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1
Sun, Jing. "Prey." Thesis, California State University, Los Angeles, 2018. http://pqdtopen.proquest.com/#viewpdf?dispub=10787932.
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The primary purpose of my research is to visually represent what can be regarded as a traditional Chinese thinking system and artistic style. This is to gain a deeper understanding of typical problem-solving processes of the Chinese culture. Through this research, I intend to encourage a bridge of communication between American and other cultures. It is my intent to help analyze problem-solving traditions in Chinese culture, and present a narrative that dramatizes this. The goal of this thesis; therefore, is to give a path of connection and appreciation for those not familiar, to a deeper understanding of contextualized Chinese beliefs. My process is aimed at constructing an effective narrative that illustrates the way a society creates change, in order to reflect broader cultural exchange and communication. The inspiration to undertake this study came from my three years’ of living in Los Angeles. Being suddenly transplanted into American culture made me critically review my own cultural beliefs. I often experienced cases of “misunderstandings” or “conflicts”. I perceived issues that were often embedded in the different ways that various cultures viewed and dealt with similar problems. There were, of course, differences in problem solving strategies, alongside differences in aesthetics, and perception. Consequently, based on these observations, I began to analyze how contrasting viewpoints and strategies could be translated into an animated narrative, and I wondered how I could effectively achieve this. Through this process, I addressed problems or crisis within various types of political systems. Can the methodology one uses to solve a problem be seen as systematic of the process of their own culture, even though the end goals and difficulties faced may be similar throughout various cultures? To critically analyze this question, I combined narrative animation and graphic watercolor renderings that visually parallel my personal experience of what could be defined as exemplary of traditional Chinese thought. An animated film resulted from this process, along with further research aimed at stimulating the public to appreciate the underlying approaches in both traditional Chinese aesthetics and culture. With this research, I intend to stimulate positive connections and appreciation between all cultures—a sentiment that extends to having increased inter-cultural communication and exchanges.
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Martin, Annik. "Predator-prey models with delays and prey harvesting." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape9/PQDD_0016/MQ49407.pdf.
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Quinones, Paige Valentine. "The Best Prey." The Ohio State University, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=osu1461176139.
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Kirkland, Shauna. "Birds of Prey." VCU Scholars Compass, 2013. http://scholarscompass.vcu.edu/etd/3019.
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As a child growing up, I was always in love with the ritual of “dress up”. Whether it was my dolls, various reluctant pets, or myself, it was always an activity I loved. It is not surprising then that adornment has become the medium through which I express myself and bring my fantasy world to life. Jewelry and accessory have the potential to lead many lives. One particular piece can change entirely by putting it on one body as opposed to another, or by removing it to see it as an object. In fashion, the body is the canvas and the runway becomes the moment of performance. My work uses the body in much the same way where the wearer becomes performer. Through this act, we construct personal forms of armor, or “power suits”, to face the battlefield of the outside world. In harnessing this act of adorning and what it encompasses, I am consistently challenged as both designer and maker. Creating alter egos, whether subtly flirtatious or overtly sexual, demure or flamboyant, are some of the many ways in which these “power suits” can be concocted. The stories we project about ourselves daily, through how we adorn our naked bodies, become empowering. Myths versus reality, ascetic versus sensual, and beautiful versus ugly are some of the concepts from which I draw inspiration. These dualities are conceptually expressed in my work through physical combinations of opposing materials. Mixing mediums, through methods such as collaging, beading, needlepointing, knitting, and sewing, are integral in my designs. With alternative materials, such as feathers, textiles, and yarns, I add softness and new scintillating sensations when juxtaposed with the hard, cold qualities of metal. Through combining such materials, I construct pieces that not only challenge one’s notion of what “pretty” is, but also inspire the way one thinks about body adornment. The objects I create become vessels that actualize the dualities I strive to express. In producing hybrids of materials, my need to explore these dichotomies is satisfied.
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Miner, Jeffrey G. "Turbidity-mediated predator-prey interactions among piscivores, prey fishes, and zooplankton /." The Ohio State University, 1990. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487685204970099.
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Rosner, Tammy Dee. "Spatial predator-prey dynamics, the effect of prey movement and environmental heterogeneity." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp01/MQ38608.pdf.
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Kato, Motomi. "Effects of enrichment on one-predator-two-prey systems with different prey profitability." 京都大学 (Kyoto University), 2001. http://hdl.handle.net/2433/86465.
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Lindström, Torsten. "Predator-prey systems and applications." Licentiate thesis, Luleå tekniska universitet, 1991. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-25928.
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Liu, Shouzong. "AGE-STRUCTURED PREDATOR-PREY MODELS." OpenSIUC, 2018. https://opensiuc.lib.siu.edu/dissertations/1577.
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In this thesis, we study the population dynamics of predator-prey interactions described by mathematical models with age/stage structures. We first consider fixed development times for predators and prey and develop a stage-structured predator-prey model with Holling type II functional response. The analysis shows that the threshold dynamics holds. That is, the predator-extinction equilibrium is globally stable if the net reproductive number of the predator $\mathcal{R}_0$ is less than $1$, while the predator population persists if $\mathcal{R}_0$ is greater than $1$. Numerical simulations are carried out to demonstrate and extend our theoretical results. A general maturation function for predators is then assumed, and an age-structured predator-prey model with no age structure for prey is formulated. Conditions for the existence and local stabilities of equilibria are obtained. The global stability of the predator-extinction equilibrium is proved by constructing a Lyapunov functional. Finally, we consider a special case of the maturation function discussed before. More specifically, we assume that the development times of predators follow a shifted Gamma distribution and then transfer the previous model into a system of differential-integral equations. We consider the existence and local stabilities of equilibria. Conditions for existence of Hopf bifurcation are given when the shape parameters of Gamma distributions are $1$ and $2$.
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Reif, V. (Vitali). "Birds of prey and grouse in Finland:do avian predators limit or regulate their prey numbers?" Doctoral thesis, University of Oulu, 2008. http://urn.fi/urn:isbn:9789514288050.
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Relationships between predators and prey may affect population dynamics of both parties. Predators may also serve as a link between populations of different prey, e.g., small game and small mammals. I used available data on the diet and reproduction of birds of prey (mainly common buzzards Buteo buteo and goshawks Accipiter gentilis) and video surveillance of their nests, as well as multiannual data on numbers of grouse and small mammals for studying food habits and population dynamics of raptors and their links with population fluctuations of voles and grouse (capercaillie Tetrao urogallus, black grouse Tetrao tetrix and hazel grouse Bonasa bonasia) in western Finland during 1980–1990s when grouse and vole numbers fluctuated in regular cycles.
Microtus voles were the main prey of the buzzards which partly switched their diet to small game (juvenile grouse and hares) in years when vole numbers declined. The nesting rate of buzzards also correlated with vole abundance, but the productivity rate and brood size tended to lag behind the vole cycle. This mismatch between the buzzards' functional and numerical responses resulted in a fairly small impact of buzzards on juvenile grouse, which did not correlate with vole density. The productivity of goshawks followed the fluctuations of grouse density closely whereas the occupancy rate of goshawk territories did so with a two-year lag. The annual numerical ratio of goshawk to grouse was inversely related to grouse density, suggesting that this predator may be a destabilising factor for grouse population dynamics. However, the goshawks' kill rate of grouse showed no clear relations to grouse density. In June–July, these birds of prey (including hen harriers Circus cyaneus) usually killed a relatively small number of grouse chicks. Losses to raptors constituted up to one quarter of grouse juvenile mortality during the two months. We did not find a strong effect of avian predators on grouse juvenile mortality. In boreal forests, predators and other factors of grouse mortality do not operate as one, and there is probably no single factor responsible for the reproductive success of grouse.
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Clements, Hayley Susan. "Incorporating prey demographics and predator social structure into prey selection and carrying capacity estimates for cheetah." Thesis, Nelson Mandela Metropolitan University, 2012. http://hdl.handle.net/10948/d1018606.
