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Cells of the endocervix are responsible for the secretion of mucins, which provide an additional layer of protection to the female reproductive tract (FRT). This barrier is likely fortified with IgA as has previously been shown in the gastrointestinal tract and lungs of mice. Mucus associated IgA can facilitate clearance of bacteria. While a similar function for IgG has been proposed, an association with mucus has not yet been demonstrated. Here we find that IgA and IgG are differentially associated with the different types of mucus of the FRT. We observed that while both IgA and IgG are stably associated with cervical mucus, only IgG is associated with cervicovaginal mucus. These findings reveal that antibodies can bind tightly to mucus, where they can play a significant role in the fortification of the mucus barriers of the FRT. It may be possible to harness this interaction in the development of vaccines designed to protect the FRT mucosal barriers from sexually transmitted diseases such as HIV. PMID:24098437
Fahrbach, Kelly M; Malykhina, Olga; Stieh, Daniel J; Hope, Thomas J
Cells of the endocervix are responsible for the secretion of mucins, which provide an additional layer of protection to the female reproductive tract (FRT). This barrier is likely fortified with IgA as has previously been shown in the gastrointestinal tract and lungs of mice. Mucus associated IgA can facilitate clearance of bacteria. While a similar function for IgG has been proposed, an association with mucus has not yet been demonstrated. Here we find that IgA and IgG are differentially associated with the different types of mucus of the FRT. We observed that while both IgA and IgG are stably associated with cervical mucus, only IgG is associated with cervicovaginal mucus. These findings reveal that antibodies can bind tightly to mucus, where they can play a significant role in the fortification of the mucus barriers of the FRT. It may be possible to harness this interaction in the development of vaccines designed to protect the FRT mucosal barriers from sexually transmitted diseases such as HIV.
Fahrbach, Kelly M.; Malykhina, Olga; Stieh, Daniel J.; Hope, Thomas J.
Immunoglobulin A1 (IgA1) protease, an enzyme that selectively cleaves human IgA1, may be a virulence factor for pathogenic organisms such as Neisseria gonorrhoeae. Host protection from the effects of IgA1 protease includes antibody-mediated inhibition of IgA1 protease activity, and it is believed that the relative balance between IgA1 protease and inhibitory antibodies contributes to the pathogenesis of disease caused by IgA1 protease-producing organisms. We have examined the levels of these two opposing factors in genital tract secretions and sera from women with uncomplicated infection with N. gonorrhoeae. When IgA1 in cervical mucus was examined by Western blotting, no evidence of cleavage fragments characteristic of IgA1 protease activity was seen in gonococcus-infected or control patients. Cleavage fragments typical of IgA1 protease were detected, however, after the addition of exogenous IgA1 protease to cervical mucus. Degraded IgA1 was detected in some vaginal wash samples, but the fragment pattern was not typical of IgA1 protease activity. All N. gonorrhoeae isolates from the infected patients produced IgA1 protease in vitro. All but two serum samples and 16 of 65 cervical mucus samples displayed inhibitory activity against gonococcal IgA1 protease, but there was no significant difference in the level of inhibitory activity between gonococcus-infected and noninfected patients in either cervical mucus or serum. There was no difference in the levels of IgA1 protease-inhibitory activity in serum or cervical mucus collected from patients at recruitment and 2 weeks later. These results suggest that cleavage of IgA1 by gonococcal IgA1 protease within the lumen of the female lower genital tract is unlikely to be a significant factor in the pathogenesis of infections by N. gonorrhoeae.
Hedges, Spencer R.; Mayo, Matthew S.; Kallman, Lisa; Mestecky, Jiri; Hook, Edward W.; Russell, Michael W.
Permanent female mimicry, in which adult males express a female phenotype, is known only from two bird species. A likely benefit of female mimicry is reduced intrasexual competition, allowing female-like males to access breeding resources while avoiding costly fights with typical territorial males. We tested this hypothesis in a population of marsh harriers Circus aeruginosus in which approximately 40 per cent of sexually mature males exhibit a permanent, i.e. lifelong, female plumage phenotype. Using simulated territorial intrusions, we measured aggressive responses of breeding males towards conspecific decoys of females, female-like males and typical males. We show that aggressive responses varied with both the type of decoys and the type of defending male. Typical males were aggressive towards typical male decoys more than they were towards female-like male decoys; female-like male decoys were attacked at a rate similar to that of female decoys. By contrast, female-like males tolerated male decoys (both typical and female-like) and directed their aggression towards female decoys. Thus, agonistic responses were intrasexual in typical males but intersexual in female-like males, indicating that the latter not only look like females but also behave like them when defending breeding resources. When intrasexual aggression is high, permanent female mimicry is arguably adaptive and could be seen as a permanent ‘non-aggression pact’ with other males.
Sternalski, Audrey; Mougeot, Francois; Bretagnolle, Vincent
Permanent female mimicry, in which adult males express a female phenotype, is known only from two bird species. A likely benefit of female mimicry is reduced intrasexual competition, allowing female-like males to access breeding resources while avoiding costly fights with typical territorial males. We tested this hypothesis in a population of marsh harriers Circus aeruginosus in which approximately 40 per cent of sexually mature males exhibit a permanent, i.e. lifelong, female plumage phenotype. Using simulated territorial intrusions, we measured aggressive responses of breeding males towards conspecific decoys of females, female-like males and typical males. We show that aggressive responses varied with both the type of decoys and the type of defending male. Typical males were aggressive towards typical male decoys more than they were towards female-like male decoys; female-like male decoys were attacked at a rate similar to that of female decoys. By contrast, female-like males tolerated male decoys (both typical and female-like) and directed their aggression towards female decoys. Thus, agonistic responses were intrasexual in typical males but intersexual in female-like males, indicating that the latter not only look like females but also behave like them when defending breeding resources. When intrasexual aggression is high, permanent female mimicry is arguably adaptive and could be seen as a permanent 'non-aggression pact' with other males. PMID:22072281
Sternalski, Audrey; Mougeot, François; Bretagnolle, Vincent
IgG is a major immunoglobulin subclass in mucosal secretions of human female genital tract, where it predominates over the IgA isotype. Despite the abundance of IgG, surprisingly little is known about whether and how IgG enters the lumen of the genital tract and the exact role of local IgG may play ...
Theory on intraguild (IG) predation predicts that coexistence of IG-predators and IG-prey is only possible for a limited set of parameter values, suggesting that IG-predation would not be common in nature. This is in conflict with the observation that IG-predation occurs in many natural systems. One possible explanation for this difference might be antipredator behaviour of the IG-prey, resulting in decreased strength of IG-predation. We studied the distribution of an IG-prey, the predatory mite Neoseiulus cucumeris (Acari: Phytoseiidae), in response to cues of its IG-predator, the predatory mite Iphiseius degenerans. Shortly after release, the majority of IG-prey was found on the patch without cues of IG-predators, suggesting that they can rapidly assess predation risk. IG-prey also avoided patches where conspecific juveniles had been killed by IG-predators. Because it is well known that antipredator behaviour in prey is affected by the diet of the predator, we also tested whether IG-prey change their distribution in response to the food of the IG-predators (pollen or conspecific juveniles), but found no evidence for this. The IG-prey laid fewer eggs on patches with cues of IG-predators than on patches without cues. Hence, IG-prey changed their distribution and oviposition in response to cues of IG-predators. This might weaken the strength of IG-predation, possibly providing more opportunities for IG-prey and IG-predators to co-exist.
Choh, Yasuyuki; van der Hammen, Tessa; Sabelis, Maurice W.
Intraguild (IG) predation is an important factor influencing community structure, yet factors allowing coexistence of IG predator and IGprey are not well understood. The existence of spatial refuges for IGprey has recently been noted for their importance in allowing coexistence. However, reduction in basal prey availability might lead IGprey to leave spatial refuges for greater access to prey, leading to increased IG predation and fewer opportunities for coexistence. We determined how the availability of prey affected space-use patterns of bobcats (Lynx rufus, IGprey) in relation to coyote space-use patterns (Canis latrans, IG predators). We located animals from fall 2007 to spring 2009 and estimated bobcat home ranges and core areas seasonally. For each bobcat relocation, we determined intensity of coyote use, distance to water, small mammal biomass, and mean small mammal biomass of the home range during the season the location was collected. We built generalized linear mixed models and used Akaike Information Criteria to determine which factors best predicted bobcat space use. Coyote intensity was a primary determinant of bobcat core area location. In bobcat home ranges with abundant prey, core areas occurred where coyote use was low, but shifted to areas intensively used by coyotes when prey declined. High spatial variability in basal prey abundance allowed some bobcats to avoid coyotes while at the same time others were forced into more risky areas. Our results suggest that multiple behavioral strategies associated with spatial variation in basal prey abundance likely allow IGprey and IG predators to coexist. PMID:20953798
Wilson, Ryan R; Blankenship, Terry L; Hooten, Mevin B; Shivik, John A
IgG is a major Ig subclass in mucosal secretions of the human female genital tract, where it predominates over the IgA isotype. Despite the abundance of IgG, surprisingly little is known about where and how IgG enters the lumen of the genital tract and the exact role local IgG plays in preventing sexually transmitted diseases. We demonstrate here that the neonatal Fc receptor, FcRn, is expressed in female genital tract epithelial cells of humans and mice and binds IgG in a pH-dependent manner. In vitro we show that FcRn mediates bidirectional IgG transport across polarized human endometrial HEC-1-A monolayers and primary human genital epithelial cells. Furthermore, endosomal acidification appears to be a prerequisite for FcRn-mediated IgG transcytosis; IgG transcytosis was demonstrated in vivo by translocation of systemically administered IgG into the genital lumen in WT but not FcRn-KO mice. The biological relevance of FcRn-transported IgG was demonstrated by passive immunization using herpes simplex virus-2 (HSV-2)–specific polyclonal serum, which conferred significantly higher protection against intravaginal challenge infection by the HSV-2 186 strain in WT mice than in FcRn-KO mice. These studies demonstrate that FcRn-mediated transport is a mechanism by which IgG can act locally in the female genital tract in immune surveillance and in host defense against sexually transmitted diseases.
A recombinant fusion protein composed of Yersinia pestis fraction 1 capsule (F1) and virulence-associated V antigen (V) (F1-V) has been developed as the next-generation vaccine against plague. In this study, female Swiss Webster mice received a single intramuscular vaccination with one of eight doses of the F1-V vaccine and exposed 4 weeks later to either Y. pestis CO92 or C12 organisms by the subcutaneous or aerosol routes of infection. Quantitative anti-F1 and anti-V immunoglobulin G (IgG) ELISAs were used to examine the relationship between survival outcome and antibody titers to F1 and V. Results suggested that each 1log(10) increase in week 4 quantitative anti-F1 and anti-V IgG ELISA titers were associated with a 1.7-fold (p=0.0051) and 2.5-fold (p=0.0054) increase in odds of survival, respectively, against either bubonic or pneumonic plague and may serve as serological correlates of protection. PMID:19925906
Little, S F; Webster, W M; Wilhelm, H; Fisher, D; Norris, S L W; Powell, B S; Enama, J; Adamovicz, J J
This activity allows the student to independently research several birds of prey and compare the predator/prey relationship. Although the research questions are limited, the background reading should lead the student to make a connection between these birds and the ecosystem in which they live. This may also lead to a discussion of food webs and food chains.
The objective of this paper is to investigate the effect of prey-taxis on predator–prey models with Paramecium aurelia as the prey and Didinium nasutum as its predator. The logistic Lotka–Volterra predator–prey models with prey-taxis are solved numerically with four different response functions, two initial conditions and one data set. Routh–Hurwitz’s stability conditions are used to obtain the bifurcation values of
Aspriha Chakraborty; Manmohan Singh; David Lucy; Peter Ridland
Using Maple, Mathmatica, or MatLab, learner should be able to develop the Lotka-Volterra model for predator-prey interactions and a two-populaton version of Eulers Method for solving a system of differential equations.
Using Maple, Mathmatica, or MatLab, learner should be able to develop and explore the Lotka-Volterra model for predator-prey interactions as a prototypical first-order system of differential equations.
We study the qualitative properties of population cycles in a predator–prey system where genetic variability allows contemporary\\u000a rapid evolution of the prey. Previous numerical studies have found that prey evolution in response to changing predation risk\\u000a can have major quantitative and qualitative effects on predator–prey cycles, including: (1) large increases in cycle period,\\u000a (2) changes in phase relations (so that
The distribution of weak and strong non-linear feeding interactions (i.e., functional responses) across the links of complex food webs is critically important for their stability. While empirical advances have unravelled constraints on single-prey functional responses, their validity in the context of complex food webs where most predators have multiple prey remain uncertain. In this study, we present conceptual evidence for the invalidity of strictly density-dependent consumption as the null model in multi-prey experiments. Instead, we employ two-prey functional responses parameterised with allometric scaling relationships of the functional response parameters that were derived from a previous single-prey functional response study as novel null models. Our experiments included predators of different sizes from two taxonomical groups (wolf spiders and ground beetles) simultaneously preying on one small and one large prey species. We define compliance with the null model predictions (based on two independent single-prey functional responses) as passive preferences or passive switching, and deviations from the null model as active preferences or active switching. Our results indicate active and passive preferences for the larger prey by predators that are at least twice the size of the larger prey. Moreover, our approach revealed that active preferences increased significantly with the predator-prey body-mass ratio. Together with prior allometric scaling relationships of functional response parameters, this preference allometry may allow estimating the distribution of functional response parameters across the myriads of interactions in natural ecosystems. PMID:21998724
Kalinkat, Gregor; Rall, Björn Christian; Vucic-Pestic, Olivera; Brose, Ulrich
Objective Cervicovaginal HIV-1-neutralizing IgA was associated with reduced HIV-1 acquisition in a cohort of commercial sex workers. We aimed to define the prevalence and correlates of HIV-1-neutralizing IgA from HIV-1-exposed seronegative (HESN) women in HIV-1-serodiscordant relationships. Methods HIV-1-serodiscordant couples in Nairobi were enrolled and followed quarterly up to two years, and women in concordant HIV-1-negative relationships were enrolled as controls. Cervicovaginal, seminal, and blood samples were collected at enrollment and follow-up. Cervicovaginal IgA was assessed for HIV-1-neutralizing activity by a peripheral blood mononuclear cell-based assay using an HIV-1 clade A primary isolate. Results HESN women in discordant relationships had significantly more HIV-1-neutralizing IgA detected in genital secretions compared to control women (36 of 155 [23%] vs. 4 of 70 [6%], respectively; odds ratio [OR] 5.0; 95% confidence interval [CI] 1.70–14.64; P=0.003). These responses persisted over time in all available follow-up cervicovaginal samples from women with detectable HIV-1-neutralizing IgA at baseline. Partner median HIV-1 plasma viral load was lower among women who had HIV-1-neutralizing IgA compared to women without detectable activity (4.3 vs. 4.8 log10 copies/ml, respectively; OR 0.70; 95% CI 0.51–0.94; P=0.02). A similar trend was found with partner seminal viral load (OR 0.57; 95% CI 0.32–1.02; P=0.06). Conclusion HESN women were 5-times more likely to have neutralizing IgA in cervicovaginal secretions than low-risk control women, and these responses were inversely associated with partner viral load. These observations support the existence of antiviral activity in the mucosal IgA fraction following sexual HIV-1 exposure.
Background: Sex hormones have been shown to influence the immune system and to modify the course of autoimmune disorders. Objective: To examine the effects of the oestrogen antagonist tamoxifen on the course of systemic lupus erythematosus (SLE) in (NZBxNZW)F1 mice. Methods: Groups of 8 week old (NZBxNZW)F1 female mice were treated with tamoxifen (800 µg/mouse; twice a week) or with double distilled water for four months. Mice were evaluated monthly for the presence of autoantibodies directed against DNA and nuclear extract (NE) by enzyme linked immunosorbent assay (ELISA). White blood cells and thrombocytes were quantified by a cell counter and proteinuria by combistix kit. At 6 months of age, all mice that did not die spontaneously were killed and evaluated for the presence of glomerular immune deposits by indirect immunofluorescence assay. IgG isotypes of autoantibodies in the mouse sera and glomeruli were determined by ? chain specific antibodies. Results: Tamoxifen treatment significantly reduced autoantibody production directed against either NE or DNA. The latter reduction was mainly in autoantibodies of the IgG3 isotype. Furthermore, tamoxifen had significant beneficial effects on the course of SLE in (NZBxNZW)F1 mice. At 6 months of age, 40% of the untreated mice died spontaneously, whereas all the tamoxifen treated mice were still alive. All untreated mice showed severe thrombocytopenia and persistent proteinuria, with diffuse glomerular immune deposits of IgG2a and IgG3 isotypes in their kidneys. In contrast, the tamoxifen treated mice had a normal number of thrombocytes and only minimal proteinuria. Moreover, glomerular immune deposits were detected in <40% of the tamoxifen treated mice. The latter were mainly of the IgG2a but not of the IgG3 isotype. Conclusion: The results clearly show the remarkable therapeutic effects of tamoxifen on SLE of (NZBxNZW)F1 female mice and suggest that these beneficial effects are related to the specific reduction of IgG3 autoantibodies.
Nutritional ecological theory predicts that predators should adjust prey capture and consumption rates depending on the prey's nutritional composition. This would affect the predator's functional response, at least at high prey densities, i.e. near predator satiation. Using a simple fruitfly-wolf spider laboratory system in Petri dishes, we found that functional responses changed from day to day over a 7 day period. After 1 to 2 days of feeding, dome-shaped functional responses (i.e. reduced predation at highest prey densities) appeared in spiders fed nutritionally imbalanced prey, compared with steadily increasing or asymptotic functional responses with nutritionally near-optimal prey. Later again (days 5-7), the difference disappeared as the level of the functional response was reduced in both treatments. Experiments with adult females in spring and subadult spiders in autumn revealed opposite patterns: a dome-shaped response with high-lipid prey for reproductive females, for which protein-rich prey are optimal, and a dome-shaped (or simply reduced) response with high-protein prey for pre-winter subadults, for which high-lipid flies are the optimal prey. Our results have implications for predation theory and models of biological control that have, so far, neglected nutritional aspects; in particular, the dynamic nutritional state of the predators should be incorporated. PMID:21367780
Food availability can strongly affect predator-prey dynamics. When change in habitat condition reduces the availability of one prey type, predators often search for other prey, perhaps in a different habitat. Interactions between behavioural and morphological traits of different prey may influence foraging success of visual predators through trait-mediated indirect interactions (TMIIs), such as prey activity and body coloration. We tested the hypothesis that foraging success of stream-dwelling cutthroat trout (Onchorhyncus clarki) on cryptically coloured, less-active benthic prey (larval mayfly; Paraleptophebia sp.) can be enhanced by the presence of distinctly coloured, active prey (larval stonefly shredder; Despaxia augusta). Cutthroat trout preyed on benthic insects when drifting invertebrates were unavailable. When stonefly larvae were present, the trout ate most of the stoneflies and also consumed a higher proportion of mayflies than under mayfly only treatment. The putative mechanism is that active stonefly larvae supplied visual cues to the predator that alerted trout to the mayfly larvae. Foraging success of visual predators on cryptic prey can be enhanced by distinctly coloured, active benthic taxa through unidirectional facilitation to the predators, which is a functional change of interspecific interaction caused by a third species. This study suggests that prey-predator facilitation through TMIIs can modify species interactions, affecting community dynamics. PMID:17426008
The sex ratios of two phytoseiid mites, Phytoseiulus persimilis and Amblyseius womersleyi, were observed under various prey conditions. Upon consumption of abundant prey, both phytoseiids produced progeny in a female-biased sex ratio (approximately 0.8 females). When few prey were consumed, the sex ratio was lowered to 0.5 (the unbiased sex ratio). Under the conditions in which the unbiased sex ratio
Summary 1. Longitudinal records of prey selection by 10 adult female sea otters on the Monterey Peninsula, California, from 1983 to 1990 demonstrate extreme inter-individual vari- ation in diet. Variation in prey availability cannot explain these differences as the data were obtained from a common spatial-temporal area. 2. Individual dietary patterns persisted throughout our study, thus indicating that they are
J. A. Estes; M. L. Riedman; M. M. Staedler; M. T. Tinker; B. E. Lyon
A predator–prey model with logistic growth in prey is modified by introducing an SIS parasite infection in the prey. We have studied the combined effect of environmental toxicant and disease on prey–predator system. It is assumed in this paper that the environmental toxicant affects both prey and predator population and the infected prey is assumed to be more vulnerable to
I compared the prey consumption by bluegills Lepomis macrochirus feeding on two size-classes of Daphnia magna with the diets predicted by the apparent-size model of foraging. The diets of fish that were acclimated to the laboratory for only 1 or 2 weeks contained significantly more small prey than predicted, but the diets of fish acclimated to the laboratory for over
1. Predators often prey on individuals that are sick or otherwise weakened. Although previous studies have shown higher abundance of parasites in prey, whether prey have elevated loads of micro-organisms remains to be determined. 2. We quantified the abundance of bacteria and fungi on feathers of woodpigeons Columba palumbus L., jays Garrulus glandarius L. and blackbirds Turdus merula L. that either fell prey to goshawks Accipiter gentilis L. or were not depredated. 3. We found an almost three-fold increase in bacterial load of prey compared with non-prey, while there was no significant difference between prey and non-prey in level of fungal infection of the plumage. 4. The results were not confounded by differences in size or mass of feathers, date of collection of feathers, or date of analysis of feathers for micro-organisms. 5. These findings suggest a previously unknown contribution of bacteria to risk of predation, with important implications for behaviour, population ecology and community ecology. PMID:22039986
Mřller, A P; Peralta-Sánchez, J M; Nielsen, J T; López-Hernández, E; Soler, J J
Adult females of the large carnivorous copepod Euchaeta elongata Esterly were collected from 1977 to 1980 in Port Susan, Washington, USA. Predation rates of the adult females increased with increasing prey abundance when fed the following 4 sizes of copepods: adult females of Calanus pacificus (average prosome length [PL] of 2 650 µm), adults of Aetideus divergens (PL of 1
It is well documented that host-related odors enable many species of parasitoids and predatory insects to locate their prey and prey habitats. This study reports the first characterization of prey and prey host odor reception in two species of lacewings, Chrysoperla carnea (Say) and Chrysopa oculata L. 2-Phenylethanol, one of the volatiles emitted from their prey’s host plants (alfalfa and corn) evoked a significant EAG response from antennae of C. carnea. Traps baited with this compound attracted high numbers of adult C. carnea, which were predominantly females. One of the sex pheromone components (1R,4aS,7S,7aR)-nepetalactol of an aphid species, Acyrthosiphon pisum (Harris) attracted only C. oculata adults. Single sensillum recordings showed that the olfactory neurons of C. carnea responded to both 2-phenylethanol and aphid sex pheromone components, but those of C. oculata only responded to the latter.
Zhu, J.; Obrycki, J. J.; Ochieng, Samuel A.; Baker, Thomas C.; Pickett, J. A.; Smiley, D.
The purpose of this study was to determine whether preferred prey of Podisus macu- liventris (Say) (Heteroptera: Pentatomidae) adult females also conferred maximal fecundity. We also studied egg development and maturation as a function of predator age, i.e., \\
This research examined the psychophysiology of emotional arousal anticipatory to potentially aversive and highly pleasant outcomes. Human brain reactions (event-related potentials) and body reactions (heart rate, skin conductance, the probe startle reflex) were assessed along motivational gradients determined by apparent distance from sites of potential punishment or reward. A predator-prey survival context was simulated using cues that signaled possible money rewards or possible losses; the cues appeared to loom progressively closer to the viewer, until a final step when a rapid key response could ensure reward or avoid a punishing loss. The observed anticipatory response patterns of heightened vigilance and physiological mobilization are consistent with the view that the physiology of emotion is founded on action dispositions that evolved in mammals to facilitate survival by dealing with threats or capturing life-sustaining rewards.
Low, Andreas; Lang, Peter J.; Smith, J. Carson; Bradley, Margaret M.
Five phytoseiid predators from the dry regions of Colombia and Ecuador, which are candidate classical biological control agents of the cassava green mite, were evaluated for preference of the predominant indigenous prey,Mononychellus caribbeanaeMcGregor, and the target prey,Mononychellus tanajoa(Bondar). Preference by adult female phytoseiids was measured in two-choice, split-leaf-disk experiments using four parameters: consumption of prey eggs, consumption of prey immatures,
Lincoln Smith; Maria Elena Cuellar; Elsa Liliana Melo
Field studies have indicated that bolas spiders attract male moth prey, apparently by mimicking the odor of female moth sex pheromones. Three moth sex pheromone compounds, (Z)-9-tetradecenyl acetate, (Z)-9-tetradecenal, and (Z)-11-hexadecenal, were identified in volatile substances emitted by hunting adult female Mastophora cornigera spiders. These compounds are components of pheromone blends that attract some of this spider's moth prey species.
Mark K. Stowe; James H. Tumlinson; Robert R. Heath
Sera from 19 colostrum-deprived calves less than 1 week old, 24 colostrum-supplemented calves less than 1 week old, 36 3-5-month-old calves and 200 females greater than 9 months of age were tested by ELISA for the presence of IgM, IgG and IgA rheumatoid factors (RF). An increasing level of IgM- and IgG-RF with age was found. IgG-RF levels in the colostrum-supplemented calves were significantly higher than in the non-supplemented calves (p < 0.001). Individual IgG-RF values correlated with serum IgG levels, as determined by zinc sulphate turbidity testing (r=0.59, p < 0.01). No IgA-RF was detected. The cross-reactivity of IgM-RF with heterologous IgG was found to be greatest with rabbit IgG, followed by mouse and chicken IgG. The significance of rheumatoid factors in relation to diagnostic testing is discussed. PMID:9613438
Evarcha culicivora is an East African jumping spider that feeds indirectly on vertebrate blood by choosing blood-fed female Anopheles mosquitoes as prey. Previous studies have shown that this predator can identify its preferred prey even when restricted to using only visual cues. Here, we used lures and virtual mosquitoes to investigate the optical cues underlying this predator's prey-choice behaviour. We made lures by dissecting and then reconstructing dead mosquitoes, combining the head plus thorax with different abdomens. Depending on the experiment, lures were either moving or motionless. Findings from the lure experiments suggested that, for E. culicivora, seeing a blood-fed female mosquito's abdomen on a lure was a necessary, but not sufficient, cue by which preferred prey was identified, as cues from the abdomen needed to be paired with cues from the head and thorax of a mosquito. Conversely, when abdomens were not visible or were identical, spiders based their decisions on the appearance of the head plus thorax of mosquitoes, choosing prey with female characteristics. Findings from a subsequent experiment using animated 3D virtual mosquitoes suggest that it is specifically the mosquito's antennae that influence E. culicivora's prey-choice decisions. Our results show that E. culicivora uses a complex process for prey classification. PMID:22675186
SUMMARY Evarcha culicivora is an East African jumping spider that feeds indirectly on vertebrate blood by choosing blood-fed female Anopheles mosquitoes as prey. Previous studies have shown that this predator can identify its preferred prey even when restricted to using only visual cues. Here, we used lures and virtual mosquitoes to investigate the optical cues underlying this predator's prey-choice behaviour. We made lures by dissecting and then reconstructing dead mosquitoes, combining the head plus thorax with different abdomens. Depending on the experiment, lures were either moving or motionless. Findings from the lure experiments suggested that, for E. culicivora, seeing a blood-fed female mosquito's abdomen on a lure was a necessary, but not sufficient, cue by which preferred prey was identified, as cues from the abdomen needed to be paired with cues from the head and thorax of a mosquito. Conversely, when abdomens were not visible or were identical, spiders based their decisions on the appearance of the head plus thorax of mosquitoes, choosing prey with female characteristics. Findings from a subsequent experiment using animated 3D virtual mosquitoes suggest that it is specifically the mosquito's antennae that influence E. culicivora's prey-choice decisions. Our results show that E. culicivora uses a complex process for prey classification.
In 9 trials, captive wolves (Canis lupus) were fed prey varying in size from snowshoe hares (Lepus americanus) to adult deer (Odocoileus virginianus), and the resulting scats were counted. Field-collectible scats were distinguished from liquid, noncollectible stools. I n collectible scats, the remains of small prey occurred in greater proportion relative to the prey's weight, and in lesser proportion relative to the prey's numbers, than did the remains of larger prey. A regression equation with an excellent, fit to the data (r2 = 0.97) was derived to estimate the weight of prey eaten per collectible scat for any prey. With this information and average prey weights, the relative numbers of different prey eaten also can be calculated.
The relationship between predator and prey plays an important role in ecosystem conservation. However, our understanding of the principles underlying the spatial distribution of predators and prey is still poor. Here we present a phase diagram of a predator-prey system and investigate the lattice formation in such a system. We show that the production of stable lattice structures depends on the limited diffusion or migration of prey as well as higher carrying capacity for the prey. In addition, when the prey's growth rate is lower than the birth rate of the predator, global prey lattice formation is initiated by microlattices at the center of prey spirals. The predator lattice is later formed in the predator spirals. But both lattice formations proceed together as the prey growth rate increases.
It is well documented that host-related odors enable many species of parasitoids and predatory insects to locate their prey and prey habitats. This study reports the first characterization of prey and prey host odor reception in two species of lacewings, Chrysoperla carnea (Say) and Chrysopa oculata L. 2-Phenylethanol, one of the volatiles emitted from their prey's host plants (alfalfa and corn) evoked a significant EAG response from antennae of C. carnea. Traps baited with this compound attracted high numbers of adult C. carnea, which were predominantly females. One of the sex pheromone components (1R,4aS,7S,7aR)-nepetalactol of an aphid species, Acyrthosiphon pisum (Harris) attracted only C. oculata adults. Single sensillum recordings showed that the olfactory neurons of C. carnea responded to both 2-phenylethanol and aphid sex pheromone components, but those of C. oculata only responded to the latter. PMID:15812573
Zhu, J; Obrycki, J J; Ochieng, Samuel A; Baker, Thomas C; Pickett, J A; Smiley, D
This study provides a clear example of female-mimicking behavior by males in insects and evaluates quantitatively the adaptive significance of this behavior, which is poorly understood in many other organisms. Males of Hylobittacus apicalis provide females with a prey arthropod during copulation. Some males mimic female behavior when interacting with males that have captured nuptial prey, resulting in males stealing prey which they will use for copulation. Males that pirate prey copulate more frequently and probably incur fewer predation-related risks. PMID:17790854
This paper investigates several strategies for prey and predator in both bounded and unbounded domains, assuming they have the same speed. The work describes how the prey should move to escape from the predator and how predator should move to catch the prey. The approach is agent-based and explicitly tracks movement of individuals as prey and predator. We show that the prey escapes one or two competing predators, while might be caught in the case of three predators. The paper also describes a strategy for finding a well camouflaged static prey which emits signals. PMID:21221589
A discrete chemotactic predator-prey model is proposed in which the prey secrets a diffusing chemical which is sensed by the predator and vice versa. Two dynamical states corresponding to catching and escaping are identified and it is shown that steady hunting is unstable. For the escape process, the predator-prey distance is diffusive for short times but exhibits a transient subdiffusive behavior which scales as a power law t1/3 with time t and ultimately crosses over to diffusion again. This allows us to classify the motility and dynamics of various predatory microbes and phagocytes. In particular, there is a distinct region in the parameter space where they prove to be infallible predators.
