaches for capturing the variety of ways species adaptively respond to the threat of predation across habitat gradients.
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Janssens, Lizanne, i Robby Stoks. "Predation risk causes oxidative damage in prey". Biology Letters 9, nr 4 (23.08.2013): 20130350. http://dx.doi.org/10.1098/rsbl.2013.0350.
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While there is increasing interest in non-consumptive effects of predators on prey, physiological effects are understudied. While physiological stress responses play a crucial role in preparing escape responses, the increased metabolic rates and shunting of energy away from other body functions, including antioxidant defence, may generate costs in terms of increased oxidative stress. Here, we test whether predation risk increases oxidative damage in Enallagma cyathigerum damselfly larvae. Under predation risk, larvae showed higher lipid peroxidation, which was associated with lower levels of superoxide dismutase, a major antioxidant enzyme in insects, and higher superoxide anion concentrations, a potent reactive oxygen species. The mechanisms underlying oxidative damage are likely to be due to the shunting of energy away from antioxidant defence and to an increased metabolic rate, suggesting that the observed increased oxidative damage under predation risk may be widespread. Given the potentially severe fitness consequences of oxidative damage, this largely overlooked non-consumptive effect of predators may be contributing significantly to prey population dynamics.
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Domenici, P., C. Lefrançois i A. Shingles. "Hypoxia and the antipredator behaviours of fishes". Philosophical Transactions of the Royal Society B: Biological Sciences 362, nr 1487 (maj 2007): 2105–21. http://dx.doi.org/10.1098/rstb.2007.2103.
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Hypoxia is a phenomenon occurring in marine coastal areas with increasing frequency. While hypoxia has been documented to affect fish activity and metabolism, recent evidence shows that hypoxia can also have a detrimental effect on various antipredator behaviours. Here, we review such evidence with a focus on the effect of hypoxia on fish escape responses, its modulation by aquatic surface respiration (ASR) and schooling behaviour. The main effect of hypoxia on escape behaviour was found in responsiveness and directionality. Locomotor performance in escapes was expected to be relatively independent of hypoxia, since escape responses are fuelled anaerobically. However, hypoxia decreased locomotor performance in some species (Mugilidae) although only in the absence of ASR in severe hypoxia. ASR allows fish to show higher escape performance than fish staying in the water column where hypoxia occurs. This situation provides a trade-off whereby fish may perform ASR in order to avoid the detrimental effects of hypoxia, although they would be subjected to higher exposure to aerial predation. As a result of this trade-off, fishes appear to minimize surfacing behaviour in the presence of aerial predators and to surface near shelters, where possible. For many fish species, schooling can be an effective antipredator behaviour. Severe hypoxia may lead to the disruption of the school unit. At moderate levels, hypoxia can increase school volume and can change the shuffling behaviour of individuals. By altering school structure and dynamics, hypoxia may affect the well functioning of schooling in terms of synchronization and execution of antipredator manoeuvres. School structure and volume appear to be the results of numerous trade-offs, where school shape may be dictated by the presence of predators, the need for energy saving via hydrodynamic advantages and oxygen level. The effects of hypoxia on aquatic organisms can be taxon specific. While hypoxia may not necessarily increase the vulnerability of fish subject to predation by other fish (since feeding in fish also decreases in hypoxia), predators from other taxa such as birds, jellyfish or aquatic mammals may take advantage of the detrimental effects of hypoxia on fish escape ability. Therefore, the effect of hypoxia on fish antipredator behaviours may have major consequences for the composition of aquatic communities.
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Combes, S. A., J. D. Crall i S. Mukherjee. "Dynamics of animal movement in an ecological context: dragonfly wing damage reduces flight performance and predation success". Biology Letters 6, nr 3 (17.03.2010): 426–29. http://dx.doi.org/10.1098/rsbl.2009.0915.
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Much of our understanding of the control and dynamics of animal movement derives from controlled laboratory experiments. While many aspects of animal movement can be probed only in these settings, a more complete understanding of animal locomotion may be gained by linking experiments on relatively simple motions in the laboratory to studies of more complex behaviours in natural settings. To demonstrate the utility of this approach, we examined the effects of wing damage on dragonfly flight performance in both a laboratory drop–escape response and the more natural context of aerial predation. The laboratory experiment shows that hindwing area loss reduces vertical acceleration and average flight velocity, and the predation experiment demonstrates that this type of wing damage results in a significant decline in capture success. Taken together, these results suggest that wing damage may take a serious toll on wild dragonflies, potentially reducing both reproductive success and survival.
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Figiel Jr., Chester R., i Raymond D. Semlitsch. "Effects of nonlethal injury and habitat complexity on predation in tadpole populations". Canadian Journal of Zoology 69, nr 4 (1.04.1991): 830–34. http://dx.doi.org/10.1139/z91-125.
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Our purpose was to determine how nonlethal prey injury and habitat complexity mediate the dynamics of a predator–prey system. We assessed rates of predation by the crayfish Procambarus acutus acutus on Hyla chrysoscelis tadpoles with four levels of tail loss (0, 25, 50, and 75% total tail length removed), and in habitats of three levels of complexity (zero, low, and high density of screen) in a 4 × 3 factorial design. We also examined the effects of tail loss on tadpole sprint velocity and distance traveled. Tadpoles with 75% tail loss were preyed upon significantly more often than tadpoles in the other tail-loss treatments. Habitat complexity did not affect tadpole survival. In addition, there was no interaction between tail loss and habitat complexity. Tail loss significantly affected both tadpole swimming velocity and sprint distance traveled. Tadpoles with 75% tail loss had slower sprint speed and swam a shorter distance than tadpoles with 0 and 25% tail loss, and tadpoles with 50% tail loss had slower sprint speed and swam a shorter distance than tadpoles in the 0% tail loss treatment. Although tadpoles generally rely on short bursts of speed, generated by the tail, to escape predators, tail injury and apparently reduced swimming performance did not increase vulnerability to predation in a simple linear fashion.
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York, Carly A., Ian K. Bartol, Paul S. Krueger i Joseph T. Thompson. "Squids use multiple escape jet patterns throughout ontogeny". Biology Open 9, nr 11 (24.09.2020): bio054585. http://dx.doi.org/10.1242/bio.054585.
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ABSTRACTThroughout their lives, squids are both predators and prey for a multitude of animals, many of which are at the top of ocean food webs, making them an integral component of the trophic structure of marine ecosystems. The escape jet, which is produced by the rapid expulsion of water from the mantle cavity through a funnel, is central to a cephalopod's ability to avoid predation throughout its life. Although squid undergo morphological and behavioral changes and experience remarkably different Reynolds number regimes throughout their development, little is known about the dynamics and propulsive efficiency of escape jets throughout ontogeny. We examine the hydrodynamics and kinematics of escape jets in squid throughout ontogeny using 2D/3D velocimetry and high-speed videography. All life stages of squid produced two escape jet patterns: (1) ‘escape jet I’ characterized by short rapid pulses resulting in vortex ring formation and (2) ‘escape jet II’ characterized by long high-volume jets, often with a leading-edge vortex ring. Paralarvae exhibited higher propulsive efficiency than adult squid during escape jet ejection, and propulsive efficiency was higher for escape jet I than escape jet II in juveniles and adults. These results indicate that although squid undergo major ecological transitions and morphology changes from paralarvae to adults, all life stages demonstrate flexibility in escape jet responses and produce escape jets of surprisingly high propulsive efficiency.This article has an associated First Person interview with the first author of the paper.
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Rosario, M. V., G. P. Sutton, S. N. Patek i G. S. Sawicki. "Muscle–spring dynamics in time-limited, elastic movements". Proceedings of the Royal Society B: Biological Sciences 283, nr 1838 (14.09.2016): 20161561. http://dx.doi.org/10.1098/rspb.2016.1561.