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There is a need for a refined understanding of large carnivore prey preference and carrying capacity (K). To date, K estimates for large carnivores have been developed from predictions of carnivore diet at a prey and predator species-level. These predictions therefore assume that all social classes within a carnivore species display similar prey preferences and that all demographic classes within a prey species are equally preferred or avoided. The objective of this study was to investigate the importance of including prey demographics and carnivore social class in carnivore diet descriptions and thereby K estimates, using cheetah Acinonyx jubatus as a study species. It was predicted that prey sex, prey age and cheetah social class influence cheetah prey preferences, when they influence the risk and ease of prey capture, and that their inclusion in a K model would improve its predictive strength. Based on an analysis of 1290 kills from South Africa, male coalition cheetah were found to prefer a broader weight range of prey than solitary cheetah. Prey demographics further influenced cheetah prey preference, when it corresponded to differences in prey size and the presence of horns. The current species-level K regression model for cheetah is based on preferred prey and thus omits highly abundant antelope that often comprise the majority of the diet, an artefact of the way in which preferences are calculated. A refinement of the species-level K regression model, to account for prey demographic- and cheetah social class-level differences in diet and the biomass of accessible prey (defined in this study as all non-avoided prey) instead of just preferred prey, doubled the predictive strength of the K model. Because group-hunting enabled predation on a broader weight range of prey, cheetah K was influenced by the ratio of male coalition cheetah to solitary cheetah in the population. The refined K regression model is derived from ecosystems supporting an intact carnivore guild. A mechanistic approach to estimating K, based on Caughley‟s (1977) maximum sustainable yield model, therefore better predicted cheetah K in systems devoid of lion Panthera leo and African wild dog Lycaon pictus, which were found to suppress cheetah density. This study improves our understanding of the relationships between prey demographics, cheetah social classes and intra-guild competition in determining cheetah prey preferences and K. This study therefore paves the way for similar work on other large carnivores.
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Gourley, Stephen Alexander. "Nonlocal effects in predator prey systems." Thesis, University of Bath, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.332378.
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May, Celia A. "VNTR studies of birds of prey." Thesis, University of Nottingham, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.358003.
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Brighton, Caroline. "Attack strategies in birds of prey." Thesis, University of Oxford, 2016. https://ora.ox.ac.uk/objects/uuid:4e8afdec-3b7b-43b1-a693-166d114c827f.
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Pursuit behaviours are vital in predator-prey interactions and in courtship for many flying animals. Existing research on target-directed flight behaviours in insects, birds and bats has aimed at identifying simple geometric rules describing the pursuit-flight trajectories. However, these geometric rules are only part of the picture as they only consider the outcome of the commanded changes in flight kinematics, and not the underlying guidance laws (dynamics) which generate these commands. To intercept a target, a pursuer implements a guidance law using sensory feedback to determine the required change in flight velocity, and the resulting kinematics determines the flight geometry. Most of the research until recently has examined insect flight systems, as the ethics of working with birds of prey are more complex and measuring their wide-ranging flight trajectories is difficult. Studies of predator-prey pursuit in birds have only described the geometrical rules for target interception, therefore overlooking the guidance laws which implement them. Therefore the aim of this thesis is to complete the picture by identifying the guidance laws used by birds of prey as they pursue and intercept targets both in the air and on the ground. I used onboard cameras and GPS to study attack flights in peregrine falcons (Falco peregrinus), and high-speed ground photogrammetry for attacks in Harris' hawks (Parabuteo unicinctus), to show that two different raptor species effectively implement the same guidance law of pure proportional navigation for intercepting manouevring and non-manouevring prey-targets. Proportional navigation is a feedback law whereby the bird's line-of-sight rate is fed back, in order to command a turn-rate in proportion to the change in line-of-sight rate, with a constant of proportionality N. Harris' hawks were found to use this guidance law in its simplest case with an N of approximately 1. This amounts to a pure pursuit course, meaning the bird maintains a heading angle of zero at all times (its velocity vector points at the target). Peregrine falcons were found to use a variety of values of N resulting in a quicker path to interception. A remarkable feature of most bird of prey eyes is that they possess two regions of high visual acuity - the shallow and deep foveae. The deep fovea is optimised for long-range vision, and is directed at approximately 45° to the side of the head. It has been proposed that the head is held in line with the body for streamlining, while the body is turned in flight to fixate the image of the prey on the deep fovea, resulting in a curved trajectory. My results contradict this theory, as falcons were seen to use saccadic head movements to maintain the image of the prey in their field of view whilst flying along curved trajectories - suggesting a different visual strategy. I provide the first quantitative analysis of how birds are able to guide their flight for successful prey capture. Not only does this provide new insights into animal behaviour and evolution, but this research has many applications in engineering, where there is a wide and growing interest in vision-based approaches to guidance and control in both civil and military spheres.
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Chrobok, Viktor. "Harvesting in the Predator - Prey Model." Master's thesis, Vysoká škola ekonomická v Praze, 2009. http://www.nusl.cz/ntk/nusl-10510.
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The paper is focused on the Predator-Prey model modified in the case of harvesting one or both populations. Firstly there is given a short description of the basic model and the sensitivity analysis. The first essential modification is percentage harvesting. This model could be easily converted to the basic one using a substitution. The next modification is constant harvesting. Solving this system requires linearization, which was properly done and brought valuable results applicable even for the basic or the percentage harvesting model. The next chapter describes regulation models, which could be used especially in applying environmental policies. All reasonable regulation models are shown after distinguishing between discrete and continuous harvesting. The last chapter contains an algorithm for maximizing the profit of a harvester using econometrical modelling tools.
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Johannesen, Asa. "Predator-prey interactions in aquatic environments." Thesis, University of Leeds, 2013. http://etheses.whiterose.ac.uk/7556/.
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In the first half of this thesis, I have focused on predator ability to locate prey using olfaction and how prey aggregation and turbulence affect prey detection. In chapter 2 I investigate the ability of three spined sticklebacks to compensate for loss of visual cues by using olfaction and find that they can use olfactory cues but that these most likely help the fish detect prey rather than locate prey. In chapter 3 I explore the effect of prey aggregation as an anti-predator strategy when avoiding an olfactory predator and find that aggregated prey survive longer than do dispersed prey. In order to further investigate why this may be, I carried out an experiment using Gammarus pulex as the predator where I recorded search time as a function of prey group size. I found that similarly to detection distance, search time relates to the square root of the number of prey. Finally, I investigate the effect that turbulence in flowing water may have on prey group detection using three spined sticklebacks in a y-maze. I find that risk of detection increases with prey group size but that turbulence lowers this risk. This may mean that there are thresholds below which size prey groups can benefit from turbulence as a ‘sensory refuge’ thus avoiding predators. In the second part of my thesis I focus on the interactions between a cleaner fish and a parasite in an aquaculture setting focusing on whether said fish is useful as a cleaner in industry. I carry out experiments to investigate the use of lumpfish as salmon cleaners in terms of cleaning efficiency and behaviour. I find that while some lumpfish do clean salmon, the required circumstances are still unknown and that further work including selective breeding, personality and effects of tanks is necessary.
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Shek, Lok Lun. "Oxygen consumption rate of copepod fecal pellets : variations among copepod species, prey types and prey nutritional values /." View abstract or full-text, 2010. http://library.ust.hk/cgi/db/thesis.pl?ENVR%202010%20SHEK.
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Becker, Matthew Smith. "Applying predator-prey theory to evaluate large mammal dynamics wolf predation in a newly-established multiple-prey system /." Thesis, Montana State University, 2008. http://etd.lib.montana.edu/etd/2008/becker/BeckerM1208.pdf.
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I studied wolf prey selection and kill rates during 1996-97 through 2006-07 winters in a newly established two-prey system in central Yellowstone National Park. Prey differed substantially in their vulnerability to wolf (Canis lupus) predation and wolves preyed primarily on elk (Cervus elaphus) but also used bison (Bison bison) to varying degrees within and among winters and packs. Winter severity, wolf abundance, distribution, and prey selection varied during the study, concurrent with variations in the demography, distribution, and behavior of elk and bison. A total of 759 wolf-killed ungulates were detected and prey selection by wolves was influenced by the absolute and relative abundance of prey types, the abundance of predators, and the duration of snow pack. Wolves strongly preferred elk calves relative to all other prey types, and elk calf abundance was inversely related to the occurrence of bison in wolf diets. Increasing wolf numbers also broadened prey selection from elk calves, and predation on bison and adult elk increased with increasing snow pack accumulation and duration, likely due to its long-term debilitating influence. Elk abundance and wolf pack size best explained variation in kill rates for elk while bison calf abundance and snow pack duration best explained kill rates of bison. The functional response of wolves for elk was best described by a Type II ratio-dependent model, indicating significant predator dependence. Prey-switching evaluations indicated increasing selection of bison with increasing bison:elk ratios, however no concurrent decrease in elk predation occurred. Increased bison predation is not solely dependent on relative abundance of the two prey species; therefore it is unlikely at this time that wolf prey-switching will stabilize the system.