A biometrical genetical analysis of IgG, IgM, and IgA levels in 134 sets of twins is reported. High heritabilities, around .8, are found for all three immunoglobulin levels, and possible reasons for lower heritabilities found in family studies are discussed. There is evidence for genetical dominance tending to decrease IgM and IgA levels, but there is no evidence for the importance of family environment although the presence of dominance may make its detection difficult. The causes of covariation in the three measurements are unclear in males but in females appear to be mainly environmental in correlations with IgA and equally genetical and environmental in the IgG-IgM correlation.
Clark, P; Jardine, R; Jones, P; Martin, N G; Walsh, R J
The goal of ecology is to understand interactions that determine the distribution and abundance of organisms. In principle, ecologists should be able to identify a small number of limiting resources for a species of interest, estimate densities of these resources at different locations across the landscape, and then use these estimates to predict the density of the focal species at these locations. In practice, however, development of functional relationships between abundances of species and their resources has proven extremely difficult, and examples of such predictive ability are very rare. Ecological studies of prey requirements of tigers Panthera tigris led us to develop a simple mechanistic model for predicting tiger density as a function of prey density. We tested our model using data from a landscape-scale long-term (1995-2003) field study that estimated tiger and prey densities in 11 ecologically diverse sites across India. We used field techniques and analytical methods that specifically addressed sampling and detectability, two issues that frequently present problems in macroecological studies of animal populations. Estimated densities of ungulate prey ranged between 5.3 and 63.8 animals per km2. Estimated tiger densities (3.2-16.8 tigers per 100 km2) were reasonably consistent with model predictions. The results provide evidence of a functional relationship between abundances of large carnivores and their prey under a wide range of ecological conditions. In addition to generating important insights into carnivore ecology and conservation, the study provides a potentially useful model for the rigorous conduct of macroecological science.
Laboratory feeding experiments using Hesperoperla pacifica (Banks), Perlidae, and Megarcys signata (Hagen), Perlodidae, as predators and Baetis tricaudatus Dodds and Ephemerella altana Allen as prey indicate a strong effect of prey morphology and mobility and predator hunger on prey selection by stoneflies. Knowledge of both dietary composition and feeding behavior was necessary to fully understand prey selection by these stoneflies.
This paper investigates several strategies for prey and predator in both bounded and unbounded domains, assuming they have\\u000a the same speed. The work describes how the prey should move to escape from the predator and how predator should move to catch\\u000a the prey. The approach is agent-based and explicitly tracks movement of individuals as prey and predator. We show that
This paper presents simulation models for the dynamics of a predator-prey system consisting of the twospotted spider mite Tetranychus urticae Koch as a prey and its predator Phytoseiulus persimilis Athias-Henriot. The percentage infestation of plant has been used as a basic unit for population densities of prey and predators. Parameter estimation has been done with the inclusion of diffusion and
Irina Kozlova; Manmohan Singh; Alan K. Easton; Peter Ridland
In two-predator, one-prey systems with intraguild predation and patchily distributed prey, the intraguild prey may face a choice between prey patches with and without intraguild predators. To minimize falling victim to intraguild predation, intraguild prey are expected to perceive cues specifically associated with the presence of intraguild predators. We investigate whether intraguild prey avoided intraguild predators and which cues triggered
Sara Magalhaes; Christian Tudorache; Marta Montserrat; Roos van Maanen; Maurice W. Sabelis
The study of the feeding ecology of amphibians is an old issue in herpetology. Notwithstanding, the lack of food resources data in many studies of amphibians feeding has lead to partial understanding of frog feeding strategies. In this study we evaluate the trophic selectivity of a red spotted green frog (Hypsiboas punctatus) population from a Middle Paraná River floodplain pond in Argentina, and discuss the importance of prey availability data when interpreting results from diet analysis. We analyzed the gut contents of 47 H. punctatus adults and compared frog's diet with the environmental food resources. Prey availability was estimated by systematically seep-netting the microhabitat where anurans were localized foraging. We identified 33 taxonomic categories from gastrointestinal contents. Numerically, the most important prey categories were dipterans, followed by hemipterans, homopterans and coleopterans. The diet similarity between males and females was high and no statistical differences in diet composition were found. The most abundant food resources in the environment were dipterans, coleopterans, homopterans and collembolans. In order to assess whether frogs were selecting their preys, we calculated Pianka's niche overlap index and Jacobs' electivity index comparing gut contents to prey availability data. Trophic niche overlap was medium but significantly higher than expected by chance. The electivity index indicated that H. punctatus foraged dipterans slightly above their environmental abundance. Among the secondary preys, hemipterans were foraged selectively, homopterans were consumed in the same proportion to their occurrence in the environment, coleopterans were foraged quite under their availability and collembolans were practically ignored by frogs. Without food resources data, H. punctatus could be classified as a specialist feeder, but dipterans also were quite abundant in the environment. Our results show that H. punctatus fit better as a generalist feeder, foraging on their main food item and some secondary preys in similar proportion to their environmental availability; even though other secondary preys are being selectively preferred or ignored by frogs. Our data illustrate the importance of including the resource availability data on diet studies to improve the understanding of amphibian feeding ecology. PMID:19928476
López, Javier A; Scarabotti, Pablo A; Medrano, María C; Ghirardi, Romina
Because group-hunting arboreal ants spread-eagle insect prey for a long time before retrieving them, these prey can be coveted by predatory flying insects. Yet, attempting to rob these prey is risky if the ant species is also an effective predator. Here, we show that trying to rob prey from Azteca andreae workers is a fatal error as 268 out of 276 potential cleptobionts (97.1 %) were captured in turn. The ant workers hunt in a group and use the "Velcro®" principle to cling firmly to the leaves of their host tree, permitting them to capture very large prey. Exceptions were one social wasp, plus some Trigona spp. workers and flies that landed directly on the prey and were able to take off immediately when attacked. We conclude that in this situation, previously captured prey attract potential cleptobionts that are captured in turn in most of the cases.
Dejean, Alain; Corbara, Bruno; Azémar, Frédéric; Carpenter, James M.
Because group-hunting arboreal ants spread-eagle insect prey for a long time before retrieving them, these prey can be coveted by predatory flying insects. Yet, attempting to rob these prey is risky if the ant species is also an effective predator. Here, we show that trying to rob prey from Azteca andreae workers is a fatal error as 268 out of 276 potential cleptobionts (97.1 %) were captured in turn. The ant workers hunt in a group and use the "Velcro®" principle to cling firmly to the leaves of their host tree, permitting them to capture very large prey. Exceptions were one social wasp, plus some Trigona spp. workers and flies that landed directly on the prey and were able to take off immediately when attacked. We conclude that in this situation, previously captured prey attract potential cleptobionts that are captured in turn in most of the cases. PMID:22710934
Dejean, Alain; Corbara, Bruno; Azémar, Frédéric; Carpenter, James M
That predators attack and prey defend is an oversimplified view. When size changes during development, large prey may be invulnerable to predators, and small juvenile predators vulnerable to attack by prey. This in turn may trigger a defensive response in adult predators to protect their offspring. Indeed, when sizes overlap, one may wonder ‘who is the predator and who is the prey’! Experiments with ‘predatory’ mites and thrips ‘prey’ showed that young, vulnerable prey counterattack by killing young predators and adult predators respond by protective parental care, killing young prey that attack their offspring. Thus, young individuals form the Achilles' heel of prey and predators alike, creating a cascade of predator attack, prey counterattack and predator defence. Therefore, size structure and relatedness induce multiple ecological role reversals.
Magalhaes, Sara; Janssen, Arne; Montserrat, Marta; Sabelis, Maurice W
BACKGROUND: Cord IgE and ECP levels are major atopic markers implicated in early childhood allergy development. Most epidemiological studies to date have not utilised current technology to establish baseline cord IgE levels, further aggravated by lack of data in this region. This study also attempts to identify a relationship between cord IgE and ECP levels as a mean to improve sensitivity for early prediction of atopy. METHODS: A total of 3183 cord blood IgE including 44 cord ECP samples of term neonates from Malay parentage were recruited. Total IgE and ECP levels were determined by ImmunoCAP and fluoroimmunoenzymatic, respectively. RESULTS: Cord IgE geometric mean was 0.15kU/L. Males had higher IgE geometric mean than females (0.17 vs. 0.13). IgE values between 17 pair of twins was not significant (p=0.169). Frequency of males (29.9%) in >0.9kU/L IgE category was higher than females (26.1%). In the <0.35kU/L category, females had a higher frequency (44.8%) than males (39.1%). Males had significantly (p=0.023) higher IgE level than females. November and February had the highest mean and median cord IgE level whereas October and December were the lowest, respectively. IgE level across months was not significant (p=0.234). Cord ECP mean was 5.21g/L and median was 3.75?g/L. There was no significant correlation (p=0.513; r=-0.101) between cord blood ECP and IgE levels. CONCLUSION: Cord blood IgE level of Malay male neonates was significantly higher than females. These results do not support cord ECP as plausible adjunct parameter to IgE for early atopic detection. PMID:23276420
As predator-prey interactions are inherently size-dependent, predator and prey body sizes are key to understanding their feeding relationships. To describe predator-prey size relationships (PPSRs) when predators can consume prey larger than themselves, we conducted field observations targeting three aquatic hemipteran bugs, and assessed their body masses and those of their prey for each hunting event. The data revealed that their PPSR varied with predator size and species identity, although the use of the averaged sizes masked these effects. Specifically, two predators had slightly decreased predator-prey mass ratios (PPMRs) during growth, whereas the other predator specialized on particular sizes of prey, thereby showing a clear positive size-PPMR relationship. We discussed how these patterns could be different from fish predators swallowing smaller prey whole. PMID:23536441
The aim of this paper is to observe the ef- fect of prey-taxis on the periodicity of predator-prey dynam- ics. The logistic Lotka-Volterra predator-prey-taxis equations with diusion and advection are solved numerically using two dieren t response functions with two data sets and two non- homogeneous initial conditions. We show that for dieren t val- ues of prey-taxis it is
|"Prey Play" is an interactive role-play activity that provides fifth-grade students with opportunities to examine predator-prey interactions. This four-part, role-play activity allows students to take on the role of a predator and prey as they reflect on the behaviors animals exhibit as they collect food and interact with one another, as well as…
Deaton, Cynthia C. M.; Dodd, Kristen; Drennon, Katherine; Nagle, Jack
Summary 1. Current formulations of functional responses assume that the prey is homogeneous and independent of intraspecific processes. Most prey populations consist of different coexisting size classes that often engage in asymmetrical intraspecific interactions, including cannibalism, which can lead to nonlinear interaction effects. This may be important as the size structure with the prey could alter the overall density-dependent predation
Sand scorpions and many other arachnids locate their prey through highly sensitive slit sensilla at the tips (tarsi) of their eight legs. This sensor array responds to vibrations with stimulus-locked action potentials encoding the target direction. We present a neuronal model to account for stimulus angle determination using a population of second-order neurons, each receiving excitatory input from one tarsus and inhibition from a triad opposite to it. The input opens a time window whose width determines a neuron's firing probability. Stochastic optimization is realized through tuning the balance between excitation and inhibition. The agreement with experiments on the sand scorpion is excellent.
Trophic cascades are often a potent force in ecological communities, but abiotic and biotic heterogeneity can diffuse their influence. For example, inducible defenses in many species create variation in prey edibility, and size-structured interactions, such as cannibalism, can shift predator diets away from heterospecific prey. Although both factors diffuse cascade strength by adding heterogeneity to trophic interactions, the consequences of their interactioh remain poorly understood. We show that inducible defenses in tadpole prey greatly intensify cannibalism in predatory larval salamanders. The likelihood of cannibalism was also strongly influenced by asymmetries in salamander size that appear to be most important in the presence of defended prey. Hence, variation in prey edibility and the size structure of the predator may synergistically affect predator-prey population dynamics by reducing prey mortality and increasing predator mortality via cannibalism. We also suggest that the indirect effects of prey defenses may shape the evolution of predator traits that determine diet breadth and how trophic dynamics unfold in natural systems. PMID:19967870
The modelling of prey–predator interactions is of major importance for the understanding of population dynamics. Classically, these interactions are modelled using ordinary differential equations, but this approach has the drawbacks of assuming continuous population variables and of being deterministic. We propose a general approach to stochastic modelling based on the concept of functional response for a prey depletion process with
Thomas Clerc; Anthony C. Davison; Louis-Félix Bersier
Using a Y-tube olfactometer, a study has been made of the response of females of the predatory miteTyphlodromus pyri Scheuten (Acarina: Phytoseiidae) to volatile kairomones of three prey species: the European red spider mite (Panonychus ulmi (Koch)), the two-spotted spider mite (Tetranychus urticae Koch) and the apple rust mite (Aculus schlechtendali (Nalepa)).
Analysis of the growth characteristics of 215 populations of walleye Sander vitreus across Ontario revealed that female walleyes reached larger asymptotic lengths in lakes in which ciscoes Coregonus artedi provided a relatively large prey species for them. The stomach contents of walleyes from a set of intensively studied lakes revealed that walleyes of all sizes depended on ciscoes but that
Investigating how prey density influences a prey's combined predation risk from multiple predator species is critical for understanding the widespread importance of multiple predator effects. We conducted experiments that crossed six treatments consisting of zero, one, or two predator species (hellgrammites, greenside darters, and creek chubs) with three treatments in which we varied the density of mayfly prey. None of the multiple predator effects in our system were independent, and instead, the presence of multiple predator species resulted in risk reduction for the prey across both multiple predator combinations and all three levels of prey density. Risk reduction is likely to have population-level consequences for the prey, resulting in larger prey populations than would be predicted if the effects of multiple predator species were independent. For one of the two multiple predator combinations, the magnitude of risk reduction marginally increased with prey density. As a result, models predicting the combined risk from multiple predator species in this system will sometimes need to account for prey density as a factor influencing per-capita prey death rates. PMID:15891830
Many predators quickly learn to avoid attacking aposematic prey. If the prey vary in toxicity, the predators may alternatively learn to capture and taste-sample prey carefully before ingesting or rejecting them (go-slow behaviour). An increase in prey toxicity is generally thought to decrease predation on prey populations. However, while prey with a higher toxin load are more harmful to ingest, they may also be easier to recognize and reject owing to greater distastefulness, which can facilitate a taste-sampling foraging strategy. Here, the classic diet model is used to study the separate effects of taste and toxicity on predator preferences. The taste-sampling process is modelled using signal detection theory. The model is applicable to automimicry and batesian mimicry. It shows that when the defensive toxin is sufficiently distasteful, a mimicry complex may be less profitable to the predator and better protected against predation if the models are moderately toxic than if they are highly toxic. Moreover, taste mimicry can reduce the profitability of the mimicry complex and increase protection against predation. The results are discussed in relation to the selection pressures acting on prey defences and the evolution of mimicry. PMID:23256198
Carnivorous plants acquire most of their nutrients by capturing ants, insects and other arthropods through their leaf-evolved biological traps. So far, the best-known attractants in carnivorous prey traps are nectar, colour and olfactory cues. Here, fresh prey traps of 14 Nepenthes, five Sarracenia, five Drosera, two Pinguicula species/hybrids, Dionaea muscipula and Utricularia stellaris were scanned at UV 366 nm. Fluorescence emissions of major isolates of fresh Nepenthes khasiana pitcher peristomes were recorded at an excitation wavelength of 366 nm. N. khasiana field pitcher peristomes were masked by its slippery zone extract, and prey capture rates were compared with control pitchers. We found the existence of distinct blue fluorescence emissions at the capture spots of Nepenthes, Sarracenia and Dionaea prey traps at UV 366 nm. These alluring blue emissions gradually developed with the growth of the prey traps and diminished towards their death. On excitation at 366 nm, N. khasiana peristome 3:1 CHCl3–MeOH extract and its two major blue bands showed strong fluorescence emissions at 430–480 nm. Masking of blue emissions on peristomes drastically reduced prey capture in N. khasiana pitchers. We propose these molecular emissions as a critical factor attracting arthropods and other visitors to these carnivorous traps. Drosera, Pinguicula and Utricularia prey traps showed only red chlorophyll emissions at 366 nm. PMID:23696970
Kurup, R; Johnson, A J; Sankar, S; Hussain, A A; Sathish Kumar, C; Sabulal, B
We attempted to study predation on various-sized prey by a male and female wolf (Canis lupus) with global positioning system (GPS) collars programmed to acquire locations every 10 min in the Superior National Forest of Minnesota. During May to August 2007, we investigated 147 clusters of locations (31% of the total) and found evidence of predation on a white-tailed deer (Odocoileus virginianus) fawn and yearling, a beaver (Castor canadensis), ruffed grouse (Bonasa umbellus), and fisher (Martes pennanti) and scavenging on a road-killed deer and other carrion. However, we missed finding many prey items and discuss the problems associated with trying to conduct such a study.
Several conceptual models describing patterns of prey selection by predators have been proposed, but such models rarely have been tested empirically, particularly with terrestrial carnivores. We examined patterns of prey selection by sympatric wolves (Canis lupus) and cougars (Puma concolor) to determine i) if both predators selected disadvantaged prey disproportionately from the prey population, and ii) if the specific nature
Jason S. Husseman; Dennis L. Murray; Gary Power; Curt Mack; C. R. Wenger; Howard Quigley
A commercial strain of Neoseiulus californicus (Spical®) has a conspicuously long postoviposition period in comparison with other strains of N. californicus or other phytoseiid mites. In many insects and mites, life span is shorter for multiple-mated females than for single-mated\\u000a females, and is shorter under poor prey conditions than under ample prey conditions. We previously showed that the postoviposition\\u000a period
This paper describes an individual-based model for simulating the swarming behavior of prey in the presence of predators. Predators and prey are represented as agents that interact through radial force laws. The prey form swarms through attractive and repulsive forces. The predators interact with the prey through an anti-Newtonian force, which is a nonconservative force that acts in the same direction for both agents. Several options for forces between predators are explored. The resulting equations are solved numerically and the dynamics are described in the context of the swarm’s ability to realistically avoid the predators. The goal is to reproduce swarm behavior that has been observed in nature with the simplest possible model.
Large oscillations in the populations of Norwegian lemmings have mystified both professional ecologists and lay public. Ecologists suspect that these oscillations are driven by a trophic mechanism: either an interaction between lemmings and their food supply, or an interaction between lemmings and their predators. If lemming cycles are indeed driven by a trophic interaction, can we tell whether lemmings act as the resource (`prey') or the consumer (`predator')? In trophic interaction models, peaks of resource density generally have a blunt, rounded shape, whereas peaks of consumer density are sharp and angular. Here we have applied several statistical tests to three lemming datasets and contrasted them with comparable data for cyclic voles. We find that vole peaks are blunt, consistent with their cycles being driven by the interaction with predators. In contrast, the shape of lemming peaks is consistent with the hypothesis that lemmings are functional predators, that is, their cycles are driven by their interaction with food plants. Our findings suggest that a single mechanism, such as interaction between rodents and predators, is unlikely to provide the `universal' explanation of all cyclic rodent dynamics.
Turchin, P.; Oksanen, L.; Ekerholm, P.; Oksanen, T.; Henttonen, H.
Biological organisms use intricate networks of chemical reactions to control molecular processes and spatiotemporal organization. In turn, these living systems are embedded in self-organized structures of larger scales, for example, ecosystems. Synthetic in vitro efforts have reproduced the architectures and behaviors of simple cellular circuits. However, because all these systems share the same dynamic foundations, a generalized molecular programming strategy should also support complex collective behaviors, as seen, for example, in animal populations. We report here the bottom-up assembly of chemical systems that reproduce in vitro the specific dynamics of ecological communities. We experimentally observed unprecedented molecular behaviors, including predator-prey oscillations, competition-induced chaos, and symbiotic synchronization. These synthetic systems are tailored through a novel, compact, and versatile design strategy, leveraging the programmability of DNA interactions under the precise control of enzymatic catalysis. Such self-organizing assemblies will foster a better appreciation of the molecular origins of biological complexity and may also serve to orchestrate complex collective operations of molecular agents in technological applications. PMID:23176248
Predators use cues associated with their prey to assess prey quality and to avoid consuming poisonous prey. Considerable attention has been given to predators' use of aposematic cues to assess prey quality, but little is known about predators that eavesdrop on prey cues that are not intended for them. Here we investigate the prey-cue\\/prey-quality associations of a predator that eavesdrops
We investigated the feeding ecology and foraging location of migrating and nursing northern fur seal (Callorhinus ursinus) adult females and migrating juvenile males from the Pribilof Islands, Alaska, using carbon (ཉC) and nitrogen (ཋN) isotope analysis of fur seal skin and whole potential prey. Post-parturient and lactating females had mean ཋN values significantly (0.8?) higher than pregnant, migratory females, and
The mechanisms underlying differential prey selection of two microcrustaceans by the common bladderwort (Utricularia vulgaris) were studied in the laboratory. Functional response experiments with single prey showed that Utricularia had a higher attack rate coefficient and a longer handling time coefficient with the cladoceran Polyphemus pediculus than with the cyclopoid copepod Eucyclops serrulatus. Observation of predation rate, defined as number
The aim of this work is to develop and analyse a mathematical model for a predator-2 preys system arising in insular environments. We are interested in the evolution of a native prey population without behavioural traits to cope with predation or competition, after the introduction of alien species. Here, we consider a long living bird population with low fertility rate.
To effectively balance investment in predator defenses versus other traits, organisms must accurately assess predation risk. Chemical cues caused by predation events are indicators of risk for prey in a wide variety of systems, but the relationship between how prey perceive risk in relation to the amount of prey consumed by predators is poorly understood. While per capita predation rate is often used as the metric of relative risk, studies aimed at quantifying predator-induced defenses commonly control biomass of prey consumed as the metric of risk. However, biomass consumed can change by altering either the number or size of prey consumed. In this study we determine whether phenotypic plasticity to predator chemical cues depends upon prey biomass consumed, prey number consumed, or both. We examine the growth response of red-eyed treefrog tadpoles (Agalychnis callidryas) to cues from a larval dragonfly (Anax amazili). Biomass consumed was manipulated by either increasing the number of prey while holding individual prey size constant, or by holding the number of prey constant and varying individual prey size. We address two questions. (i) Do prey reduce growth rate in response to chemical cues in a dose dependent manner? (ii) Does the magnitude of the response depend on whether prey consumption increases via number or size of prey? We find that the phenotypic response of prey is an asymptotic function of prey biomass consumed. However, the asymptotic response is higher when more prey are consumed. Our findings have important implications for evaluating past studies and how future experiments should be designed. A stronger response to predation cues generated by more individual prey deaths is consistent with models that predict prey sensitivity to per capita risk, providing a more direct link between empirical and theoretical studies which are often focused on changes in population sizes not individual biomass. PMID:23082171
McCoy, Michael W; Touchon, Justin C; Landberg, Tobias; Warkentin, Karen M; Vonesh, James R
To effectively balance investment in predator defenses versus other traits, organisms must accurately assess predation risk. Chemical cues caused by predation events are indicators of risk for prey in a wide variety of systems, but the relationship between how prey perceive risk in relation to the amount of prey consumed by predators is poorly understood. While per capita predation rate is often used as the metric of relative risk, studies aimed at quantifying predator-induced defenses commonly control biomass of prey consumed as the metric of risk. However, biomass consumed can change by altering either the number or size of prey consumed. In this study we determine whether phenotypic plasticity to predator chemical cues depends upon prey biomass consumed, prey number consumed, or both. We examine the growth response of red-eyed treefrog tadpoles (Agalychnis callidryas) to cues from a larval dragonfly (Anax amazili). Biomass consumed was manipulated by either increasing the number of prey while holding individual prey size constant, or by holding the number of prey constant and varying individual prey size. We address two questions. (i) Do prey reduce growth rate in response to chemical cues in a dose dependent manner? (ii) Does the magnitude of the response depend on whether prey consumption increases via number or size of prey? We find that the phenotypic response of prey is an asymptotic function of prey biomass consumed. However, the asymptotic response is higher when more prey are consumed. Our findings have important implications for evaluating past studies and how future experiments should be designed. A stronger response to predation cues generated by more individual prey deaths is consistent with models that predict prey sensitivity to per capita risk, providing a more direct link between empirical and theoretical studies which are often focused on changes in population sizes not individual biomass.
McCoy, Michael W.; Touchon, Justin C.; Landberg, Tobias; Warkentin, Karen M.; Vonesh, James R.
Generalist predators may be confronted by different types of prey in different patches: sedentary and conspicuous, cryptic (with or without refugia), conspicuous and nonsocial, or conspicuous and social. I argue that, where encounter rates with prey are of most importance, patch revisitation should be a profitable tactic where prey have short 'recovery' times (conspicuous, nonsocial prey), or where anti-predator response (e.g. shoaling) may increase conspicuousness. Predictions are made for how temporal changes in prey encounter rates should affect revisit schedules and feeding rates for the 4 different prey types.
Predator-prey interactions, including between large mammalian wildlife species, can be represented as a “space race”, where prey try to minimize and predators maximize spatial overlap. Human activity can also influence the distribution of wildlife species. In particular, high-human disturbance can displace large carnivore predators, a trait-mediated direct effect. Predator displacement by humans could then indirectly benefit prey species by reducing predation risk, a trait-mediated indirect effect of humans that spatially decouples predators from prey. The purpose of this research was to test the hypothesis that high-human activity was displacing predators and thus indirectly creating spatial refuge for prey species, helping prey win the “space race”. We measured the occurrence of eleven large mammal species (including humans and cattle) at 43 camera traps deployed on roads and trails in southwest Alberta, Canada. We tested species co-occurrence at camera sites using hierarchical cluster and nonmetric multidimensional scaling (NMS) analyses; and tested whether human activity, food and/or habitat influenced predator and prey species counts at camera sites using regression tree analysis. Cluster and NMS analysis indicated that at camera sites humans co-occurred with prey species more than predator species and predator species had relatively low co-occurrence with prey species. Regression tree analysis indicated that prey species were three times more abundant on roads and trails with >32 humans/day. However, predators were less abundant on roads and trails that exceeded 18 humans/day. Our results support the hypothesis that high-human activity displaced predators but not prey species, creating spatial refuge from predation. High-human activity on roads and trails (i.e., >18 humans/day) has the potential to interfere with predator-prey interactions via trait-mediated direct and indirect effects. We urge scientist and managers to carefully consider and quantify the trait-mediated indirect effects of humans, in addition to direct effects, when assessing human impacts on wildlife and ecosystems.
Predator-prey interactions, including between large mammalian wildlife species, can be represented as a "space race", where prey try to minimize and predators maximize spatial overlap. Human activity can also influence the distribution of wildlife species. In particular, high-human disturbance can displace large carnivore predators, a trait-mediated direct effect. Predator displacement by humans could then indirectly benefit prey species by reducing predation risk, a trait-mediated indirect effect of humans that spatially decouples predators from prey. The purpose of this research was to test the hypothesis that high-human activity was displacing predators and thus indirectly creating spatial refuge for prey species, helping prey win the "space race". We measured the occurrence of eleven large mammal species (including humans and cattle) at 43 camera traps deployed on roads and trails in southwest Alberta, Canada. We tested species co-occurrence at camera sites using hierarchical cluster and nonmetric multidimensional scaling (NMS) analyses; and tested whether human activity, food and/or habitat influenced predator and prey species counts at camera sites using regression tree analysis. Cluster and NMS analysis indicated that at camera sites humans co-occurred with prey species more than predator species and predator species had relatively low co-occurrence with prey species. Regression tree analysis indicated that prey species were three times more abundant on roads and trails with >32 humans/day. However, predators were less abundant on roads and trails that exceeded 18 humans/day. Our results support the hypothesis that high-human activity displaced predators but not prey species, creating spatial refuge from predation. High-human activity on roads and trails (i.e., >18 humans/day) has the potential to interfere with predator-prey interactions via trait-mediated direct and indirect effects. We urge scientist and managers to carefully consider and quantify the trait-mediated indirect effects of humans, in addition to direct effects, when assessing human impacts on wildlife and ecosystems. PMID:21399682
Teleost fishes capture prey using ram, suction, and biting behaviors. The relative use of these behaviors in feeding on midwater\\u000a prey is well studied, but few attempts have been made to determine how benthic prey are captured. This issue was addressed\\u000a in the wrasses (Labridae), a trophically diverse lineage of marine reef fishes that feed extensively on prey that take
L. A. Ferry-Graham; P. C. Wainwright; M. W. Westneat; D. R. Bellwood
We attempted to study predation on various-sized prey by a male and female wolf (Canis lupus) with global positioning system (GPS) collars programmed to acquire locations every 10 min in the Superior National Forest\\u000a of Minnesota. During May to August 2007, we investigated 147 clusters of locations (31% of the total) and found evidence of\\u000a predation on a white-tailed deer (Odocoileus
The ability of 2nd and 4th instars and adult females of the cursorial spider, Hibana futilis (Banks), to prey on different stages of two mirid pests of cotton was examined. Small nymphs, large nymphs, and adults of the cotton fleahopper, Pseudomatoscelis seriatus (Reuter) and Creontiades signatus (...
Megaselia nidanurae Disney sp. nov. is described from a series of males and females reared from larvae preying on the eggs of the foam-nesting frog Leptodactylus fuscus (Schneider) in Trinidad. The general biology of the association suggests that this is an obligate relationship for the fly. This is the first description of a ‘frogfly’ attacking foam-nests hidden in burrows.
J. R. Downie; R. H. L. Disney; L. Collins; E. G. Hancock
To determine whether yam-boxthorn noodle, a newly developed functional noodle, has immunomodulatory effects in vivo, we measured the changes in visceral organ weight, immunoglobulin (Ig) A, IgE, IgG, IgM serum level and IgA level in the intestinal lavage fluid of female BALB/c mice after continuously consuming the test diet for 5 weeks. We found that body weights and absolute and relative organ weights (lung, heart, liver, spleen and kidney) in female BALB/c mice did not significantly change compared with those from the control group. The IgA and IgG serum levels in the experimental group significantly increased in a dose-dependent manner when the yam-boxthorn noodle concentration in the AIN 76 diet rose from 3% to 30%. However, the IgE and IgM level in the serum and the IgA level in the intestinal lavage fluid did not significantly change. These experiments demonstrate that the functional noodle, yam-boxthorn noodle, exhibits immunomodulatory effects in vivo with increasing serum antibody levels, especially in IgA and IgG. These results are valuable for future nutraceutical and immuno-pharmacological use. PMID:16109455
The medicinal leech, Hirudo verbana, is an aquatic predator that utilizes water waves to locate its prey. However, to reach their prey, the leeches must move within the same water that they are using to sense prey. This requires that they either move ballistically towards a pre-determined prey location or that they account for their self-movement and continually track prey. We found that leeches do not localize prey ballistically. Instead, they require continual sensory information to track their prey. Indeed, in the event that the prey moves, leeches will approach the prey's new location. While leeches need to continually sense water disturbances to update their percept of prey location, their own behavior is discontinuous--prey involves switching between swimming, crawling and non-locomoting. Each of these behaviors may allow for different sensory capabilities and may require different sensory filters. Here, we examined the sensory capabilities of leeches during each of these behaviors. We found that while one could expect the non-locomoting phases to direct subsequent behaviors, crawling phases were more effective than non-locomotor phases for providing direction. During crawling bouts, leeches adjusted their heading so as to become more directed towards the stimulus. This was not observed during swimming. Furthermore, in the presence of prey-like stimuli, leeches crawled more often and for longer periods of time. PMID:23785108
Harley, Cynthia M; Rossi, Matthew; Cienfuegos, Javier; Wagenaar, Daniel
In this study, prey composition and numbers of prey ingested by orb-web spiders (actual prey), as well as the food resources available in the habitat (potential prey), the retention efficiency of spider webs, and the prey selectivity of spiders, which bias the prey composition, were investigated for the garden spider Araneus diadematus and the wasp-like spider Argiope bruennichi in two
Flagellate feeding efficiency appears to depend on mor- phological characteristics of prey such as cell size and motility, as well as on other characteristics such as digest- ibility and cell surface characteristics. Bacteria of varying morphological characteristics (cell size) and mineral nutrient characteristics or food quality (as determined by the C:N:P ratio) were obtained by growing Pseudomonas fluorescens in chemostats
S. Paul Shannon; Thomas H. Chrzanowski; James P. Grover
In this activity, learners will simulate the interactions between a predator population of gray wolves and a prey population of deer in a forest. After collecting the data, the learners plot the data and then extend the graph to predict the populations for several more generations.