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Muscle contractions that load in-series springs with slow speed over a long duration do maximal work and store the most elastic energy. However, time constraints, such as those experienced during escape and predation behaviours, may prevent animals from achieving maximal force capacity from their muscles during spring-loading. Here, we ask whether animals that have limited time for elastic energy storage operate with springs that are tuned to submaximal force production. To answer this question, we used a dynamic model of a muscle–spring system undergoing a fixed-end contraction, with parameters from a time-limited spring-loader (bullfrog: Lithobates catesbeiana ) and a non-time-limited spring-loader (grasshopper: Schistocerca gregaria ). We found that when muscles have less time to contract, stored elastic energy is maximized with lower spring stiffness (quantified as spring constant). The spring stiffness measured in bullfrog tendons permitted less elastic energy storage than was predicted by a modelled, maximal muscle contraction. However, when muscle contractions were modelled using biologically relevant loading times for bullfrog jumps (50 ms), tendon stiffness actually maximized elastic energy storage. In contrast, grasshoppers, which are not time limited, exhibited spring stiffness that maximized elastic energy storage when modelled with a maximal muscle contraction. These findings demonstrate the significance of evolutionary variation in tendon and apodeme properties to realistic jumping contexts as well as the importance of considering the effect of muscle dynamics and behavioural constraints on energy storage in muscle–spring systems.
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Campbell, Diane R. "Early snowmelt projected to cause population decline in a subalpine plant". Proceedings of the National Academy of Sciences 116, nr 26 (10.06.2019): 12901–6. http://dx.doi.org/10.1073/pnas.1820096116.
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How climate change influences the dynamics of plant populations is not well understood, as few plant studies have measured responses of vital rates to climatic variables and modeled the impact on population growth. The present study used 25 y of demographic data to analyze how survival, growth, and fecundity respond to date of spring snowmelt for a subalpine plant. Fecundity was estimated by seed production (over 15 y) and also divided into flower number, fruit set, seeds per fruit, and escape from seed predation. Despite no apparent effects on flower number, plants produced more seeds in years with later snowmelt. Survival and probability of flowering were reduced by early snowmelt in the previous year. Based on demographic models, earlier snowmelt with warming is expected to lead to negative population growth, driven especially by changes in seedling establishment and seed production. These results provide a rare example of how climate change is expected to influence the dynamics of a plant population. They furthermore illustrate the potential for strong population impacts even in the absence of more commonly reported visual signs, such as earlier blooming or reduced floral display in early melting years.
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Abdul Manaf, Zati Iwani, i Mohd Hafiz Mohd. "Dynamical System Analysis of the Prey-predator Interactions involving Prey Refuge and Herd Behaviors in Preys". Malaysian Journal of Fundamental and Applied Sciences 18, nr 1 (28.02.2022): 105–15. http://dx.doi.org/10.11113/mjfas.v18n1.2415.
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By employing a prey refuge mechanism, more preys can be protected from predation. Prey species are also better protected from predation when they congregate in herds. However, what if the prey refuge and herd behavior mechanisms were combined in a system? To investigate this phenomenon, we consider two different prey-predator systems with prey refuge capacity. The first system is a simple prey-predator with prey refuge, whereas the second system considers prey refuge and prey herd behavior mechanisms. Using these models, we explore how different prey refuge strategies affect species interactions in both systems. To accomplish this, we use theoretical techniques (e.g., computing steady states and performing the stability analysis) and numerical bifurcation analysis to demonstrate various dynamical behaviors of these two prey-predator systems. Once prey refuge is treated as a bifurcation parameter, we observe the occurrence of supercritical Hopf and transcritical bifurcations in both systems. Furthermore, we explore the dynamic effects of prey refuge and predator handling time on species population interactions: our findings reveal that using both prey refuge and herd behavior as escape strategies; it is possible to dilute the predation pressure and ensure species biodiversity.
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Macale, Daniele, Massimiliano Scalici i Alberto Venchi. "Growth, mortality, and longevity of the Egyptian tortoise Testudo kleinmanni Lortet, 1883". Israel Journal of Ecology and Evolution 55, nr 2 (6.05.2009): 133–47. http://dx.doi.org/10.1560/ijee.55.2.133.
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Both demography and population regulation play an important role in the theory of sustainable exploitation and conservation of threatened taxa, such as terrestrial Chelonia. Here, we show and discuss some dynamic aspects of Testudo kleinmanni using modal progression analysis of length compositions. Although the Testudinata physiology is very different from that of fish, their growth model conforms to the Von Bertalanffy growth model. We observed a maximum of three age classes for both juveniles and females, and four classes for males. No appreciable between-sex differences were found in growth patterns, except for the diverse asymptotic length. Females should be subject to a strong sexual selection to quickly reach a large size in order to optimize lifetime reproductive output. The T. kleinmanni male size could be driven by predation escape and by easy accessibility to females, rather than by fighting for them. Thus, male reproductive success increases with the ability to fertilize females and female reproductive success increases with the ability to produce eggs, creating a large divergence in the context of selection between sexes. Different selective (synergetic or antagonistic) forces would appear to favor divergence in size between sexes. Additional properties found in the study regard the elevated mortality rate, probably also due to the human impact (poaching), and the relatively high longevity (26 and 22 years for females and males, respectively). Dynamics studies are useful for planning in situ activities of monitoring the population status, and could have a role in introducting programs and in control of reintroduced individuals during a restocking project.
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Ortega-Jimenez, Victor M., Ardian Jusufi, Christian E. Brown, Yu Zeng, Sunny Kumar, Robert Siddall, Baekgyeom Kim i in. "Air-to-land transitions: from wingless animals and plant seeds to shuttlecocks and bio-inspired robots". Bioinspiration & Biomimetics 18, nr 5 (8.08.2023): 051001. http://dx.doi.org/10.1088/1748-3190/acdb1c.
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Abstract Recent observations of wingless animals, including jumping nematodes, springtails, insects, and wingless vertebrates like geckos, snakes, and salamanders, have shown that their adaptations and body morphing are essential for rapid self-righting and controlled landing. These skills can reduce the risk of physical damage during collision, minimize recoil during landing, and allow for a quick escape response to minimize predation risk. The size, mass distribution, and speed of an animal determine its self-righting method, with larger animals depending on the conservation of angular momentum and smaller animals primarily using aerodynamic forces. Many animals falling through the air, from nematodes to salamanders, adopt a skydiving posture while descending. Similarly, plant seeds such as dandelions and samaras are able to turn upright in mid-air using aerodynamic forces and produce high decelerations. These aerial capabilities allow for a wide dispersal range, low-impact collisions, and effective landing and settling. Recently, small robots that can right themselves for controlled landings have been designed based on principles of aerial maneuvering in animals. Further research into the effects of unsteady flows on self-righting and landing in small arthropods, particularly those exhibiting explosive catapulting, could reveal how morphological features, flow dynamics, and physical mechanisms contribute to effective mid-air control. More broadly, studying apterygote (wingless insects) landing could also provide insight into the origin of insect flight. These research efforts have the potential to lead to the bio-inspired design of aerial micro-vehicles, sports projectiles, parachutes, and impulsive robots that can land upright in unsteady flow conditions.
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Schooley, Robert L., Peter B. Sharpe i Beatrice Van Horne. "Can shrub cover increase predation risk for a desert rodent?" Canadian Journal of Zoology 74, nr 1 (1.01.1996): 157–63. http://dx.doi.org/10.1139/z96-020.