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Cresswell, Will. "Wintering raptors and their avian prey : a study of the behavioural and ecological effects of predator-prey interactions." Thesis, University of Edinburgh, 1993. http://hdl.handle.net/1842/14744.
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Raptor predation was studied by direct observation of sparrowhawks, peregrines, and merlins, hunting a known prey population, and subsequent recovery of kills. Raptor predation was shown to be the most significant cause of mortality in most wader species. Kleptoparasitism of raptors carrying prey, by carrion crows, significantly increased the over winter mortality of some waders. Redshank populations were most affected by raptor predation; over 50% of the total population and over 90% of the juvenile population were taken in two winters. No selection for body size in redshank was found, but juveniles were more likely to be killed by raptors. This was a consequence of adult redshank risk-averse foraging, and excluding juveniles from low-risk and low-feeding profitability areas. Juveniles, even though feeding in a relatively profitable area compared to adults, still showed risk-prone foraging within that area. Flocking reduced an individual redshank's probability of being killed by a raptor. Larger flocks were preferentially attacked, but an attack was significantly more likely to succeed on a smaller flock. Within a larger flock a redshank was less at risk through the 'dilution' effect, vigilance effects (which were shown to be a direct consequence of flock size) and probably also the 'confusion' effect. Redshank did not gain any foraging benefits within larger flocks. Reduced individual risk of predation appeared to be the main reason for flocking. Redshank responded differently when attacked in a similar way by the three species of raptor. During an attack the probability of capture depended on the escape response. The response that was most likely to lead to escape from a sparrowhawk was most likely to lead to capture on peregrine attack, showing that raptor discrimination was an important determinant of over-winter survival.
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Cantryll-Stewart, Ricki. "A discernment of prey selection by the ancient Maya : white-tailed deer (Odocoileus virginianus) : pest, prey, or domesticate." Thesis, University of Nottingham, 2018. http://eprints.nottingham.ac.uk/50198/.
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This thesis investigates the demographics of paleo-populations of white-tailed deer (Odocoileus virginianus) as a means of testing the hypothesis that this species was domesticated or managed as a vital cultural and economic resource by the ancient Maya in Mesoamerica. To do so it employs a set of standardized bone measurements derived from a modern population and compares them with 1100 deer bone samples recovered by archaeologists from Maya sites dating from 450 B.C. to the late 16th century. These measurements were also applied to modern white-tailed deer specimens representing a discrete population from south eastern Florida of know age, and sex, for use as a baseline. The recorded measurements were used for side by side comparisons and to generate log ratios testing population stature and sexual dimorphism represented in the archaeological materials. Changes in deer stature and mortality profile over time are examined and tested against standard methods for the detection of herd management strategies, that may potentially reveal deer domestication or resource management. Pathologies common to white-tailed deer are identified and their potential for assessing the ontological age of mature deer is investigated. The results show variations in white-tailed deer stature over time and space, suggesting dynamic alterations in prey selection that may be reflective of changes in Maya social complexity.
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Johansson, Markus, and Martin Torstensson. "Hostile Takeovers : The Power of the Prey." Thesis, Jönköping University, JIBS, Business Administration, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:hj:diva-1321.
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Takeovers are used as a mean for companies to grow and gain entry to new markets. Hos-tile takeovers, apart from the friendly takeovers, is when an acquirer tries to takeover a corporation against the will of management, shareholders and board of directors of the target company. All listed companies run the risk of being a target for a hostile takeover, and to-day many companies are trying to involve actions protecting them from possible threats. Lacking protection can evolve into a costly defense program with actions with fictitious names such as White knight, Pac-man and Poison pills. The purpose with this thesis is to describe and analyze hostile takeovers and hostile takeover attempts in Sweden, and the defense tactics involved in the process.
In this thesis a deductive approach will be used, where theories are used as guidance when searching for explanations. On the basis of the defense tactics described in the theory empirical data has been gathered with the purpose of seeing if the expectations reflect reality, and conclusions about their efficiency. The thesis has used a quantitative research method where the focus is on what, where and when. The aim of the thesis is to classify targeted features and count them, with the intent to construct statistical models with an underlying purpose of explaining what is observed.
The most frequently used defense tactic used by the target company in a hostile takeover in the Swedish market is to attack the logic of the bid. Around 56 percent of the targets in a hostile takeover or a hostile takeover attempt have used this defense tactic to avoid a hos-tile takeover. The aim with an implemented defense tactic is to avoid a hostile bid or making it impossible for the hostile bidder to proceed with the bid and close the deal. The White knight and White squire defense tactic is the most successful defense tactic when it comes to not finalizing the hostile bid, in 90 percent of the cases the deal is not closed if the target chooses to use a White knight as a defense tactic. A secondary objective with a defense tactic is to force the hostile bidder to increase the bid and pay more for the target company. In the Swedish market, the use of Corporate restructuring as a defense tactic has made the hostile bidder to increase the bid in 67 percent of the cases and the use of Positive public information has forced the hostile bidder to increase the bid in more than half of the cases.
The question why these defense tactics are the most frequently used strategies, is explained by two variables. The first one is the cost and simplicity variable, where Attack the logic of the bid and Public information ends up. These defense tactics are cost efficient and can be seen as natural step for the target company when deciding not to approve of the offer made by the acquirer. The second variable is the proven efficiency, where the target knows if implementing this defense tactic the risk of being acquired by the hostile bidder is relatively low, a good example of this is the White knight defense.
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Supriatna, Asep K. "Optimal harvesting theory for predator-prey metapopulations /." Title page, contents and abstract only, 1998. http://web4.library.adelaide.edu.au/theses/09PH/09phs959.pdf.
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Van, Leeuwen Edwin. "Mathmatical Modelling of Predator-Multiple Prey Interactions." Thesis, Royal Holloway, University of London, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.499202.
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Lerner, Thomas Ryan. "Modification of prey peptidoglycan by Bdellovibrio bacteriovorus." Thesis, University of Nottingham, 2012. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.631749.
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Siekmann, Ivo. "Mathematical modelling of pathogen-prey-predator interactions." München Verl. Dr. Hut, 2009. http://d-nb.info/99326039X/04.
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London, Josh M. "Harbor seals in Hood Canal : predators and prey /." Thesis, Connect to this title online; UW restricted, 2006. http://hdl.handle.net/1773/5394.
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Garza, Mark Isaac. "Predator induced defenses in prey with diverse predators." Texas A&M University, 2005. http://hdl.handle.net/1969.1/3309.
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Phenotypic plasticity is an environmentally based change in phenotype and can be
adaptive. Often, the change in an organism's phenotype is induced by the presence of a
predator and serves as a defense against that predator. Defensive phenotypes are induced
in freshwater physid snails in response to both crayfish and molluscivorous fish.
Alternative morphologies are produced depending on which of these two predators snails
are raised with, thus protecting them from each of these predators' unique mode of
predation. Snails and other mollusks have been shown to produce thicker, differently
shaped shells when found with predators relative to those found without predators. This
production of thicker, differently shaped shells offers better protection against predators
because of increased predator resistance.
The first study in this thesis explores costs and limits to plasticity using the snailfish-
crayfish system. I exposed juvenile physid snails (using a family structure) to either
early or late shifts in predation regimes to assess whether developmental flexibility is
equally possible early and late in development. Physid snails were observed to produce
alternative defensive morphologies when raised in the presence of each of the two
predators. All families responded similarly to the environment in which they were raised.
Morphology was found to be heritable, but plasticity itself was not heritable. Morphology was found to become less flexible as snails progressed along their respective
developmental pathways.
In the second study, I raised physid snails with and without shell-crushing sunfish
and examined the differences in shell thickness, shell mass, shell size and shell
microstructural properties between the two treatment groups. Shells of snails raised with
predators were found to be larger, thicker and more massive than those raised without
predators, but differences in microstructure were found to be insignificant. I conclude that
the observed shell thickening is accomplished by the snails' depositing more of the same
material into their shells and not by producing a more complex shell composition.
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Huggard, David John. "Prey selectivity of wolves in Banff National Park." Thesis, University of British Columbia, 1991. http://hdl.handle.net/2429/29880.
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The functional response of wolves to changes in the abundance of their prey must be understood to manage wolf-ungulate systems, but is difficult to measure directly. In this study, behavioral and environmental components of wolf predation were assessed and used to predict features of the dynamics of the wolf-large ungulate system in Banff National Park, Alberta. Elk were the most abundant ungulate, while white-tailed deer, mule deer, bighorn sheep, mountain goats, moose and several non-ungulate species provided a diverse prey base.