The importance of prey processing as an integral part of foraging behaviour has long been acknowledged, but little theoretical consideration has been given to the optimization of the processing behaviour itself. Processing renders food down to ingestible, palatable portions, and also removes non-essential mass thus reducing transport costs. Here, several models of processing are developed for a central place forager.
SEAN A. RANDS; ALASDAIR I. HOUSTON; CATHERINE E. GASSON
In this paper, we present and analyze a predator-prey model, in which both predator and prey can be infected. Each of the predator and prey is divided into two categories, susceptible and infected. The epidemics cannot be transmitted between prey and predator by predation. The predation ability of susceptible predators is stronger than infected ones. Likewise, it is more difficult to catch a susceptible prey than an infected one. And the diseases cannot be hereditary in both of the predator and prey populations. Based on the assumptions above, we find that there are six equilibrium points in this model. Using the base reproduction number, we discuss the stability of the equilibrium points qualitatively. Then both of the local and global stabilities of the equilibrium points are analyzed quantitatively by mathematical methods. We provide numerical results to discuss some interesting biological cases that our model exhibits. Lastly, we discuss how the infectious rates affect the stability, and how the other parameters work in the five possible cases within this model.
In this paper, a prey?predator dynamics, where the predator species partially depends upon the prey species, in a two patch habitat with diffusion and there is a non?diffusing additional resource for the prey population, is modeled and analyzed. It is shown, that there exists a positive, monotonic, continuous steady state solution with continuous matching at the interface for both the
Aberrant glycosylation in IgA nephropathy (IgAN). Immunoglobulin A nephropathy (IgAN) patients exhibit circulating IgA1 with reduced galactose (Gal) and\\/or sialic acid (Neu5Ac) and increased exposure of N-acetylgalactosamine (GalNAc). These IgA glycoforms fix complement and in mesangial cells regulate integrin expression, enhance nitric oxide synthase (NOS) activity, decrease endothelial growth factor synthesis, meanwhile depressing proliferation and increasing apoptotis. Drugs can be
Rotational flow is often observed in lotic ecosystems, such as streams and rivers. For example, when an obstacle interrupts water flowing in a stream, energy dissipation and momentum transfer can result in the formation of rotational flow, or a vortex. In this study, I examined how rotational flow affects a predator–prey system by constructing a spatially explicit lattice model consisting of predators, prey, and plants. A predation relationship existed between the species. The species densities in the model were given as S (for predator), P (for prey), and G (for plant). A predator (prey) had a probability of giving birth to an offspring when it ate prey (plant). When a predator or prey was first introduced, or born, its health state was assigned an initial value of 20 that subsequently decreased by one with every time step. The predator (prey) was removed from the system when the health state decreased to less than zero. The degree of flow rotation was characterized by the variable, R. A higher R indicates a higher tendency that predators and prey move along circular paths. Plants were not affected by the flow because they were assumed to be attached to the streambed. Results showed that R positively affected both predator and prey survival, while its effect on plants was negligible. Flow rotation facilitated disturbances in individuals' movements, which consequently strengthens the predator and prey relationship and prevents death from starvation. An increase in S accelerated the extinction of predators and prey.
An 8 1/2-month-old infant with absent IgM had recurrent Pseudomonas infections. IgG and IgA, but no IgM-containing plasma cells, were identified in the spleen by immunofluorescence. The spleen and lymph nodes lacked germinal centers, but Peyer's patches a...
W. P. Faulk W. S. Kiyasu M. D. Cooper H. H. Fudenberg
To clarify the underlying mechanisms of IgA nephropathy (IgAN) induced by nivalenol (NIV), a trichothecene mycotoxin, we examined the time and dose relationships of glomerular deposition of IgA by NIV in BALB/c mice (Experiment 1), and also evaluated the modification of NIV on spontaneous IgAN in an inbred murine model, a high IgA strain (HIGA), during its early stage of pathogenesis (Experiment 2). In Experiment 1, female BALB/c mice were given a diet containing 0, 12, or 24 ppm concentration of NIV for 4 or 8 weeks. An increase in serum IgA levels was found at 24 ppm from 4 weeks. At week 8 of treatment, dose-dependent increases in serum IgA levels and glomerular deposition of IgA and IgG were observed without accompanying histopathological glomerular changes. On the other hand, in Experiment 2, control HIGA mice exhibited rather high levels of serum IgA as compared with BALB/c mice from 4 weeks of experiment as well as glomerular deposition of IgA and IgG and mesangial proliferation as revealed at week 8. NIV at 24ppm further increased serum IgA in this strain; however, it did not enhance glomerular immunoglobulin deposition or histopathological lesion. These results suggest that NIV-induced increase of serum IgA levels may be primarily responsible for glomerular immunoglobulin deposition; however, NIV does not enhance glomerular IgA deposition that may lead to exacerbation of predisposed IgAN in the short term, irrespective of the further elevation of serum IgA from the high basal levels. PMID:19783131
The nesting behaviors of 10 females of Tachysphex inconspicuus (Kirby) (Hymenoptera: Crabronidae) were studied on a sandy, mowed lawn at the La Selva Biological Station in northeastern Costa Rica on 27–29 April 1980. Twenty-four completed nests were observed, excavated, and measured. The nests had oblique, short burrows leading to one or two shallow cells. Prey cockroaches belonging to 11 species of Chorisoneura and Riatia fulgida (Saussure) (Blattaria: Blattellidae), all tropical wet forest canopy indicator species, were removed from the cells, weighed, and identified. The cockroaches consisted mainly of adult females, selectively preyed upon over adult males and nymphs due to their larger sizes. The aggregate prey mass in cells was separable into prospective larger (heavier) female and smaller (lighter) male cells. Wasps usually oviposited on the heaviest cockroach in a cell, in most cases an adult female. Atypical genus behavior included (1) prey being carried to one side of the wasp and perhaps grasped by a hindleg during removal of the temporary entrance closure and nest entry and (2) wasp's egg being laid affixed to a forecoxal corium and extending backward in a longitudinally posteriad position across the prey's ventral thorax. A comparison with the nesting behavior of other species in the Tachysphex obscuripennis species group is made.
Kurczewski, Frank E.; Coville, Rollin E.; Schal, Coby
Flagellate feeding efficiency appears to depend on morphological characteristics of prey such as cell size and motility, as\\u000a well as on other characteristics such as digestibility and cell surface characteristics. Bacteria of varying morphological\\u000a characteristics (cell size) and mineral nutrient characteristics or food quality (as determined by the C:N:P ratio) were obtained\\u000a by growing Pseudomonas fluorescens in chemostats at four
S. Paul Shannon; Thomas H. Chrzanowski; James P. Grover
The Gause-Lotka-Volterra (GLV) equations are an idealized model for competition between n species. The n-RPS and May Leonard competing species models are specific cases of (GLV) which define interaction between various species differently. n-RPS couples n equations in a ?Rock-Paper-Scissors? (RPS)-type relation in which each species has both a unique predator and prey such that the n species interact with
Unpalatable insects frequently adopt multimodal signals to ward off predators, incorporating sounds and odours into their colourful displays. Pyrazine is an odour commonly used in insect warning displays, and has previously been shown to elicit unlearned biases against common warning colours, e.g. yellow and red in naive predators. We designed two experiments to test for similar effects of pyrazine on the conspicuousness of prey, perhaps the most ubiquitous aspect of aposematic coloration. In the first experiment, we offered predators (Gallus gallus domesticus) a choice between conspicuous crumbs and cryptic crumbs in the presence or absence of pyrazine. In the second experiment, we manipulated the birds' experience of conspicuous prey during an initial training phase. Only in the presence of pyrazine did birds show a bias against conspicuously coloured food, and this occurred whether or not they had previously experienced food that contrasted with the background. This emergent behaviour relied upon the visual and odorous signal components being presented together. These unlearned, yet hidden, responses against conspicuousness demonstrate that there are initial benefits to prey being conspicuous when the multimodal nature of warning signals is accounted for.
Background All vectors of human malaria, a disease responsible for more than one million deaths per year, are female mosquitoes from the genus Anopheles. Evarcha culicivora is an East African jumping spider (Salticidae) that feeds indirectly on vertebrate blood by selecting blood-carrying female mosquitoes as preferred prey. Methodology/Principal Findings By testing with motionless lures made from mounting dead insects in lifelike posture on cork discs, we show that E. culicivora selects Anopheles mosquitoes in preference to other mosquitoes and that this predator can identify Anopheles by static appearance alone. Tests using active (grooming) virtual mosquitoes rendered in 3-D animation show that Anopheles' characteristic resting posture is an important prey-choice cue for E. culicivora. Expression of the spider's preference for Anopheles varies with the spider's size, varies with its prior feeding condition and is independent of the spider gaining a blood meal. Conclusions/Significance This is the first experimental study to show that a predator of any type actively chooses Anopheles as preferred prey, suggesting that specialized predators having a role in the biological control of disease vectors is a realistic possibility.
Coupling of several predator-prey oscillations can generate intriguing patterns of synchronization and chaos. Theory predicts that prey species will fluctuate in phase if predator-prey cycles are coupled through generalist predators, whereas they will fluctuate in anti-phase if predator-prey cycles are coupled through competition between prey species. Here, we investigate predator-prey oscillations in a long-term experiment with a marine plankton community. Wavelet analysis of the species fluctuations reveals two predator-prey cycles that fluctuate largely in anti-phase. The phase angles point at strong competition between the phytoplankton species, but relatively little prey overlap among the zooplankton species. This food web architecture is consistent with the size structure of the plankton community, and generates highly dynamic food webs. Continued alternations in species dominance enable coexistence of the prey species through a non-equilibrium 'killing-the-winner' mechanism, as the system shifts back and forth between the two predator-prey cycles in a chaotic fashion. PMID:19845726
Benincŕ, Elisa; Jöhnk, Klaus D; Heerkloss, Reinhard; Huisman, Jef
High-contrast markings, called distractive or dazzle markings, have been suggested to draw and hold the attention of a viewer, thus hindering detection or recognition of revealing prey characteristics, such as the body outline. We tested this hypothesis in a predation experiment with blue tits (Cyanistes caeruleus) and artificial prey. We also tested whether this idea can be extrapolated to the background appearance and whether high-contrast markings in the background would improve prey concealment. We compared search times for a high-contrast range prey (HC-P) and a low-contrast range prey (LC-P) in a high-contrast range background (HC-B) and a low-contrast range background (LC-B). The HC-P was more difficult to detect in both backgrounds, although it did not match the LC-B. Also, both prey types were more difficult to find in the HC-B than in the LC-B, in spite of the mismatch of the LC-P. In addition, the HC-P was more difficult to detect, in both backgrounds, when compared with a generalist prey, not mismatching either background. Thus, we conclude that distractive prey pattern markings and selection of microhabitats with distractive features may provide an effective way to improve camouflage. Importantly, high-contrast markings, both as part of the prey coloration and in the background, can indeed increase prey concealment.
Dimitrova, Marina; Stobbe, Nina; Schaefer, H. Martin; Merilaita, Sami
Studies of prey detection have typically focused on how search image affects the capture of cryptic items. This study also considers how background vegetation influences cryptic prey detection. Blue jays, Cyanocitta cristata, searched digitized images for two Catocala moths: C. ilia, which is cryptic on oak, and C. relicta, which is cryptic on birch. Some images contained moths while others did not. The ability of blue jays to detect prey during repeated presentations of one prey type within a session was compared with their performance during randomly alternating presentations of both prey types within a session to examine search-image formation under two background conditions (informative and ambiguous). In the informative background condition, both trees in the image were of the same species and therefore, the background was a reliable indicator of which prey type might be present. In the ambiguous background condition, there was one tree of each species in the image and either prey type could be present. The results indicate that: (1) a search-image effect was observed only for the more cryptic prey type and only when the background was informative; (2) as accuracy on prey images (those with moths) increased, response latency remained unchanged; (3) performance on nonprey images (those without moths) was primarily determined by the difficulty of searching the background and not by the prey type in the accompanying prey images; and (4) search-image effects disappeared with extended practice. These results suggest that the ability to detect prey is influenced by background and that the presence of either multiple backgrounds or multiple prey types interferes with search-image formation. Copyright 1998 The Association for the Study of Animal Behaviour. PMID:9790707
IgG and IgM isotype antibodies to polyclonal human IgA, myeloma IgA1, and myeloma IgA2 were estimated in 38 IgA-deficient children aged between 0.9 and 15 years. All children had IgM anti-IgA antibodies. IgG antibodies against either polyclonal IgA, IgA1, or IgA2 were present in 63% of the IgA-deficient children. IgG anti-IgA antibodies were detected against all three antigens in 8
F. H. Sennhauser; C. S. Hosking; C. L. Jones; R. A. Macdonald; N. Mermelstein; D. M. Roberton
Carnivorous plants match their animal prey for speed of movements and hence offer fascinating insights into the evolution of fast movements in plants. Here, we describe the mechanics of prey capture in aquatic bladderworts Utricularia stellaris, which prey on swimming insect larvae or nematodes to supplement their nitrogen intake. The closed Utricularia bladder develops lower-than-ambient internal pressures by pumping out water from the bladder and thus setting up an elastic instability in bladder walls. When the external sensory trigger hairs on their trapdoor are mechanically stimulated by moving prey, the trapdoor opens within 300-700 ?s, causing strong inward flows that trap their prey. The opening time of the bladder trapdoor is faster than any recorded motion in carnivorous plants. Thus, Utricularia have evolved a unique biomechanical system to gain an advantage over their animal prey. PMID:21389013
Carnivorous plants match their animal prey for speed of movements and hence offer fascinating insights into the evolution of fast movements in plants. Here, we describe the mechanics of prey capture in aquatic bladderworts Utricularia stellaris, which prey on swimming insect larvae or nematodes to supplement their nitrogen intake. The closed Utricularia bladder develops lower-than-ambient internal pressures by pumping out water from the bladder and thus setting up an elastic instability in bladder walls. When the external sensory trigger hairs on their trapdoor are mechanically stimulated by moving prey, the trapdoor opens within 300–700 ?s, causing strong inward flows that trap their prey. The opening time of the bladder trapdoor is faster than any recorded motion in carnivorous plants. Thus, Utricularia have evolved a unique biomechanical system to gain an advantage over their animal prey.
Large carnivores range more widely than many other terrestrial mammals, and this behavior tends to bring them into frequent conflict with humans. Within any carnivore population, individual variation in patterns of space use should be expected to make some animals more vulnerable than others to risks of mortality from humans and other sources. In this study, our goal was to document variation among individuals in space use by female spotted hyenas (Crocuta crocuta). We examined predictions of hypotheses suggesting that space use by female hyenas is affected by reproductive state, social rank, and local prey abundance. Home-range size, distance at which females were found from the current communal den, and distance at which they were found from the nearest territorial boundary all varied significantly with the 3 independent variables. Females with den-dwelling cubs had smaller home ranges, were found closer to the communal den, and were found farther from the territorial boundary than were females with no den-dwelling cubs. Neither social rank nor prey availability significantly influenced the space-use patterns of females with den-dwelling cubs. Among females with no den-dwelling cubs, high-ranking females had smaller home ranges, were closer to the communal den, and were farther from the territorial boundary than were low-ranking females. The females ranging most widely were low-ranking individuals with no den-dwelling cubs when they were observed during periods of prey scarcity.
Boydston, E. E.; Kapheim, K. M.; Szykman, M.; Holekamp, K. E.
Recently, Kohlmeier and Ebenhöh showed that cannibalism can stabilize population cycles in a Lotka-Volterra type predator-prey model. Population cycles in their model are due to the interaction between logistic population growth of the prey and a hyperbolic functional response. In this paper, we consider a predator-prey system where cyclic population fluctuations are due to the age structure in the predator
Recently, Kohlmeier and Ebenhh showed that cannibalism can stabilize population cycles in a Lotka-Volterra type predator-prey\\u000a model. Population cycles in their model are due to the interaction between logistic population growth of the prey and a hyperbolic\\u000a functional response. In this paper, we consider a predator-prey system where cyclic population fluctuations are due to the\\u000a age structure in the predator
. In this paper we discuss uniform persistence (UP) criteria of two prey- one predator systems, where we consider that the\\u000a predator's diet selection is a sigmoidal function of the most profitable prey type in place of a step function of conventional\\u000a diet choice theory. We also derive UP results of the system with direct interspecific competition between the prey.
Prey preferences of large carnivores (tiger (Panthera tigris), leopard (Panthera pardus) and dhole (Cuon alpinus)) in the tropical forest of Anamalai Tiger Reserve (ATR) were evaluated. This was the first study in ATR to estimate the\\u000a density of prey and the food habits of these large carnivores. The 958-km2 intensive study area was found to have a high mammalian prey
Arumugam Kumaraguru; R. Saravanamuthu; K. Brinda; S. Asokan
We studied prey processing in the Siamese fighting fish (Betta splendens), involving slow, easily observed head-bobbing movements, which were compared with prey processing in other aquatic feeding vertebrates. We hypothesized that head-bobbing is a unique prey-processing behaviour, which alternatively could be structurally and functionally analogous with raking in basal teleosts, or with pharyngognathy in neoteleosts. Modulation of head-bobbing was elicited by prey with different motility and toughness. Head-bobbing involved sustained mouth occlusion and pronounced cranial elevation, similar to raking. However, the hyoid and pectoral girdle were protracted, and not retracted as in both raking and pharyngognathy. High-speed videofluoroscopy of hyoid movements confirmed that head-bobbing differs from other known aquatic prey-processing behaviours. Nevertheless, head-bobbing and other prey-processing behaviours converge on a recurrent functional theme in the trophic ecology of aquatic feeding vertebrates; the use of intraoral and oropharyngeal dentition surfaces to immobilize, reduce and process relatively large, tough or motile prey. Prey processing outside the pharyngeal region has not been described for neoteleosts previously, but morphological evidence suggests that relatives of Betta might use similar processing behaviours. Thus, our results suggest that pharyngognathy did not out-compete ancestral prey-processing mechanisms completely during the evolution of neoteleosts. PMID:23612845
Konow, Nicolai; Krijestorac, Belma; Sanford, Christopher P J; Boistel, Renauld; Herrel, Anthony
Bdellovibrio bacteriovorus?HD100 is an obligate predator that invades and grows within the periplasm of Gram-negative bacteria, including mcl-polyhydroxyalkanoate (PHA) producers such as Pseudomonas putida. We investigated the impact of prey PHA content on the predator fitness and the potential advantages for preying on a PHA producer. Using a new procedure to control P.?putida?KT2442 cell size we demonstrated that the number of Bdellovibrio progeny depends on the prey biomass and not on the viable prey cell number or PHA content. The presence of mcl-PHA hydrolysed products in the culture supernatant after predation on P.?putida?KT42Z, a PHA producing strain lacking PhaZ depolymerase, confirmed the ability of Bdellovibrio to degrade the prey's PHA. Predator motility was higher when growing on PHA accumulating prey. External addition of PHA polymer (latex suspension) to Bdellovibrio preying on the PHA minus mutant P.?putida?KT42C1 restored predator movement, suggesting that PHA is a key prey component to sustain predator swimming speed. High velocities observed in Bdellovibrio preying on the PHA producing strain were correlated to high intracellular ATP levels of the predator. These effects brought Bdellovibrio fitness benefits as predation on PHA producers was more efficient than predation on non-producing bacteria. PMID:23227863
Martínez, Virginia; Jurkevitch, Edouard; García, José Luis; Prieto, María Auxiliadora
Background: Riedel's thyroiditis (RT) is a very rare chronic fibrosing disorder of unknown etiology that is often associated with multifocal fibrosclerosis (MFS). IgG4-related sclerosing disease (IgG4-RSD), a new clinico-pathological entity also associated with MFS, is characterized by IgG4+ plasma cell infiltration and fibrosis in one or more organs. Although the association of RT and IgG4-RSD has been suggested, it has seldom been studied or reported. We report a classical case of RT with serological (IgG4 levels) and immunohistochemical (IgG and IgG4) assessment, in search of an underlying IgG4-RSD. Patient: The patient was a 57-year-old female who underwent a subtotal thyroidectomy for a long-standing goiter with a rapidly enlarging isthmic nodule. Results: Histopathological examination of the surgical specimen revealed all of the morphological features of RT and IgG4-RSD, including partial fibrosis of the thyroid gland with destruction of the thyroid follicular architecture; obliterative phlebitis; and a mixed infiltrate composed of lymphocytes, eosinophils, and plasma cells. The fibro-inflammatory process extended beyond the thyroid capsule into the surrounding tissues. Immunohistochemical examination revealed up to 70 IgG4+ plasma cells per high power field with an IgG4/IgG ratio of 35%. Although serum levels of IgG4 were normal (20 mg/dl), total IgG levels were slightly elevated (1,370 mg/dl). There was no evidence of involvement of other organs at the time of RT diagnosis. Conclusions: The morphological similarities between RT and IgG4-RSD suggest that these entities are closely related. Therefore, RT with increased IgG4+ plasma cells, with or without elevated IgG4 serum levels, may represent the first clinical manifestation of an underlying IgG4-RSD. However, due to the rarity of both conditions and the limited specificity and sensitivity of both IgG4 serum levels and IgG/IgG4 immunohistochemistry in the diagnosis of IgG4-RSD, further studies are needed to verify this hypothesis. PMID:22612375
Background Rheumatoid factors (RFs) and antibodies against cyclic citrullinated peptides (CCPs) of IgG, IgA and IgM isotype have been shown to precede disease onset by years. Objective To evaluate serological risk markers in first-degree relatives from multicase families in relation to genetic and environmental risk factors. Methods 51 multicase families consisting of 163 individuals with rheumatoid arthritis (RA) (mean±SD age, 60±14 years; disease duration 21 years; 71.8% female) and with 157 first-degree relatives unaffected by RA (54±17 years; 59.9% female) were recruited. Isotypes of antibodies against CCPs (IgG, IgA and IgM) and RFs (IgM and IgA) were determined using automated enzyme immunoassays. Cut-off levels were established using receiver operating characteristic curves based on values for 100 unrelated healthy controls. Results The concentrations and frequencies of all anti-CCP and RF isotypes were significantly increased in first-degree relatives and patients with RA compared with unrelated healthy controls. The relative distribution of IgA and IgM isotypes was higher than IgG in the relatives, whereas the IgG isotype dominated in patients with RA. The patients carried human leucocyte antigen-shared epitope (HLA-SE) significantly more often than the relatives (71.4% vs 53.9%, p=0.01), while the frequency of the PTPN22 T variant was similar. HLA-SE, combined with smoking, was significantly related to all combinations of anti-CCP and RF isotypes in patients with RA. No such relationships were found for the first-degree relatives. Conclusions All anti-CCP and RF isotypes analysed occurred more commonly in unaffected first-degree relatives from multicase families than in controls, but with different isotype distribution from patients with RA.
Longstanding theory in behavioral ecology predicts that prey should evolve decreased foraging rates under high predation threat. However, an alternative perspective suggests that growth into a size refuge from gape-limited predation and the future benefits of large size can outweigh the initial survival costs of intense foraging. Here, I evaluate the relative contributions of selection from a gape-limited predator (Ambystoma opacum) and spatial location to explanations of variation in foraging, growth, and survival in 10 populations of salamander larvae (Ambystoma maculatum). Salamander larvae from populations naturally exposed to intense A. opacum predation risk foraged more actively under common garden conditions. Higher foraging rates were associated with low survival in populations exposed to free-ranging A. opacum larvae. Results demonstrate that risky foraging activity can evolve in high predation-risk habitats when the dominant predators are gape-limited. This finding invites the further exploration of diverse patterns of prey foraging behavior that depends on natural variation in predator size-selectivity. In particular, prey should adopt riskier behaviors under predation threat than expected under existing risk allocation models if foraging effort directly reduces the duration of risk by growth into a size refuge. Moreover, evidence from this study suggests that foraging has evolved over microgeographic scales despite substantial modification by regional gene flow. This interaction between local selection and spatial location suggests a joint role for adaptation and maladaptation in shaping species interactions across natural landscapes, which is a finding with implications for dynamics at the population, community, and metacommunity levels. PMID:17724339
Organisms with complex life histories (CLH) often cross habitat or ecosystem boundaries as they develop from larvae to adults, coupling energy flow between ecosystems as both prey (bottom-up) and consumers (top-down). Predation effects on one stage of this life cycle can therefore cascade across ecosystems, magnifying the impact of local predation. The majority of predation studies have assessed effects only on a local level, within the habitat of the predator. I used large outdoor stream mesocosms to test the hypothesis that predation in an aquatic habitat alters the magnitude and trophic structure of a prey assemblage in a terrestrial habitat. I also tested how a consumer in the terrestrial habitat (web-weaving spiders) responded to these changes in prey export. Two fish species were the predators (red shiner, Cyprinella lutrensis and orangethroat darter, Etheostoma spectabile) in an experiment with three treatments: both fish species monocultures plus a fishless control. Fish predation reduced aquatic insect emergence biomass by 50% compared to the fishless control and altered the trophic structure of the emergent community, reducing emerging insect predator biomass by 50%, but had no effect on other insect trophic groups. Spiders captured only insects that were unaffected by fish predation (mostly chironomids) and therefore did not respond numerically to overall changes in insect abundance or biomass. Patterns of insect emergence were largely driven by a strong negative relationship between fish and a predatory dragonfly (Pantala flavescens). The results of this experiment show that predation in one habitat can have strong effects on the biomass and trophic structure of subsidies entering adjacent habitats, resulting in contrasting predictions for the role of these subsidies in recipient food webs. In the absence of fish, aquatic habitats produced terrestrial insect communities with higher biomass (bottom-up potential) and a higher proportion of predators (top-down potential) than when fish were present. PMID:20503875
The relative abundance and size of prey fish in the stomachs of the predator Acestrorhynchus pantaneiro were compared with those recorded in the field to estimate prey selection. Fish samples were taken monthly in the Manso Reservoir (State of Mato Grosso, Brazil) immediately after the impoundment, from March 2000 to February 2001 (period I) and from March 2003 to February 2004 (period II). In period I, the small relative dominance of the prey in the environment seemed to have lead to random foraging. In period II, however, when the forage fish Moenkhausia dichroura was dominant in the environment, the predator shifted its diet, foraging mainly on this prey. Species with short relative body depth were positively selected. The prey size classes between 30 and 49 mm, and 50 and 69 mm standard length (L(S)) were the most abundant in the environment. Small prey were predominantly selected by A. pantaneiro. Even when a given prey or prey size was predominant in the environment, A. pantaneiro was a selective predator and maintained its preferences associated to prey type and L(S), although it consumed the most abundant resource. PMID:20738483
Gauss's competitive exclusive principle states that two competing species having analogous environment cannot usually occupy the same space at a time but in order to exploit their common environment in a different manner, they can co-exist only when they are active in different times. On the other hand, several studies on predators in various natural and laboratory situations have shown that competitive coexistence can result from predation in a way by resisting any one prey species from becoming sufficiently abundant to outcompete other species such that the predator makes the coexistence possible. It has also been shown that the use of refuges by a fraction of the prey population exerts a stabilizing effect in the interacting population dynamics. Further, the field surveys in the Sundarban mangrove ecosystem reveal that two detritivorous fishes, viz. Liza parsia and Liza tade (prey population) coexist in nature with the presence of the predator fish population, viz. Lates calcarifer by using refuges. In view of such observations in mind, a three-component model consisting of two prey and one predator population is considered in the present investigation with the inclusion of Holling type-II response function incorporating a constant proportion of prey refuge. The essential mathematical features of the present model have been analyzed thoroughly in terms of the local and the global stability and the bifurcations arising in some selected situations as well. The threshold values for some parameters indicating the feasibility and the stability conditions of some equilibria are also determined. The ranges of the significant parameters under which the system admits a Hopf bifurcation are investigated. The explicit formulae for determining the stability, direction and other properties of bifurcating periodic solutions are also derived with the use of both the normal form and the central manifold theory. Numerical illustrations are performed finally in order to validate the applicability of the model under consideration. PMID:22944143
Titi monkeys (genus Callicebus) are small-bodied platyrrhines that supplement their predominantly frugivorous diet with variable amounts of leaves, seeds, and/or arthropod prey. Notable interspecific variation in the amount of insect prey in the diet has been observed in Callicebus, ranging from 0% to 20%. In this study, I investigate the degree and type of prey foraging in a little-known species, Callicebus oenanthe inhabiting a fragmented, secondary forest on the foothills of the Andes in northern Peru. I present data on prey type, prey search and capture techniques, substrate/vegetation use, foraging height, prey capture efficiency, and seasonal variation of insect prey foraging in one group of C. oenanthe observed from January to August 2005. Insect prey accounted for 22% of the diet, the highest amount reported for any Callicebus species to date, and insects from at least six different orders were included. C. oenanthe was mainly an investigative forager of hidden prey, manipulating easy-to-open substrates such as rolled up leaves, and hunted ant swarms and larger insects opportunistically. Insect foraging was predominant during the dry season (26%) and decreased during the wet season (13%). The study group foraged mostly in the understory (2-6 m) within vine-laden shrubs and trees, which may conform to an anti-predator strategy of crypticity. Overall the group had an 83% insect capture success rate. These data suggest that insect prey is an important part of the diet of C. oenanthe and may be especially notable during periods of resource scarcity. This study adds to the knowledge concerning insect prey foraging in Callicebus, which can have an important role in defining ecological strategies in the selection of secondary protein food resources within a given ecosystem. PMID:22311736
New research shows how bats use echolocation unexpectedly to detect silent and stationary prey in darkness. Bats may use acoustic search images to identify potential prey when prey-generated noises, visual and olfactory cues are absent. PMID:23518059
Out of 732 renal biopsies performed from 1988 to 1995 in Queen Elizabeth Hospital, 65 patients (8.9%, 43 male, 22 female) were diagnosed to have IgM mesangial nephropathy (IgMN). The mean age of the patients was 35 ±2 years. The clinical manifestations and progression of IgMN were studied in 39 of these 65 patients. The initial manifestations of the disease
Relevant to the investigation of genetic factors involved in allergic response is the mode of inheritance of IgE levels, an important factor in allergic disease. Serum total IgE levels in 208 Pennsylvania Amish individuals from 23 nuclear families were studied. Males had a significantly higher mean in IgE level than females. There was also a significant negative relationship between age
Abstract Predation is an established cause of cycling in prey species. Here, the ability of predation to explain periodic travelling waves in prey populations, which have recently been found in a number of spatiotemporal field studies, is examined. The nature of periodic waves in these systems, and the way in which they can be generated by the invasion of predators
This paper describes the prey-predator multiagent system which can be considered as an abstraction of more complex real-world models. Both the prey and the predators are considered as autonomous agents with their own behaviors and perception of the environment. In particular, we propose a simulator which lets study different strategies such as cooperation and individualism. An extensive experiment has been
Abstract Food habits of tigers Panthera tigris and population attributes of prey species (population structure, density and biomass) were studied in the tropical dry deciduous forest of Pench National Park, Central India, from November 1998 to April 1999. Scat analysis and line transect method were used to estimate tiger food habits and density of major prey species, respectively. The 61.1
Response of newly hatched, predatory snails to competing chemical cues from co-occurring species ofprey were determined in laboratory experiments. Eggcapsules of Urosalpinx cinerea were collected from an intertidal, vertically zoned community of prey species. The most prevalent prey were barnacles Semibalanus balanoides and Balanus eburneus, oysters Crassostrea virginica, mussels Mytilus edulis, and bryozoans Membranipora tenuis and Schizoporella irrorata. Snail chemotaxis
LESLIE G. WILLIAMS; DAN RI; BETSY BROWN; MELBOURNE R. CARRIKER
Aposematic prey warn predators of their toxicity using conspicuous signals. However, predators regularly include aposematic prey in their diets, particularly when they are in a poor energetic state and in need of nutrients. We investigated whether or not an environmental factor, ambient temperature, could change the energetic state of predators and lead to an increased intake of prey that they know to contain toxins. We found that European starlings, Sturnus vulgaris, increased their consumption of mealworm, Tenebrio molitor, prey containing quinine (a mild toxin) when the ambient temperature was reduced below their thermoneutral zone from 20 °C to 6 °C. The birds differed in their sensitivity to changes in ambient temperature, with heavier birds increasing the number of toxic prey they ate more rapidly with decreasing temperature compared to birds with lower body mass. This could have been the result of their requiring more nutrients at lower temperatures or being better able to detoxify quinine. Taken together, our results suggest that conspicuous coloration may be more costly at lower temperatures, and that aposematic prey may need to invest more in chemical defences as temperatures decline. Our study also provides novel insights into what factors affect birds' decisions to eat toxic prey, and demonstrates that selection pressures acting on prey defences can vary with changing temperature across days, seasons, climes, and potentially in response to climate change.