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Previous research indicates that predation risk may influence activity patterns, habitat partitioning, and community structure of nocturnal desert rodents. Shrub microhabitat is typically considered safer than open microhabitat for these small mammals. We investigated predation risk for Townsend's ground squirrels (Spermophilus townsendii), which are diurnal desert rodents that detect predators visually and use burrows for refuge. Our results suggested that shrub cover may increase risk for these squirrels by decreasing their ability to escape from predators. Our field experiment indicated that running speeds of juvenile squirrels were lower in shrub (Ceratoides lanata) habitat than in open areas. Shrub cover was also associated with shorter predator-detection distances (mammalian and avian) and fewer refuges (burrow entrances per hectare) than in open areas in one year but not in another. Our study demonstrated that the visual and locomotive obstruction of vegetative cover may increase predation risk for diurnal desert rodents and that elements of habitat-dependent risk may be temporally dynamic.
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Khurana, Ekta, i J. S. Singh. "Ecology of seed and seedling growth for conservation and restoration of tropical dry forest : a review". Environmental Conservation 28, nr 1 (marzec 2001): 39–52. http://dx.doi.org/10.1017/s0376892901000042.
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Dry forests are among the most threatened ecosystems and have been extensively converted into grasslands, secondary forest, savanna or agricultural land. Knowledge of seed germination and seedling establishment is required for the success of efforts on restoration of these forests. This review focuses on the ecological requirements at seed and seedling stages, and collates the current knowledge of seed viability, dormancy, germination pattern and seedling behaviour of dry tropical tree species. The spatio-temporal variations within the tropical dry forest biome in soil moisture, light, temperature, nutrients and intensity of predation, significantly affect the seed and seedling traits of component species. The majority of dry tropical species possess orthodox seeds which are characterized by dormancy, while a few have recalcitrant seeds which possess little or no dormancy. Seed coat dormancy, which can be overcome by mechanical or acid scarification or sometimes by transit through animal guts, is most prevalent in the dry tropical forest species. Persistent species dominating the undisturbed portions of the forest have bigger seeds compared to those that mostly occur in disturbed regions and require shade for the survival of their seedlings. Shade demand is associated with drought endurance, and may be absolute in species such as Guettarda parviflora and Coccoloba microstachya, or facultative as in Plumeria alba and Bursera simaruba. The fluctuation in temperature significantly affects seed germination in several species of dry Afromontane forest trees of Ethiopia. Seedling mortality is primarily a function of moisture stress during the dry period. Adaptive responses of seedlings to drought stress include increased chlorophyll content, for example in Acacia catechu, and root biomass, as in several dry forest species (for example Drypetes parvifolia, Teclia verdoornia) of Ghana. Mulching, application of fertilizers, interplanting of leguminous species and mycorrhizal inoculation are useful tools for promoting seedling establishment in nutrient-poor dry tropical soils. Periodic forest fires, and predation affect recruitment and seedling development according to their intensity. Many species experiencing frequent fires have evolved thick seed coats, produce fire-hardy seedlings, or escape the effect by temporal separation of seed dispersal and fire events. Predation may result in abortion of fruits or may enhance germination and recruitment by scarification and dispersal, as in most species of the Guanacaste dry forest. Exposure to elevated CO2 has increased relative growth rate, total leaf area and water use efficiency in most of the dry tropical seedlings tested, but the magnitude of the effect has varied markedly among species. Due to the availability of a large source of energy, large seeds show higher germination percentage, greater seedling survival and increased growth. Seeds originating from different provenances exhibit differences in germination and seedling growth (for example Prosopis cineraria, Albizia lebbeck, Eucalyptus camaldulensis and Acacia mangium), efficiency of nodulation (for example Acacia nilotica, A. auriculiformis), and stress resistance (for example Populus deltoides, Dalbergia sissoo). The review points out the need for coordinated, long-term, field-based studies for identification of multiple cues and niches for germination, on seed and seedling dynamics in response to fire, and on within-species genetic variability for selection of suitable provenances. Field-based studies at species and community levels are also needed to permit manipulations of biotic components to augment the recruitment of desired species and to suppress that of undesirable species.
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Chen, Yuxin, i Theodore Kolokolnikov. "A minimal model of predator–swarm interactions". Journal of The Royal Society Interface 11, nr 94 (6.05.2014): 20131208. http://dx.doi.org/10.1098/rsif.2013.1208.
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We propose a minimal model of predator–swarm interactions which captures many of the essential dynamics observed in nature. Different outcomes are observed depending on the predator strength. For a ‘weak’ predator, the swarm is able to escape the predator completely. As the strength is increased, the predator is able to catch up with the swarm as a whole, but the individual prey is able to escape by ‘confusing’ the predator: the prey forms a ring with the predator at the centre. For higher predator strength, complex chasing dynamics are observed which can become chaotic. For even higher strength, the predator is able to successfully capture the prey. Our model is simple enough to be amenable to a full mathematical analysis, which is used to predict the shape of the swarm as well as the resulting predator–prey dynamics as a function of model parameters. We show that, as the predator strength is increased, there is a transition (owing to a Hopf bifurcation) from confusion state to chasing dynamics, and we compute the threshold analytically. Our analysis indicates that the swarming behaviour is not helpful in avoiding the predator, suggesting that there are other reasons why the species may swarm. The complex shape of the swarm in our model during the chasing dynamics is similar to the shape of a flock of sheep avoiding a shepherd.
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Jeon, Wonju, i Sang-Hee Lee. "Stochastic rules for predator and prey hunting and escape behavior in a lattice-based model". International Journal of Biomathematics 09, nr 06 (2.08.2016): 1650089. http://dx.doi.org/10.1142/s1793524516500893.
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Understanding of ecosystem resilience and stability requires comprehending predator–prey dynamics because ecosystems consist of dynamically interacting subsystems that include predator–prey relationships. This relationship is closely related to the hunting–escaping strategies employed by the predator and prey. Therefore, understanding the effects of hunting and escaping strategies on ecosystems will lead to a better understanding of these systems. As an approach for describing the predator–prey interaction, lattice-based models have been adopted because this approach has strong advantages for simulating various dynamical processes of individual–individual interaction. In the models, each lattice cell is either considered as an attractive/repulsive cell, or an individual cell, or else it is empty. The attractive (or repulsive cell) can be interpreted as the prey (or predator) of the individual. These states allow us to incorporate the ecological processes of local antagonistic interactions, namely the spread of disturbances (by the predator) and regrowth or recovery (by the prey). These processes are directly related to the strategic behavior of individuals, such as hunting and escaping. In this study, we suggest a simple and effective mapping formula as a stochastic rule to describe the hunting and escaping behavior. This formula could be widely used not only in the behavior but also in competitive and cooperative relationships.
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Villalba, Luis Alberto, Minoru Kasada, Luca Zoccarato, Sabine Wollrab i Hans Peter Grossart. "Differing Escape Responses of the Marine Bacterium Marinobacter adhaerens in the Presence of Planktonic vs. Surface-Associated Protist Grazers". International Journal of Molecular Sciences 23, nr 17 (3.09.2022): 10082. http://dx.doi.org/10.3390/ijms231710082.
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Protist grazing pressure plays a major role in controlling aquatic bacterial populations, affecting energy flow through the microbial loop and biogeochemical cycles. Predator-escape mechanisms might play a crucial role in energy flow through the microbial loop, but are yet understudied. For example, some bacteria can use planktonic as well as surface-associated habitats, providing a potential escape mechanism to habitat-specific grazers. We investigated the escape response of the marine bacterium Marinobacter adhaerens in the presence of either planktonic (nanoflagellate: Cafeteria roenbergensis) or surface-associated (amoeba: Vannella anglica) protist predators, following population dynamics over time. In the presence of V. anglica, M. adhaerens cell density increased in the water, but decreased on solid surfaces, indicating an escape response towards the planktonic habitat. In contrast, the planktonic predator C. roenbergensis induced bacterial escape to the surface habitat. While C. roenbergensis cell numbers dropped substantially after a sharp initial increase, V. anglica exhibited a slow, but constant growth throughout the entire experiment. In the presence of C. roenbergensis, M. adhaerens rapidly formed cell clumps in the water habitat, which likely prevented consumption of the planktonic M. adhaerens by the flagellate, resulting in a strong decline in the predator population. Our results indicate an active escape of M. adhaerens via phenotypic plasticity (i.e., behavioral and morphological changes) against predator ingestion. This study highlights the potentially important role of behavioral escape mechanisms for community composition and energy flow in pelagic environments, especially with globally rising particle loads in aquatic systems through human activities and extreme weather events.