Two packs of wolves were followed using radio-telemetry and snow-tracking, and 652 scats and 130 animals killed by wolves were analyzed to determine wolf diet. Aerial total counts, ground classified counts, incidental sightings during field work and pellet group counts were used to estimate the numbers, composition and herd sizes of the ungulate prey species. Numerous animals killed on the road and railway provided information on the age structure and physical condition of the elk population.
Non-ungulate prey were used by one wolf pack, when ungulate prey were scarce. All available ungulate species were included in the diet of wolves. Bighorn sheep and mountain goats were underrepresented in the diet, due to their use of habitats segregated from the wolves. For social ungulates, the herd is the unit of available prey, and herd size and composition substantially influenced the selectivity of wolves. Abundance, habitat overlap and herd size determined encounter rates and were more important in determining diet than inherent preferences of the wolves, since all ungulate species were expected to be equally profitable upon encounter. How wolves encounter their prey determined the predicted functional response of wolves to different prey species.
Within elk, wolves preferred calves over adults and took adult males and females equally, but herd size and composition resulted in a slight overall selectivity for calves and adult males, and apparent avoidance of females. Adult elk killed by wolves were older than elk killed on the road or railway, but this may be due to a bias in obtaining the population age distribution from a mortality source, rather than due to selectivity by the wolves. Adult elk, but not calves, killed by wolves had lower reserves of marrow fat than road and rail kills.
Wolf kill rates increased with depth of snowpack and wolves killed primarily calf elk in moderately deep snow (51-58cm) and adults in deeper snow. Scavenging occurred more often in shallow snow and at low kill rates, because wolves travelled more and encountered more scavengeable carcasses under these conditions.
In an auxiliary study, the error associated with telemetry relocations in a mountainous environment and the effect of this error on assessment of habitat use were measured. Mean error distance in complex topography was greater than in simple topography (234m versus 156m). The error distance was correlated weakly with observer distance and size of the map error polygon, but neither was a good predictor of the error of a single relocation. Simulations showed that the habitat of a radio-collared animal would be assessed correctly 80% of the time for large habitat units, and would decline rapidly for units comprising less than 2% of the study area. Matrices were developed to correct for biases in habitat use information which is based on telemetry relocations.Science, Faculty of
Zoology, Department of
Graduate
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Pupovac-Velikonja, Ankica. "Environmental factors affecting predator-prey relationships among yeasts." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp01/MQ39869.pdf.
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Daiquin, Li. "Prey preferences of specialized jumping spiders (Araneae : Salticidae)." Thesis, University of Canterbury. Zoology, 1996. http://hdl.handle.net/10092/5867.
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I studied prey preferences of two groups of specialized jumping spiders (Salticidae), ant-eating ('myrmicophagic') species and spider-eating ('araneophagic') species, in the laboratory. Spiders and ants have in common being unusual and dangerous prey for a salticid. Ten salticid species, four species of Portia (P. africana, P. fimbriata, P. labiata and P. schultzi) which specialize at catching other species of spiders (araneophagic species) and six myrmicophagic species (Chalcotropis sp., Habrocestum pulex, Siler sp., Telamonia masinloc, and two new species of euophryines in a new genus) were studied. Each of these specialized salticid species, whether araneophagic or myrmicophagic, uses prey-specific capture behaviour against its unusual prey and also shows pronounced preferences for these prey (ants or spiders, depending on the species). The capture behaviour of the four species of Portia was known prior to the present study, but the description of capture behaviour of the six ant-eating salticids and the data on preferences of all species are new in this study.
Although all myrmicophagic and all araneophagic salticid species tested resemble each other by having prey-specific capture behaviour against ants and spiders, respectively, details of the predatory behaviour used against ants vary among the species, and the same is true for behaviour used against spiders.
All Portia species studied are known to have different prey-specific capture behaviour for use against spiders and insects. Also, they are all shown in the present study to have distinctive preferences for web-building spiders over insects as prey. However, the capture behaviour of P. fimbriata from Queensland is also known to differ depending on whether the prey is a web-building spider or a
cursorial salticid spider: a specialized behaviour ('cryptic stalking') is used by Queensland P. fimbriata, but not by other Portia, for catching other salticids. In the present study, Queensland P. fimbriata is known also to prefer salticid spiders not only to insects but also to web-building spiders. In contrast, the other Portia species (P. africana, P. labiata and P. schultzi) studied prefer web-building spiders to salticid spiders as prey. This study suggests that, in specialized salticids, the trend is: when a species has a special capture behaviour for a particular type of prey, it also shows a preference for that type of prey.
Portia shows intersexual variation in preference. In all Portia species studied, both the males and the females behave similarly during capture sequences against spiders (i.e., use the same prey-specific capture behaviour). Also, both the males and the females of Portia are shown in the present study to have similar preferences for taxonomic categories of prey. However, there are intersexual differences in the size of prey preferred: males prefer smaller prey, and females prefer larger prey. Factors affecting intersexual differences in prey-size preference are discussed.
A study of P. labiata from Los Banos in the Philippines illustrates how prey-specific capture behaviour and prey preference may interrelate at a more fine-grain level. In nature, the diet of the Los Banos Portia includes Scytodes, an unusually dangerous prey spider. Scytodes is a genus of spiders with a unique predatory behaviour: these spiders spit a sticky gum from their fangs onto prey, and onto predators. I investigated interactions between Scytodes and four species of web-invading salticids, including P. fimbriata from Queensland, P. labiata from the Philippines and P. labiata from Sri Lanka. Los Banos P. labiata, but neither Queensland P. fimbriata nor Sri Lanka P. labiata, uses a Scytodes-specific capture behaviour, and also it prefers Scytodes as prey.
A brooding Scytodes, compared to a non-brooding Scytodes, is a safer prey for a Portia because the brooding Scytodes carries her eggs in her fangs, effectively blocking the spitting weapons. As an apparent refinement of its predatory strategy, Los Banos P. labiata distinctively prefers brooding Scytodes over non-brooding ones.
Optimal foraging theory is considered in a discussion of the factors that may have been important in the evolution of prey preferences.
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Ahlm, Kristoffer. "Prey specialization and diet of frogs in Borneo." Thesis, Umeå universitet, Institutionen för ekologi, miljö och geovetenskap, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-102020.
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Earlier studies of the diet of frogs indicate that most adult frogs are mainly insectivorous. Overall, frogs are viewed more as generalists than specialists in terms of their diet. However, despite earlier studies, there are still gaps in our knowledge regarding what frogs tend to eat and the degree of specialization. The aim of this study was to investigate the diet choice of frogs in a tropical ecosystem. The present study was conducted in a well-known hotspot for frogs with 66 of the 156 known frog species in Borneo found in a protected area comprising of primary rainforest. Frogs were caught in the field and their stomachs were flushed. The stomach content was retrieved, sorted to prey categories, and the diet analysed. In addition, the frogs were identified to species level. The frogs belonged to five families: Bufonidae, Dicroglossidae, Megophryidae, Microhylidae and Ranidae. My results show that the most common food source was ants, which constituted 63.7 % of the total food for all studied frog families. Termites, beetles and spiders made up 11.7 %, 4.2 % and 2.8 % of the total prey, respectively. The results from the analysis of Shannon’s diversity index supported two diet specialist families, the Bufonidae and Megophridae, which had a significantly lower mean diversity index compared to the generalist Dicroglossidae. To better reveal differences in frog’s diet in this ecosystem, further studies using larger sample size are needed.
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Watt, Jon. "Prey selection by coastal otters (Lutra lutra L.)." Thesis, University of Aberdeen, 1991. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?pid=128373.
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The thesis investigated the proximate factors affecting selection among different prey types by coastal otters. From a broad description of coastal otter diet, and its relationship to prey availability, the work progressed to a detailed study of the predatory behaviour of individuals and age classes, and thence to the formulation and testing of specific hypotheses regarding prey choice. Spraint analysis showed that the diet of otters in Loch Spelve consisted principally of small, demersal inshore fishes and shore crabs. It was demonstrated that while the frequency of occurrence of most fish species in spraints seemed to reflect availability, the occurrence of shore crabs did not. Direct observations of foraging otters showed that there were large differences in prey selection and foraging behaviour between age classes of otter. In particular shore crabs were consumed almost exclusively by juvenile otters and rarely appeared in the diets of adults. Foraging efficiency was shown to improve gradually with age and experience, and as it did so the proportion of shore crab in the diet decreased. It was surmised that shore crabs were not a preferred prey, but were relatively easy for juvenile otters to locate and capture. It was hypothesised that the apparent preferences of otters for certain prey types, such as for fish over shore crabs, were based on the relative energetic profitabilities of those prey types. A detailed examination of the costs and benefits, in terms of time and energy respectively, to otters of feeding on the main prey species supported this hypothesis. Shore crabs were markedly unprofitable, requiring considerable time expenditure for relatively little energy return. An apparent preference for rocklings and eelpout over butterfish was also consistent with the relative profitabilities of these species.