Predator kills rate (i.e., kills per predator per time) is routinely presupposed to depend exclusively on prey density. However, per capita rates of killing may typically depend on the density of both prey and predator. Unfortunately, our perception of many ecological phenomena may be limited by the inappropriate assumption that kill rates do not depend on predator density. One of
John A. Vucetich; Rolf O. Peterson; Carrie L. Schaefer
Summary 1. There exists a continuing dilemma in prioritizing conservation actions for large carnivores. Habitat loss, poaching, and prey depletion have often been cited as the three primary threats, but there is debate over the relative importance of each. 2. We assess the relative importance of poaching and prey depletion rates, and use existing information in the literature and multi-type
Guillaume Chapron; Dale G. Miquelle; Amaury Lambert; John M. Goodrich; Stéphane Legendre; Jean Clobert
Variation in the temporal pattern of vulnerability can provide important insights into predator-prey relationships and the evolution of antipredator behavior. We illustrate these points with a system that has coyotes (Canis latrans) as a predator and two species of congeneric deer (Odocoileus spp.) as prey. The deer employ different antipredator tactics (aggressive defense vs. flight) that result in contrasting patterns of age-dependent vulnerability in their probability of being captured when encountered by coyotes. We use long-term survival data and a simple mathematical model to show that (1) species differences in age-dependent vulnerability are reflected in seasonal predation rates and (2) seasonal variation in prey vulnerability and predator hunt activity, which can be associated with the availability of alternative prey, interact to shape seasonal and annual predation rates for each prey species. Shifting hunt activity from summer to winter, or vice versa, alleviated annual mortality on one species and focused it on the other. Our results indicate that seasonal variation in prey vulnerability and hunt activity interact to influence the impact that a predator has on any particular type of prey. Furthermore, these results indicate that seasonal variation in predation pressure is an important selection pressure shaping prey defenses. PMID:18840071
Lingle, Susan; Feldman, Alex; Boyce, Mark S; Wilson, W Finbarr
The functional response is a key element in predator–prey models as well as in food chains and food webs. Classical models consider it as a function of prey abundance only. However, many mechanisms can lead to predator dependence, and there is increasing evidence for the importance of this dependence. Identification of the mathematical form of the functional response from real
To investigate whether Northern Goshawk (Accipiter gentilis) reproduction is food-limited, we evaluated the reproductive output from 401 goshawk breeding opportunities on the Kaibab Plateau, Arizona during 1999-2002. Concurrently, we estimated densities of 10 goshawk prey species (seven birds, three mammals) using distance sampling. We then assessed the relationship between goshawk produc- tivity (number of fledglings produced) and prey density within
SUSAN R. SALAFSKY; RICHARD T. R EYNOLDS; BARRY R. NOON
Predators can have positive impacts on their prey through such mechanisms as nutrient mineralization and prey transport. These positive feedbacks have the potential to change predictions based on food web theory, such as the assertion that enrichment is destabilizing. We present a model of a simple food web, consisting of a resource, a consumer, and its predator. We assume that
David H. Brown; Howard Ferris; Shenglei Fu; Richard Planta
Habitat loss and fragmentation are among the greatest threats to biodiversity, and these threats can be exacerbated or alleviated by the presence of interacting species. The effect of habitat loss and fragmentation on predator-prey systems has received extensive theoretical attention, but empirical studies of these systems yield few clear patterns. I examined the influence of prey abundance and spatial distribution
Stalking is a crime typified by repeated harassment of another person and intrusion upon his or her privacy. Cyberstalking extends stalking into the realm of cyberspace wherein a predator stalks a victim or prey through Internet technologies such as emails, chat rooms, and instant messaging. This paper describes the Predator and Prey Alert (PAPA) system. PAPA consists of a set
Sudhir Aggarwal; Mike Burmester; Peter Henry; Leo Kermes; Judie Mulholland
In habitats where prey is either rare or difficult to predict spatiotemporally, such as open habitats, predators must be adapted to react effectively to variations in prey abundance. Open-habitat foraging bats have a wing morphology adapted for covering long distances, possibly use information transfer to locate patches of high prey abundance, and would therefore be expected to show an aggregative response at these patches. Here, we examined the effects of prey abundance on foraging activities of open-habitat foragers in comparison to that of edge-habitat foragers and closed-habitat foragers. Bat activity was estimated by counting foraging calls recorded with bat call recorders (38,371 calls). Prey abundance was estimated concurrently at each site using light and pitfall traps. The habitat was characterized by terrestrial laser scanning. Prey abundance increased with vegetation density. As expected, recordings of open-habitat foragers clearly decreased with increasing vegetation density. The foraging activity of edge- and closed-habitat foragers was not significantly affected by the vegetation density, i.e., these guilds were able to forage from open habitats to habitats with dense vegetation. Only open-habitat foragers displayed a significant and proportional aggregative response to increasing prey abundance. Our results suggest that adaptations for effective and low-cost foraging constrains habitat use and excludes the guild of open-habitat foragers from foraging in habitats with high prey abundance, such as dense forest stands. PMID:22218944
Müller, Jörg; Mehr, Milenka; Bässler, Claus; Fenton, M Brock; Hothorn, Torsten; Pretzsch, Hans; Klemmt, Hans-Joachim; Brandl, Roland
The IgM serum level was determined in the members of 29 healthy families. The IgM mean concentrations between fathers and mothers and between sons and daughters were significantly different (P less than .01), with higher serum IgM levels in females than in males. Simple linear regression analysis was done for the following intrafamilial combinations: son-father, daughter-father, son-mother, and daughter-mother. Significant correlation coefficients (P less than .05) were obtained in all four combinations, which does not support the X-linked gene hypothesis (i.e., that the X chromosome carries quantitative genes for immunoglobulin M). An alternative explanation for the differences between sexes for IgM serum concentration is considered.
Guizar-Vazquez, J; Saint-Martin, F P; Rostenberg, I; Suarez, P E; Armendares, S
Background: Determination of reference ranges of each serum protein in normal population of each country is required for studies and clinical interpretation. The aim of this study was defining reference range values of immunoglobulins and complement components in Iranian healthy children. Methods: This study was conducted from June 2003 to June 2006 in Immunology, Asthma and Allergy Research Institute, Tehran University of Medical Sciences. Serum levels of IgG, IgM, IgA, C3 and C4 in 800 Iranian healthy children from newborn to 18 years of age in four population were measured by nephelometry. Kolmogrov-Smirnov tests and Pearson correlation tests were used for analysis. Results: Our results mainly agree with previous reports, except for some discrepancy that might be due to the ethnic and geographic variety. There was a significant difference between two sexes only with IgA in the group of 1–3 months old, which was higher in male group and IgM in groups of 3–5, 6–8 and 9–11 years old that were higher in female groups. Mean of other serum immunoglobulins and complements was not significantly different between male and female groups. Conclusion: These results can be considered as a local reference for use in laboratories, clinical interpretations, and research for Iranian children.
Kardar, GA; Oraei, M; Shahsavani, M; Namdar, Z; Kazemisefat, GE; Haghi Ashtiani, MT; Shams, S; Pourpak, Z; Moin, M
We have constructed a synthetic ecosystem consisting of two Escherichia coli populations, which communicate bi-directionally through quorum sensing and regulate each other's gene expression and survival via engineered gene circuits. Our synthetic ecosystem resembles canonical predator–prey systems in terms of logic and dynamics. The predator cells kill the prey by inducing expression of a killer protein in the prey, while the prey rescue the predators by eliciting expression of an antidote protein in the predator. Extinction, coexistence and oscillatory dynamics of the predator and prey populations are possible depending on the operating conditions as experimentally validated by long-term culturing of the system in microchemostats. A simple mathematical model is developed to capture these system dynamics. Coherent interplay between experiments and mathematical analysis enables exploration of the dynamics of interacting populations in a predictable manner.
Balagadde, Frederick K; Song, Hao; Ozaki, Jun; Collins, Cynthia H; Barnet, Matthew; Arnold, Frances H; Quake, Stephen R; You, Lingchong
Prey size and species selection of pikeperch Sander lucioperca and Volga pikeperch Sander volgensis were investigated in relation to predator size in the shallow Lake Balaton, Hungary. Although their gape sizes were similar, S. lucioperca shifted to piscivory earlier and consumed fewer, but larger, prey than S. volgensis. Prey species preference of the two piscivores also differed. A bimodal prey size distribution resulted in a reclining sigmoid curve for the life span predator size to prey size relationship with inflexion points between 266 and 284 mm predator standard length (L(S) ) in S. lucioperca. In S. volgensis, as well as in S. lucioperca L(S) ? 350 mm, prey size increased monotonically with predator L(S) , following a power trend for all prey size variables. Prey depth to predator L(S) relationship varied significantly with prey species and prey number in both piscivores, and prey depth tended to be smaller in predators consuming more than one prey. Both predator species characteristically selected less active, benthic prey fishes in spite of their spiny fin rays, and small- and mid-sized predators selected for small prey. Relatively large prey were also eaten, however, especially by the smallest and largest S. lucioperca. PMID:22141894
In freshwater ecosystems, rotifers and cladocerans are ideal prey for fish larvae whereas copepods, due to their purported low growth rate and predatory tendency, are not. We recently isolated the parthenogenetic Elaphoidella grandidieri (Gueme et Richard, 1893) a benthic freshwater harpacticoid, from a fish farm in the State of Morelos, central Mexico and tested its potential as a live prey organism for larval vertebrates. Population growth and life table demography experiments were conducted, in 100 ml recipients with 50 ml of test medium on a diet of Scenedesmus acutus at a density of 1.0 X 10(6) cell ml(-1); the former on live algae alone while the latter on live algae as well as detritus. We also conducted experiments to document the prey preference for this copepod by the larval Ameca splendens (Pisces: Goodeidae) and Ambystoma mexicanum (Amphibia: Ambystomatidae), fed the rotifer Plationus patulus, the ostracod Heterocypris incongruens, and the cladocerans Moina macrocopa and Daphnia pulex. Elaphoidella grandidieri is relatively easy to maintain under laboratory conditions, reaching densities (copepodites and adults) of more than 10,000 l(-1). The generation time ranged between 30-45 days, depending on the diet. The net reproductive rate was as high as 60 nauplii female(-1) day (1). Population growth rates ranged between 0.03 and 0.11 d(-1), live algae being the superior diet compared to detritus. Both predators showed no preference for E. grandidieri, but in the absence of alternate prey they consumed 80% of the harpacticoids offered. The data have been discussed in relation to the potential of E. grandidierias live food for aquaculture. PMID:22315830
Autoimmune pancreatitis (AIP) type 1 is commonly associated with simultaneous involvement of extrapancreatic organs. Sclerosing cholangitis, sialadenitis, retroperitoneal fibrosis, Sjögren syndrome, and other extrapancreatic lesions are often observed concurrently with AIP. High levels of immunoglobulin G4 (IgG4) in the blood serum and affected tissues are typical of this diagnostic entity. We describe a case report of a 58-year-old female with findings of AIP (according to Asian criteria), IgG4-positive mastitis, and histologically verified Mikulicz syndrome. The effect of corticoid therapy supported the diagnosis of AIP and simultaneously led to the eradication of recurrent mastitis. To the best of our knowledge, this is the first reported case of concurrent findings of AIP and IgG4 mastitis. Our case report supports the concept of systemic IgG4 syndrome with multisystem involvement. Timely diagnosis and appropriate therapy can be effective in a high percentage of patients.
Autoimmune pancreatitis (AIP) type 1 is commonly associated with simultaneous involvement of extrapancreatic organs. Sclerosing cholangitis, sialadenitis, retroperitoneal fibrosis, Sjögren syndrome, and other extrapancreatic lesions are often observed concurrently with AIP. High levels of immunoglobulin G4 (IgG4) in the blood serum and affected tissues are typical of this diagnostic entity. We describe a case report of a 58-year-old female with findings of AIP (according to Asian criteria), IgG4-positive mastitis, and histologically verified Mikulicz syndrome. The effect of corticoid therapy supported the diagnosis of AIP and simultaneously led to the eradication of recurrent mastitis. To the best of our knowledge, this is the first reported case of concurrent findings of AIP and IgG4 mastitis. Our case report supports the concept of systemic IgG4 syndrome with multisystem involvement. Timely diagnosis and appropriate therapy can be effective in a high percentage of patients. PMID:24073323
Portia fimbriata from Queensland, Australia, is an araneophagic jumping spider (Salticidae) that includes in its predatory strategy a tactic (cryptic stalking) enabling it to prey effectively on a wide range of salticids from other genera. Optical cues used by P. fimbriata to identify the salticid species on which it most commonly preys, Jacksonoides queenslandicus, were investigated experimentally in the laboratory
The size of predators that consume the most fish and the size of prey fish that are the most vulnerable to predation are important factors to consider when assessing the predation risks to valued prey fish such as Chinook salmon Oncorhynchus tshawytscha in the Pacific Northwest. We found that native salmonids' risk of predation by nonnative smallmouth bass Micropterus dolomieu
Megaselia dentata sp. nov., M. ficaria sp. nov., M. parvorata sp. nov., M. surophila sp. nov. and M. vorata sp. nov. are described from South Africa. M. dentata and M. parvorata are reported from Zambia also. The larvae develop in the fruits of figs (Ficus spp.). The adult females of M. vorata and M. parvorata, at least, prey upon adult
Working from archaeofaunal trends in the Mediterranean Basin and modern wildlife data, we present a demographic interpretation\\u000a of Paleolithic prey “choice” with the aid of computer simulation modeling. Archaeological indications of expanding dietary\\u000a breadth with the onset of the Upper Paleolithic period associate with increasing exploitation of highly productive small animals\\u000a and smaller ungulate species, despite the higher procurement costs
Mary C. Stiner; Joseph E. Beaver; Natalie D. Munro; Todd A. Surovell
Ecosystem-based management (EBM) of marine resources attempts to conserve interacting species. In contrast to single-species fisheries management, EBM aims to identify and resolve conflicting objectives for different species. Such a conflict may be emerging in the northeastern Pacific for southern resident killer whales (Orcinus orca) and their primary prey, Chinook salmon (Oncorhynchus tshawytscha). Both species have at-risk conservation status and
Rob Williams; Martin Krkošek; Erin Ashe; Trevor A. Branch; Steve Clark; Philip S. Hammond; Erich Hoyt; Dawn P. Noren; David Rosen; Arliss Winship
Elevated water temperatures, a decrease in ocean pH, and an increasing prevalence of severe storms have lead to bleaching and death of the hard corals that underpin coral reef ecosystems. As coral cover declines, fish diversity and abundance declines. How degradation of coral reefs affects behavior of reef inhabitants is unknown. Here, we demonstrate that risk assessment behaviors of prey are severely affected by coral degradation. Juvenile damselfish were exposed to visual and olfactory indicators of predation risk in healthy live, thermally bleached, and dead coral in a series of laboratory and field experiments. While fish still responded to visual cues in all habitats, they did not respond to olfactory indicators of risk in dead coral habitats, likely as a result of alteration or degradation of chemical cues. These cues are critical for learning and avoiding predators, and a failure to respond can have dramatic repercussions for survival and recruitment. PMID:23403754
Lönnstedt, Oona M; McCormick, Mark I; Chivers, Douglas P
During the examination of 158 birds of prey -- Buteo buteo (85), Falco tinnunculus (30), Accipiter gentilis (19), Accipiter nisus (18), Circus aeruginosus (2), Circus pygargus (1), Pandion haliaetus (1), Pernis apivorus (1), Falco subbuteo (1) and faeces samples of Falco tinnunculus 4 protozoan species, 1 trematode species, 2 cestode species, 13 nematode species, 2 acanthocephalan species and 5 mallophaga species could be detected. In the buzzard, kestrel and goshawk a new species of Capillaria could be found and described as Eucoleus suppereri spec. nov. A new species of Synhimantus, Synhimantus (Dispharynx) falconis spec. nov. was diagnosed. The infestation frequency of endo- and ectoparasites was relatively high, whereas the infestation intensity was small or mediocre on an average. The highest rate of infestation was found with trematodes and cestodes. The significance of the analysis of crop- and stomach-cntents as a guarantee of diagnosis "psuedoparasitism" was pointed out. PMID:7212374
Elevated water temperatures, a decrease in ocean pH, and an increasing prevalence of severe storms have lead to bleaching and death of the hard corals that underpin coral reef ecosystems. As coral cover declines, fish diversity and abundance declines. How degradation of coral reefs affects behavior of reef inhabitants is unknown. Here, we demonstrate that risk assessment behaviors of prey are severely affected by coral degradation. Juvenile damselfish were exposed to visual and olfactory indicators of predation risk in healthy live, thermally bleached, and dead coral in a series of laboratory and field experiments. While fish still responded to visual cues in all habitats, they did not respond to olfactory indicators of risk in dead coral habitats, likely as a result of alteration or degradation of chemical cues. These cues are critical for learning and avoiding predators, and a failure to respond can have dramatic repercussions for survival and recruitment.
Lonnstedt, Oona M; McCormick, Mark I; Chivers, Douglas P
Interactions between predators and their prey are influenced by the habitat they occupy. Using created oyster (Crassostrea virginica) reef mesocosms, we conducted a series of laboratory experiments that created structure and manipulated complexity as well as prey density and "predator-free space" to examine the relationship between structural complexity and prey survivorship. Specifically, volume and spatial arrangement of oysters as well as prey density were manipulated, and the survivorship of prey (grass shrimp, Palaemonetes pugio) in the presence of a predator (wild red drum, Sciaenops ocellatus) was quantified. We found that the presence of structure increased prey survivorship, and that increasing complexity of this structure further increased survivorship, but only to a point. This agrees with the theory that structural complexity may influence predator-prey dynamics, but that a threshold exists with diminishing returns. These results held true even when prey density was scaled to structural complexity, or the amount of "predator-free space" was manipulated within our created reef mesocosms. The presence of structure and its complexity (oyster shell volume) were more important in facilitating prey survivorship than perceived refugia or density-dependent prey effects. A more accurate indicator of refugia might require "predator-free space" measures that also account for the available area within the structure itself (i.e., volume) and not just on the surface of a structure. Creating experiments that better mimic natural conditions and test a wider range of "predator-free space" are suggested to better understand the role of structural complexity in oyster reefs and other complex habitats. PMID:22145037
Humphries, Austin T; La Peyre, Megan K; Decossas, Gary A
Interactions between predators and their prey are influenced by the habitat they occupy. Using created oyster (Crassostrea virginica) reef mesocosms, we conducted a series of laboratory experiments that created structure and manipulated complexity as well as prey density and "predator-free space" to examine the relationship between structural complexity and prey survivorship. Specifically, volume and spatial arrangement of oysters as well as prey density were manipulated, and the survivorship of prey (grass shrimp, Palaemonetes pugio) in the presence of a predator (wild red drum, Sciaenops ocellatus) was quantified. We found that the presence of structure increased prey survivorship, and that increasing complexity of this structure further increased survivorship, but only to a point. This agrees with the theory that structural complexity may influence predator-prey dynamics, but that a threshold exists with diminishing returns. These results held true even when prey density was scaled to structural complexity, or the amount of "predator-free space" was manipulated within our created reef mesocosms. The presence of structure and its complexity (oyster shell volume) were more important in facilitating prey survivorship than perceived refugia or density-dependent prey effects. A more accurate indicator of refugia might require "predator-free space" measures that also account for the available area within the structure itself (i.e., volume) and not just on the surface of a structure. Creating experiments that better mimic natural conditions and test a wider range of "predator-free space" are suggested to better understand the role of structural complexity in oyster reefs and other complex habitats. ?? 2011 This is an open-access article, free of all copyright, and may be freely reproduced, distributed, transmitted, modified, built upon, or otherwise used by anyone for any lawful purpose. The work is made available under the Creative Commons CC0 public domain dedication.
Interactions between predators and their prey are influenced by the habitat they occupy. Using created oyster (Crassostrea virginica) reef mesocosms, we conducted a series of laboratory experiments that created structure and manipulated complexity as well as prey density and “predator-free space” to examine the relationship between structural complexity and prey survivorship. Specifically, volume and spatial arrangement of oysters as well as prey density were manipulated, and the survivorship of prey (grass shrimp, Palaemonetes pugio) in the presence of a predator (wild red drum, Sciaenops ocellatus) was quantified. We found that the presence of structure increased prey survivorship, and that increasing complexity of this structure further increased survivorship, but only to a point. This agrees with the theory that structural complexity may influence predator-prey dynamics, but that a threshold exists with diminishing returns. These results held true even when prey density was scaled to structural complexity, or the amount of “predator-free space” was manipulated within our created reef mesocosms. The presence of structure and its complexity (oyster shell volume) were more important in facilitating prey survivorship than perceived refugia or density-dependent prey effects. A more accurate indicator of refugia might require “predator-free space” measures that also account for the available area within the structure itself (i.e., volume) and not just on the surface of a structure. Creating experiments that better mimic natural conditions and test a wider range of “predator-free space” are suggested to better understand the role of structural complexity in oyster reefs and other complex habitats.
Humphries, Austin T.; La Peyre, Megan K.; Decossas, Gary A.
Many different and phylogenetically distant species of bats forage for insects above water bodies and take insects from and close to the surface; the so-called ‘trawling behaviour’. Detection of surface-based prey by echolocation is facilitated by acoustically smooth backgrounds such as water surfaces that reflect sound impinging at an acute angle away from the bat and thereby render a prey object acoustically conspicuous. Previous measurements had shown that the echo amplitude of a target on a smooth surface is higher than that of the same target in mid-air, due to an acoustic mirror effect. In behavioural experiments with three pond bats (Myotis dasycneme), we tested the hypothesis that the maximum distances at which bats can detect prey are larger for prey on smooth surfaces than for the same prey in an airborne situation. We determined the moment of prey detection from a change in echolocation behaviour and measured the detection distance in 3D space from IR-video recordings using stereo-photogrammetry. The bats showed the predicted increase in detection distance for prey on smooth surfaces. The acoustic mirror effect therefore increases search efficiency and contributes to the acoustic advantages encountered by echolocating bats when foraging at low heights above smooth water surfaces. These acoustic advantages may have favoured the repeated evolution of trawling behaviour.
Siemers, Björn M.; Baur, Eric; Schnitzler, Hans-Ulrich
This study was designed to evaluate prey selection (type and size) by the octocoral Carijoa riisei at Porto de Galinhas beach, Northeast Brazil, relating prey availability in plankton with the content inside polyps. Diatoms and cyanophytes were the predominant items found in both polyp gastric cavity and plankton. A correlation between prey abundance in the plankton and in the gastric cavity of C. riisei polyps was observed. Mastogloia sp. showed the highest positive electivity index (0.99). Benthonic items were found, with 0.51% of total consumed preys. The size amplitude of prey items in the plankton was similar to those found inside the polyps, although the mean prey size in the polyps (112.7 µm) was significantly lower than the value found in the plankton (240.5 µm). Thus, the study indicates some size selectivity in this species or at least size limitation. From the results, we concluded that the octocoral C. riisei is an opportunistic polyphagous species in the Brazilian northeast coast, showing suspensivorous passive filtering feeding habit with a preference for small prey items and evidencing its important ecological role in the reefal ecosystem as responsible for bidirectional energy transference between pelagic zones and the benthos. PMID:22392040
Gomes, Paula B; Lira, Ana K F; Naud, Jean-Philippe; Santos, Andre M; Pérez, Carlos D
This study was designed to evaluate prey selection (type and size) by the octocoral Carijoa riisei at Porto de Galinhas beach, Northeast Brazil, relating prey availability in plankton with the content inside polyps. Diatoms and cyanophytes were the predominant items found in both polyp gastric cavity and plankton. A correlation between prey abundance in the plankton and in the gastric cavity of C. riisei polyps was observed. Mastogloia sp. showed the highest positive electivity index (0.99). Benthonic items were found, with 0.51% of total consumed preys. The size amplitude of prey items in the plankton was similar to those found inside the polyps, although the mean prey size in the polyps (112.7 µm) was significantly lower than the value found in the plankton (240.5 µm). Thus, the study indicates some size selectivity in this species or at least size limitation. From the results, we concluded that the octocoral C. riisei is an opportunistic polyphagous species in the Brazilian northeast coast, showing suspensivorous passive filtering feeding habit with a preference for small prey items and evidencing its important ecological role in the reefal ecosystem as responsible for bidirectional energy transference between pelagic zones and the benthos. PMID:22441605
Gomes, Paula B; Lira, Ana K F; Naud, Jean-Philippe; Santos, Andre M; Pérez, Carlos D
Negative density dependent selection on individuals in prey aggregations (negative DDS, the preferential selection by predators of spatially isolated prey) is assumed to contribute in many cases to the evolution and maintenance of aggregation. Both positive and negative DDS on prey groups have been documented in nature but there is no existing framework to predict when each of these forms of natural selection is most likely. By exploiting the tendency of artificial neural networks to exhibit consumer-like emergent behaviours, I isolate at least two environmental factors impinging on the consumer organism that may determine which form of density dependent natural selection is shown: the distribution of prey group size attacked by the predator and the spatial conformation (dispersed or compacted) of the prey group. Numerous forms of DDS on artificial prey (positive, negative, and non-DDS) are displayed through different combinations of these factors. I discuss in detail how the predictions of the model may be tested by empiricists in order to assess the usefulness of the framework presented. I stress the importance of understanding DDS on prey groups given the recent emergence of these systems as test beds for ideas on biological self-organisation. PMID:21540037
Foraging theory seeks to explain how the distribution and abundance of prey influence the evolution of predatory behaviour, including the allocation of effort to searching for prey and handling them after they are found. While experiments have shown that many predators alter their behaviour phenotypically within individual lifetimes, few have examined the actual evolution of predatory behaviour in light of this theory. Here, we test the effects of prey density on the evolution of a predator's searching and handling behaviours using a bacterial predator, Myxococcus xanthus. Sixteen predator populations evolved for almost a year on agar surfaces containing patches of Escherichia coli prey at low or high density. Improvements in searching rate were significantly greater in those predators that evolved at low prey density. Handling performance also improved in some predator populations, but prey density did not significantly affect the magnitude of these gains. As the predators evolved greater foraging proficiency, their capacity diminished to produce fruiting bodies that enable them to survive prolonged periods of starvation. More generally, these results demonstrate that predators evolve behaviours that reflect at least some of the opportunities and limitations imposed by the distribution and abundance of their prey.
Hillesland, Kristina L.; Velicer, Gregory J.; Lenski, Richard E.