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Bryce, Caleb M., Christopher C. Wilmers i Terrie M. Williams. "Energetics and evasion dynamics of large predators and prey: pumasvs.hounds". PeerJ 5 (17.08.2017): e3701. http://dx.doi.org/10.7717/peerj.3701.
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Quantification of fine-scale movement, performance, and energetics of hunting by large carnivores is critical for understanding the physiological underpinnings of trophic interactions. This is particularly challenging for wide-ranging terrestrial canid and felid predators, which can each affect ecosystem structure through distinct hunting modes. To compare free-ranging pursuit and escape performance from group-hunting and solitary predators in unprecedented detail, we calibrated and deployed accelerometer-GPS collars during predator-prey chase sequences using packs of hound dogs (Canis lupus familiaris, 26 kg,n = 4–5 per chase) pursuing simultaneously instrumented solitary pumas (Puma concolor, 60 kg,n = 2). We then reconstructed chase paths, speed and turning angle profiles, and energy demands for hounds and pumas to examine performance and physiological constraints associated with cursorial and cryptic hunting modes, respectively. Interaction dynamics revealed how pumas successfully utilized terrain (e.g., fleeing up steep, wooded hillsides) as well as evasive maneuvers (e.g., jumping into trees, running in figure-8 patterns) to increase their escape distance from the overall faster hounds (avg. 2.3× faster). These adaptive strategies were essential to evasion in light of the mean 1.6× higher mass-specific energetic costs of the chase for pumas compared to hounds (mean: 0.76vs.1.29 kJ kg−1 min−1, respectively). On an instantaneous basis, escapes were more costly for pumas, requiring exercise at ≥90% of predicted $\dot {\mathrm{V }}{\mathrm{O}}_{2\mathrm{MAX}}$ and consuming as much energy per minute as approximately 5 min of active hunting. Our results demonstrate the marked investment of energy for evasion by a large, solitary carnivore and the advantage of dynamic maneuvers to postpone being overtaken by group-hunting canids.
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Cho, Jung-Hee, i Sang-Hee Lee. "Effects of predator and prey hunting and escape strategies on ecosystem dynamics". Journal of the Korean Physical Society 64, nr 5 (marzec 2014): 746–54. http://dx.doi.org/10.3938/jkps.64.746.
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Lacubtan, Roger Joseph L., i Mark Nolan P. Confesor. "Robust method of trapping self-propelling particles". International Journal of Modern Physics: Conference Series 36 (styczeń 2015): 1560010. http://dx.doi.org/10.1142/s2010194515600101.
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The ability to collect self-propelling particles (SPP) is an essential requirement for possible use of SPP in technological applications. In this paper we proposed a novel way of trapping SPP's, through guided trapping of SPP's in V-shaped trap. We performed brownian dynamic simulation via a modified Escape and Predation model developed by L. Angelani (Phys. Rev. Lett., 2012) to assess the validity of the proposed trapping method.
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FURUICHI, NOZOMU. "Dynamics between a Predator and a Prey Switching Two Kinds of Escape Motions". Journal of Theoretical Biology 217, nr 2 (lipiec 2002): 159–66. http://dx.doi.org/10.1006/jtbi.2002.3027.
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Cooper, William E., i Wade C. Sherbrooke. "FEAR and DREAD: starting distance, escape decisions and time hiding in refuge". Behaviour 152, nr 10 (2015): 1371–89. http://dx.doi.org/10.1163/1568539x-00003283.
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Flight initiation distance (FID = predator–prey distance when escape begins) increases as starting distance (predator–prey distance when approach begins) increases. The flush early and avoid the rush (FEAR) hypothesis proposes that this relationship exists because monitoring an approach is costly. Hypothesized causes are increase in assessed risk and decrease in obtainable benefits while monitoring as starting distance increases. We propose the delay risking emergence and avoid dying (DREAD) hypothesis: hiding time in refuge increases as starting distance increases because prey use risk assessed during approach to estimate risk upon emerging. In the lizard Callisaurus draconoides, FID increased as standardized starting distance increased at faster approach speeds, supporting the FEAR hypothesis. In its first test, the DREAD hypothesis was supported: hiding time in the lizard Sceloporus virgatus increased as standardized starting distance increased. No large benefits were attainable, suggesting that dynamic increase in assessed risk accounts for these findings.
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PENG, J., i J. O. DABIRI. "Transport of inertial particles by Lagrangian coherent structures: application to predator–prey interaction in jellyfish feeding". Journal of Fluid Mechanics 623 (6.03.2009): 75–84. http://dx.doi.org/10.1017/s0022112008005089.
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We use a dynamical systems approach to identify coherent structures from often chaotic motions of inertial particles in open flows. We show that particle Lagrangian coherent structures (pLCS) act as boundaries between regions in which particles have different kinematics. They provide direct geometric information about the motion of ensembles of inertial particles, which is helpful to understand their transport. As an application, we apply the methodology to a planktonic predator–prey system in which moon jellyfish Aurelia aurita uses its body motion to generate a flow that transports small plankton such as copepods to its vicinity for feeding. With the flow field generated by the jellyfish measured experimentally and the dynamics of plankton described by a modified Maxey–Riley equation, we use the pLCS to identify a capture region in which prey can be captured by the jellyfish. The properties of the pLCS and the capture region enable analysis of the effect of several physiological and mechanical parameters on the predator–prey interaction, such as prey size, escape force, predator perception, etc. The methods developed here are equally applicable to multiphase and granular flows, and can be generalized to any other particle equation of motion, e.g. equations governing the motion of reacting particles or charged particles.
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Afolabi, Abdulkareem Ibrahim, i Normah Maan. "A Dual-Aggressive Model of Tumor-Immune System Interactions". International Journal of Online and Biomedical Engineering (iJOE) 15, nr 10 (27.06.2019): 155. http://dx.doi.org/10.3991/ijoe.v15i10.10877.
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<p class="0abstract">Biomedical literature suggested that the tumor-immune system physical phenomenon usually climaxes into either tumor elimination or escape. In retort to the phenomenological mechanics of tumor-immune system interaction, researchers had used Mathematical models mostly prey-predator and competitive extensively, to model the dynamics of tumor immune system interaction. However, these models had not accounted for total elimination and, or escape of tumor as hypothesizes by immunoediting hypotheses. In this work, we propose a dual aggressive model based on the biological narration of tumor-immune system interactions. The stability analyses of tumor-negative steady state are stable if the rate at which body cells dies is less than their proliferation rate a confirmation of biological listed causes of the tumor. The tumor-positive steady state is always unstable and saddle with the likelihood of either elimination or escape of tumor. Numerical analysis validates our analytical results and provides insight into the dynamics of the benignant and malignant tumor. The immunosuppression by tumor is not only visible but also validated by both analytical and numerical analysis.</p>
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Dulk, Paul den, Bram T. Heerebout i R. Hans Phaf. "A Computational Study into the Evolution of Dual-Route Dynamics for Affective Processing". Journal of Cognitive Neuroscience 15, nr 2 (1.02.2003): 194–208. http://dx.doi.org/10.1162/089892903321208132.