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Linkie, Matthew. "Tigers, prey loss and deforestation patterns in Sumatra." Thesis, University of Kent, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.405517.
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Botham, Marc Stephen. "Prey choice behaviour in three major Trinidadian piscovores." Thesis, University of Leeds, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.421976.
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Jiang, Bin [Verfasser]. "Predators promote trait diversification in prey / Bin Jiang." Berlin : Freie Universität Berlin, 2018. http://d-nb.info/1169832156/34.
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Klepac, Petra. "Interacting populations : hosts and pathogens, prey and predators." Thesis, Massachusetts Institute of Technology, 2007. http://hdl.handle.net/1721.1/38995.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Biology, 2007.Includes bibliographical references.
The interactions between populations can be positive, neutral or negative. Predation and parasitism are both relationships where one species benefits from the interaction at the expense of the other. Predators kill their prey instantly and use it only for food, whereas parasites use their hosts both as their habitat and their food. I am particularly interested in microbial parasites (including bacteria, fungi, viri, and some protozoans) since they cause many infectious diseases. This thesis considers two different points in the population-interaction spectrum and focuses on modeling host-pathogen and predator-prey interactions. The first part focuses on epidemiology, i. e., the dynamics of infectious diseases, and the estimation of parameters using the epidemiological data from two different diseases, phocine distemper virus that affects harbor seals in Europe, and the outbreak of HIV/AIDS in Cuba. The second part analyzes the stability of the predator-prey populations that are spatially organized into discrete units or patches. Patches are connected by dispersing individuals that may, or may not differ in the duration of their trip. This travel time is incorporated via a dispersal delay in the interpatch migration term, and has a stabilizing effect on predator-prey dynamics.
by Petra Klepac.
Ph.D.
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Bolohan, Noah. "Seasonal Variation in a Predator-Predator-Prey Model." Thesis, Université d'Ottawa / University of Ottawa, 2020. http://hdl.handle.net/10393/40899.
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Seasonal shifts in predation habits, from a generalist in the summer to a specialist in the winter, have been documented for the great horned owl (Bulbo virginialis) in the boreal forest. This shift occurs largely due to varying prey availability. There is little study of this switching behaviour in the current literature. Since season length is predicted to change under future climate scenarios, it is important to understand resulting effects on species dynamics. Previous work has been done on a two-species seasonal model for the great horned owl and its focal prey, the snowshoe hare (Lepus americanus). In this thesis, we extend the model by adding one of the hare's most important predators, the Canadian lynx (Lynx canadensis). We study the qualitative behaviour of this model as season length changes using tools and techniques from dynamical systems. Our main approach is to determine when the lynx and the owl may invade the system at low density and ask whether mutual invasion of the predators implies stable coexistence in the three-species model. We observe that, as summer length increases, mutual invasion is less likely, and we expect to see extinction of the lynx. However, in all cases where mutual invasion was satisfied, the three species stably coexist.
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Jurcak, Ana M. "Defining the reaction space of predator-prey interactions." Bowling Green State University / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1521461052087018.
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Sogoni, Msimelelo. "The paradox of enrichment in predator-prey systems." University of Western Cape, 2020. http://hdl.handle.net/11394/7737.
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>Magister Scientiae - MScIn principle, an enrichment of resources in predator-prey systems show prompts destabilisation of a framework, accordingly, falling trophic communication, a phenomenon known to as the \Paradox of Enrichment" [54]. After it was rst genius postured by Rosenzweig [48], various resulting examines, including recently those of Mougi-Nishimura [43] as well as that of Bohannan-Lenski [8], were completed on this problem over numerous decades. Nonetheless, there has been a universal none acceptance of the \paradox" word within an ecological eld due to diverse interpretations [51]. In this dissertation, some theoretical exploratory works are being surveyed in line with giving a concise outline proposed responses to the paradox. Consequently, a quantity of di usion-driven models in mathematical ecology are evaluated and analysed. Accordingly, piloting the way for the spatial structured pattern (we denote it by SSP) formation in nonlinear systems of partial di erential equations [36, 40]. The central point of attention is on enrichment consequences which results toward a paradoxical state. For this purpose, evaluating a number of compartmental models in ecology similar to those of [48] will be of great assistance. Such displays have greater in uence in pattern formations due to diversity in meta-population. Studying the outcomes of initiating an enrichment into [9] of Braverman's model, with a nutrient density (denoted by n) and bacteria compactness (denoted by b) respectively, suits the purpose. The main objective behind being able to transform [9]'s system (2.16) into a new model as a result of enrichment. Accordingly, n has a logistic- type growth with linear di usion, while b poses a Holling Type II and nonlinear di usion r2 nb2 [9, 40]. Five fundamental questions are imposed in order to address and guide the study in accordance with the following sequence: (a) What will be the outcomes of introducing enrichment into [9]'s model? (b) How will such a process in (i) be done in order to change the system (2.16)'s stability state [50]? (c) Whether the paradox does exist in a particular situation or not [51]? Lastly, (d) If an absurdity in (d) does exist, is it reversible [8, 16, 54]? Based on the problem statement above, the investigation will include various matlab simulations. Therefore, being able to give analysis on a local asymptotic stability state when a small perturbation has been introduced [40]. It is for this reason that a bifurcation relevance comes into e ect [58]. There are principal de nitions that are undertaken as the research evolves around them. A study of quantitative response is presented in predator-prey systems in order to establish its stability properties. Due to tradeo s, there is a great likelihood that the growth rate, attack abilities and defense capacities of species have to be examined in line with reviewing parameters which favor stability conditions. Accordingly, an investigation must also re ect chances that leads to extinction or coexistence [7]. Nature is much more complex than scienti c models and laboratories [39]. Therefore, di erent mechanisms have to be integrated in order to establish stability even when a system has been under enrichment [51]. As a result, SSP system is modeled by way of reaction-di usion di erential equations simulated both spatially and temporally. The outcomes of such a system will be best suitable for real-world life situations which control similar behaviors in the future. Comparable models are used in the main compilation phase of dissertation and truly re ected in the literature. The SSP model can be regarded as between (2018-2011), with a stability control study which is of an original.
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Halstead, Brian J. "Predator behavior and prey demography in patchy habitats." [Tampa, Fla] : University of South Florida, 2008. http://purl.fcla.edu/usf/dc/et/SFE0002414.
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Topham, Eric. "Biodiversity and ecosystem functioning in predator-prey communities." Thesis, University of Oxford, 2015. https://ora.ox.ac.uk/objects/uuid:c51b2a47-39bc-4b00-a749-5846ed75675d.
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Once regarded as little more than simple model systems, microbial communities are now understood to drive major earth processes and patterns of biodiversity. In order to more fully understand them, there is a need to investigate the mechanisms that determine the structure and function of microbial systems. Predator-prey interactions have been studied for a long time in macroecological systems and are known for their role in determining community structure and dynamics. Functional diversity has come to the fore of ecology to take a central role in understanding what links species to biodiversity and ecosystem function. In this thesis I investigated the biodiversity and ecosystem functioning of microbial predator-prey communities. I used naturally occurring bacterial communities in combination with co-occurring heterotrophic protists to perform manipulative experiments to investigate: a) the functional diversity of heterotrophic protists and their interactive contributions to ecosystem functioning; b) the effects of bacterial prey community diversity and composition on these attributes of protists; and c) the role of functional diversity in maintaining protist community diversity. I found that not only is it possible to classify functional diversity by species interactions, but that the effects of prey community diversity and composition highlight the flexible nature of this property, particularly in predators. I also found evidence of negative biodiversity-functioning relationships and strong competitive interactions among heterotrophic protists. However, their functional diversity allowed them to maintain higher diversity in disturbed environments. Taken together, my thesis has advanced the understanding of the role of predator-prey interactions and functional diversity in regulating interactions and ecosystem functioning in microbial systems.