BACKGROUND: To avoid anaphylactic reactions, immunoglobulin (Ig)A-deficient patients with anti-IgA should be transfused with IgA-deficient blood compo- nents. There is a need for fast and robust assays for demonstration of IgA deficiency and for detection of anti-IgA. STUDY DESIGN AND METHODS: Recombinant human IgA1 and IgA2 anti-D molecules were con- structed, expressed in Chinese hamster ovary cells, and purified. These
1.?Predation rate (PR) and kill rate are both fundamental statistics for understanding predation. However, relatively little is known about how these statistics relate to one another and how they relate to prey population dynamics. We assess these relationships across three systems where wolf-prey dynamics have been observed for 41 years (Isle Royale), 19 years (Banff) and 12 years (Yellowstone). 2.?To provide context for this empirical assessment, we developed theoretical predictions of the relationship between kill rate and PR under a broad range of predator-prey models including predator-dependent, ratio-dependent and Lotka-Volterra dynamics. 3.?The theoretical predictions indicate that kill rate can be related to PR in a variety of diverse ways (e.g. positive, negative, unrelated) that depend on the nature of predator-prey dynamics (e.g. structure of the functional response). These simulations also suggested that the ratio of predator-to-prey is a good predictor of prey growth rate. That result motivated us to assess the empirical relationship between the ratio and prey growth rate for each of the three study sites. 4.?The empirical relationships indicate that PR is not well predicted by kill rate, but is better predicted by the ratio of predator-to-prey. Kill rate is also a poor predictor of prey growth rate. However, PR and ratio of predator-to-prey each explained significant portions of variation in prey growth rate for two of the three study sites. 5.?Our analyses offer two general insights. First, Isle Royale, Banff and Yellowstone are similar insomuch as they all include wolves preying on large ungulates. However, they also differ in species diversity of predator and prey communities, exploitation by humans and the role of dispersal. Even with the benefit of our analysis, it remains difficult to judge whether to be more impressed by the similarities or differences. This difficulty nicely illustrates a fundamental property of ecological communities. Second, kill rate is the primary statistic for many traditional models of predation. However, our work suggests that kill rate and PR are similarly important for understanding why predation is such a complex process. PMID:21569029
Vucetich, John A; Hebblewhite, Mark; Smith, Douglas W; Peterson, Rolf O
A model of the bat sensorimotor system is developed using acoustics, signal processing, and control theory to illustrate the fundamental issues in accomplishing prey capture with echolocation. This model indicates that successful nonpredictive tracking of an ideal prey can be accomplished with a very simple system. Circular apertures approximate the mouth and ears for deriving acoustic beam patterns, using the big brown bat Eptesicus fuscus as a model. Fundamental and overtone frequency components in the emissions allow two simultaneous acoustic beams to be defined. A pair of nonlinear, time-variable, sampled-data controllers alter the bat's heading by applying yaw and pitch heading corrections. The yaw correction attempts to position the prey in the midsagittal plane by nulling the interaural intensity difference of the fundamental component. The pitch correction compares the intensities of the overtone and fundamental components and acts to null their difference. By initiating pitch correction when the overtone intensity first exceeds that of the fundamental, the ambiguity problem is solved and the prey is directed to the capture region. Simulations of passive prey capture indicate that the capture probability decreases as the prey speed increases. Both quick and sluggish prey are considered, with sluggish prey found to be caught with slightly better efficiency. The magnitude of the prey's lateral motion just prior to capture is observed to be an important factor determining capture. The presence of a blind stage is considered, during which the interference of the emission with the echo is assumed to disrupt any sonar information. The presence of such a blind stage is found to have negligible effect on capture efficiency. PMID:7963018
The introduction of invasive alien predators often has catastrophic effects on populations of naďve native prey, but in situations where prey survive the initial impact a predator may act as a strong selective agent for prey that can discriminate and avoid it. Using two common species of Australian small mammals that have persisted in the presence of an alien predator, the European red fox Vulpes vulpes, for over a century, we hypothesised that populations of both would perform better where the activity of the predator was low than where it was high and that prey individuals would avoid signs of the predator's presence. We found no difference in prey abundance in sites with high and low fox activity, but survival of one species-the bush rat Rattus fuscipes-was almost twofold higher where fox activity was low. Juvenile, but not adult rats, avoided fox odour on traps, as did individuals of the second prey species, the brown antechinus, Antechinus stuartii. Both species also showed reduced activity at foraging trays bearing fox odour in giving-up density (GUD) experiments, although GUDs and avoidance of fox odour declined over time. Young rats avoided fox odour more strongly where fox activity was high than where it was low, but neither adult R. fuscipes nor A. stuartii responded differently to different levels of fox activity. Conservation managers often attempt to eliminate alien predators or to protect predator-naďve prey in protected reserves. Our results suggest that, if predator pressure can be reduced, otherwise susceptible prey may survive the initial impact of an alien predator, and experience selection to discriminate cues to its presence and avoid it over the longer term. Although predator reduction is often feasible, identifying the level of reduction that will conserve prey and allow selection for avoidance remains an important challenge. PMID:22042524
Kovacs, Eszter Krasznai; Crowther, Mathew S; Webb, Jonathan K; Dickman, Christopher R
An animal model for IgA immune complex nephritis was developed. IgA immune complexes formed in vitro with an IgA anti-dinitrophenyl (DNP) derived from MOPC-315 plasmacytoma, and dinitrophenylated bovine serum albumin (DNP-BSA) produced mild focal glomerulonephritis in mice. Similar, but more severe pathological changes were produced with complexes formed in vivo either in normal mice or MOPC-315 tumor- bearing mice. In contrast to the focal nature of the PAS-positive glomerular lesions observed by light microscopy, immunofluorescent examination revealed IgA deposits in all glomeruli. This discrepancy between immunofluorescent and histopathologic findings as well as the distribution of the immune complexes within the affected glomeruli, are some of the features which bear resemblance between this experimental model and human IgA nephropathy. Fixation of complements by DNP-BSA-IgA immune complexes, formed in vitro or in vivo, was shown to occur in the glomeruli of mice with IgA immune complex nephropathy. The pattern of C3 glomerular deposits was similar to that of IgA. However, complement proved to be nonessential for complex deposition. This conclusion is based on the observation that decomplemented mice, although showing no deposition of C3 in their glomerulus, developed glomerular immunohistological changes similar to those observed in experimental mice that were not decomplemented. Polymeric IgA was observed to be critical for renal deposition of complexes and induction of nephritic histological changes. In contrast, monomeric IgA immune complexes failed to produce glomerular deposits. This finding raises the possibility that secretory IgA, which is predominantly polymeric, may play a role in human IgA-associated glomerulonephritis.
When approaching prey, a stalking predator should consider trade-offs between the probabilities of early detection (by the prey, before the strike), spontaneous departure (of prey, before the strike), prey escape (following the strike) and interference (by rivals or predators). In this study we tested the response of a jumping spider,Plexippus paykullito a background with two different camouflaging properties, and two
We conducted laboratory and field experiments to determine the effects of plant quality and prey abundance on the intensity of interactions involving an omnivorous insect, its two herbivorous prey, and their shared host plant. We found that variation in plant quality, prey abundance, and presence of alternative prey altered the functional re- sponse of the omnivorous big-eyed bug, Geocoris punctipes
We study a system arising from a 3-component prey-predator model with prey- dependent and ratio-dependent functional responses, where cross diusion is included in such a way that predator chases the prey and the prey runs away from the predator. We prove that the cross-diusion can generate the Stationary Patterns (non-constant positive steady states).
This paper presents a simulation of predator (pursuer) and prey (evader) agents operating within a competitive co-evolution process. The aim of the study was to investigate the effects of different resource (food for the prey) distributions and amounts on the adaptation of predator (pursuit) and prey (evasion) behaviors. Predator and prey use Artificial Neural Network (ANN) controllers to simulate behavior,
Summary The kinematics of feeding on two prey types is studied quantitatively in the common snapping turtle, Chelydra serpentina, to provide a description of prey capture mechanisms and to determine whether kinematic patterns can be altered in response to prey that vary in escape capability. High-speed video recordings of prey capture (200 fields s\\
We estimated annual prey supply and predator demand distributions for the fish assemblage of Norris Reservoir, Tennessee, to assess potential prey deficiencies. Prey supply was defined as the surplus biomass that could be removed without affecting future prey generations and was limited to cohorts consumed by predators. Demand was represented by the annual consumption by the predator community (piscivorous fishes)
Scott W. Raborn; Leandro E. Miranda; M. Todd Driscoll
Synopsis Experiments with the Danube bleak, Chalcalburnus chalcoides mento, an obligatory planktivore, were carried out to test some basic assumptions of foraging theory regarding prey selection. The results of experiments in which two prey types were offered simultaneously were compared with results of corresponding experiments with single prey types. Although the fish always selected for the more profitable prey they
Apostatic selection, in which predators overlook rare prey types while consuming an excess of abundant ones, has been assumed to contribute to the maintenance of prey polymorphisms. Such an effect requires predators to respond to changes in the relative abundance of prey, switching to alternatives when a focal prey type becomes less common,. Apostatic selection has often been investigated using
Summary Polybia sericea (Hymenoptera: Vespidae) prey foraging was studied by following individual foragers as they hunted in the field, by observing how wasps handled prey once they had captured it, and by observing wasps as they returned to the nest with prey. Wasps were most likely to forage for prey between 0700 and 1300 hours and between 1600 and 1700
We investigated potential advantages in birth timing for mountain lion (Puma concolor) cubs. We examined cub body mass, survival, and age of natal dispersal in relation to specific timing of birth. We also investigated the role of maternal age relative to timing of births. We captured mountain lion cubs while in the natal den to determine birth date, which allowed for precise estimates of the population birth pulse and age of natal dispersal. A birth pulse occurred during June–August. Body mass of cubs was related to litter size and timing of birth; heaviest cubs occurred in litters of 2, and those born after 1 July. Cubs born within pulse months exhibited similar survival to those born out of the pulse. We found that cubs born April–June dispersed at younger ages than those born after 1 July. There was less variation in birth timing for 1st litters of females than older females. We hypothesize that cubs born after the peak in births of neonate prey are advantaged by the abundance of vulnerable prey and those cubs and mothers realize an evolutionary advantage.
Foraging rates and maneuvers were ex- amined in breeding female Red-faced Warblers (Car- dellina rubrzfrons) among egg-laying, incubation, and nestling stages. All measures varied among nesting stages, with prey attack rate and search speed signifi- cantly increasing from egg-laying to incubation through the nestling stage. During egg-laying and in- cubation, birds gleaned stationary prey from a fixed perch, but shifted
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...
Odorous waste products such as urine and faeces are unavoidable for most animals and are widely exploited by predators and their prey. Consequently, waste accumulations can be risky and prey which increase their mobility in order to disperse and dilute their waste should avoid a high predation risk until this benefit is balanced by the increasing risks of random predator encounter. This hypothesis was tested for voles (Microtus spp.) in Finland which are vulnerable to predation due to the scent and ultraviolet attractiveness of their urine. The mortality and mobility of radio-collared voles showed a U-shaped relationship, regardless of vole sex, species or population cycle phase. The low risks for prey making intermediate movements suggest that predation risk can exert strong selective pressures on prey such that they have little respite from the risk of being killed.
The influence of habitat destruction on a population of predators and prey is studied. We show, via Monte Carlo simulations of a lattice model, that with growing devastation the oscillations in the densities of both species, as well as cross-correlations between the two densities diminish. As should be expected, predators are more vulnerable and disappear before the prey. Devastation of the habitat is never beneficial and the percentage of coexisting (prey and predators) states decreases with destruction. Because of the high fragmentation of the environment in the case of large devastation, animals’ populations are separated into small sub-populations living in restricted areas. Such small populations become extinct more easily. We have also shown that in the case of large habitat devastation the density of the population of prey depends on its history.
The current extinction of many of Earth's large terrestrial carnivores has left some extant prey species lacking knowledge about contemporary predators, a situation roughly parallel to that 10,000 to 50,000 years ago, when naive animals first encountered colonizing human hunters. Along present-day carnivore recolonization fronts, brown (also called grizzly) bears killed predator-naive adult moose at disproportionately high rates in Scandinavia, and moose mothers who lost juveniles to recolonizing wolves in North America's Yellowstone region developed hypersensitivity to wolf howls. Although prey that had been unfamiliar with dangerous predators for as few as 50 to 130 years were highly vulnerable to initial encounters, behavioral adjustments to reduce predation transpired within a single generation. The fact that at least one prey species quickly learns to be wary of restored carnivores should negate fears about localized prey extinction. PMID:11161215
Prey have evolved myriad strategies to escape predation. Ground squirrels tailor their defensive signals to the predator at hand and use infrared warning signals in response to heat-sensitive rattlesnakes. PMID:18029251
In mutual intraguild predation (IGP), the role of individual guild members is strongly context dependent and, during ontogeny, can shift from an intraguild (IG) prey to a food competitor or to an IG predator. Consequently, recognition of an offspring's predator is more complex for IG than classic preyfemales. Thus, IGpreyfemales should be able to modulate their oviposition decisions by integrating multiple IG predator cues and by experience. Using a guild of plant-inhabiting predatory mites sharing the spider mite Tetranychus urticae as prey and passing through ontogenetic role shifts in mutual IGP, we assessed the effects of single and combined direct cues of the IG predator Amblyseius andersoni (eggs and traces left by a female on the substrate) on prey patch selection and oviposition behaviour of naďve and IG predator-experienced IGpreyfemales of Phytoseiulus persimilis. The IGpreyfemales preferentially resided in patches without predator cues when the alternative patch contained traces of predator females or the cue combination. Preferential egg placement in patches without predator cues was only apparent in the choice situation with the cue combination. Experience increased the responsiveness of females exposed to the IG predator cue combination, indicated by immediate selection of the prey patch without predator cues and almost perfect oviposition avoidance in patches with the cue combination. We argue that the evolution of the ability of IGpreyfemales to evaluate offspring's IGP risk accurately is driven by the irreversibility of oviposition and the functionally complex relationships between predator guild members. PMID:23264692
Sequential study of the IgA system in relapsing IgA nephropathy.Cellular and immunochemical parameters of the IgA system were studied in 15 subjects with IgA nephropathy (IgAN) and 15 age–matched controls. In IgAN remission no abnormalities of the IgA system were detectable by the methods used. In IgAN relapse, [macroscopic hematuria associated with upper respiratory tract infection (URTI) (N = 6)
John Feehally; T James Beattie; Paul EC Brenchley; Beatrice M Coupes; Netar P Mallick; Robert J Postlethwaite
Currently, the International GPS Service (IGS) provides a set of clock products for both satellites and tracking receivers, tabulated at 5-min intervals. These products allow users to determine consistent coordinates and clock values for an isolated GPS receiver with an internal accuracy at the few-cm level. However, because the underlying time scale for the IGS combined clocks is based on
Currently, the International GPS Service (IGS) provides a set of clock products for both satellites and tracking receivers, tabulated at 5-minute intervals. These products provide users with sufficient information to determine consistent coordinates and clock values for an isolated GPS receiver with a precision at roughly the 5-cm level. However, because the underlying time scale for the IGS combined clocks
Linking local communities to a metacommunity can positively affect diversity by enabling immigration of dispersal-limited species and maintenance of sink populations. However, connectivity can also negatively affect diversity by allowing the spread of strong competitors or predators. In a microcosm experiment with five ciliate species as prey and a copepod as an efficient generalist predator, we analysed the effect of connectivity on prey species richness in metacommunities that were either unconnected, connected for the prey, or connected for both prey and predator. Presence and absence of predator dispersal was cross-classified with low and high connectivity. The effect of connectivity on local and regional richness strongly depended on whether corridors were open for the predator. Local richness was initially positively affected by connectivity through rescue of species from stochastic extinctions. With predator dispersal, however, this positive effect soon turned negative as the predator spread over the metacommunity. Regional richness was unaffected by connectivity when local communities were connected only for the prey, while predator dispersal resulted in a pronounced decrease of regional richness. The level of connectivity influenced the speed of richness decline, with regional species extinctions being delayed for one week in weakly connected metacommunities. While connectivity enabled rescue of prey species from stochastic extinctions, deterministic extinctions due to predation were not overcome through reimmigration from predator-free refuges. Prey reimmigrating into these sink habitats appeared to be directly converted into increased predator abundance. Connectivity thus had a positive effect on the predator, even when the predator was not dispersing itself. Our study illustrates that dispersal of a species with strong negative effects on other community members shapes the dispersal-diversity relationship. When connections enable the spread of a generalist predator, positive effects of connectivity on prey species richness are outweighed by regional extinctions through predation. PMID:22194992
Normal form theory is one important tool in local analysis of nonlinear dynamical systems near an equilibrium point. In this paper a systematic procedure based on normal form theory is proposed to investigate nonlinear effects arising from the perturbation model of the predator-prey dynamic model of Lotka Volterra. Using this method, a second-order model of the predator-prey is proposed in
To determine whether perching dragonflies visually assess the distance to potential prey items, we presented artificial prey,\\u000a glass beads suspended from fine wires, to perching dragonflies in the field. We videotaped the responses of freely foraging\\u000a dragonflies (Libellula luctuosa and Sympetrum vicinum—Odonata, suborder Anisoptera) to beads ranging from 0.5 mm to 8 mm in diameter, recording whether or not the dragonflies\\u000a took
R. M. Olberg; A. H. Worthington; J. L. Fox; C. E. Bessette; M. P. Loosemore
Studies of prey detection have typically focused on how search image affects the capture of cryptic items. This study also considers how background vegetation influences cryptic prey detection. Blue jays,Cyanocitta cristata, searched digitized images for twoCatocalamoths:C.ilia, which is cryptic on oak, andC.relicta, which is cryptic on birch. Some images contained moths while others did not. The ability of blue jays
In this paper we study the effects of a protection zone ?0 for the prey on a diffusive predator–prey model with Holling type II response and no-flux boundary condition. We show the existence of a critical patch size described by the principal eigenvalue ?1D(?0) of the Laplacian operator over ?0 with homogeneous Dirichlet boundary conditions. If the protection zone is
Female Black-capped Chickadees (Poecile atricapillus) solicit extrapair copulations (EPCs) from neighboring high-ranking males, and these EPCs result in extrapair young. Females might choose to locate their nests near the territory boundaries of attractive males to facilitate access to EPCs. Other hypotheses might also explain choice of nest site, namely (1) habitat characteristics, (2) prey abundance, and (3) previous experience. We
Scott M. Ramsay; Ken A. Otter; Laurene M. Ratcliffe
Ecological theory traditionally describes predator–prey interactions in terms of a law of mass action in which the prey mortality rate depends on the density of predators and prey. This simplifying assumption makes population-based models more tractable but ignores potentially important behaviors that characterize predator–prey dynamics. Here, we expand traditional predator–prey models by incorporating directed and random movements of both predators
James J. Anderson; Eliezer Gurarie; Richard W. Zabel
Although water availability is primarily seen as a factor affecting food availability (a bottom-up process), we examined its effect on predator-prey interactions through an influence on prey behavior (a top-down process). We documented a link between water availability, predation risk, and reproductive success in a goose species (Chen caerulescens atlantica) inhabiting an Arctic environment where water is not considered a limited commodity. To reach water sources during incubation recesses, geese nesting in mesic tundra (low water availability) must move almost four times as far from their nest than those nesting in wetlands, which reduced their ability to defend their nest against predators and led to a higher predation rate. Nesting success was improved in high rainfall years due to increased water availability, and more so for geese nesting in the low water availability habitat. Likewise, nesting success was improved in years where the potential for evaporative water loss (measured by the atmospheric water vapor pressure) was low, presumably because females had to leave their nest less often to drink. Females from water-supplemented nests traveled a shorter distance to drink, and their nesting success was enhanced by 20% compared to the control. This shows that water availability and rainfall can have a strong effect on predator-prey dynamics and that changes in precipitation brought by climate change could have an impact on some Arctic species through a top-down effect. PMID:19323230
Background In group-living animals, social interactions and their effects on other life activities such as foraging are commonly determined by discrimination among group members. Accordingly, many group-living species evolved sophisticated social recognition abilities such as the ability to recognize familiar individuals, i.e. individuals encountered before. Social familiarity may affect within-group interactions and between-group movements. In environments with patchily distributed prey, group-living predators must repeatedly decide whether to stay with the group in a given prey patch or to leave and search for new prey patches and groups. Methodology/Principal Findings Based on the assumption that in group-living animals social familiarity allows to optimize the performance in other tasks, as for example predicted by limited attention theory, we assessed the influence of social familiarity on prey patch exploitation, patch-leaving, and inter-patch distribution of the group-living, plant-inhabiting predatory mite Phytoseiulus persimilis. P. persimilis is highly specialized on herbivorous spider mite prey such as the two-spotted spider mite Tetranychus urticae, which is patchily distributed on its host plants. We conducted two experiments with (1) groups of juvenile P. persimilis under limited food on interconnected detached leaflets, and (2) groups of adult P. persimilis females under limited food on whole plants. Familiar individuals of both juvenile and adult predator groups were more exploratory and dispersed earlier from a given spider mite patch, occupied more leaves and depleted prey more quickly than individuals of unfamiliar groups. Moreover, familiar juvenile predators had higher survival chances than unfamiliar juveniles. Conclusions/Significance We argue that patch-exploitation and -leaving, and inter-patch dispersion were more favorably coordinated in groups of familiar than unfamiliar predators, alleviating intraspecific competition and improving prey utilization and suppression.
Zach, Gernot J.; Peneder, Stefan; Strodl, Markus A.; Schausberger, Peter
In this paper, we investigate Hopf bifurcation and center stability of a predator-prey biological economic model. By employing the local parameterization method, Hopf bifurcation theory and the formal series method, we obtain some testable results on these issues. The economic profit is chosen as a positive bifurcation parameter here. It shows that a phenomenon of Hopf bifurcation occurs as the economic profit increases beyond a certain threshold. Besides, we also find that the center of the biological economic model is always unstable. Finally, some numerical simulations are given to illustrate the effectiveness of our results.
Many species of snakes use constriction-the act of applying pressure via loops of their trunk-to subdue and kill their prey. Constriction is costly and snakes must therefore constrict their prey just long enough to ensure death. However, it remains unknown how snakes determine when their prey is dead. Here, we demonstrate that boas (Boa constrictor) have the remarkable ability to detect a heartbeat in their prey and, based on this signal, modify the pressure and duration of constriction accordingly. We monitored pressure generated by snakes as they struck and constricted warm cadaveric rats instrumented with a simulated heart. Snakes responded to the beating heart by constricting longer and with greater total pressure than when constricting rats with no heartbeat. When the heart was stopped midway through the constriction, snakes abandoned constriction shortly after the heartbeat ceased. Furthermore, snakes naive to live prey also responded to the simulated heart, suggesting that this behaviour is at least partly innate. These results are an example of how snakes integrate physiological cues from their prey to modulate a complex and ancient behavioural pattern. PMID:22258447
Boback, Scott M; Hall, Allison E; McCann, Katelyn J; Hayes, Amanda W; Forrester, Jeffrey S; Zwemer, Charles F
Individual specialization underpins the division of labour within ant societies, but only in a small minority do morphological specialists, or physical castes, exist in the workforce. The genetic conditions that allow such castes to evolve are well understood, but the ecological pressures that select for them are not. We provide compelling evidence that the task of transporting novel prey selected for an exaggerated transport caste, or ‘submajor’, in the army ant Eciton burchellii. This species is the only Eciton that preys upon large arthropods as well as ants, the ancestral prey type, and by comparing load-transport among Eciton species and within E. burchellii, we show that this mixed diet significantly constrains transport efficiency. Crucially, however, we also show that E. burchellii submajors are highly specialized on transporting non-ant prey, and we demonstrate experientially that it is specifically this prey type that constrains prey-transport efficiency. Our study also suggests that phylogenetic constraints associated with the Eciton lifestyle intensified selection for the exaggerated submajor of E. burchellii. Thus, we propose that a novel task may only select for a special caste when phylogenetic constraints preclude the evolution of alternative solutions. This identifies a new and potentially general scenario for the evolution of physical castes.
Nematodes are presumably the most numerous Metazoans in terrestrial habitats. They are represented at all trophic levels and are known to respond to nutrient limitation, prey availability, and microbial resources. Predatory nematodes reside at the highest trophic level, and as such their feeding habits could have a major impact on soil food web functioning. Here, we investigate the effects of gender and developmental stage on the nematode body sizes in coarse and loamy soils. Besides Neodiplogasteridae, our predators are much larger than other soil-dwelling nematodes from their early developmental stage onwards. From juvenile to adult, the predatory Aporcelaimellus (Kruskal-Wallis P < 0.001), Dorylaimoides, and Tripyla (both P < 0.01) show great length increases during their developmental growth, in contrast to their possible prey (almost all P < 0.001). Less than 4% of the prey exceeds the length of the predatory adults, but more than 30% of the prey exceeds the length of the predatory juveniles. Potential body size ratios and some physical problems experienced by small fluid feeders attacking large prey are discussed in an attempt to summarize different prey-searching mechanisms and aggregative predatory responses in the soil system. PMID:22393508
Nematodes are presumably the most numerous Metazoans in terrestrial habitats. They are represented at all trophic levels and are known to respond to nutrient limitation, prey availability, and microbial resources. Predatory nematodes reside at the highest trophic level, and as such their feeding habits could have a major impact on soil food web functioning. Here, we investigate the effects of gender and developmental stage on the nematode body sizes in coarse and loamy soils. Besides Neodiplogasteridae, our predators are much larger than other soil-dwelling nematodes from their early developmental stage onwards. From juvenile to adult, the predatory Aporcelaimellus (Kruskal–Wallis P < 0.001), Dorylaimoides, and Tripyla (both P < 0.01) show great length increases during their developmental growth, in contrast to their possible prey (almost all P < 0.001). Less than 4% of the prey exceeds the length of the predatory adults, but more than 30% of the prey exceeds the length of the predatory juveniles. Potential body size ratios and some physical problems experienced by small fluid feeders attacking large prey are discussed in an attempt to summarize different prey-searching mechanisms and aggregative predatory responses in the soil system.
Recent studies have provided evidence that spiders’ color and pattern may attract prey items to their webs, thus increasing\\u000a their foraging success. However, these studies were conducted on tropical spiders, and no studies have examined this phenomenon\\u000a in temperate spiders. We examined the role of color and pattern in a North American spiny orb-weaver, Micrathena gracilis. We found that prey
E. Natasha Vanderhoff; Catherine J. Byers; Chadwick J. Hanna
We study a reaction diffusion system arising from a three-species prey-predator model with prey-dependent and ratio- dependent functional responses. The main aim of this paper is to study the global existence and bifurcation of non-constant positive steady-states. In particular, we will show that even though the unique positive constant steady-state is stable for the ODE dynamics, non-constant positive steady-states exist
Prey selection by a spider wasp,Batozonellus lacerticida, was investigated at the riverside of the Toyohira River in Misumai, Sapporo, Hokkaido over 7 years from 1981 to 1987. Seventeen\\u000a species of araneid spiders were found in the study area and six of them were hunted by the wasps. Most (97.3%) of the 223\\u000a prey records obtained were of three species,Araneus macacus,
Prey abundance and food habits of the San Joaquin kit fox (Vulpes velox macrotis) were investigated at Camp Roberts Army National Guard Training site, California, from November 1988 through September 1991. The sampling methods initially used to assess abundance of prey species resulted in indices too low to be of value. Because of this, the relationship between relative abundance and frequency of occurrence of prey species could not be examined. Six hundred forty-nine fecal samples (scats) were analyzed to determine the frequency of occurrence of prey items. California ground squirrels (Spermophilus beecheyi) and lagomorphs primarily desert cottontails (Sylvilagus audubonii) and black-tailed jackrabbits (Lepus californicus) were the most frequently occurring mammalian prey items found in scats (35.0% and 12.2%, respectively). The frequency of occurrence of ground squirrel (but not lagomorph) remains in scats collected from juveniles was significantly higher than in scats collected from adults. The frequency of occurrence of ground squirrel and lagomorph remains in scats collected from males was not significant different than in scats collected from females. There were significant variations in the frequency of ground squirrel remains among the years 1989--1991 and during the June--November periods between 1989 and 1990 and between 1990 and 1991. The frequency of lagomorph remains collected during the June--November period differed significantly among the years 1989--1991 and between 1990 and 1991.
Logan, C.G.; Berry, W.H.; Standley, W.G.; Kato, T.T.
Bats have remarkable echolocation capabilities to detect prey in darkness. While it is clear how bats do this for prey that is isolated, moving, or noisy, their ability to find still and quiet prey within clutter has remained a mystery. A video published by the ChiRoPing group shows the gleaning bat Micronycteris microtis capturing a still dragonfly specimen sitting on a leaf surface. While hovering over the dragonfly, the bat's wings exert air forces that cause the dragonfly wings to deflect in synchrony with the bat's wing beats. This paper illustrates that echoes from such deflecting wings vary in both amplitude and time-of-flight, producing robust echo cues that permit prey detection, even when the prey is embedded within clutter. Experiments with a dragonfly specimen mounted on a leaf driven by periodic air puffs produced wing deflections that were sensed with sonar pulses. Results demonstrate that echo variations synchronized with periodic air puffs are easily distinguishable from surrounding clutter, even when clutter produces the first echoes. These results suggest a strategy that bats can employ to detect still and silent prey embedded within cluttered environments. PMID:22978904
Predators in nature include an array of prey types in their diet, and often select certain types over others. We examined (i) prey selection by sea stars (Asterias vulgaris) and rock crabs (Cancer irroratus) when offered two prey types, juvenile sea scallops (Placopecten magellanicus) and blue mussels (Mytilus edulis), and (ii) the effect of prey density on predation, prey selection,
Intraguild (IG) prey is commonly confronted with multiple IG predator species. However, the IG predation (IGP) risk for prey is not only dependent on the predator species, but also on inherent (intraspecific) characteristics of a given IG predator such as its life-stage, sex or gravidity and the associated prey needs. Thus, IGprey should have evolved the ability to integrate multiple IG predator cues, which should allow both inter- and intraspecific threat-sensitive anti-predator responses. Using a guild of plant-inhabiting predatory mites sharing spider mites as prey, we evaluated the effects of single and combined cues (eggs and/or chemical traces left by a predator female on the substrate) of the low risk IG predator Neoseiulus californicus and the high risk IG predator Amblyseius andersoni on time, distance and path shape parameters of the larval IGprey Phytoseiulus persimilis. IGprey discriminated between traces of the low and high risk IG predator, with and without additional presence of their eggs, indicating interspecific threat-sensitivity. The behavioural changes were manifest in distance moved, activity and path shape of IGprey. The cue combination of traces and eggs of the IG predators conveyed other information than each cue alone, allowing intraspecific threat-sensitive responses by IGprey apparent in changed velocities and distances moved. We argue that graded responses to single and combined IG predator cues are adaptive due to minimization of acceptance errors in IGprey decision making. PMID:23750040
We present a different approach to a class of pursuit games: the Multi-Predator Multi-Prey domain. In the typical game, a group of predators tries to capture a group of prey, and all the agents have perfect knowledge of prey and predator positions. In our problem definition the prey-agent and the predator-agent have only local information provided by its vision range, each predator independently tries to capture a prey in a one-predator-one-prey-pair way. The predator-prey-pair capture is not known in advance and both predators and prey are moving in the environment. We show that simple greedy local predator rules are enough to capture all prey.