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The evolutionary justification by LeDoux (1996) for his dual-route model of fear processing was analyzed computationally by applying genetic algorithms to artificial neural networks. The evolution was simulated of a neural network controlling an agent that gathered food in an artificial world and that was occasionally menaced by a predator. Connections could not change in the agent's “lifetime,” so there was no learning in the simulations. Only if the smells of food and predator were hard to distinguish and the fitness reflected time pressures in escaping from the predator did the type of dual processing postulated by LeDoux emerge in the surviving agents. Processing in the “quick and dirty” pathway of the fear system ensured avoidance of both predators and food, but a distinction between food and predator was made only in the long pathway. Elaborate processing inhibited the avoidance reaction and reversed it into an approach reaction to food, but strengthened the avoidance reaction to predators (and more finely tuned the direction of escape). It is suggested that “computational neuroethology” (Beer, 1990) may help constrain reasoning in evolutionary psychology, particularly when applied to specific neurobiological models, and in the future may even generate new hypotheses for cognitive neuroscience.
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Mountcastle, Andrew M., Teressa M. Alexander, Callin M. Switzer i Stacey A. Combes. "Wing wear reduces bumblebee flight performance in a dynamic obstacle course". Biology Letters 12, nr 6 (czerwiec 2016): 20160294. http://dx.doi.org/10.1098/rsbl.2016.0294.
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Previous work has shown that wing wear increases mortality in bumblebees. Although a proximate mechanism for this phenomenon has remained elusive, a leading hypothesis is that wing wear increases predation risk by reducing flight manoeuvrability. We tested the effects of simulated wing wear on flight manoeuvrability in Bombus impatiens bumblebees using a dynamic obstacle course designed to push bees towards their performance limits. We found that removing 22% wing area from the tips of both forewings (symmetric wear) caused a 9% reduction in peak acceleration during manoeuvring flight, while performing the same manipulation on only one wing (asymmetric wear) did not significantly reduce maximum acceleration. The rate at which bees collided with obstacles was correlated with body length across all treatments, but wing wear did not increase collision rate, possibly because shorter wingspans allow more room for bees to manoeuvre. This study presents a novel method for exploring extreme flight manoeuvres in flying insects, eliciting peak accelerations that exceed those measured during flight through a stationary obstacle course. If escape from aerial predation is constrained by acceleration capacity, then our results offer a potential explanation for the observed increase in bumblebee mortality with wing wear.
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Wilson, John W., Michael G. L. Mills, Rory P. Wilson, Gerrit Peters, Margaret E. J. Mills, John R. Speakman, Sarah M. Durant, Nigel C. Bennett, Nikki J. Marks i Michael Scantlebury. "Cheetahs, Acinonyx jubatus , balance turn capacity with pace when chasing prey". Biology Letters 9, nr 5 (23.10.2013): 20130620. http://dx.doi.org/10.1098/rsbl.2013.0620.
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Predator–prey interactions are fundamental in the evolution and structure of ecological communities. Our understanding, however, of the strategies used in pursuit and evasion remains limited. Here, we report on the hunting dynamics of the world's fastest land animal, the cheetah, Acinonyx jubatus . Using miniaturized data loggers, we recorded fine-scale movement, speed and acceleration of free-ranging cheetahs to measure how hunting dynamics relate to chasing different sized prey. Cheetahs attained hunting speeds of up to 18.94 m s −1 and accelerated up to 7.5 m s −2 with greatest angular velocities achieved during the terminal phase of the hunt. The interplay between forward and lateral acceleration during chases showed that the total forces involved in speed changes and turning were approximately constant over time but varied with prey type. Thus, rather than a simple maximum speed chase, cheetahs first accelerate to decrease the distance to their prey, before reducing speed 5–8 s from the end of the hunt, so as to facilitate rapid turns to match prey escape tactics, varying the precise strategy according to prey species. Predator and prey thus pit a fine balance of speed against manoeuvring capability in a race for survival.
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van Zwieten, Paul A. M., Jeppe Kolding, Michael J. Plank, Robert E. Hecky, Thomas B. Bridgeman, Sally MacIntyre, Ole Seehausen i Greg M. Silsbe. "The Nile perch invasion in Lake Victoria: cause or consequence of the haplochromine decline?" Canadian Journal of Fisheries and Aquatic Sciences 73, nr 4 (kwiecień 2016): 622–43. http://dx.doi.org/10.1139/cjfas-2015-0130.
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We review alternative hypotheses and associated mechanisms to explain Lake Victoria’s Nile perch (Lates niloticus) takeover and concurrent reduction in haplochromines through a (re)analysis of long-term climate, limnological, and stock observations in comparison with size-spectrum model predictions of co-existence, extinction, and demographic change. The empirical observations are in agreement with the outcomes of the model containing two interacting species with life histories matching Nile perch and a generalized haplochromine. The dynamic interactions may have depended on size-related differences in early juvenile mortality: mouth-brooding haplochromines escape predation mortality in early life stages, unlike Nile perch, which have miniscule planktonic eggs and larvae. In our model, predation on the latter by planktivorous haplochromine fry acts as a stabilizing factor for co-existence, but external mortality on the haplochromines would disrupt this balance in favor of Nile perch. To explain the observed switch, mortality on haplochromines would need to be much higher than the fishing mortality that can be realistically reconstructed from observations. Abrupt concomitant changes in algal and zooplankton composition, decreased water column transparency, and widespread hypoxia from increased eutrophication most likely caused haplochromine biomass decline. We hypothesize that the shift to Nile perch was a consequence of an externally caused, climate-triggered decrease in haplochromine biomass and associated recruitment failure rather than a direct cause of the introduction.
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Théry, Marc, i Jérôme Casas. "The multiple disguises of spiders: web colour and decorations, body colour and movement". Philosophical Transactions of the Royal Society B: Biological Sciences 364, nr 1516 (6.11.2008): 471–80. http://dx.doi.org/10.1098/rstb.2008.0212.
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Diverse functions have been assigned to the visual appearance of webs, spiders and web decorations, including prey attraction, predator deterrence and camouflage. Here, we review the pertinent literature, focusing on potential camouflage and mimicry. Webs are often difficult to detect in a heterogeneous visual environment. Static and dynamic web distortions are used to escape visual detection by prey, although particular silk may also attract prey. Recent work using physiological models of vision taking into account visual environments rarely supports the hypothesis of spider camouflage by decorations, but most often the prey attraction and predator confusion hypotheses. Similarly, visual modelling shows that spider coloration is effective in attracting prey but not in conveying camouflage. Camouflage through colour change might be used by particular crab spiders to hide from predator or prey on flowers of different coloration. However, results obtained on a non-cryptic crab spider suggest that an alternative function of pigmentation may be to avoid UV photodamage through the transparent cuticle. Numerous species are clearly efficient locomotory mimics of ants, particularly in the eyes of their predators. We close our paper by highlighting gaps in our knowledge.
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Schwaner, M. Janneke, Grace A. Freymiller, Rulon W. Clark i Craig P. McGowan. "How to Stick the Landing: Kangaroo Rats Use Their Tails to Reorient during Evasive Jumps Away from Predators". Integrative and Comparative Biology 61, nr 2 (3.05.2021): 442–54. http://dx.doi.org/10.1093/icb/icab043.