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Lemos, Felipe de. "Spider mite web protects prey and predator alike." Universidade Federal de Viçosa, 2011. http://locus.ufv.br/handle/123456789/3958.
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Em todo o mundo lavouras de tomate sofrem o ataque de pragas. Uma das principais pragas do tomate é o ácaro vermelho Tetranychus evansi Baker & Pritchard (Acari: Tetranychidae). Uma característica marcante de T. evansi é a sua alta produção de teia sobre suas plantas hospedeiras. Essa teia pode afetar diretamente os inimigos naturais, reduzindo a sua eficiência de predação ou indiretamente alterando seu comportamento de busca. No entanto, alguns ácaros predadores da família Phytoseiidae podem ser bem adaptados para lidar com a teia dos ácaros fitófagos. Para selecionar agentes de controle biológico eficientes é importante compreender as interações diretas e indiretas entre os organismos envolvidos no agroecossistema em questão. Nesta dissertação, foi investigado o papel da teia produzida por T. evansi como mediadora de interações diretas e indiretas com seus inimigos naturais. No Capítulo 1 foram investigados os efeitos da teia produzida por T. evansi em suas interações com o ácaro predador Phytoseiulus longipes Evans (Acari: Phytoseiidae). Foi avaliado se fêmeas de T. evansi reconhecem sinais químicos do predador e se estes sinais podem induzir os ácaros a produzirem mais teia. Os resultados mostram que a presa não produz mais teia em resposta a estímulos de risco de predação, no entanto, passa a depositar uma maior parcela de seus ovos suspensos na teia, longe da superfície da folha. Esses ovos suspensos sofreram uma menor predação por P. longipes do que os ovos que se encontravam na superfície da folha. Entretanto a taxa de predação de P. longipes sobre ovos de T. evansi em discos com e sem teia não diferiram, indicando que esse predador não é afetado negativamente pela teia de sua presa. No segundo capítulo foi estudado se a teia produzida por T. evansi pode afetar o comportamento de forragemamento de P. longipes modulando a sua preferência entre ambientes e presas. Estudou-se também se ocorre predação intraguilda entre P. longipes e outro ácaro predador Phytoseiulus macropilis (Banks) (Acari: Phytoseiidae), que podem coocorrerem sobre as mesmas plantas. Observou-se que P. longipes prefere as metades de discos de folhas que apresentavam uma estrutura mais complexa (mesmo quando eles não tinham alimento) em relação às metades dos discos com ovos e sem teia de T. evansi. Esta preferência por ambientes de estrutura complexa pode ser explicada pela menor taxa de predação intraguilda de P. macropilis observada em discos de tomate com teia de ácaros. A presença da teia reduziu a capacidade predatória de P. macropilis. A diferença entre ambos os predadores para lidar com a teia de ácaros fitófagos pode ser explicado em parte pelas diferenças no comprimento das setas dorsais j3, z2 e z4, que são mais longas em P. longipes. Com relação à preferência de P. longipes por espécies de presas, observou-se que os ácaros predadores escolheram T. evansi a T. urticae, tanto em presença quanto ausência de teia. Esses resultados indicam que a teia de T. evansi pode mediar o comportamento de forrageamento de ácaros da família Phytoseiidae de acordo com seus níveis de adaptações morfológicas e comportamentais. Em linhas gerais, pode-se concluir que os ácaros predadores P. longipes são bem adaptados para lidar com a grande quantidade de teia produzida por T. evansi. Além de não evitar plantas com elevada quantidade de teia, esse ácaro predador pode se beneficiar desse ambiente complexo, reduzindo a competição com outros predadores. No entanto, a presença do predador estimula T. evansi a mudar seu comportamento de oviposição, reduzindo a eficiência predatória de P. longipes. Assim, ao alterar o seu comportamento de oviposição em resposta aos sinais dos predadores, as fêmeas de T. evansi utilizam mais eficientemente sua teia para protegerem sua prole.
Worldwide, tomato suffers from herbivory. One of the most important tomato pests is the red spider mite Tetranychus evansi Baker & Pritchard (Acari: Tetranychidae). A striking characteristic of T. evansi is its high production of web over its host plants. The web can directly affect natural enemies by reducing its predation efficiency or indirectly by changing its foraging behaviour. However some Phytoseiidae can be well adapted to cope with spider mite webbing. To select efficient biologicol control agents, it is important to understand the direct and indirect interactions between the organims involved in the agroecosystem. In this dissertation, I investigated how the web produced by T. evansi mediates direct and indirect interactions with its natural enemies. In Chapter 1 I investigate the effects of the web produced by T. evansi on its interactions with the predatory mite Phytoseiulus longipes Evans. We tested whether spider mite females recognize predator cues and whether these can induce the spider mites to produce denser web. We found that the prey did not produce denser web in response to such cues, but laid more eggs suspended in the web, away from the leaf surface. These suspended eggs suffered less predation by P. longipes than eggs that were laid on the leaf surface, under the web. However the predation rate of P. longipes on eggs of T. evansi on discs with and without web was not different, indicating that this predatory mite is not negatively affected by the spider mite web. In the second Chapter I studied whether the complex web produced by spider mites could affect the foraging behaviour of P. longipes modulating its preference between patches and prey. Was also studied if there is intraguild predation between the predatory mites P. longipes and Phytoseiulus macropilis (Banks) (Acari: Phytoseiidae), which can co-occur on the same plants. We observed that P. longipes always preferred the leaf discs halves with more complex environmental structure (even when there was no food on it) to discs half with eggs and no web of T. evansi. The strong preference for patches with complex structure could be explained by the reduced rate of intraguild predation by P. macropilis observed on tomato discs with spider mite web. As observed, the presence of spider mite web reduced the predatory efficiency of P. macropilis in intraguild predation experiment. The difference between both predatory mites to cope with the web of spider mites could be explained in part by the differences in length of the setae j3, z2 and z4 that are longer in P. longipesi, but is needed manipulation of these traits. With respect to the preference of P. longipes by prey species, we observed that the predator chose T. evansi to T. urticae, both in the presence and absence of web. These results indicate that spider mite web can mediate the foraging behaviour of phytoseiid mites according to their level of morphological and behavioral adaptation to webbing. In general, we conclude that the predatory mite P. longipes is well adapted to cope with the higher web densities produced by T. evansi. Besides not avoid thus plants with high amounts of web, P. longipes can benefit from this complex environment by reducing competition with others predators. However the presence of the predatory mite stimulates T. evansi to change its oviposition behaviour, reducing the predation efficiency of P. longipes. Thus, by altering their oviposition behaviour in response to predator cues, females of T. evansi make better use of their web to protect their offspring.
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Glaspie, Cassandra N. "Marine benthic predator-prey interactions and global change." W&M ScholarWorks, 2016. https://scholarworks.wm.edu/etd/1539616667.
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Anthropogenic stressors such as habitat loss, extreme weather events, and acidification can change predator-prey interactions. An understanding of the mechanisms by which these stressors impact predator-prey interactions may elucidate the fate of bivalves in the face of global change. My dissertation research informs management of marine resources in Chesapeake Bay, which has experienced substantial seagrass and oyster reef loss, increased storm activity, and combined estuarine and atmospheric CO2 acidification. In my dissertation, I used field survey data, field caging experiments, laboratory mesocosm experiments, time-series analysis, and density-dependent mathematical models to assess the role of habitat, major storm events, acidification, and predators on bivalve distribution in lower Chesapeake Bay, with a special focus on the commercially important, thin-shelled clam species Mya arenaria, which has declined significantly in the past few decades.;In field surveys, seagrass supported one additional bivalve functional group (based on bivalve morphology and feeding mode) than all other habitat types, and bivalve diversity was 2754% higher in seagrass than in shell hash, oyster shell, coarse sand, and detrital mud habitats. The odds of finding M arenaria were higher in seagrass than in all other habitats. Predators likely consumed seasonal pulses of juveniles each year. In field caging experiments, blue crabs Callinectes sapidus were likely responsible for most of the mortality of juvenile M arenaria, which was 76.6% higher for caged juveniles than for uncaged individuals over 5 d. In mesocosm feeding trials, M arenaria maintained a low-density refuge from predation by blue crabs, and had higher survival in oyster shell or shell habitats as compared to sand or seagrass habitats. Time series analysis suggested M arenaria was subjected to a storm-driven phase shift to low abundance in 1972, which has been maintained by blue crab predation. Density-dependent predator-prey models parameterized with data from laboratory and field experiments confirmed the presence of a coexistence steady state at low densities of M arenaria, providing the theoretical proof-of-concept that M arenaria can exist in a low-density stable state in the face of blue crab predation. Acidification altered behavior of both predator (C. sapidus) and prey (M arenaria), resulting in no net change in proportional mortality of clams between acidified and control feeding trials.;My dissertation examined multiple lines of evidence to address the importance of structured habitat, extreme weather events, and acidification in the mediation of predator-prey dynamics. For the crab-bivalve predator-prey interactions examined here, predation exacerbated the effects of some anthropogenic stressors (habitat loss, extreme weather events) and ameliorated the impacts of other stressors (acidification) on bivalve prey. An understanding of density-dependent predation is a necessary component of an adaptive management strategy that can cope with climate change.