The influence of a resource subsidy on predator-prey interactions is examined using a mathematical model. The model arises from the study of a biological system involving arctic foxes (predator), lemmings (prey), and seal carcasses (subsidy). In one version of the model, the predator, prey and subsidy all occur in the same location; in a second version, the predator moves between two patches, one containing only the prey and the other containing only the subsidy. Criteria for feasibility and stability of the different equilibrium states are studied both analytically and numerically. At small subsidy input rates, there is a minimum prey carrying capacity needed to support both predator and prey. At intermediate subsidy input rates, the predator and prey can always coexist. At high subsidy input rates, the prey cannot persist even at high carrying capacities. As predator movement increases, the dynamic stability of the predator-prey-subsidy interactions also increases. PMID:22877320
Anthropogenic disturbances have been demonstrated to affect animal behavior, distribution, and abundance, but assessment of their impacts on fitness-related traits has received little attention. We hypothesized that human activities and infrastructure cause a decrease in the individual performance of preys because of anthropogenically enhanced predation risk. We evaluated the impacts of commercial logging and road networks on the fitness of a large herbivore known to be sensitive to human disturbance: the forest-dwelling woodland caribou (Rangifer tarandus caribou). For 8 consecutive years (2004-2011) we monitored 59 individuals using GPS telemetry in the Charlevoix region of Québec, Canada. We also used Very High Frequency telemetry locations collected on 28 individuals from 1999-2000. We related habitat selection of adult caribou at various spatio-temporal scales to their probability of dying from predation, and to indices of their reproductive success and energy expenditure. The probability that adult caribou died from predation increased with the proportion of recent disturbances (including cutblocks ?5 years old) in their annual home range. The respective effects of increasing paved and forestry road densities depended upon the overall road density within the home range of caribou. At a finer scale of 10 to 15 days before their death, caribou that were killed by a predator selected for recent disturbances more than individuals that survived, and avoided old mature conifer stands. The home range area of caribou increased with road density. Finally, the composition of the home range of females had no effect on their reproductive success. We show that human activities and infrastructure may influence the individual performance of large prey species in highly managed regions. We outline the need to consider the full set of impacts that human development may have on threatened animal populations, with particular emphasis on predator-prey relationships and population dynamics. PMID:24040029
Biological and population parameters of the predatory bugs Macrolophus costalis Fieber and Macrolophus pygmaeus Rambur preying on the tobacco aphid Myzus persicae (Sulzer) were examined. Tobacco was used as host plant and all experiments were carried out at 23 degrees C and L16:D8. In M. costalis, the developmental time for eggs and the total duration of nymphal instars was 13.1 and 22.2 days and in M. pygmaeus 13.0 and 20.2 days, respectively. Both species completed their nymphal development feeding only on plant juices although they required significantly more time to attain adulthood than when feeding on prey. The longevity of M. costalis females and the preoviposition period were 49.9 and 5.6 days and those of M. pygmaeus were 50.3 and 6.3 days, respectively. Adult males showed a higher longevity than females in both species. The intrinsic rate of increase and the mean total number of eggs laid were 0.0644 and 121 in M. costalis and 0.0615 and 104 in M. pygmaeus, respectively. Mean total aphid consumption by nymphs of M. costalis was 61 aphids, about twice that of M. pygmaeus (37 aphids). Total aphid consumption by a male and female pair of M. costalis and M. pygmaeus until the death of the female was 244 and 285 aphids, respectively. The results of the study are discussed in relation to the impact of the two predatory bugs on tobacco aphid populations. PMID:12593681
Margaritopoulos, J T; Tsitsipis, J A; Perdikis, D C
Inexperienced predators are assumed to select for similarity of warning signals in aposematic species (Müllerian mimicry) when learning to avoid them. Recent theoretical work predicts that if co-mimic species have unequal defences, predators attack them according to their average unpalatability and mimicry may not be beneficial for the better defended co-mimic. In this study, we tested in a laboratory environment whether a uniform warning signal is superior to a variable one in promoting predator learning, and simultaneously whether co-mimics are preyed upon according to their average unpalatability. There was an interaction of signal variation and unpalatability but inexperienced birds did not select for signal similarity in artificial prey; when the prey was moderately defended a variable signal was even learnt faster than a uniform one. Due to slow avoidance learning, moderately defended prey had higher mortality than highly defended prey (although this was not straightforward), but mixing high and moderate unpalatability did not increase predation compared with high unpalatability. This does not support the view that predators are sensitive to varying unpalatability. The results suggest that inexperienced predators may neither strongly select for accurate Müllerian mimicry nor affect the benefits of mimicry when the co-mimics are unequally defended. PMID:17305843
Summary We investigated the retention of dimethylsulfoniopropionate (DMSP) in phototrophic dinoflagellates arising from mixotrophy by estimating the cellular content of DMSP in Karlodinium veneficum (mixotrophic growth) fed for 7–10 days on either DMSP-rich Amphidinium carterae (phototrophic growth only) or DMSP-poor Teleaulax sp. (phototrophic growth only). In K. veneficum fed on DMSP-poor prey, the cellular content of DMSP remained almost unchanged regardless of the rate of feeding, whereas the cellular content of DMSP in cells of K. veneficum fed on DMSP-rich prey increased by as much as 21 times the cellular concentration derived exclusively from phototrophic growth. In both cases, significant fractions (10–32% in the former case and 55–65% in the latter) of the total DMSP ingested by K. veneficum were transformed into dimethylsulfide and other biochemical compounds. The results may indicate that the DMSP content of prey species affects temporal variations in the cellular DMSP content of mixotrophic dinoflagellates, and that mixotrophic dinoflagellates produce DMS through grazing on DMSP-rich preys. Additional studies should be performed to examine the universality of our finding in other mixotrophic dinoflagellates feeding on diverse prey species.
Lee, Hyunwoo; Park, Ki-Tae; Lee, Kitack; Jeong, Hae Jin; Yoo, Yeong Du
Extrapolating ecological processes from small-scale experimental systems to scales of natural populations usually entails a considerable increase in spatial heterogeneity, which may affect process rates and, ultimately, population dynamics. We demonstrate how information on the heterogeneity of natural populations can be taken into account when scaling up laboratory-derived process functions, using the technique of moment approximation. We apply moment approximation to a benthic crustacean predator-prey system, where a laboratory-derived functional response is made spatial by including correction terms for the variance in prey density and the covariance between prey and predator densities observed in the field. We also show how moment approximation may be used to incorporate spatial information into a dynamic model of the system. While the nonspatial model predicts stable dynamics, its spatial equivalent also produces bounded fluctuations, in agreement with observed dynamics. A detailed analysis shows that predator-prey covariance, but not prey variance, destabilizes the dynamics. We conclude that second-order moment approximation may provide a useful technique for including spatial information in population models. The main advantage of the method is its conceptual value: by providing explicit estimates of variance and covariance effects, it offers the possibility of understanding how heterogeneity affects ecological processes. PMID:16670984
The dynamics of predator-prey interactions vary enormously, due both to the heterogeneity of natural environments and to wide variability in the sensorimotor systems of predator and prey. In addition, most predators pursue a range of different types of prey, and most organisms are preyed upon by a variety of predators. We do not yet know whether predators employ a general kinematic and behavioral strategy, or whether they tailor their pursuits to each type of prey; nor do we know how widely prey differ in their survival strategies and sensorimotor capabilities. To gain insight into these questions, we compared aerial predation in 4 species of libelluid dragonflies pursuing 4 types of dipteran prey, spanning a range of sizes. We quantified the proportion of predation attempts that were successful (capture success), as well as the total time spent and the distance flown in pursuit of prey (capture efficiency). Our results show that dragonfly prey-capture success and efficiency both decrease with increasing size of prey, and that average prey velocity generally increases with size. However, it is not clear that the greater distances and times required for capturing larger prey are due solely to the flight performance (e.g., speed or evasiveness) of the prey, as predicted. Dragonflies initiated pursuits of large prey when they were located farther away, on average, as compared to small prey, and the total distance flown in pursuit was correlated with initial distance to the prey. The greater initial distances observed during pursuits of larger prey may arise from constraints on dragonflies' visual perception; dragonflies typically pursued prey subtending a visual angle of 1°, and rarely pursued prey at visual angles greater than 3°. Thus, dragonflies may be unable to perceive large prey flying very close to their perch (subtending a visual angle greater than 3-4°) as a distinct target. In comparing the performance of different dragonfly species that co-occur in the same habitat, we found significant differences that are not explained by body size, suggesting that some dragonflies may be specialized for pursuing particular types of prey. Our results underscore the importance of performing comparative studies of predator-prey interactions with freely behaving subjects in natural settings, to provide insight into how the behavior of both participants influences the dynamics of the interaction. In addition, it is clear that gaining a full understanding of predator-prey interactions requires detailed knowledge not only of locomotory mechanics and behavior, but also of the sensory capabilities and constraints of both predator and prey. PMID:23784698
Combes, S A; Salcedo, M K; Pandit, M M; Iwasaki, J M
Immunoglobulin (IgG) 4-related disease is characterized by elevated serum IgG4 and tissue infiltration by IgG4-positive plasma cells. We report a case of IgG4-related inflammation of the orbit simulating extranodal marginal zone B-cell lymphoma (EMZL). A 72-year-old female complained of bilateral eyelid swelling for three years. A MRI scan demonstrated two kinds of lesions, tumor 1, presenting with a predominantly low density, and tumor 2, of relatively high density. Laboratory tests showed high serum IgG4 concentrations, measuring 991 mg/dl. Partial resection of each tumor was conducted in September 2011. Based on the clinicopathological findings, tumors 1 and 2 were diagnosed as IgG4-related inflammation and EMZL, respectively. The patient initially received oral prednisolone at 30 mg/per day, followed by irradiation with a total dosage of 30 Gy to both eyes. The bilateral tumors consequently diminished, and she is currently well with no recurrence or systemic involvement. In conclusion, EMZL can arise from massive IgG4-related orbital inflammation. Since IgG4-related inflammation can represent multiple nodular lesions, biopsies from multiple sites within the lesion are required to make a correct diagnosis in selected cases. Oral prednisolone combined with radiotherapy is an effective treatment for patients with IgG4-related ophthalmic disease simulating EMZL. PMID:23749941
Capture ELISAs, for canine IgG, IgM, IgA and albumin, were developed and used to analyse immunoglobulin (Ig) concentrations in both serum and secretions. Matched samples of serum, saliva and tears were taken from 31 dogs, assigned to two groups based on age, whilst bile samples were obtained from nine adult dogs at post-mortem. Serum and tear IgA concentrations were significantly
To investigate the feeding by the newly described mixotrophic dinoflagellate Paragymnodinium shiwhaense (GenBank accession number=AM408889), we explored the feeding process and the kinds of prey species that P. shiwhaense is able to feed on using several different types of microscopes, including a transmission electron microscope and high-resolution video-microscopy. In addition, we measured the growth and ingestion rates of P. shiwhaense on its optimal algal prey Amphidinium carterae as a function of prey concentration. We also measured these parameters for edible prey at a single concentration at which the growth and ingestion rates of P. shiwhaense on A. carterae were saturated. Paragymnodinium shiwhaense feed on algal prey using a peduncle after anchoring the prey by a tow filament. Among the algal prey offered, P. shiwhaense ingested small algal species that had equivalent spherical diameters (ESDs) < or =11 microm (e.g. the prymnesiophyte Isochrysis galbana, the cryptophytes Teleaulax sp. and Rhodomonas salina, the raphidophyte Heterosigma akashiwo, and the dinoflagellates Heterocapsa rotundata and A. carterae). However, it did not feed on larger algal species that had ESDs > or =12 microm (e.g. the dinoflagellates Prorocentrum minimum, Heterocapsa triquetra, Scrippsiella trochoidea, Alexandrium tamarense, Prorocentrum micans, Gymnodinium catenatum, Akashiwo sanguinea, and Lingulodinium polyedrum) or the small diatom Skeletonema costatum. The specific growth rates for P. shiwhaense feeding upon A. carterae increased rapidly with increasing mean prey concentration before saturating at concentrations of ca. 350 ng C/ml (5,000 cells/ml). The maximum specific growth rate (i.e. mixotrophic growth) of P. shiwhaense on A. carterae was 1.097/d at 20 degrees C under a 14:10 h light-dark cycle of 20 microE/m(2)/s, while its growth rate (i.e. phototrophic growth) under the same light conditions without added prey was -0.224/d. The maximum ingestion and clearance rates of P. shiwhaense on A. carterae were 0.38 ng C/grazer/d (5.4 cells/grazer/d) and 0.7 microl/grazer/h, respectively. The calculated grazing coefficients for P. shiwhaense on co-occurring Amphidinium spp. was up to 0.07/h (i.e. 6.7% of the population of Amphidinium spp. was removed by P. shiwhaense populations in 1 h). The results of the present study suggest that P. shiwhaense can have a considerable grazing impact on algal populations. PMID:20487129
Yoo, Yeong Du; Jeong, Hae Jin; Kang, Nam Seon; Song, Jae Yoon; Kim, Kwang Young; Lee, Gitack; Kim, Juhyoung
ddY mice spontaneously develop IgA nephropathy (IgAN) with a variable age of disease onset. Establishing a model with early-onset IgAN could aid the investigation of mechanisms that underlie the pathogenesis of this disease. On the basis of histologic grading in serial biopsies, we previously classified ddY mice into early-onset, late-onset, and quiescent groups. Here, we selectively mated mice with the early-onset phenotype for >20 generations and established “grouped ddY” mice that develop IgAN within 8 weeks of age. Similar to human IgAN, the prognosis was worse for male mice than females. These mice homogeneously retained genotypes of four marker loci previously associated with the early-onset phenotype, confirming a close association of these loci with early-onset IgAN in ddY mice. Grouped ddY mice comprised two sublines, however, which had distinct genotypes at a susceptibility locus for high serum IgA levels, which maps within the Ig heavy-chain gene complex. The subline bearing the Igh-2a IgA allotype had a more rapid course of fatal disease and lower oligosaccharide content, suggesting that aberrant IgA glycosylation may promote the progression of murine IgAN. Taken together, these data indicate that grouped ddY mice may be a useful model for the identification of susceptibility genes and the underlying molecular mechanisms involved in the pathogenesis of human IgAN.
Sabre-like canines clearly have the potential to inflict grievous wounds leading to massive blood loss and rapid death. Hypotheses concerning sabretooth killing modes include attack to soft parts such as the belly or throat, where biting deep is essential to generate strikes reaching major blood vessels. Sabretoothed carnivorans are widely interpreted as hunters of larger and more powerful prey than that of their present-day nonsabretoothed relatives. However, the precise functional advantage of the sabretooth bite, particularly in relation to prey size, is unknown. Here, we present a new point-to-point bite model and show that, for sabretooths, depth of the killing bite decreases dramatically with increasing prey size. The extended gape of sabretooths only results in considerable increase in bite depth when biting into prey with a radius of less than ?10 cm. For sabretooths, this size-reversed functional advantage suggests predation on species within a similar size range to those attacked by present-day carnivorans, rather than “megaherbivores” as previously believed. The development of the sabretooth condition appears to represent a shift in function and killing behaviour, rather than one in predator-prey relations. Furthermore, our results demonstrate how sabretoothed carnivorans are likely to have evolved along a functionally continuous trajectory: beginning as an extension of a jaw-powered killing bite, as adopted by present-day pantherine cats, followed by neck-powered biting and thereafter shifting to neck-powered shear-biting. We anticipate this new insight to be a starting point for detailed study of the evolution of pathways that encompass extreme specialisation, for example, understanding how neck-powered biting shifts into shear-biting and its significance for predator-prey interactions. We also expect that our model for point-to-point biting and bite depth estimations will yield new insights into the behaviours of a broad range of extinct predators including therocephalians (gorgonopsian + cynodont, sabretoothed mammal-like reptiles), sauropterygians (marine reptiles) and theropod dinosaurs.
Background: Most ecological models assume that predator and prey populations interact solely through consumption: predators reduce prey densities by killing and consuming individual prey. However, predators can also reduce prey densities by forcing prey to adopt costly defensive strategies. Methodology\\/Principal Findings: We build on a simple Lotka-Volterra predator-prey model to provide a heuristic tool for distinguishing between the demographic effects
Laboratory studies have shown that the nonindigenous Asian shore crab, Hemigrapsus sanguineus, readily consumes three species of commercial bivalves: blue mussels, Mytilus edulis, soft-shell clams, Mya arenaria, and oysters, Crassostrea virginica. Although crabs can eat bivalves of a wide size range, they preferred the smaller prey (=10 mm SL). Prey critical size limits exist for M. edulis and C. virginica, but not M. arenaria, possibly because of differences in shell characteristics among the three species. Crabs preferred M. arenaria over both M. edulis and C. virginica, and M. edulis was strongly preferred over C. virginica in pairwise comparison tests. Experiments to determine feeding rates on mussels showed that H. sanguineus can consume large numbers of mussels daily (12.7+/-11.6 mussels day(-1); sexes pooled; N=59). Mussel consumption rates increased with size of the predator and male crabs consumed more mussels than did similarly sized female crabs. The high densities of Hemigrapsus that occur in the wild, their effectiveness as predators of juvenile bivalves and their large appetites suggest an important role for these predators in restructuring the prey communities in habitats into which they have been introduced. PMID:11445087
Large carnivores are highly threatened, yet the processes underlying their population declines are still poorly understood and widely debated. We explored how body mass and prey abundance influence carnivore density using data on 199 populations obtained across multiple sites for 11 carnivore species. We found that relative decreases in prey abundance resulted in a five- to sixfold greater decrease in the largest carnivores compared with the smallest species. We discuss a number of possible causes for this inherent vulnerability, but also explore a possible mechanistic link between predator size, energetics and population processes. Our results have important implications for carnivore ecology and conservation, demonstrating that larger species are particularly vulnerable to anthropogenic threats to their environment, especially those which have an adverse affect on the abundance of their prey.
Carbone, Chris; Pettorelli, Nathalie; Stephens, Philip A.
Small fishes and cephalopods associated with both pelagic and inshore habitats composed the major prey for the blue shark, Prionace glauca, near Santa Catalina Island, Calif. The northern anchovy, Engraulis mordax, was the predominant prey for sharks in t...
Although biologists routinely label animals as predators and prey, the ecological role of individuals is often far from clear. There are many examples of role reversals in predators and prey, where adult prey attack vulnerable young predators. This implies that juvenile prey that escape from predation and become adult can kill juvenile predators. We show that such an exposure of juvenile prey to adult predators results in behavioural changes later in life: after becoming adult, these prey killed juvenile predators at a faster rate than prey that had not been exposed. The attacks were specifically aimed at predators of the species to which they had been exposed. This suggests that prey recognize the species of predator to which they were exposed during their juvenile stage. Our results show that juvenile experience affects adult behaviour after a role reversal.
Choh, Yasuyuki; Ignacio, Maira; Sabelis, Maurice W.; Janssen, Arne
This paper investigates the dynamics of a competitive single-prey n-predators model of integrated pest management, which is subject to periodic and impulsive controls, from the viewpoint of finding sufficient conditions for the extinction of prey and for prey and predator permanence. The per capita death rates of prey due to predation are given in abstract, unspecified forms, which encompass large classes of death rates arising from usual predator functional responses, both prey-dependent and predator-dependent. The stability and permanence conditions are then expressed as balance conditions between the cumulative death rate of prey in a period, due to predation from all predator species and to the use of control, and to the cumulative birth rate of prey in the same amount of time. These results are then specialized for the case of prey-dependent functional responses, their biological significance being also discussed. PMID:23123675
The population parameters and biological characteristics of the predator Macrolophus pygmaeus Rambur when feeding on eggplant, Solanum melongena L., and tomato, Lycopersicon esculentum (Miller) (both Solanaceae), without access to prey, were investigated at several temperatures. The experiments were conducted at 15, 20, 25, and 30 degrees C, 65 +/- 5% RH, and a photoperiod of 16:8 (L:D) h. Females oviposited on both plant species at all temperatures, with the exception of tomato at 30 degrees C. Fecundity was highest at 20 degrees C (21.55 and 8.28 eggs per female on eggplant and tomato, respectively). Adult longevity on both host plants was greatest at 15 degrees C, reaching 38.72 and 34.20 d for females and 92.88 and 62.80 d for males, on eggplant and tomato, respectively. The estimated values of population parameters showed that this predator increased its numbers on eggplant at all temperatures tested, but the highest intrinsic rate of increase occurred at 25 degrees C (0.0401 d(-1)). On tomato, this predator could not increase in number, although it could survive for a relatively long period. Results demonstrated that M. pygmaeus can survive on both host plants in periods of prey scarcity, particularly on eggplant. Therefore, phytophagy can positively contribute to the effectiveness of this biological control agent. The importance of eggplant as a reservoir for the predator in mixed crops that are less suitable host plants is discussed. PMID:15384340
Perdikis, Dionyssios Ch; Lykouressis, Dionyssios P
Background and Objectives: Although immunoglobulin (Ig) preparations including RhIg have been noted for their record of safety, recent reports of hepatitis C virus (HCV) transmission by some Ig preparations have raised concern. This analysis examined the safety of RhIg manufactured in the US by comparing the prevalence and incidence of viral markers in Rh–negative and Rh–positive female blood donors. Materials
Kevin K. Watanabe; Michael P. Busch; George B. Schreiber; Thomas F. Zuck
Although prey-detecting and searching abilities of predatory leeches of rhynchobdellid or the Erpobdelliformes of arhynchobdellid\\u000a species have been studied in the past, hirudiniformes leeches are rarely mentioned. In this study, we investigated the chemosensory\\u000a ability for prey-detecting and searching in Whitmania laevis, a hirudiniformes species that mainly preys on freshwater snails, and examined if such ability aided in their prey
1.Field studies were conducted with second and third instar spiderlings of the orb weaver Nephila clavipes. The influences of prey type, prey condition, and web structure on feeding and predation were assessed.2.After emergence from the egg sac, spiderlings inhabited a communal, tangled web. Juveniles readily ate dead or immobile siblings and insect prey but did not attack live prey.3.Communal web
Interactions between foragers may seriously affect individual foraging efficiency. In a laboratory study of handling time,\\u000a prey value and prey-size preference in northern pike and signal crayfish, we show that risk of intraspecific interactions\\u000a between predators does not affect handling time or value of prey. However, the presence of agonistic intraspecific interactors\\u000a shifts prey-size preference in these predators. Neither northern
In this work we present a predator-prey model that incorporates individual behavior of the predators. A classical Lotka-Volterra model with self-limiting prey describes the predator-prey interaction. Predator individuals can use two behavioral tactics to dispute a prey when they meet, the classical hawk and dove tactics. Each individual can use both tactics along its life. The predator behavioral change is
In this work we present a predator–prey model that incorporates individual behavior of the predators. A classical Lotka–Volterra model with self-limiting prey describes the predator–prey interaction. Predator individuals can use two behavioral tactics to dispute a prey when they meet, the classical hawk and dove tactics. Each individual can use both tactics along its life. The predator behavioral change is
Pierre Auger; Rafael Bravo de la Parra; Serge Morand; Eva Sánchez
Species that sequester toxins from prey for their own defense against predators may exhibit population-level variation in their chemical arsenal that reflects the availability of chemically defended prey in their habitat. Rhabdophis tigrinus is an Asian snake that possesses defensive glands in the skin of its neck (‘nuchal glands’), which typically contain toxic bufadienolide steroids that the snakes sequester from consumed toads. In this study, we compared the chemistry of the nuchal gland fluid of R. tigrinus from toad-rich and toad-free islands in Japan and determined the effect of diet on the nuchal gland constituents. Our findings demonstrate that captive-hatched juveniles from toad-rich Ishima Island that had not been fed toads possess defensive bufadienolides in their nuchal glands, presumably due to maternal provisioning of these sequestered compounds. Wild-caught juveniles from Ishima possess large quantities of bufadienolides, which could result from a combination of maternal provisioning and sequestration of these defensive compounds from consumed toads. Interestingly, juvenile females from Ishima possess larger quantities of bufadienolides than do juvenile males, whereas a small sample of field-collected snakes suggests that adult males contain larger quantities of bufadienolides than do adult females. Captive-born hatchlings from Kinkasan Island lack bufadienolides in their nuchal glands, reflecting the absence of toads on that island, but they can sequester bufadienolides by feeding on toads (Bufo japonicus) in captivity. The presence of large quantities of bufadienolides in the nuchal glands of R. tigrinus from Ishima may reduce the risk of predation by providing an effective chemical defense, whereas snakes on Kinkasan may experience increased predation due to the lack of defensive compounds in their nuchal glands.
Hutchinson, D A; Savitzky, A H; Burghardt, G M; Nguyen, C; Meinwald, J; Schroeder, F C; Mori, A
The enzyme-linked immunospot assay was used to enumerate both the number and the frequency of spontaneous IgG, IgA, and IgM immunoglobulin-secreting cells and IgA- and IgM-rheumatoid factor (RF)-producing cells present in the gingivae and peripheral blood of adult periodontitis patients. Cells from 29 patients were incubated on plates coated with human IgG, Fc, or F(ab')2 fragments and on plates coated
Harold Z. Hirsch; Andrej Tarkowski; William J. Koopman; Jiri Mestecky
Currently, the International GPS Service (IGS) provides a set of clock products for both satellites and tracking receivers, tabulated at 5-min intervals. These products allow users to determine consistent coordinates and clock values for an isolated GPS receiver with an internal accuracy at the few-cm level. However, because the underlying time scale for the IGS combined clocks is based on a linear alignment to broadcast GPS Time for each day separately, the day-to-day stability of this reference is poor. We show the results of a new filter package written to automate the production of an integrated IGS frequency scale based on a dynamically weighted ensemble of the included frequency standards. The new scale is loosely steered to GPS Time. PMID:12839170
In an analysis of 67 pitfall trap studies in different environments a positive correlation is found between the abundance of spiders and their potential prey, individual main prey groups and individual predator groups. The body-size of spiders and potential prey is significantly correlated both during the day in one locality and between five different localities. Spiders match the size spectrum
The accuracies of examining uneaten prey remains collected at feeding sites and of directly observing fish captured while birds forage, common methods of determining the species composition and size structure of prey in the diets of ospreys (Pandion haliaetus), were tested during the summer of 1992 at two shallow lakes in northeastern Scotland. Prey remains were collected below feeding perches
Virtual plant models of plant architecture have been developed to examine the impact of canopy structure and connectedness on the location of prey by randomly moving predators. The results show that as canopy connectedness increases, the time to locate a static prey decreases, but that the time to prey location increases with the complexity of the canopy. These results are
To develop robust agents capable of adapting to changes in environment conditions we analyze the effects of introducing noise into multi-agent communication and varying prey movement patterns in a version of the predator-prey pursuit problem. In this simulation, predators communicate with languages evolved using a genetic algorithm. We show the time it takes to capture prey increases as more noise
Todd M. Bacastow; Brian R. Cook; Kam-Chuen Jim; C. Lee Giles
The pink hibiscus mealybug Maconellicoccus hirsutus (Green) (Hemiptera: Pseudococcidae) is a major pest of economically important crops. The apefly Spalgis epius (Westwood) (Lepidoptera: Lycaenidae) is a potential predator of various species of mealybugs. Studies of its preying potential\\u000a and preference for prey stages on M. hirsutus are incomplete. An investigation was undertaken to determine the daily prey consumption and preference
Populations in nature face a number of factors that can alter their traits and subsequent performance. Predation is one factor that can have widespread effects on the mean trait value in a prey population because predators can impact prey traits through a number of processes. Predators can directly induce prey phenotypes through visual and chemical cues, predators can indirectly alter
Claw morphology, and claw-closing forces of four species of intertidal crabs from San Juan Island, Washington were compared and related these findings were related to prey size selection, shell breaking times and total handling times on their snail prey, Littorina sitkana Philippi. Two functional groups of crabs emerged: generalists and specialists on hard-shelled prey. The generalist, Hemigrapsus nudus (Dana), has
Predator and prey attack-escape performance is likely to be the outcome of an evolutionary arms race. Predatory birds are typically larger than their prey, suggesting different flight performances. We analyze three idealized attack-escape situations between predatory and prey birds: climbing flight escape, horizontal speeding, and turning and escape by diving. Generally a smaller bird will outclimb a larger predator and
This study explores the effect of the length of learning period on capture rate of a previously unfamiliar prey by an invasive\\u000a freshwater crayfish (Procambarus clarkii). Juvenile crayfish were subjected to different periods of contact (learning period) with a larvae prey (Chaoborus sp.). The length of the learning period significantly affected the number of prey consumed by the predator. Our
We compared intraoral prey transport in venomous snake species from four families (two atractaspidids, nine elapids, three colubrids, 44 viperids) with that in eight non-venomous colubrid species, most feeding on similar mammalian prey. The morphology of the venom delivery system suggests that intraoral prey transport performance should be slightly decreased in atractaspidids, unmodified in most elapids and venomous colubrids, and
Materials eliciting increased tongue flicking and prey attack in garter snakes were isolated from both earthworm and fish prey. New extraction methods based on chloroform-methanol mixtures are valuable adjuncts to the more typical aqueous preparations. Both high- and low-molecular weight components from earthworms and fish were active. The similarity between the active chemicals in these two classes of prey was
FOLK nest cavities of the Red-cockaded Woodpecker (Picoides borealis) were monitored with automatic cameras to determine the prey selected to feed nestlings. Twelve adults were photographed making nearly 3000 nest visits. Prey in 28 arthropod taxa were recognizable in 65% of the photographic slides. Wood roaches in the genus (Parcoblutta) made up 69.4% of the prey fed to nestlings. Other
...Rules for the Morley Nelson Snake River Birds of Prey National Conservation Area AGENCY...700-acre Morley Nelson Snake River Birds of Prey National Conservation Area (NCA...Record of Decision (ROD). The Snake River Birds of Prey NCA RMP identifies...
A mathematical model is proposed to study the simultaneous ef- fects of toxicant and infectious disease on Lotka-Volterra prey-predator system. It is considered in the model that only the prey population is being afiected by disease and toxicant both, and the susceptible and infected prey populations are being predated by predator. All the feasible equilibrium of the model are obtained
|We developed a predator-prey activity with eighth-grade students in which they used wolf spiders ("Lycosa carolinensis"), house crickets ("Acheta domestica"), and abiotic factors to address how (1) adaptations in predators and prey shape their interaction and (2) abiotic factors modify the interaction between predators and prey. We tested student…
|This paper develops a mathematical model for the nonselective harvesting of a prey-predator system in which both the prey and the predator obey the Gompertz law of growth and some prey avoid predation by hiding. The steady states of the system are determined, and the dynamical behaviour of both species is examined. The possibility of existence of…
Eciton burchelli workers frequently form groups to retrieve large prey items. Such groups have a definite structure. There is a constant relationship between total ant dry weight and prey item dry weight for both individual porters and groups, and this relation is such that a larger weight of ant or ants can carry disproportionately heavy items. Furthermore, all prey items
Schistosoma haematobium antigen recognition profiles of the human isotypes IgA, IgE, IgG1 and IgG4 were compared by image analysis of western blots. Adult worm antigens separated by two-dimensional gel electrophoresis were probed with pooled sera from Zimbabweans resident in a S. haematobium endemic area, followed by the identification of individual antigenic parasite proteins using mass spectrometry. Overall, IgG1 reacted with the largest number of antigens, followed by IgE and IgA which detected the same number, while IgG4 detected the fewest antigens. IgE recognized all antigens reactive with IgG4 as well as an additional four antigens, an isoform of 28-kDa GST, phosphoglycerate kinase, actin 1 and calreticulin. IgG1 additionally recognized fatty acid–binding protein, triose-phosphate isomerase and heat shock protein 70, which were not recognized by IgA. Recognition patterns varied between some isoforms, e.g. the two fructose 1-6-bis-phosphate aldolase isoforms were differentially recognized by IgA and IgG1. Although the majority of S. haematobium adult worm antigens are recognized by all of the four isotypes, there are clear restrictions in antibody recognition for some antigens. This may partly explain differences observed in isotype dynamics at a population level. Differential recognition patterns for some isoforms indicated in the study have potential importance for vaccine development.