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Synopsis Tails are widespread in the animal world and play important roles in locomotor tasks, such as propulsion, maneuvering, stability, and manipulation of objects. Kangaroo rats, bipedal hopping rodents, use their tail for balancing during hopping, but the role of their tail during the vertical evasive escape jumps they perform when attacked by predators is yet to be determined. Because we observed kangaroo rats swinging their tails around their bodies while airborne following escape jumps, we hypothesized that kangaroo rats use their tails to not only stabilize their bodies while airborne, but also to perform aerial re-orientations. We collected video data from free-ranging desert kangaroo rats (Dipodomys deserti) performing escape jumps in response to a simulated predator attack and analyzed the rotation of their bodies and tails in the yaw plane (about the vertical-axis). Kangaroo rat escape responses were highly variable. The magnitude of body re-orientation in yaw was independent of jump height, jump distance, and aerial time. Kangaroo rats exhibited a stepwise re-orientation while airborne, in which slower turning periods corresponded with the tail center of mass being aligned close to the vertical rotation axis of the body. To examine the effect of tail motion on body re-orientation during a jump, we compared average rate of change in angular momentum. Rate of change in tail angular momentum was nearly proportional to that of the body, indicating that the tail reorients the body in the yaw plane during aerial escape leaps by kangaroo rats. Although kangaroo rats make dynamic 3D movements during their escape leaps, our data suggest that kangaroo rats use their tails to control orientation in the yaw plane. Additionally, we show that kangaroo rats rarely use their tail length at full potential in yaw, suggesting the importance of tail movement through multiple planes simultaneously.
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Firestone, C. Z., i W. H. Warren. "Why does the rabbit escape the fox on a zig-zag path? Predator-prey dynamics and the constant bearing strategy". Journal of Vision 10, nr 7 (13.08.2010): 1049. http://dx.doi.org/10.1167/10.7.1049.
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Liu, Baisen, Liangliang Wang i Jiguo Cao. "Bayesian estimation of ordinary differential equation models when the likelihood has multiple local modes". Monte Carlo Methods and Applications 24, nr 2 (1.06.2018): 117–27. http://dx.doi.org/10.1515/mcma-2018-0010.
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Abstract Ordinary differential equations (ODEs) are popularly used to model complex dynamic systems by scientists; however, the parameters in ODE models are often unknown and have to be inferred from noisy measurements of the dynamic system. One conventional method is to maximize the likelihood function, but the likelihood function often has many local modes due to the complexity of ODEs, which makes the optimizing algorithm be vulnerable to trap in local modes. In this paper, we solve the global optimization issue of ODE parameters with the help of the Stochastic Approximation Monte Carlo (SAMC) algorithm which is shown to be self-adjusted and escape efficiently from the “local-trapping” problem. Our simulation studies indicate that the SAMC method is a powerful tool to estimate ODE parameters globally. The efficiency of SAMC method is demonstrated by estimating a predator-prey ODEs model from real experimental data.
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Casas, Jérôme, i Thomas Steinmann. "Predator-induced flow disturbances alert prey, from the onset of an attack". Proceedings of the Royal Society B: Biological Sciences 281, nr 1790 (7.09.2014): 20141083. http://dx.doi.org/10.1098/rspb.2014.1083.
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Many prey species, from soil arthropods to fish, perceive the approach of predators, allowing them to escape just in time. Thus, prey capture is as important to predators as prey finding. We extend an existing framework for understanding the conjoint trajectories of predator and prey after encounters, by estimating the ratio of predator attack and prey danger perception distances, and apply it to wolf spiders attacking wood crickets. Disturbances to air flow upstream from running spiders, which are sensed by crickets, were assessed by computational fluid dynamics with the finite-elements method for a much simplified spider model: body size, speed and ground effect were all required to obtain a faithful representation of the aerodynamic signature of the spider, with the legs making only a minor contribution. The relationship between attack speed and the maximal distance at which the cricket can perceive the danger is parabolic; it splits the space defined by these two variables into regions differing in their values for this ratio. For this biological interaction, the ratio is no greater than one, implying immediate perception of the danger, from the onset of attack. Particular attention should be paid to the ecomechanical aspects of interactions with such small ratio, because of the high degree of bidirectional coupling of the behaviour of the two protagonists. This conclusion applies to several other predator–prey systems with sensory ecologies based on flow sensing, in air and water.
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Jakobsen, Lasse, Mads Nedergaard Olsen i Annemarie Surlykke. "Dynamics of the echolocation beam during prey pursuit in aerial hawking bats". Proceedings of the National Academy of Sciences 112, nr 26 (15.06.2015): 8118–23. http://dx.doi.org/10.1073/pnas.1419943112.
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In the evolutionary arms race between prey and predator, measures and countermeasures continuously evolve to increase survival on both sides. Bats and moths are prime examples. When exposed to intense ultrasound, eared moths perform dramatic escape behaviors. Vespertilionid and rhinolophid bats broaden their echolocation beam in the final stage of pursuit, presumably as a countermeasure to keep evading moths within their “acoustic field of view.” In this study, we investigated if dynamic beam broadening is a general property of echolocation when catching moving prey. We recorded three species of emballonurid bats, Saccopteryx bilineata, Saccopteryx leptura, and Rhynchonycteris naso, catching airborne insects in the field. The study shows that S. bilineata and S. leptura maintain a constant beam shape during the entire prey pursuit, whereas R. naso broadens the beam by lowering the peak call frequency from 100 kHz during search and approach to 67 kHz in the buzz. Surprisingly, both Saccopteryx bats emit calls with very high energy throughout the pursuit, up to 60 times more than R. naso and Myotis daubentonii (a similar sized vespertilionid), providing them with as much, or more, peripheral “vision” than the vespertilionids, but ensonifying objects far ahead suggesting more clutter. Thus, beam broadening is not a fundamental property of the echolocation system. However, based on the results, we hypothesize that increased peripheral detection is crucial to all aerial hawking bats in the final stages of prey pursuit and speculate that beam broadening is a feature characterizing more advanced echolocation.
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Mansano, AS, KF Hisatugo, MA Leite, AP Luzia i MH Regali-Seleghim. "Seasonal variation of the protozooplanktonic community in a tropical oligotrophic environment (Ilha Solteira reservoir, Brazil)". Brazilian Journal of Biology 73, nr 2 (maj 2013): 321–30. http://dx.doi.org/10.1590/s1519-69842013000200012.
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The seasonal variation of the protozooplanktonic community (ciliates and testate amoebae) was studied in a tropical oligotrophic reservoir in Brazil, which was under the influence of two contrasting climatic seasons (rainy/warm and dry/cold). The aim of this study was to evaluate the effect of these climatic changes on physical, chemical and biological variables in the dynamic of this community. The highest mean density of total protozoans occurred in the rainy/warm season (5683.2 ind L−1), while the lowest was in the dry/cold (2016.0 ind L−1). Considering the seasonal variations, the protozoan groups that are truly planktonic, such as the oligotrichs (Spirotrichea), predominated in the dry season, whereas during the rainy season, due to the material input and resuspension of sediment, sessile protozoans of the Peritrichia group were the most important ones. The dominant protozoans were Urotricha globosa, Cothurnia annulata, Pseudodifflugia sp. and Halteria grandinella. The highest densities of H. grandinella were associated with more oxygenated and transparent water conditions, while the highest densities of C. annulata occurred in sites with high turbidity, pH and trophic state index (TSI). The study demonstrated that density and composition of protozooplanktonic species and groups of the reservoir suffered seasonal variation due to the environmental variables (mainly temperature, turbidity, water transparency, dissolved oxygen and TSI) and the biological variables (e.g. morphological characteristics, eating habits and escape strategies from predation of the species).
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Pertzelan, Assaf, Gil Ariel i Moshe Kiflawi. "Schooling of light reflecting fish". PLOS ONE 18, nr 7 (21.07.2023): e0289026. http://dx.doi.org/10.1371/journal.pone.0289026.