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Murali, Suraj. "Reinforcement Learning for a Hunter and Prey Robot." Thesis, Uppsala universitet, Institutionen för informationsteknologi, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-389998.
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The surge in the use of adaptive Artificial Intelligent (AI) systems have been made possible by leveraging the increasing processing and storage power that modern computers are able to provide. These systems are designed to make quality decisions that assist in making predictions in a wide variety of application fields. When such a system is fueled by data, the foundation for a Machine Learning (ML) approach can be modelled. Reinforcement Learning (RL) is an active model of ML going beyond the traditional supervised or unsupervised ML methods. RL studies algorithms to take actions so that the resulting reward is expected to be optimal. This thesis investigates the use of methods of RL in a context where the reward is highly time-varying: a setup is studied where two agents compete for a common resource. Specifically, we study a robotic setting inspired by the "cat-and-mouse" (hunter-prey) game. We refer to the hunter robot as to Tom, and to the competing prey robot as Jerry. In order to study this setup, two practical setups are considered. The first one is based on a LEGO platform, enabling us to run a number of actual experiments. The second one is based on a known RL simulator environment, enabling us to run many virtual experiments. We use these environments to explore the setting: indicate the non-stationary solution it generates, evaluate a number of de-facto standard approaches to RL, and identify key future avenues to be addressed.
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Go, Dong-Hun. "Three Essays in Economics of Prey-Predator Relation." DigitalCommons@USU, 2018. https://digitalcommons.usu.edu/etd/7031.
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This dissertation explores how natural ecosystem can be integrated with economic system through two case studies of multiple species interactions, or predator-prey relations. By the inclusion of biological, ecological and economic aspects, the integrated approaches aim at more clearly understanding of how regional ecosystem and economy interact with each other, given threats of resource extinction and environmental shock. I also explain strategies and policy regimes that can be considered to achieve efficient and sustainable ecosystem management in those circumstances.
The first case study focuses on a predator-prey relation in the Pacific Ocean between the United States and Canada, where endangered/threatened predators feed primarily on commercially valuable species as prey. Accounting for the importance of those predators as critical natural resources for whale watching industry, this case study synthesizes the species biological and the regional economic systems, and analyzes possible management strategies for both ecosystem conservation and sustainable economic growth.
A long-term drought and fragmented management has been one of the critical issues in the Great Salt Lake (GSL) ecosystem that is linked with its regional economy in Utah. For this issue, the second case study builds an integrated model for describing how the lakes main natural resources, such as water, brine shrimp, and migratory birds, are related to primary industries in the region including agriculture, mining, fishery, and recreation. With the model framework, the study presents how the prolonged drought affects both the GSL ecosystem and its rigional economy, and suggests economic management strategies for the lakes ecosystem recovery in the presence of drought.
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Davison, Bruce. "Raptor communities in hill habitats in south-eastern Zimbabwe." Thesis, Rhodes University, 1998. http://hdl.handle.net/10962/d1005438.
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The interrelationships between species composition, resource-use and availability, breeding and competition were studied in two hill habitat raptor communities in a conserved reserve and an unprotected communal land in Zimbabwe in 1995 and 1996. The conserved Lonestar Study Area (LSA) and the unprotected Communal Land Study area (CLSA) had 38 and 31 raptor species, high and normal diversities for the area sizes respectively. An estimated 147 pairs of 21 raptor species bred in 40km² in the LSA compared to only 26 pairs of 22 raptor species per 40km² in the CLSA. Six species (African Hawk Eagle Hieraaetus spilogaster, Black Eagle Aquila verreauxii, Crowned Eagle Stephanoaetus coronatus, Little Banded Goshawk Accipiter badius, Barn Owl Tyto alba,and Barred Owl Glancidium capense made up 69% of breeding raptors in the LSA, while African Hawk Eagles, Little Banded Goshawks, Barn Owls and Barred Owls made up 58% of the breeding raptors in the CLSA. The abundance of Black, Crowned and African Hawk Eagles in the LSA was linked to abundant hyrax, Heterohyrax brucei and Procavia capensis and juvenile bushbuck Tragelaphus prey, and the high reproduction rates of Natal Francolin Francolinus natalensis (0.7 per ha when not breeding). Little Banded Goshawk and Barn Owl abundances were linked to their ability to change prey preferences according to prey availability. A fairly high rate of breeding attempts by eagles in the LSA in both years (60 - 76% of all pairs per year)was probably also linked to prey abundance, Most breeding failures were predator related, and were more common in areas of relatively low nesting densities indicating lower parental vigilance there. High eagle breeding densities were associated with small mean territory sizes in the LSA (7.7 - 10.7km² for the main eagle species). Eagles in the LSA usually nested closer to another eagle species than a conspecific, resulting in regular distributions of nests and no territory overlap within species. Differences in daily flight activity of eagles in both study areas, and in the onset of breeding between LSA eagles probably reduced interspecific aggression. Interspecific competition food and nest sites amongst LSA eagles was possibly lessened by slight ditferences in resource selection. Raptor resources were mostly unaffected by human activities in either study area during the study period. Differences in the raptor communities were probably as a result of natural habitat differences. The CLSA raptors potentially face resource loss through forest clearing and hunting. An expansion of the present CAMPFIRE program will protect the CLSA raptors.
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Truemper, Holly A. "Food habits and prey size-selection of yellow perch in extreme southern Lake Michigan, with emphasis on the prey : round goby." Virtual Press, 2003. http://liblink.bsu.edu/uhtbin/catkey/1260485.
Full textAbstract:
Food habits for yellow perch Perca flavescens were compared using current and previous diet studies from southern Lake Michigan index sites. Yellow perch were not gape limited but size-selective in consumption of the newly established round goby Neogobius melanostomus. Ingested fish ranged from 7 to 47% of the yellow perch's total length and 2 to 53% of their gape. Currently, yellow perch diets are dominated in volume by fish/fish products (85%), which is double from previous studies. Utilization of zooplankton and insect prey items in the yellow perch diet has decreased to <1% by volume in 2002, contrasting with previous consumption of 4 to 20% and 5 to 17%, respectively, from previous studies during 1971-1993. Yellow perch are exhibiting opportunistic, generalist feeding strategy that incorporates both exotic and native prey items, allowing the population to use multiple prey items with the changing prey base in Lake Michigan.Department of Biology
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Rowlands, William Llewelyn. "Is prey selection in young gadoids in the Irish Sea limited by gape size or by the spectrum of prey available?" Thesis, University of Liverpool, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.406715.
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Dohet, Loïc. "Coevolution in the specific predator-prey system Rhizophagus grandis-Dendroctonus micans: with emphasis on the predator’s oviposition kairomones and prey symbioses." Doctoral thesis, Universite Libre de Bruxelles, 2016. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/232990.