MUTAPI, F; BOURKE, C; HARCUS, Y; MIDZI, N; MDULUZA, T; TURNER, C M; BURCHMORE, R; MAIZELS, R M
Two closely located islands on the west coast of South Africa support widely different benthic communities. The biota at Malgas Island is dominated by seaweeds and by rock lobsters that consume settling mussels, thereby preventing the establishment of the mussels. They also prey on whelks, although one species, Burnupena papyracea, is protected from predation by a commensal bryozoan that covers
Understanding and predicting the consequences of trophic interactions for community processes requires knowledge of the role of food availability, which is often wrongly conflated with prey abundance. For prey animals in groups, this is not fully understood. Previous work has shown that oystercatchers more frequently attack solitary rather than aggregated limpets and are more successful in predation attempts on singletons. It has also been demonstrated that an attack on one limpet in a group alerts the entire group, all of which then clamp down and become unavailable. I show that Eurasian Oystercatchers (Haematopus ostralegus L.) attack only one limpet in a group and then move on to attack another individual limpet, and I also demonstrate that the distance they move is greater than the distance at which groups of limpets have been known to detect attacks. Thus in the oystercatcher-limpet predator-prey system on rocky shores, groups of limpets are actually one prey item independently of the number of limpets in the group. This has implications for assessment of food supply for avian predators on rocky shores, with consequences for our understanding of previously documented trophic cascades. PMID:18705365
Throughout the study of ecology, there has been a growing realization that indirect effects among species cause complexity in food webs. Understanding and predicting the behavior of ecosystems consequently depends on our ability to identify indirect effects and their mechanisms. The present study experimentally investigates indirect interactions arising between two prey species that share a common predator. In a natural
Sabre-like canines clearly have the potential to inflict grievous wounds leading to massive blood loss and rapid death. Hypotheses concerning sabretooth killing modes include attack to soft parts such as the belly or throat, where biting deep is essential to generate strikes reaching major blood vessels. Sabretoothed carnivorans are widely interpreted as hunters of larger and more powerful prey than
Ki Andersson; David Norman; Lars Werdelin; Daphne Soares
Summary 1. Management decisions for threatened and endangered species require risks to be identified and prioritized, based on the degree to which they influence population dynamics. The potential for recovery of small populations at risk may be determined by multiple factors, including intrinsic population characteristics (inbreeding, sex ratios) and extrinsic variables (prey availability, disease, human disturbance). Using Bayesian statistical methods,
Generalist predators are widely acknowledged to contribute valuable levels of biological con- trol in agroecosystems throughout the world. Although their feeding habits can result in the rejection of target pests in favor of preferred and often more nutritious non-pest prey, these natural enemies are capable of colonizing habitats prior to the arrival of pests by subsisting on alternative sources of
The hypothesis that carnivores can significantly suppress prey populations after they collapse during drought was tested by predator-removal experiments. Low populations of rabbits (Oryctolagus cuniculus) responded with significantly accelerated growth where foxes (Vulpes vulpes) and feral cats (Felis catus) were continually shot. Experiments in years of good pasture and poor were confirmatory. After only 14 months, the rabbits were well
Nemerteans are predators of a wide variety of animals, but little is known of their role as prey for other animals. The presence of toxins in the tissues and secretions of these worms has led to the assumption usually suggested that they are ingested only rarely. However, analysis of a Food Habits Data Base from the United States National Marine
Planktonic bacteria may represent a substantial nutrient resource available to support the next higher trophic level in the microbial loop (heterotrophic flagellates). In this work we examined the utilization of different size classes of bacteria by flagellated protozoan predators of various sizes. The emphasis was to determine if prey-size selection was a function of predator size. Pseudomonas sp. was grown
Although measures of evenness of archaeological faunas are increasingly used in zooarchaeological analyses, the widely accepted hypothesis that increasing evenness should indicate increasing dietary breadth has not been tested. In this paper, I examine three factors that can contribute to changing evenness values—changing encounter rates with high-ranked prey types, changing diet breadth, and similarity between the return rates of the
It is now well understood that including spatial structure and stochastic noise in models for predator-prey interactions invalidates the classical deterministic Lotka-Volterra picture of neutral population cycles. In contrast, stochastic models yield long-lived, but ultimately decaying erratic population oscillations, which can be understood through a resonant amplification mechanism for density fluctuations. Simulations of spatial stochastic predator-prey systems yield striking complex spatio-temporal structures. These spreading activity fronts induce persistent correlations between predators and prey. Here, we address the influence of spatially varying reaction rates on a stochastic two-species Lotka-Volterra lattice model. The effects of this quenched randomness on population densities, transient oscillations, spatial correlations, and invasion fronts are investigated through Monte Carlo simulations. We find that spatial variability in the predation rate results in more localized activity patches. Population fluctuations in rare favorable regions in turn cause a remarkable increase in the asymptotic population densities of both predators and prey, and also lead to accelerated front propagation.
It is well-established that including spatial structure and stochastic noise in models for predator-prey interactions invalidates the classical deterministic Lotka-Volterra picture of neutral population cycles. In contrast, stochastic models yield long-lived, but ultimately decaying erratic population oscillations, which can be understood through a resonant amplification mechanism for density fluctuations. In Monte Carlo simulations of spatial stochastic predator-prey systems, one observes striking complex spatio-temporal structures. These spreading activity fronts induce persistent correlations between predators and prey. In the presence of local particle density restrictions (finite prey carrying capacity), there exists an extinction threshold for the predator population. The accompanying continuous non-equilibrium phase transition is governed by the directed-percolation universality class. We employ field-theoretic methods based on the Doi-Peliti representation of the master equation for stochastic particle interaction models to (i) map the ensuing action in the vicinity of the absorbing state phase transition to Reggeon field theory, and (ii) to quantitatively address fluctuation-induced renormalizations of the population oscillation frequency, damping, and diffusion coefficients in the species coexistence phase.
It is well-established that including spatial structure and stochastic noise in models for predator-prey interactions invalidates the classical deterministic Lotka-Volterra picture of neutral population cycles. In contrast, stochastic models yield long-lived, but ultimately decaying erratic population oscillations, which can be understood through a resonant amplification mechanism for density fluctuations. In Monte Carlo simulations of spatial stochastic predator-prey systems, one observes striking complex spatio-temporal structures. These spreading activity fronts induce persistent correlations between predators and prey. In the presence of local particle density restrictions (finite prey carrying capacity), there exists an extinction threshold for the predator population. The accompanying continuous non-equilibrium phase transition is governed by the directed-percolation universality class. We employ field-theoretic methods based on the Doi-Peliti representation of the master equation for stochastic particle interaction models to (i) map the ensuing action in the vicinity of the absorbing state phase transition to Reggeon field theory, and (ii) to quantitatively address fluctuation-induced renormalizations of the population oscillation frequency, damping, and diffusion coefficients in the species coexistence phase. [See Preprint arXiv:1105.4242, and further refs. therein.
Southern sea otters (Enhydra lutris nereis), in recovering from near extinction, are gradually extending their range to include areas from which they have been absent for more than one hundred years. This study took advantage of the otters' relatively sudden arrival in the area near Santa Cruz, California, to monitor their prey selection in the first two years of residence
Secondary plant metabolites (allelochemicals) play a major role in plant-insect interactions. Glucosinolates (GLS) and their degradation products from Brassica species are attractants and feeding stimulants for Brassicaceae specialist insects but are generally repellent and toxic for generalist herbivores. The impact of these compounds on crucifer specialist insects are well known but their effect on generalist predators is still not well documented. Prey host plant influence on reproduction of an aphidophagous beneficial, the two spot ladybird, was determined using the cabbage aphid, Brevicoryne brassicae reared on a crucifer plant, namely Brassica napus containing low GLS levels. As ladybird developmental and reproductive parameters were already shown to be strongly affected by the allelochemical presence in its preys, the unsuitable aphid and host plant combination was only momentary used to feed the A. bipunctata adults. A strong impact of the diet was observed on the beetle fecundity and the emerging offspring. Changing B. brassicae aphid to a suitable prey slowly improved the temporary negative effect of the former diet. These results enhance the food environmental effect and the importance of tritrophic relations in pest management strategies by predators. Indeed, more than the choice of the beneficial species, the prey host plant has a major influence on the potential efficacy of biological agent to control herbivore species such as aphids. PMID:12696423
In order to understand the effect the diet of Steller sea lions may have had on their decline in the North West Pacific and the Gulf of Alaska, a database of the energetic contents of Steller sea lion's prey was compiled and added to the database of general conversions used by the students and researchers at the Fisheries Centre. Multiple
Two species of ctenophores coexist in the north?east Atlantic, one (Bolinopsis infundibulum) forages on crustaceans, while the other (Beroë cucumis) feeds exclusively on the former. Some introductory aspects on the chemical ecology of this predator?prey relationship are reported here. In laboratory experiments, Bolinopsis demonstrated an escape response to mechanical stimuli directed towards the frontal lobes, as well as to direct
Two common nemertines of the European Wadden Sea, Lineus viridis and Amphiporus lactifloreus, occur preferentially in clusters of mussels, spread over sedimentary flats in the upper intertidal near the island of Sylt. The heteronemerUne L. viridis preys mainly on the polychaete Nereis diversicolor. The hoplonemertine A. lactifloreus feeds almost exclusively on the amphipod Gammarus Iocusta. Abundance of both predators and
Sustainable management of economically important squid requires monitoring of changes in their abundance, which are related inter alia, to their success in the food chain. the highest mortality is expected in the paralarval stages, which are prone to starvation. Causes of starvation may be linked to the lack of suitable prey. A multiple detection system was developed for the simultaneous
J. D. Venter; S. van Wyngaardt; J. A. Verschoor; M. R. Lipi?ski; H. M. Verheye
In this paper we study a two prey one predator model with team approach. We analyze local stability behaviour of the system with the help of linearization and persistence behaviour of the system with the help of persistence of all three teams individually.
We model a prey predator with model with two discrete delays. Hopf-bifurcation analysis with respect to both delay parameters is performed. An algorithm has been developed to draw bifurcation diagram to obtain stability domain with respect to both delays. Complex dynamical behavior including chaos is obtained outside the domain of stability. Properties of periodic solutions are also determined.
Cryptically coloured animals commonly occur in several distinct pattern variants. Such phenotypic diversity may be promoted by frequency-dependent predation, in which more abundant variants are attacked disproportionately often, but the hypothesis has never been explicitly tested. Here we report the first controlled experiment on the effects of visual predators on prey crypticity and phenotypic variance, in which blue jays (Cyanocitta
Blue jays learned to respond differentially to the presence or absence of Catocala moths in slides. This detection of the moths by the jays was affected by the background upon which the moth was placed and its body orientation, thus providing an objective measure of crypticity. These procedures are useful for the study of visual detection of prey.
We investigated the energy source fuelling the post-feeding metabolic upregulation (specific dynamic action, SDA) in pythons (Python regius). Our goal was to distinguish between two alternatives: (i) snakes fuel SDA by metabolizing energy depots from their tissues; or (ii) snakes fuel SDA by metabolizing their prey. To characterize the postprandial response of pythons we used transcutaneous ultrasonography to measure organ-size
J. Matthias Starck; Patrick Moser; Roland A. Werner; Petra Linke
Predictable prey locations reduce search time and energetic costs of foraging; thus marine predators often exploit locations where prey concentrations persist. In our study, we examined whether this association is influenced by differences among predator species in foraging modes (travel cost, surface feeder or diver) or whether the predator species is a central place forager or not. We examined distributions of two seabird species during their nesting period, the surface-feeding black-legged kittiwake (Rissa tridactyla) and the pursuit-diving thick-billed murre (Uria lomvia), and two baleen whale species, the humpback whale (Megaptera novaeangliae) and the fin whale (Balaenoptera physalus), in relation to two key prey, age-1 walleye pollock (Theragra chalcogramma) and euphausiids (Euphausiidae). Prey surveys were conducted once each year during 2004 and 2006-2010. Concurrent predator surveys were conducted in 2006-2010 (seabirds) and 2008 and 2010 (whales). We compared the seabird and whale foraging locations to where age-1 pollock and euphausiids were concentrated and considered the persistence of these concentrations, where the time-scale of persistence is year (i.e., a comparison among surveys that are conducted once each year). Euphausiids were widespread and concentrations often were reliably found within specific 37 km×37 km blocks ('persistent hot spots of prey'). In contrast, age-1 pollock were more concentrated and their hot spots were persistent only on coarser scales (>37 km). Both seabird species, regardless of foraging mode, were associated with age-1 pollock but not with euphausiids, even though age-1 pollock were less persistent than euphausiids. The higher travel cost central place foragers, thick-billed murres, foraged at prey concentrations nearer their island colonies than black-legged kittiwakes, which were more widespread foragers. Humpback whales were not tied to a central place and mostly were located only where euphausiids were concentrated, and further, often in locations where these concentrations were persistent. Fin whales were associated with locations where age-1 pollock were more likely, similar to black-legged kittiwakes and thick-billed murres, but their association with euphausiids was unclear. Our results suggest that a predator's foraging mode and their restrictions during breeding affect their response to prey persistence.
Sigler, Michael F.; Kuletz, Kathy J.; Ressler, Patrick H.; Friday, Nancy A.; Wilson, Christopher D.; Zerbini, Alexandre N.
Laboratory and clinical data are presented in fifteen patients under the age of sixteen years with selective IgA deficiency, all of whom had normal serum IgG, IgM, IgD and IgE. Results indicate a high incidence of autoimmune disease, autoimmune phenomenon or unusual antibody formation. Three patients had thyroiditis, one cerebral vasculitis, one pulmonary haemosiderosis, one cystic fibrosis and nine had recurrent upper respiratory tract infections. Ten out of fifteen were positive for one or more `autoantibodies.' Selective IgA deficiency cannot always be considered a benign entity and individuals with this defect warrant complete investigation.
Theoretical efforts suggest that the relative sizes of predators and their prey can shape community dynamics, the structure of food webs, and the evolution of life histories. However, much of this work has assumed static predator and prey body sizes. The timing of recruitment and the growth patterns of both predator and prey have the potential to modify the strength of predator-prey interactions. In this study, I examined how predator size dynamics in 40 temporary ponds over a 3-year period affected the survival of spotted salamander (Ambystoma maculatum) larvae. Across communities, gape-limited predator richness, but not size, was correlated with habitat duration (pond permanence). Within communities, mean gape-limited predator size diminished as the growing season progressed. This size reduction occurred because prey individuals grew into a body size refuge and because the largest of the predators left ponds by mid-season. Elevated gape-limited predation risk across time and space was predicted by the occurrence of two large predatory salamanders: marbled salamander larvae (Ambystoma opacum) and red-spotted newt adults (Notophthalmus viridescens). The presence of the largest gape-limited predator, A. opacum, predicted A. maculatum larval survival in the field. The distribution of large predatory salamanders among ponds and across time is expected to lead to differing community dynamics and to generate divergent natural selection on early growth and body size in A. maculatum. In general, a dynamic perspective on predator size often will be necessary to understand the ecology and evolution of species interactions. This will be especially true in frequently disturbed or seasonal habitats where phenology and ontogeny interact to determine body size asymmetries. PMID:17891545
Changes in intraoral pressure during prey capture were recorded for a trophic generalist, Hexagrammos decagrammus, feeding on different prey species. Prey were grouped into elusive (shrimps), grasping (isopods and crabs) and non-elusive (pieces of shrimp) categories. Elusive and grasping prey elicited strikes with a larger and faster reduction in buccal pressure than did non-elusive prey. The suction force generated by the predator differed for strikes among the shrimp genera in the elusive prey category. The most sedentary shrimps (Crangon alaskensis and C. nigricauda) elicited the fastest and greatest reduction in pressure relative to the most evasive shrimps (Pandalus danae and Heptacarpus stylus). A preparatory phase, during which the buccal cavity is compressed prior to the strike, occurred significantly more frequently in strikes at grasping prey than in strikes at elusive and non-elusive prey, and more frequently for elusive than for non-elusive prey. Prey size did not influence the suction force generated by the predator. No differences in buccal pressure patterns were detected between strikes that resulted in a capture or a miss, suggesting that misses were due to the escape behavior of the prey and were not the result of an inappropriate suction force. These data support the current view that fish can modify their feeding mode in response to prey behavior, and they emphasize that the behavioral responses of the individual prey must be considered when defining the appropriate strategy for prey capture. The use of a flexible, modifiable feeding behavior is associated with a broad diet in H. decagrammus and may increase capture success on diverse prey relative to that of other species showing stereotypical feeding responses. PMID:9320058
While foraging theory predicts that predatory responses should be determined by the energy content and size of prey, it is becoming increasingly clear that carnivores regulate their intake of specific nutrients. We tested the hypothesis that prey nutrient composition and predator nutritional history affects foraging intensity, consumption, and prey selection by the wolf spider, Pardosa milvina. By altering the rearing environment for fruit flies, Drosophila melanogaster, we produced high quality flies containing more nitrogen and protein and less lipid than low quality fruit flies. In one experiment, we quantified the proportion of flies taken and consumption across a range of densities of either high or low quality flies and, in a second experiment, we determined the prey capture and consumption of spiders that had been maintained on contrasting diets prior to testing. In both cases, the proportion of prey captured declined with increasing prey density, which characterizes the Type II functional response that is typical of wolf spiders. Spiders with similar nutritional histories killed similar numbers of each prey type but consumed more of the low quality prey. Spiders provided high quality prey in the weeks prior to testing killed more prey than those on the low quality diet but there was no effect of prior diet on consumption. In the third experiment, spiders were maintained on contrasting diets for three weeks and then allowed to select from a mixture of high and low quality prey. Interestingly, feeding history affected prey preferences: spiders that had been on a low quality diet showed no preference but those on the high quality diet selected high quality flies from the mixture. Our results suggest that, even when prey size and species identity are controlled, the nutritional experience of the predator as well as the specific content of the prey shapes predator-prey interactions. PMID:23145130
Schmidt, Jason M; Sebastian, Peter; Wilder, Shawn M; Rypstra, Ann L
Uptake of nitrogen from prey and substrate and partitioning of prey-derived nitrogen were studied in the carnivorous plant species Pinguicula alpina, P. villosa, P. vulgaris and Drosera rotundifolia in a subarctic environment. Efficiency in nitrogen uptake from prey was evaluated by tracing 15N from 15N-enriched Drosophila flies fed to the plants. The in situ uptake efficiency differed somewhat between species
Adaptations of snakes to overpower and ingest relatively large prey have attracted considerable research, whereas lizards\\u000a generally are regarded as unable to subdue or ingest such large prey items. Our data challenge this assumption. On morphological\\u000a grounds, most lizards lack the highly kinetic skulls that facilitate prey ingestion in macrostomate snakes, but (1) are capable\\u000a of reducing large items into
The feeding strategy and prey selection of haddock Melanogrammus aeglefinus related to the benthic infauna in the field were investigated in three different study areas (boxes) in the northern North Sea in 2007. The stomach contents of M. aeglefinus were dominated by invertebrates in all three boxes, mainly echinoderms and polychaetes, similar to the benthic communities in the field. Prey densities in the field significantly determined prey selection and, thus the feeding strategy of M. aeglefinus appeared highly opportunistic. Other prey characteristics, such as the position in the sediment or its palatability, had no significant effect on the selection process although trends were apparent that tubicolous polychaetes of the family spionids, especially Spiophanes kröyeri and Spiophanes bombyx as well as the tentaculate Phoronis spp., were not consumed and potentially avoided due to their ability to withdraw below the feeding depths or due to chemical deterrents. High abundances of echinoderm species with hard calcareous shells in the M. aeglefinus stomachs, such as the ophiurid Ophiocten affinis and the echinoid Echinocyamus pusillus, indicated their use as grinding elements. A gradual shift from benthos to fish feeding with increasing M. aeglefinus size was not found. PMID:20646141
Using rotifer–algal microcosms, we tracked rapid evolution resulting from temporally changing natural selection in ecological predator–prey dynamics. We previously demonstrated that predator–prey oscillations in rotifer–algal laboratory microcosms are qualitatively altered by the presence of genetic variation within the prey. In that study, changes in algal gene frequencies were inferred from their effects on population dynamics but not observed directly. Here, we document rapid prey evolution in this system by directly observing changes in Chlorella vulgaris genotype frequencies as the abundances of these algae and their consumer, Brachionus calyciflorus, change through time. We isolated a group of algal clones that we could distinguish by using microsatellite-DNA markers, and developed an allele-specific quantitative PCR technique (AsQ-PCR) to quantify the frequencies of pairs of clones in mixed culture. We showed that two of these genotypes exhibited a fitness tradeoff in which one was more resistant to predation (more digestion-resistant), and the other had faster population growth under limiting nitrogen concentrations. A fully specified mathematical model for the rotifer–algal population and evolutionary dynamics predicted that these two clones would undergo a single oscillation in clonal frequencies followed by asymptotic fixation of the more resistant clone, rather than the recurrent oscillations previously observed with other algal clones. We used AsQ-PCR to confirm this prediction: the superior competitor dominated initially, but as rotifer densities increased, the more predator-resistant clone predominated.
Meyer, Justin R.; Ellner, Stephen P.; Hairston, Nelson G.; Jones, Laura E.; Yoshida, Takehito
In the European Wadden Sea, the nemertine Tetrastemma melanocephalumoccurs together with its prey, the amphipod Corophium arenarium, in the upper intertidal zone. T. melanocephalumleaves the sediment when the tide has receded and captures C. arenarium in its U-shaped burrow. Highest abundances of T. melanocephalumon the sediment surface were found on summer evenings, 2–4 h after high tide, when just a
In the European Wadden Sea, the nemertine Tetrastemma melanocephalumoccurs together with its prey, the amphipod Corophium arenarium, in the upper intertidal zone. T. melanocephalumleaves the sediment when the tide has receded and captures C. arenariumin its U-shaped burrow. Highest abundances of T. melanocephalumon the sediment surface were found on summer evenings, 2-4 h after high tide, when just a thin
A model is developed to describe the interaction between a predator and two prey types located in different regions. Conditions for stability and persistence are analysed. The effects of harvesting the predators are investigated by making the predator mortality rate habitat dependent. Results demonstrate that for any given set of parameter values there is a value of the intrinsic preference of the predator for each prey type at which the system undergoes a Hopf bifurcation. Above this critical value the system evolves towards a stable equilibrium, whereas below it, stable limit cycles arise by Hopf bifurcations. Simulations demonstrate that the presence of demographic stochasticity may destabilise oscillatory populations, thereby causing population extinctions. An application of the model to the foraging behaviour of North Sea cod is described. It is shown that if the preferred prey is more productive, it is likely that the equilibrium will be stable, whereas if the less preferred prey is more productive, populations are likely to display cycles and in the stochastic case become extinct. As cod fishing mortality is increased, the point of bifurcation and region of parameter space for which the system is unstable decreases. An increased understanding of how cod behave may enable fish stocks to be managed more successfully, for example by indicating where marine reserves should be placed. PMID:17443393
Edwards, Helen J; Dytham, Calvin; Pitchford, Jonathan W; Righton, David
Low mean concentrations of serum immunoglobulin A (IgA) and an increased frequency of overt IgA deficiency (IgAD) in certain dog breeds raises the question whether it is a breeding-enriched phenomenon or a legacy from the dog's ancestor, the gray wolf (Canis lupus). The IgA concentration in 99 serum samples from 58 free-ranging and 13 captive Scandinavian wolves, was therefore measured by capture ELISA. The concentrations were markedly lower in the wolf serum samples than in the dog controls. Potential differences in the IgA molecule between dogs and wolves were addressed by sequencing the wolf IgA heavy chain constant region encoding gene (IGHA). Complete amino acid sequence homology was found. Detection of wolf and dog IgA was ascertained by showing identity using double immunodiffusion. We suggest that the vast majority of wolves, the ancestor of the dog, are IgA deficient. PMID:23352622
Frankowiack, Marcel; Hellman, Lars; Zhao, Yaofeng; Arnemo, Jon M; Lin, Miaoli; Tengvall, Katarina; Mřller, Torsten; Lindblad-Toh, Kerstin; Hammarström, Lennart
Developmental studies have shown that environmental stimulation received by a developing sensory system can alter the developmental outcome of both that sensory system and other aspects of the nervous system. We investigated the ecologically relevant question of whether prior exposure to prey early in development within one sensory modality could influence later prey choice within a different sensory modality. Cuttlefish are visual predators; they can detect prey odors but attacks on prey cannot be elicited without visual stimulation. Cuttlefish eggs were exposed to the odor of shrimp (preferred prey), crabs (non-preferred prey), mollusks (non-prey), or a seawater control (no prey). Seven days after hatching, prey preferences were tested with a visual choice test between crabs and shrimp. Hatchlings exposed to crabs odors and the seawater control were significantly more likely to attack shrimp. Hatchlings exposed to mollusk odors showed no visual prey preference, while those exposed to shrimp preferentially attacked crabs. These results demonstrate a complex relationship between an early sensory exposure and later prey preference PMID:21157990
The functional response is a critical link between consumer and resource dynamics, describing how a consumer's feeding rate varies with prey density. Functional response models often assume homogenous prey size and size-independent feeding rates. However, variation in prey size due to ontogeny and competition is ubiquitous, and predation rates are often size dependent. Thus, functional responses that ignore prey size may not effectively predict predation rates through ontogeny or in heterogeneous populations. Here, we use short-term response-surface experiments and statistical modeling to develop and test prey size-dependent functional responses for water bugs and dragonfly larvae feeding on red-eyed treefrog tadpoles. We then extend these models through simulations to predict mortality through time for growing prey. Both conventional and size-dependent functional response models predicted average overall mortality in short-term mixed-cohort experiments, but only the size-dependent models accurately captured how mortality was spread across sizes. As a result, simulations that extrapolated these results through prey ontogeny showed that differences in size-specific mortality are compounded as prey grow, causing predictions from conventional and size-dependent functional response models to diverge dramatically through time. Our results highlight the importance of incorporating prey size when modeling consumer-prey dynamics in size-structured, growing prey populations. PMID:21597252
McCoy, Michael W; Bolker, Benjamin M; Warkentin, Karen M; Vonesh, James R
We show that uloborid spiders, which lack the poison glands typical of nearly all other spiders, employ thousands of wrapping movements with their hind legs and up to hundreds of meters of silk line to make a shroud that applies substantial compressive force to their prey. Shrouds sometimes break the prey’s legs, buckle its compound eyes inward, or kill it outright. The compressive force apparently results from the summation of small tensions on sticky lines as they are applied to the prey package. Behavioral details indicate that wrapping is designed to compact prey; in turn, compaction probably functions to facilitate these spiders’ unusual method of feeding. This is the first demonstration that prey wrapping by spiders compacts and physically damages their prey, rather than simply restraining them.
Eberhard, William G.; Barrantes, Gilbert; Weng, Ju-Lin
Predation intensity depends on factors that affect both the predator’s ability to locate prey as well as defensive responses by prey to approaching predators. The interactive effects of short-term hypoxia and predation were tested on the survival of two bivalves (Tapes philippinarum and Musculista senhousia) through laboratory experiments using the crab Carcinus aestuarii as predator. We found M. senhousia to be a focal prey of C. aestuarii but, after non-lethal hypoxia, the crabs’ preference for the focal prey was influenced by the presence of the other prey, T. philippinarum. We observed an environmentally-mediated, non-reciprocal indirect interaction between the two prey species, probably caused by differences in specific traits. Identifying the influence of short-term disturbance on predator-prey relationships is critical for predicting the effects of changes in water quality on trophic interactions and food web dynamics in transitional systems.
Predators can affect prey populations and, via trophic cascades, predators can indirectly impact resource populations (2 trophic levels below the predator) through consumption of prey (density-mediated indirect effects; DMIEs) and by inducing predator-avoidance behavior in prey (trait-mediated indirect effects; TMIEs). Prey often employ multiple predator-avoidance behaviors, such as dispersal or reduced foraging activity, but estimates of TMIEs are usually on individual behaviors. We assessed direct and indirect predator effects in a mesocosm experiment using a marine food chain consisting of a predator (toadfish--Opsanus tau), prey (mud crab--Panopeus herbstii) and resource (ribbed musse--Geukensia demissa). We measured dispersal and foraging activity of prey separately by manipulating both the presence and absence of the predator, and whether prey could or could not disperse into a predator-free area. Consumption of prey was 9 times greater when prey could not disperse, probably because mesocosm boundaries increased predator capture success. Although predator presence did not significantly affect the number of crabs that emigrated, the presence of a predator decreased resource consumption by prey, which resulted in fewer resources consumed for each prey that emigrated in the presence of a predator, and reduced the overall TMIE. When prey were unable to disperse, TMIEs on mussel survival were 3 times higher than the DMIEs. When prey were allowed to disperse, the TMIEs on resource survival increased to 11-times the DMIEs. We found that restricting the ability of prey to disperse, or focusing on only one predator-avoidance behavior, may be underestimating TMIEs. Our results indicate that the relative contribution of behavior and consumption in food chain dynamics will depend on which predator-avoidance behaviors are allowed to occur and measured. PMID:23408957
Predators can affect prey populations and, via trophic cascades, predators can indirectly impact resource populations (2 trophic levels below the predator) through consumption of prey (density-mediated indirect effects; DMIEs) and by inducing predator-avoidance behavior in prey (trait-mediated indirect effects; TMIEs). Prey often employ multiple predator-avoidance behaviors, such as dispersal or reduced foraging activity, but estimates of TMIEs are usually on individual behaviors. We assessed direct and indirect predator effects in a mesocosm experiment using a marine food chain consisting of a predator (toadfish – Opsanus tau), prey (mud crab - Panopeus herbstii) and resource (ribbed mussel – Geukensia demissa). We measured dispersal and foraging activity of prey separately by manipulating both the presence and absence of the predator, and whether prey could or could not disperse into a predator-free area. Consumption of prey was 9 times greater when prey could not disperse, probably because mesocosm boundaries increased predator capture success. Although predator presence did not significantly affect the number of crabs that emigrated, the presence of a predator decreased resource consumption by prey, which resulted in fewer resources consumed for each prey that emigrated in the presence of a predator, and reduced the overall TMIE. When prey were unable to disperse, TMIEs on mussel survival were 3 times higher than the DMIEs. When prey were allowed to disperse, the TMIEs on resource survival increased to 11-times the DMIEs. We found that restricting the ability of prey to disperse, or focusing on only one predator-avoidance behavior, may be underestimating TMIEs. Our results indicate that the relative contribution of behavior and consumption in food chain dynamics will depend on which predator-avoidance behaviors are allowed to occur and measured.
Sera from 308 healthy Greek females of reproductive age were examined for specific IgG antibodies to human parvovirus B19 by recombinant-Elisa to determine the immunity rates of this part of population to parvovirus B19. Also paired maternal sera and amniotic fluids from nine pregnancies with hydrops fetalis were investigated for specific IgG and IgM antibodies and parvovirus DNA by polymerase
Vassiliki Kyriazopoulou; Maria Simitsopoulou; John Bondis; Evdoxia Diza; Athanasios Athanasiadis; Filanthi Frantzidou; Efimia Souliou
We screened cord blood or serum samples from 101 infants at risk for congenital syphilis and serum samples from their mothers for immunoglobulin G (IgG), IgM, and IgA antibodies to Treponema pallidum by western blotting (immunoblotting). Clinical evaluation showed that six infants had signs and/or symptoms consistent with congenital syphilis. The sera from five of these infants were IgM blot positive, and four were IgA blot positive. Four asymptomatic infants had serologic evidence of congenital syphilis. The sera from three of these infants were IgM blot positive, and two were IgA blot positive. However, the IgM reactivity of the serum from one asymptomatic infant, which was also IgA positive, was abolished by protein G treatment. An IgM capture enzyme-linked immunosorbent assay corroborated the presence of IgM antibodies in six of seven IgM blot-reactive sera. Overall, for detection of symptomatic congenital syphilis, a sensitivity of 83% for IgM blotting and 67% for IgA blotting was obtained. The significance of positive IgM or IgA Western blots for asymptomatic infants requires further study to confirm infection in these infants. Images
Schmitz, J L; Gertis, K S; Mauney, C; Stamm, L V; Folds, J D
Background In many species males face a higher predation risk than females because males display elaborate traits that evolved under sexual selection, which may attract not only females but also predators. Females are, therefore, predicted to avoid such conspicuous males under predation risk. The present study was designed to investigate predator-induced changes of female mating preferences in Atlantic mollies (Poecilia mexicana). Males of this species show a pronounced polymorphism in body size and coloration, and females prefer large, colorful males in the absence of predators. Results In dichotomous choice tests predator-naďve (lab-reared) females altered their initial preference for larger males in the presence of the cichlid Cichlasoma salvini, a natural predator of P. mexicana, and preferred small males instead. This effect was considerably weaker when females were confronted visually with the non-piscivorous cichlid Vieja bifasciata or the introduced non-piscivorous Nile tilapia (Oreochromis niloticus). In contrast, predator experienced (wild-caught) females did not respond to the same extent to the presence of a predator, most likely due to a learned ability to evaluate their predators' motivation to prey. Conclusions Our study highlights that (a) predatory fish can have a profound influence on the expression of mating preferences of their prey (thus potentially affecting the strength of sexual selection), and females may alter their mate choice behavior strategically to reduce their own exposure to predators. (b) Prey species can evolve visual predator recognition mechanisms and alter their mate choice only when a natural predator is present. (c) Finally, experiential effects can play an important role, and prey species may learn to evaluate the motivational state of their predators.