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One of the hallmarks of the collective movement of large schools of pelagic fish are waves of shimmering flashes that propagate across the school, usually following an attack by a predator. Such flashes arise when sunlight is reflected off the specular (mirror-like) skin that characterizes many pelagic fishes, where it is otherwise thought to offer a means for camouflage in open waters. While it has been suggested that these ‘shimmering waves’ are a visual manifestation of the synchronized escape response of the fish, the phenomenon has been regarded only as an artifact of esthetic curiosity. In this study we apply agent-based simulations and deep learning techniques to show that, in fact, shimmering waves contain information on the behavioral dynamics of the school. Our analyses are based on a model that combines basic rules of collective motion and the propagation of light beams in the ocean, as they hit and reflect off the moving fish. We use the resulting reflection patterns to infer the essential dynamics and inter-individual interactions which are necessary to generate shimmering waves. Moreover, we show that light flashes observed by the school members themselves may extend the range at which information can be communicated across the school. Assuming that fish pay heed to this information, for example by entering an apprehensive state of reduced response-time, our analysis suggests that it can speed up the propagation of information across the school. Further still, we use an artificial neural network to show that light flashes are, on their own, indicative of the state and dynamics of the school, and are sufficient to infer the direction of attack and the shape of the school with high accuracy.
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Ferreira, Mariana Silva, Maja Kajin, Rui Cerqueira i Marcus Vinícius Vieira. "Marsupial population dynamics in a tropical rainforest: intraspecific competition and nonlinear effect of rainfall". Journal of Mammalogy 97, nr 1 (20.10.2015): 121–27. http://dx.doi.org/10.1093/jmammal/gyv161.
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Abstract Population fluctuations are the result of the combined action of endogenous (feedback structure) and exogenous factors (large- and local-scale climate variables). In this paper, we used a 13-year time series to identify the feedback structure in a population of the brown 4-eyed opossum Metachirus nudicaudatus and to test a hypothesis on the effects of El Niño Southern Oscillation and rainfall using Royama’s theoretical framework. Metachirus nudicaudatus was regulated by a strong 1st-order negative feedback, with intraspecific competition for food resources as the probable factor governing the endogenous system. Contrary to our expectations, El Niño did not explain the marsupial dynamics better than 1-year lagged rainfall, that may operate in 2 different manners: as a nonlinear perturbation effect influencing the strength of density dependence (intraspecific competition and intraguild predation) or as a lateral perturbation effect influencing the carrying capacity of the environment. As flutuações populacionais são resultado da ação conjunta de fatores endógenos (estrutura de retroalimentação) e exógenos (variáveis climáticas locais e de larga escala). A partir de uma série temporal de 13 anos, nós identificamos a estrutura de retroalimentação da população da cuíca marrom de quatro olhos Metachirus nudicaudatus , e testamos hipóteses a respeito dos efeitos do El Niño Oscilação Sul e chuva utilizando a abordagem teórica de Royama. Metachirus nudicaudatus é regulado por uma forte retroalimentação negativa de primeira ordem, com a competição intraespecífica por recursos alimentares como o provável fator que rege o sistema endógeno. Ao contrário do que esperávamos, o El Niño não explicou a dinâmica populacional deste marsupial melhor do que a chuva com a defasagem de 1 ano, que pode atuar em duas formas: como um efeito de perturbação não-linear, influenciando a força da dependência densidade (competição intraespecífica e predação intraguilda), ou como um efeito de perturbação lateral, influenciando a capacidade de suporte do ambiente.
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Bockhorst, Tobias, i Uwe Homberg. "Interaction of compass sensing and object-motion detection in the locust central complex". Journal of Neurophysiology 118, nr 1 (1.07.2017): 496–506. http://dx.doi.org/10.1152/jn.00927.2016.
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Goal-directed behavior is often complicated by unpredictable events, such as the appearance of a predator during directed locomotion. This situation requires adaptive responses like evasive maneuvers followed by subsequent reorientation and course correction. Here we study the possible neural underpinnings of such a situation in an insect, the desert locust. As in other insects, its sense of spatial orientation strongly relies on the central complex, a group of midline brain neuropils. The central complex houses sky compass cells that signal the polarization plane of skylight and thus indicate the animal’s steering direction relative to the sun. Most of these cells additionally respond to small moving objects that drive fast sensory-motor circuits for escape. Here we investigate how the presentation of a moving object influences activity of the neurons during compass signaling. Cells responded in one of two ways: in some neurons, responses to the moving object were simply added to the compass response that had adapted during continuous stimulation by stationary polarized light. By contrast, other neurons disadapted, i.e., regained their full compass response to polarized light, when a moving object was presented. We propose that the latter case could help to prepare for reorientation of the animal after escape. A neuronal network based on central-complex architecture can explain both responses by slight changes in the dynamics and amplitudes of adaptation to polarized light in CL columnar input neurons of the system. NEW & NOTEWORTHY Neurons of the central complex in several insects signal compass directions through sensitivity to the sky polarization pattern. In locusts, these neurons also respond to moving objects. We show here that during polarized-light presentation, responses to moving objects override their compass signaling or restore adapted inhibitory as well as excitatory compass responses. A network model is presented to explain the variations of these responses that likely serve to redirect flight or walking following evasive maneuvers.
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Lu, Hong-Liang, Xiang Ji i Wei-Guo Du. "Tail loss reduces locomotor ability but not metabolic rate in a viviparous skink, Sphenomorphus indicus". Animal Biology 63, nr 3 (2013): 369–80. http://dx.doi.org/10.1163/15707563-00002419.
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Tail autotomy is an efficient predator escape form, but imposes locomotor costs in many lizard species. It has been hypothesized that locomotor impairment following tail autotomy results from the altered running dynamics or loss of energy available for locomotion, but there is a paucity of data available to demonstrate such effects. We evaluated the locomotor costs of tail loss in a viviparous skink, Sphenomorphus indicus, and examined whether locomotor costs were related to changes in gait characteristics and metabolic rate. Of 24 field-captured adult males with original intact tails, 12 individuals were used as experimental animals, and the remaining 12 as controls. Locomotor performance and CO2 production were measured for the experimental skinks before and after tail removal; the same parameters were measured at the same time for the control skinks. Compared with tailed skinks, the mean locomotor speed and stamina of tailless skinks was reduced by approximately 26% and 17%, respectively. At any given speed, tailless skinks had a shorter stride length for hindlimbs (but not for forelimbs) and a greater stride frequency than did tailed skinks. In S. indicus, locomotor impairment may be a result of the reduced stride length, and energetic constraints on stride frequency. We found no significant change in standard metabolic rate after the skinks underwent tail removal, which may reflect a minor effect on energy expenditure for maintenance. Although the reduction in metabolically active tissue might cause a lower metabolic rate, tail regeneration counteracted such an effect because it was energetically expensive.
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de la Cruz Barron, Magali, Ellen van Velzen, Uli Klümper, Markus Weitere, Thomas U. Berendonk i David Kneis. "Shifts from cooperative to individual-based predation defense determine microbial predator-prey dynamics". ISME Journal, 28.02.2023. http://dx.doi.org/10.1038/s41396-023-01381-5.
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AbstractPredation defense is an important feature of predator-prey interactions adding complexity to ecosystem dynamics. Prey organisms have developed various strategies to escape predation which differ in mode (elude vs. attack), reversibility (inducible vs. permanent), and scope (individual vs. cooperative defenses). While the mechanisms and controls of many singular defenses are well understood, important ecological and evolutionary facets impacting long-term predator-prey dynamics remain underexplored. This pertains especially to trade-offs and interactions between alternative defenses occurring in prey populations evolving under predation pressure. Here, we explored the dynamics of a microbial predator-prey system consisting of bacterivorous flagellates (Poteriospumella lacustris) feeding on Pseudomonas putida. Within five weeks of co-cultivation corresponding to about 35 predator generations, we observed a consistent succession of bacterial defenses in all replicates (n = 16). Initially, bacteria expressed a highly effective cooperative defense based on toxic metabolites, which brought predators close to extinction. This initial strategy, however, was consistently superseded by a second mechanism of predation defense emerging via de novo mutations. Combining experiments with mathematical modeling, we demonstrate how this succession of defenses is driven by the maximization of individual rather than population benefits, highlighting the role of rapid evolution in the breakdown of social cooperation.