Full textAbstract:
Rhizophagus grandis is one of the rare examples of totally specific predators: it only preys upon the bark beetle Dendroctonus micans in its native range (Europe and Asia). In the course of coevolution in such predator-prey systems, prey are selected for avoidance and resistance mechanisms against predators. Previous laboratory trials suggested that R. grandis could lay more eggs in presence of exotic prey species with an ecology similar to that of D. micans, but which could not evolve resistances against this predator, such as the North American parasitic bark beetles D. punctatus and D. valens. The specificity of the association R. grandis-D. micans is thought to depend on chemical signals (kairomones) used by the predator to find a gallery of its prey and to adjust its oviposition to the number of prey larvae available inside. However, the exact nature of the chemical signals regulating R. grandis’ oviposition is still unknown. While these signals seem specific in nature, stimulation of the predator’s oviposition by exotic prey species suggests that specificity may be constrained by geography. Unlike most bark beetles, which kill living trees or feed on dying trees, D. micans completes its development on healthy trees as a true parasite. This niche is highly defended by tree toxicants (terpenes among others) to which both D. micans and R. grandis are resistant. Insects possess their own detoxification processes, but they may also rely on symbiotic microorganisms (bacteria and fungi) to contend with the specific constraints of their niche. In comparison to other bark beetles, microbial communities of parasitic bark beetles are yet poorly known, as in the case of D. micans and D. punctatus. Apart from detoxification, insect symbionts may provide nutritional supplementation, protection against pathogens, or components of the chemical communication, which affect the hosts as well as partners of the tritrophic relationship tree-bark beetle-natural enemies. The system R. grandis-D. micans is a unique opportunity to study several aspects of this coevolution which are poorly understood to date. The objectives of this thesis were:- (1) the comparison of the oviposition performances of R. grandis on the specific prey D. micans, and on the exotic prey D. punctatus and D. valens, in order to emphasize possible prey resistance mechanisms; - (2) the identification of the chemical signals regulating R. grandis’ oviposition, and the evaluation of their role in the specificity of the association with D. micans, in presence of the exotic prey D. punctatus and D. valens; - (3) the characterization of the bacterial and fungal communities associated with non-aggressive populations of the bark beetles D. micans, D. punctatus and D. valens, and investigating how these microbial symbionts may affect bark beetle hosts in respect of their ecology as well as the tritrophic relationship tree-bark beetle-natural enemies. Our results show that R. grandis laid equivalent numbers of eggs with the native prey D. micans and with the exotic prey D. punctatus and D. valens, which could illustrate that R. grandis’ specificity is constrained by geography but which does not emphasize possible prey resistance mechanisms against the long-standing predator. We identified robust candidates to the stimulation and inhibition of R. grandis’ oviposition which should be confirmed in bioassays. Finally, we report that the bacterial and fungal communities of non-aggressive populations of D. micans, D. punctatus and D. valens are mainly composed of widespread environmental Enterobacteria and yeasts, and we discuss the various ways they may influence bark beetle hosts in respect of their life histories including the attacked trees and their natural enemies. Overall, this thesis illustrates the need to encompass all levels of complexity, from prey symbionts and semiochemicals to predators, to study systems like R. grandis-D. micans.Rhizophagus grandis est un des rares exemples de prédateurs totalement spécifiques :présent en Europe et en Asie, il se nourrit exclusivement du scolyte Dendroctonus micans. Dans de telles associations, la coévolution prédateur-proie mène à la sélection de mécanismes d’évitement ou de résistance chez la proie, contre le prédateur. De précédentes observations en laboratoire ont suggéré que R. grandis pouvait pondre davantage d’œufs en présence de proies exotiques d’écologie comparable à celle de D. micans, mais qui n’auraient pu développer de résistance à l’encontre de ce prédateur, à l’instar des scolytes parasitiques nord-américains D. punctatus et D. valens. Il semble que la spécificité de l’association R. grandis-D. micans repose sur des signaux chimiques (kairomones) qui permettent au prédateur de repérer les galeries de sa proie et d’y ajuster le nombre d’œufs déposé à la quantité de larves de proies disponible. Néanmoins, on ignore encore la nature exacte des signaux régulant l’oviposition de R. grandis. Le fait que l’oviposition soit stimulée par des proies exotiques indique que la spécificité de cette association pourrait être limitée par des barrières géographiques. Contrairement à la plupart des scolytes qui tue des arbres ou s’attaque à des arbres mourants, D. micans se développe intégralement sur des arbres en bonne santé, en véritable parasite. Cette niche est fortement défendue par les composés toxiques de l’arbre (en particulier les terpènes), auxquels à la fois D. micans et R. grandis sont résistants. Certains insectes possèdent leurs propres processus de détoxification, mais ils peuvent également bénéficier de l’aide de microorganismes symbiotiques (bactéries et champignons). En comparaison avec les autres scolytes, les communautés microbiennes associées aux scolytes parasitiques est très peu documentée, comme dans le cas de D. micans et D. punctatus. En dehors de la détoxification, les symbiotes d’insectes peuvent contribuer à leur nutrition, les protéger contre des pathogènes, ou intervenir dans la communication chimique, ce qui affecte leurs hôtes comme les autres acteurs de la relation tritrophique arbre-scolyte-ennemi naturel. L’association R. grandis-D. micans est une opportunité unique d’étudier des aspects méconnus de la coévolution. Les objectifs de cette thèse étaient de :- (1) comparer le nombre d’œufs pondu par R. grandis sur sa proie spécifique, D. micans, et sur les proies exotiques D. punctatus et D. valens, afin de mettre en évidence de possibles résistances ;- (2) identifier les signaux chimiques qui régulent l’oviposition de R. grandis, et évaluer leur rôle dans la spécificité de l’association avec D. micans, en présence des proies exotiques D. punctatus et D. valens ;- (3) caractériser les communautés bactérienne et fongique associées aux populations parasitiques des scolytes D. micans, D. punctatus et D. valens, et investiguer comment ces microorganismes symbiotiques peuvent influencer leurs hôtes, selon leurs contraintes écologiques, ainsi que leurs ennemis naturels et arbres-hôtes. Nos résultats révèlent une oviposition équivalente de R. grandis en présence de la proie native D. micans et des proies exotiques D. punctatus et D. valens, ce qui illustre que la spécificité de cette association pourrait être limitée par des barrières géographiques mais ne met pas en évidence de possibles résistances à l’encontre du prédateur de longue date. Nous avons identifié des candidats robustes à la stimulation et à l’inhibition de la ponte de R. grandis, et leur rôle devrait être confirmé par des bioessais. Enfin, nous rapportons que la communauté microbienne associée aux populations parasitiques des scolytes D. micans, D. punctatus et D. valens est principalement constituée d’Entérobactéries et de levures répandues, et nous discutons des différentes façons dont ces symbiotes peuvent affecter leurs hôtes et autres acteurs de la relation tritrophique arbre-scolyte-ennemi naturel, selon leurs écologies respectives. Dans son ensemble, cette thèse souligne l’importance de considérer tous les niveaux de complexité biologique, des microorganismes associés aux proies jusqu’aux prédateurs, afin d’étudier des systèmes comme R. grandis-D. micans.
Doctorat en Sciences
info:eu-repo/semantics/nonPublished
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Nizinski, Martha. "Caribbean spiny lobster and their molluscan prey: Are top-down forces key in structuring prey assemblages in a Florida Bay seagrass system." W&M ScholarWorks, 1998. https://scholarworks.wm.edu/etd/1539616795.
Full textAbstract:
Relative importance of predator-prey dynamics and several environmental variables in structuring gastropod and bivalve diversity and distribution was investigated in the subtropical seagrass and macroalgal community of Florida Bay, a highly productive system and primary nursery and foraging ground for finfish and invertebrate predators, including the numerically dominant Caribbean spiny lobster, Panulirus argus. The molluscan assemblage, a primary food source for P. argus in particular, is speciose (75 gastropod and 25 bivalve species) and a significant component of epifaunal and infaunal invertebrate assemblages within Florida Bay. Two experimental areas, located within separate basins and each comprised of two experimental sites, were selected within Everglades National Park. Each site consisted of an array of four replicates of each of four structural treatments designed to manipulate predator abundances and composition. The predator guild associated with experimental structures was monitored at periodic intervals (July 1993 to Aug. 1995), at which time benthic suction samples were taken to evaluate diversity, abundance, and distribution of the molluscan assemblage. Experimental areas were significantly different from each other and were representative of separate subenvironments within Florida Bay. Predator abundances were successfully manipulated locally; experimental structures providing more overhead cover attracted significantly more predators. Predator densities were representative of naturally occurring fauna utilizing seagrass beds rather than abnormally high densities reported in studies utilizing artificial reefs. No significant predation impacts by lobster and finfishes on abundance and species richness of the molluscan assemblage were observed. Predation by P. argus and finfishes did not structure gastropod and bivalve mollusc assemblages in these habitats. Area differences, however, had some influence on prey abundance and diversity given the consistent significant area effects prevalent throughout the data. Moreover, lobsters at densities recorded in this study, can not be considered a keystone or even dominant predator in this system Predation in Florida Bay, as in other tropical and sub-tropical systems, is differentiated in time and space, probably due to habitat heterogeneity, spatial and temporal variability in predator and prey abundances, high diversity of prey, and other factors. The Florida Bay benthic community is likely influenced through bottom-up or physical factors and microhabitat characteristics.