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Kaushik, Rajat, i Sandip Banerjee. "Predator–Prey System: Bachelor Herding of the Prey Imposes Ecological Constraints on Predation". International Journal of Bifurcation and Chaos 31, nr 14 (listopad 2021). http://dx.doi.org/10.1142/s0218127421502114.
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Bachelor herd behavior is very common among juvenile animals who have not become sexually matured but have left their parent groups. The complex grouping or schooling behavior provides vulnerable juveniles refuge from predation and opportunities for foraging, especially when their parents are not within the area to protect them. In spite of this, juvenile/immature prey may easily become victims because of their greenness while on the other hand, adult prey may be invulnerable to attack due to their tricky manoeuvring abilities to escape from the predators. In this study, we propose a stage-structured predator–prey model, in which predators attack only the bachelor herds of juvenile prey while adult prey save themselves due to small predator–prey size ratio and their fleeing capability, enabling them to avoid confrontation with the predators. Local and global stability analysis on the equilibrium points of the model are performed. Sufficient conditions for uniform permanence and the impermanence are derived. The model exhibits both transcritical as well as Hopf bifurcations and the corresponding numerical simulations are carried out to support the analytical results. Bachelor herding of juvenile prey as well as inaccessibility of adult prey restricts the uncontrolled predation so that prey abundance and predation remain balanced. This investigation on bachelor group defence brings out some unpredictable results, especially close to the zero steady state. Altogether, bachelor herding of the juvenile prey, which causes unconventional behavior near the origin, plays a significant role in establishing uniform permanence conditions, also increases richness of the dynamics in numerical simulations using the bifurcation theory and thereby, shapes ecosystem properties tremendously and may have a large influence on the ecosystem functioning.
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Bogdziewicz, Michał, Dries Kuijper, Rafał Zwolak, Marcin Churski, Bogumiła Jędrzejewska, Emilia Wysocka-Fijorek, Anna Gazda, Stanisław Miścicki i Tomasz Podgórski. "Emerging infectious disease triggered a trophic cascade and enhanced recruitment of a masting tree". Proceedings of the Royal Society B: Biological Sciences 289, nr 1970 (2.03.2022). http://dx.doi.org/10.1098/rspb.2021.2636.
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There are several mechanisms that allow plants to temporarily escape from top-down control. One of them is trophic cascades triggered by top predators or pathogens. Another is satiation of consumers by mast seeding. These two mechanisms have traditionally been studied in separation. However, their combined action may have a greater effect on plant release than either process alone. In 2015, an outbreak of a disease (African swine fever, ASF) caused a crash in wild boar ( Sus scrofa ) abundance in Białowieża Primeval Forest. Wild boar are important consumers of acorns and are difficult to satiate relative to less mobile granivores. We hypothesized that the joint action of the ASF outbreak and masting would enhance regeneration of oaks ( Quercus robur ). Data from ungulate exclosures demonstrated that ASF led to reduction in acorn predation. Tree seedling data indicated that oak recruitment increased twofold relative to pre-epidemic period. Our results showed that perturbations caused by wildlife disease travel through food webs and influence forest dynamics. The outbreak of ASF acted synergistically with masting and removed herbivore top-down control of oaks by mobile consumers. This illustrates that the ASF epidemic that currently occurs across Europe can have broad effects on forest dynamics.
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Hargreaves, Katherine R., Cesar O. Flores, Trevor D. Lawley i Martha R. J. Clokie. "Abundant and Diverse Clustered Regularly Interspaced Short Palindromic Repeat Spacers in Clostridium difficile Strains and Prophages Target Multiple Phage Types within This Pathogen". mBio 5, nr 5 (26.08.2014). http://dx.doi.org/10.1128/mbio.01045-13.
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ABSTRACT Clostridium difficile is an important human-pathogenic bacterium causing antibiotic-associated nosocomial infections worldwide. Mobile genetic elements and bacteriophages have helped shape C. difficile genome evolution. In many bacteria, phage infection may be controlled by a form of bacterial immunity called the clustered regularly interspaced short palindromic repeats/CRISPR-associated (CRISPR/Cas) system. This uses acquired short nucleotide sequences (spacers) to target homologous sequences (protospacers) in phage genomes. C. difficile carries multiple CRISPR arrays, and in this paper we examine the relationships between the host- and phage-carried elements of the system. We detected multiple matches between spacers and regions in 31 C. difficile phage and prophage genomes. A subset of the spacers was located in prophage-carried CRISPR arrays. The CRISPR spacer profiles generated suggest that related phages would have similar host ranges. Furthermore, we show that C. difficile strains of the same ribotype could either have similar or divergent CRISPR contents. Both synonymous and nonsynonymous mutations in the protospacer sequences were identified, as well as differences in the protospacer adjacent motif (PAM), which could explain how phages escape this system. This paper illustrates how the distribution and diversity of CRISPR spacers in C. difficile, and its prophages, could modulate phage predation for this pathogen and impact upon its evolution and pathogenicity. IMPORTANCE Clostridium difficile is a significant bacterial human pathogen which undergoes continual genome evolution, resulting in the emergence of new virulent strains. Phages are major facilitators of genome evolution in other bacterial species, and we use sequence analysis-based approaches in order to examine whether the CRISPR/Cas system could control these interactions across divergent C. difficile strains. The presence of spacer sequences in prophages that are homologous to phage genomes raises an extra level of complexity in this predator-prey microbial system. Our results demonstrate that the impact of phage infection in this system is widespread and that the CRISPR/Cas system is likely to be an important aspect of the evolutionary dynamics in C. difficile .
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Sheldon, Elizabeth L., Benjamin Feit, Anna Feit i Mike Letnic. "Negative frequency dependent prey selection by two canid predators and its implications for the conservation of a threatened rodent in arid Australia". Biodiversity and Conservation, 13.03.2023. http://dx.doi.org/10.1007/s10531-023-02570-6.
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AbstractUnprecedented anthropogenic changes to biodiversity and biogeography demand a greater understanding of the consequences of altered faunal composition for ecosystem functioning. Selective predation has important, yet poorly understood effects on ecosystem stability, and can be strongly influenced by the relative frequencies of different prey types in the environment. Yet, how predators adjust their selection for prey according to their environmental frequency is often overlooked. Here, we assessed frequency dependent selection of prey by dingoes and foxes in the Australian desert, biannually, across a nine-year period (2007–2016). Both predators exhibited potentially destabilizing, negative frequency dependent selection for prey. Foxes persisted to preferentially consume a threatened, native rodent (Notomys fuscus) when it was environmentally scarce. Bolstered by the observation that N.fuscus occurs at low densities in areas where foxes are common, our results suggest that N.fuscus is particularly vulnerable to predation by this predator; possibly because it is naïve and/or lacks adaptations to avoid or escape predation by the relatively recently introduced fox. Dingoes tended to consume reptiles when they were scarce; potentially constituting a conservation concern if selected reptilian taxa are threatened. Foxes avoided, thus were unlikely to control populations of overabundant kangaroos, while both foxes and dingoes showed a preference for, and may therefore control populations of invasive rabbits. The integration of our results into the relative suites of (de)stabilizing influences exerted by dingoes and foxes is important to provide a more dynamic insight into how each predator impacts their naturally fluctuating ecosystems.