In environments with high spatiotemporal variability in resources, animals may exhibit nomadic movements for resource tracking as opposed to long-term area fidelity. Polar bears ( Ursus maritimus) inhabit the dynamic sea ice, preying on seals, and demonstrate considerable intraspecific variation in space use. We studied patterns of fidelity and annual range size for 74 adult female polar bears captured in
We studied the effect of various factors on body size variation of the Eurasian lynx in Norway, using data from 374 lynx collected between 1960 and 1976 and whose locality of capture, year of birth, sex, and age were known. Body size of lynx in Norway was mainly affected by sex and age. Female skull size (and by implication body size) was also positively affected by the availability of its main prey (roe deer) and by latitude, and negatively by the North Atlantic Oscillation (NAO). Male size was not affected by any of the environmental factors examined. We interpret the effects of NAO and latitude on body size through their effect on the local climate and particularly snow conditions. We suggest that females are more sensitive to environmental factors than males. PMID:21404822
Context: Recurrent Aphthous Ulcer (RAU) is an inflammatory disease characterized by recurrent, painful oral ulcers. It is of multifactorial etiology. Salivary immunoglobulins have important role in the protection of mucosal surfaces. Aim: The aim of this study was to determine salivary immunoglobulin A1 (IgA1) and IgA2 in acute and remission phases of the disease. Materials and Methods: Thirty clinically confirmed cases of RAU and 30 age-and sex-matched controls were included in the study. After detailed case history and thorough clinical examination, 2 mL of saliva was collected in both acute and remission phases of the disease. The obtained saliva samples were subjected to quantification of IgA1 and IgA2 levels using RID kit. Results: The mean IgA2 level was significantly higher (P<.001) in both acute and remission phase of the study group. The mean IgA1 level also showed a significant increase in the acute phase compared to remission as well as controls (P<.05). Females exhibited a higher level in acute phase for IgA1 and in both phases for IgA2 (P<.05). Conclusion: The results associated with clinical observations suggest that acute phase is characterized with increase in IgA2 that might reflect increased immune response as a possible result of the microbial stimulation seen in the acute phase in comparison to the remission period. IgA plays an important role in the pathogenesis of RAU and it can be used as a parameter to assess the mucosal immune status
The fundamental currency of normative models of animal decision making is Darwinian fitness. In foraging ecology, empirical studies typically assess foraging strategies by recording energy intake rates rather than realized reproductive performance. This study provides a rare empirical link, in a vertebrate predator-prey system, between a predator's foraging behavior and direct measures of its reproductive fitness. Goshawks Accipiter gentilis selectively kill rare color variants of their principal prey, the feral pigeon Columba livia, presumably because targeting odd-looking birds in large uniform flocks helps them overcome confusion effects and enhances attack success. Reproductive performance of individual hawks increases significantly with their selectivity for odd-colored pigeons, even after controlling for confounding age effects. Older hawks exhibit more pronounced dietary preferences, suggesting that hunting performance improves with experience. Intriguingly, although negative frequency-dependent predation by hawks exerts strong selection against rare pigeon phenotypes, pigeon color polymorphism is maintained through negative assortative mating. PMID:22503502
Prey use their locomotory capacity to escape predators, and there should thus be strong viability selection on locomotory morphology of prey. We compared feather morphology of wood pigeons Columba palumbus killed by goshawks Accipiter gentilis with that of survivors to quantify directional and quadratic selection on primary and rectrix feathers. The goshawk is mainly a predator attacking by surprise, leaving wood pigeons with an ability to accelerate fast at a selective advantage. There was directional selection for light primary feathers with a narrow calamus. In addition, there was directional selection for increased area of rectrices. These patterns of natural selection were confirmed in multivariate analyses of selection that showed selection for light primary feathers with a large area and narrow calamus and for a large area of rectrix feathers. These results provide evidence of selection on different aspects of feather morphology directly related to flight performance and thus escape ability from predators. PMID:19344382
In contrast to the neutral population cycles of the deterministic mean-field Lotka–Volterra rate equations, including spatial structure and stochastic noise in models for predator–prey interactions yields complex spatio-temporal structures associated with long-lived erratic population oscillations. Environmental variability in the form of quenched spatial randomness in the predation rates results in more localized activity patches. Our previous study showed that population fluctuations in rare favorable regions in turn cause a remarkable increase in the asymptotic densities of both predators and prey. Very intriguing features are found when variable interaction rates are affixed to individual particles rather than lattice sites. Stochastic dynamics with demographic variability in conjunction with inheritable predation efficiencies generate non-trivial time evolution for the predation rate distributions, yet with overall essentially neutral optimization.
Changes in olfactory-mediated behaviour caused by elevated CO2 levels in the ocean could affect recruitment to reef fish populations because larval fish become more vulnerable to predation. However, it is currently unclear how elevated CO2 will impact the other key part of the predator-prey interaction – the predators. We investigated the effects of elevated CO2 and reduced pH on olfactory
Ingrid L. Cripps; Philip L. Munday; Mark I. McCormick
In the present paper a general overview on parasites in birds of prey and owls is given. This part is followed by a study investigating the prevalences and species of parasites in free-ranging birds of prey and owls in Berlin and Brandenburg State, Germany. Over a one year period, 84 birds of prey and owls of the following species were examined for the presence of endo- and ectoparasites: Common Buzzard (Buteo buteo) (n = 32), Kestrel (Falco tinnunculus) (n = 20), Sparrowhawk (Accipiter nisus) (n = 9), Goshawk (Accipiter gentilis) (n = 8), Black Kite (Milvus migrans) (n = 4), Peregrine Falcon (Falco peregrinus) (n = 3), Marsh Harrier (Circus aeruginosus) (n = 1), White-tailed-Sea Eagle (Haliaeetus albicilla) (n = 1), Tawny Owl (Strix aluco) (n = 4), Long-eared Owl (Asio otus) (n = 1) and Barn Owl (Tyto alba) (n = 1). In 97.6% of the cases, ectoparasites (feather mites and hippoboscid flies) were found. Especially eyasses (93.3%) were positive for hippoboscid flies. Trichomonas was detected in 28.6% of all birds of prey and owls examined. A prevalence of 100% was established in the Sparrow Hawks as well as Peregrine Falcons. Leucozytozoon sp. and Hemoproteus sp. as blood parasites were found in 26.9% of the birds in total. Common Buzzards showed the highest prevalence (44.8%). 58.3% of birds examined were positive for endoparasites. Flukes were found in 16.7%, tapeworms in 14.3%, round-worms in 48.8% and acanthocephales in 2.4% of the cases. Interestingly, Tylodelphis clavata (in a Common Buzzard) and Hovorkonema variegatum (in a Goshawk) were found for the first time in raptors. The results of this study underline the importance of a parasitological examination in the process of raptor rehabilitation. PMID:11852683
Hornyhead turbot, Pleuronichthys verticalis (Pleuronectiformes: Pleuronectidae), are morphologically asymmetrical teleosts with substantial bilateral asymmetry in the neurocranium, suspensorium and anterior jaws. In order to quantify the kinematics of prey capture and to test for functional bilateral asymmetries, four individuals of this species were video-taped feeding using a high-speed video system at 200 fields s21. Frame-by-frame analysis revealed several features not
Reduced suspended-sediment loads (i.e., turbidity) in many Midwestern prairie rivers have been hypothesized as contributing to the replacement of species that historically occupied highly turbid main-channel habitats by visually feeding species that are competitively superior in less-turbid waters. We examined the relationship between prey consumption and turbidity for six fish species from the Canadian River (New Mexico, Oklahoma, and Texas)
Background/Aims Local variations in patient demographics and medical practice can contribute to differences in renal outcomes in patients with IgA nephropathy. We report the experiences of two groups of Asians with IgA nephropathy across continents. Materials and methods We retrospectively examined two cohorts of Asian patients with IgA nephropathy from The King Chulalongkorn Memorial Hospital registry, Thailand (1994 ? 2005), and The Metropolitan Toronto Glomerulonephritis registry, Canada (1975 ? 2006), and compared their baseline characteristics. Slope of estimated glomerular filtration rate (eGFR) in each group was approximated using separate repeated measures regression models for each country. Results There were 152 Canadian and 76 Thai patients. At the time of first presentation, Thai patients were more likely to be female (63.2 vs. 44.1%, p = 0.01), have less baseline proteinuria (1.2 vs. 1.7 g/d, p = 0.08) and more likely to receive angiotensin-converting enzyme inhibitors (ACE-I) or angiotensin receptor blockers (ARB) (64.0 vs. 15.2%, p < 0.01), or prednisone (41.3 vs. 4.6%, p < 0.01). The annual change in estimated glomerular filtration rate (eGFR) for the Thai and Canadian groups were ?0.82 ml/min/1.73 m2/year and ?3.35 ml/min/1.73 m2/year, respectively, after adjustment for age, sex, mean arterial pressure (MAP), proteinuria, body mass index, Haas histological grade, chronicity scores and baseline medications. Conclusions Although disease severity was similar among IgA nephropathy patients in Canada and Thailand, more Thai patients were on ACE-I/ARB or prednisone therapy at baseline. Further prospective research is needed to explore international differences in demographic and environmental factors, health resources, and disease management to determine how they may impact long-term outcomes in Asians with IgA nephropathy.
Using quantitative PCR that amplified a prey-specific mtDNA 214 bp amplicon from the COI mitochondrial gene of the Colorado potato beetle, Leptinotarsa decemlineata (Say) (Coleoptera: Chrysomelidae), prey eggs of known age and number were fed to larvae of the generalist predator lady beetle Coleomegilla maculata (De Geer) (Coleoptera: Coccinellidae), to elucidate the effects of time and diet since consumption, number
Predator-prey system, as an essential element of ecological dynamics, has been recently studied experimentally with synthetic biology. We developed a global probabilistic landscape and flux framework to explore a synthetic predator-prey network constructed with two Escherichia coli populations. We developed a self consistent mean field method to solve multidimensional problem and uncovered the potential landscape with Mexican hat ring valley shape for predator-prey oscillations. The landscape attracts the system down to the closed oscillation ring. The probability flux drives the coherent oscillations on the ring. Both the landscape and flux are essential for the stable and coherent oscillations. The landscape topography characterized by the barrier height from the top of Mexican hat to the closed ring valley provides a quantitative measure of global stability of system. The entropy production rate for the energy dissipation is less for smaller environmental fluctuations or perturbations. The global sensitivity analysis based on the landscape topography gives specific predictions for the effects of parameters on the stability and function of the system. This may provide some clues for the global stability, robustness, function and synthetic network design. PMID:21423576
A prey animal surveying its environment must decide whether there is a dangerous predator present or not. If there is, it may flee. Flight has an associated cost, so the animal should not flee if there is no danger. However, the prey animal cannot know the state of its environment with certainty, and is thus bound to make some errors. We formulate a probabilistic automaton model of a prey animal's life and use it to compute the optimal escape decision strategy, subject to the animal's uncertainty. The uncertainty is a major factor in determining the decision strategy: only in the presence of uncertainty do economic factors (like mating opportunities lost due to flight) influence the decision. We performed computer simulations and found that in silico populations of animals subject to predation evolve to display the strategies predicted by our model, confirming our choice of objective function for our analytic calculations. To the best of our knowledge, this is the first theoretical study of escape decisions to incorporate the effects of uncertainty, and to demonstrate the correctness of the objective function used in the model. PMID:21559347
The long rostrum of the paddlefish (Polyodon spathula), a Mississippi river inhabitant, supports an extensive array of ampullary electroreceptors that are used to locate its favorite prey, water fleas, in dark and muddy water. Neuronal coding of such real-world events is often considered to be optimal in the sense of minimizing a mean-square reconstruction error or maximizing likelihood. Implementation of these theoretically motivated optimality criteria is, however, computationally very costly. For the juvenile paddlefish we exhibit  a computationally cheap and geometrically simple algorithm with the neuronal activity ?n of its electroreceptors 1<= n <= N as input and evaluating the turning direction \\varphi required to catch the prey through the so-called population-vector code \\varphi^estimate = arg [sumn ?n exp(i \\varphi_n)]. This explains experimentally found prey-detection statistics more convincingly than minimization of the mean-square reconstruction error. The only assumption concerns the neuronal time scale of the sensory organs.  C. Leibold, K.B. Reuter, L. Voigts, W. Wojtenek, and J.L. van Hemmen, manuscript in preparation.
Only five species of sharks have been recorded in the Southern Ocean, where their biology is essentially unknown. We investigated the feeding habits of the three commonest species from stomach content analysis of specimens taken as bycatches of the fishery targeting the Patagonian toothfish ( Dissostichus eleginoides) in upper slope waters of the Kerguelen Archipelago. The three species prey upon a diversity of fishes and cephalopods. They segregate by feeding on different species of squids of different sizes. The small lanternsharks ( Etmopterus cf. granulosus; 0.3 m on average) feed on small-sized Mastigoteuthis psychrophila, while the large porbeagles ( Lamna nasus; 1.9 m) feed on small-sized histioteuthids ( Histioteuthis atlantica and H. eltaninae) and on medium-sized juvenile ommastrephids of the genus Todarodes. Finally, the huge sleeper sharks ( Somniosus cf. microcephalus; 3.9 m) prey upon large-sized cephalopods ( Kondakovia longimana and Taningia danae) and giant squids ( Mesonychoteuthis hamiltoni and Architeuthis dux). Thus sleeper shark is a fish with sperm whale-like feeding habits and, hence, the second top predator known to science to rely significantly on giant squids. Prey species and biology indicate that porbeagles are pelagic predators in the entire water column, while sleeper sharks are mainly benthic top predators and scavengers. The present study also underlines the diversity and biomass of the poorly known cephalopod fauna, including giant squids, occurring in outer shelf and upper slope waters surrounding subantarctic islands.
Species with a large adult-offspring size ratio and a preferred predator-prey mass ratio undergo ontogenetic trophic niche shift(s) throughout life. Trophic interactions between such species vary throughout life, resulting in different species-level interaction motifs depending on the maximum adult sizes and population size distributions. We explore the assembly and potential for coexistence of small communities where all species experience ontogenetic trophic niche shifts. The life-history of each species is described by a physiologically structured model and species identity is characterised by the trait: size at maturation. We show that a single species can exist in two different states: a 'resource driven state' and a 'cannibalistic state' with a large scope for emergent Allee effects and bistable states. Two species can coexist in two different configurations: in a 'competitive coexistence' state when the ratio between sizes at maturation of the two species is less than a predator-prey mass ratio and the resource level is low to intermediate, or in a 'trophic ladder' state if the ratio of sizes at maturation is larger than the predator-prey mass ratio at all resource levels. While there is a large scope for coexistence of two species, the scope for coexistence of three species is limited and we conclude that further trait differentiation is required for coexistence of more species-rich size-structured communities. PMID:23927897
A prey animal surveying its environment must decide whether there is a dangerous predator present or not. If there is, it may flee. Flight has an associated cost, so the animal should not flee if there is no danger. However, the prey animal cannot know the state of its environment with certainty, and is thus bound to make some errors. We formulate a probabilistic automaton model of a prey animal's life and use it to compute the optimal escape decision strategy, subject to the animal's uncertainty. The uncertainty is a major factor in determining the decision strategy: only in the presence of uncertainty do economic factors (like mating opportunities lost due to flight) influence the decision. We performed computer simulations and found that in silico populations of animals subject to predation evolve to display the strategies predicted by our model, confirming our choice of objective function for our analytic calculations. To the best of our knowledge, this is the first theoretical study of escape decisions to incorporate the effects of uncertainty, and to demonstrate the correctness of the objective function used in the model.
We investigated the energy source fuelling the post-feeding metabolic upregulation (specific dynamic action, SDA) in pythons (Python regius). Our goal was to distinguish between two alternatives: (i) snakes fuel SDA by metabolizing energy depots from their tissues; or (ii) snakes fuel SDA by metabolizing their prey. To characterize the postprandial response of pythons we used transcutaneous ultrasonography to measure organ-size changes and respirometry to record oxygen consumption. To discriminate unequivocally between the two hypotheses, we enriched mice (= prey) with the stable isotope of carbon (13C). For two weeks after feeding we quantified the CO2 exhaled by pythons and determined its isotopic 13C/12C signature. Ultrasonography and respirometry showed typical postprandial responses in pythons. After feeding, the isotope ratio of the exhaled breath changed rapidly to values that characterized enriched mouse tissue, followed by a very slow change towards less enriched values over a period of two weeks after feeding. We conclude that pythons metabolize their prey to fuel SDA. The slowly declining delta13C values indicate that less enriched tissues (bone, cartilage and collagen) from the mouse become available after several days of digestion.
Starck, J Matthias; Moser, Patrick; Werner, Roland A; Linke, Petra
Immunoglobulin D multiple myeloma (IgD MM) accounts for almost 2% of all myeloma cases. It is associated with an increased frequency of undetectable or small monoclonal (M)-protein levels on electrophoresis; osteolytic lesions; extramedullary involvement; amyloidosis; a lambda (lambda) light chain predilection; renal failure; hypercalcemia; and, often, advanced disease at diagnosis. Immunoglobulin E (IgE) MM is rare, with fewer than 50 cases reported in the literature. IgE MM presents with features similar to those of IgD MM, along with a higher incidence of plasma cell leukemia. The hallmark of IgE MM is t(11;14) (q13;q32). IgD and IgE levels are generally very low and hence may escape detection; thus, it is important that, when myeloma is suspected, patients be screened for the presence of IgD and IgE if they have an apparently free monoclonal immunoglobulin light chain in the serum. Although survival of patients with IgD MM or IgE MM is shorter in comparison to those with immunoglobulin G (IgG) MM or immunoglobulin A (IgA) MM, the outcome for patients with IgD and IgE subtypes is improving with the use of novel agents and autologous transplantation. PMID:24133829
There has been considerable development and implementation of new contraceptive methods over the last 15 years. However, sterilization has remained the most widely used method around the world. Ideally, the procedure should be safe, have a high efficacy, be readily accessible, and be personally and culturally acceptable. The cost for each procedure would be low and the method would be simple, quick, easily learned and be able to be performed in an outpatient setting without general anesthesia. A transuterine method of female sterilization has long been the ideal for the gynecologist. The Essure system fulfils many of the criteria, and is the first one to be approved by the US FDA. However, there is still a need for further research to find a device with the success rate of the Essure but without its irreversibility. PMID:18573050
Ecosystems are fragmented by natural and anthropogenic processes that affect organism movement and ecosystem dynamics. When a fragmentation restricts predator but not prey movement, then the prey produced on one side of an ecosystem edge can subsidize predators on the other side. When prey flux is high, predator density on the receiving side increases above that possible by in situ prey productivity, and when low, the formerly subsidized predators can impose strong top-down control of in situ prey-in situ prey experience apparent competition from the subsidy. If predators feed on some evolutionary clades of in situ prey over others, then subsidy-derived apparent competition will induce phylogenetic structure in prey composition. Dams fragment the serial nature of river ecosystems by prohibiting movement of organisms and restricting flowing water. In the river tailwater just below a large central Mexican dam, fish density was high and fish gorged on reservoir-derived zooplankton. When the dam was closed, water flow and the zooplankton subsidy ceased, densely packed pools of fish formed, fish switched to feed on in situ prey, and the tailwater macroinvertebrate community was phylogenetic structured. We derived expectations of structure from trait-based community assembly models based on macroinvertebrate body size, tolerance to anthropogenic disturbance, and fish-diet selectivity. The diet-selectivity model best fit the observed tailwater phylogenetic structure. Thus, apparent competition from subsidies phylogenetically structures prey communities, and serial variation in phylogenetic community structure can be indicative of fragmentation in formerly continuous ecosystems. PMID:23649751
Helmus, Matthew R; Mercado-Silva, Norman; Vander Zanden, M Jake
Theoretical and empirical evidence in a one-predator two-prey system consistently indicates a regular trend that the less profitable (therefore, less vulnerable) prey increases in abundance with enrichment. The response in the abundance of the more profitable (more vulnerable) prey to enrichment has, however, remained unclear. Previous theoretical models have assumed the less profitable prey as inedible, though its actual profitability is unknown. Here, relaxing this assumption, we show that the response of the more profitable prey abundance to enrichment depends critically on the profitability of the less profitable prey. Specifically, the more profitable prey increases in abundance with enrichment if the profitability of the less profitable prey is lower than a critical value so that it cannot support the predator population by itself even at high densities (in this case, the prey is referred to as 'unpalatable') and decreases otherwise. This establishes a more general rule which unifies the previous works and resolves the indeterminacy on the response of the more profitable prey.
Predator-prey interactions are vital to the stability of many ecosystems. Yet, few studies have considered how they are mediated due to substantial challenges in quantifying behavior over appropriate temporal and spatial scales. Here, we employ high-resolution sonar imaging to track the motion and interactions among predatory fish and their schooling prey in a natural environment. In particular, we address the relationship between predator attack behavior and the capacity for prey to respond both directly and through collective propagation of changes in velocity by group members. To do so, we investigated a large number of attacks and estimated per capita risk during attack and its relation to the size, shape, and internal structure of prey groups. Predators were found to frequently form coordinated hunting groups, with up to five individuals attacking in line formation. Attacks were associated with increased fragmentation and irregularities in the spatial structure of prey groups, features that inhibit collective information transfer among prey. Prey group fragmentation, likely facilitated by predator line formation, increased (estimated) per capita risk of prey, provided prey schools were maintained below a threshold size of approximately 2 m(2). Our results highlight the importance of collective behavior to the strategies employed by both predators and prey under conditions of considerable informational constraints. PMID:22683262
Handegard, Nils Olav; Boswell, Kevin M; Ioannou, Christos C; Leblanc, Simon P; Tjřstheim, Dag B; Couzin, Iain D
Recent research has shown that exposure to elevated carbon dioxide (CO2) affects how fishes perceive their environment, affecting behavioral and cognitive processes leading to increased prey mortality. However, it is unclear if increased mortality results from changes in the dynamics of predator-prey interactions or due to prey increasing activity levels. Here we demonstrate that ocean pCO2 projected to occur by 2100 significantly effects the interactions of a predator-prey pair of common reef fish: the planktivorous damselfish Pomacentrus amboinensis and the piscivorous dottyback Pseudochromis fuscus. Prey exposed to elevated CO2 (880 µatm) or a present-day control (440 µatm) interacted with similarly exposed predators in a cross-factored design. Predators had the lowest capture success when exposed to elevated CO2 and interacting with prey exposed to present-day CO2. Prey exposed to elevated CO2 had reduced escape distances and longer reaction distances compared to prey exposed to present-day CO2 conditions, but this was dependent on whether the prey was paired with a CO2 exposed predator or not. This suggests that the dynamics of predator-prey interactions under future CO2 environments will depend on the extent to which the interacting species are affected and can adapt to the adverse effects of elevated CO2. PMID:23484032
Allan, Bridie J M; Domenici, Paolo; McCormick, Mark I; Watson, Sue-Ann; Munday, Philip L
Aging is accompanied by a progressive decline in almost all functions of the immune system. To investigate a possible impact of age on IgE production, this study evaluated total and allergen-specific serum IgE levels in a large cohort of allergic patients. This study included 6,370 allergic patients (2,961 females, 3,409 males; mean age, 21.7 years; age range, 0-96 years). Total and allergen-specific serum IgE levels were measured by immunoenzymatic assay. The analysis of variance showed a significant difference (P<0.0001) in the mean value of total IgE among the different age groups of patients. Moreover, specific IgE levels for all allergens examined differed significantly among the age groups of patients (P<0.0001), with a specific trend pattern for each allergen. Total IgE increased with age, but allergen-specific IgE levels significantly decreased with age, with a trend specific for each allergen tested.
Dissimilar vulnerabilities of different prey types and preferences of predators are factors likely to contribute to community dynamics. This may happen via differential individual properties of prey animals (e.g. vigilance, escape) or via habitat effects making hunting by a predator easier and more rewarding in some habitats, or both. Furthermore, community dynamics may be influenced by predator mediated apparent competition, in which an increase in one prey type has negative effects on another prey type indirectly via the shared predator. We summarize the current knowledge from the field in a model predator-prey system consisting of sympatric boreal vole species and their common specialist predator and review field studies using predator manipulation and studies on the responses of individuals in the laboratory and in outdoor enclosures. The vole species studied represent different prey types that are thought to have different vulnerabilities. Our observations on the main resident specialist predator, the least weasel (Mustela nivalis nivalis L.), show that it hunts according to prey availability and suitability of the hunting habitat. Prey voles respond to the presence of the predator behaviorally in various ways to avoid predation. We conclude that even if the least weasel is a specialized predator of small rodents it acts like a generalist predator within the small rodent guild and may facilitate the coexistence of prey species via predator switching. This may lead to interspecific synchrony between prey populations, which has often been observed. We suggest that the processes determining the community impact of predator-prey interactions are driven by the behavioral arms race between the predator and the prey, together with the habitat-dependent density of prey and net gain for the predator. PMID:21396051
Ecological risk assessments tend to focus on contaminant effects on single species in isolation. However, additional effects from interactions between species (e.g., predator-prey interactions) may also occur in natural systems. The present study investigated the consequences of sublethal contaminant effects in prey on predator-prey interactions, particularly the interaction between prey behavioral changes and predation by predators with different hunting strategies. Ambush (Ischnura elegans Vander Linden [Insecta, Odonata]) and active (Notonecta glauca Linnaeus [Insecta, Heteroptera]) predator species were used in conjunction with three prey species (Asellus aquaticus Linnaeus [Crustacea, Isopoda], Cloion dipterum Linnaeus [Insecta, Ephemeroptera], and Chironomus riparius Meigen [Insecta, Diptera]). Immobilized prey demonstrated the importance of prey behavior for determining predation rates for both single- and multiple-prey species. Chironomus riparius was less responsive following exposure to cadmium, becoming more vulnerableto attack by the active but not the ambush predator. Some evidence was also observed for reduced general activity in C. dipterum following cadmium exposure. Sublethal exposure of prey did not affect the prey choice of active predators, possibly because of prey behavioral changes being insufficient to influence their relative availabilities. However, cadmium exposure of prey did alter their susceptibility to ambush predators. There was a reduced proportion of C. dipterum and an increased proportion of A. aquaticus in the diet of ambush predators, possibly because of reduced activity in C. dipterum affecting their relative encounter rates with predators. Sublethal exposures can therefore result in reduced prey survival that would not be predicted by single-species toxicity tests. PMID:19572771
Brooks, Amy C; Gaskell, Paul N; Maltby, Lorraine L
Ecological theory suggests that the behaviour, growth and abundance of predators will be strongly influenced by the abundance of prey. Predators may in turn play an important role in structuring prey populations and communities. Responses of predators to variation in prey abundance have most commonly been demonstrated in low-diversity communities where food webs are relatively simple. How predators respond in highly diverse assemblages such as in coral reef habitats is largely unknown. This study describes an experiment that examined how the movement, diet and growth of the coral reef piscivore, Cephalopholis boenak (Serranidae) responded to variation in the abundance of its prey. Predator densities were standardised on small patch reefs made from the lagoonal reef-building coral, Porites cylindrica. These patch reefs exhibited natural variation in the abundance and community structure of multiple species of prey. However, our experiment generated a relatively simple predator-prey relationship, with C. boenak primarily responding to the most abundant species of prey. Three responses of predators were observed: aggregative, functional and developmental. Thirty-one per cent of individuals moved between patch reefs during the experiment, all from areas of relatively low to high prey density. Feeding rates were higher on patch reefs of high prey density, while growth rates of fish that remained on low prey density reefs throughout the experiment were lower. Growth rates of C. boenak on the experimental reefs were also much higher than for those living on natural patch reefs over the same time period, corresponding with overall differences in prey abundance. These results suggest that local abundance, feeding rate and growth of C. boenak were closely linked to the abundance of their main prey. This combination of predatory responses is a potential mechanism behind recent observations of density-dependent mortality and population regulation of prey in coral reef fish communities.
Beukers-Stewart, B. D.; Beukers-Stewart, J. S.; Jones, G. P.
IgA nephropathy (IgAN) is a complex trait determined by genetic and environmental factors. Most IgAN patients exhibit a characteristic undergalactosylation of the O-glycans of the IgA1 hinge region, which promotes formation and glomerular deposition of immune complexes. It is not known whether this aberrant glycosylation is the result of an acquired or inherited defect, or whether the presence of aberrant IgA1 glycoforms alone can produce IgAN. A newly validated lectin enzyme-linked immunosorbent assay (ELISA) was used to determine the serum level of galactose-deficient IgA1 (Gd-IgA1) in a cohort of 89 IgAN patients and 266 of their relatives. High Gd-IgA1 levels (> or =95th percentile for controls) were observed in all 5 available patients with familial IgAN, in 21 of 45 (47%) of their at-risk relatives (assuming autosomal dominant inheritance), and in only 1 of 19 (5%) of unrelated individuals who married into the family. This provides evidence that abnormal IgA1 glycosylation is an inherited rather than acquired trait. Similarly, Gd-IgA1 levels were high in 65 of 84 (78%) patients with sporadic IgAN and in 50 of 202 (25%) blood relatives. Heritability of Gd-IgA1 was estimated at 0.54 (P = 0.0001), and segregation analysis suggested the presence of a major dominant gene on a polygenic background. Because most relatives with abnormal IgA1 glycoforms were asymptomatic, additional cofactors must be required for IgAN to develop. The fact that abnormal IgA1 glycosylation clusters in most but not all families suggests that measuring Gd-IgA1 may help distinguish patients with different pathogenic mechanisms of disease. PMID:18272841
Gharavi, Ali G; Moldoveanu, Zina; Wyatt, Robert J; Barker, Catherine V; Woodford, Susan Y; Lifton, Richard P; Mestecky, Jiri; Novak, Jan; Julian, Bruce A
Echolocating bats have successfully exploited a broad range of habitats and prey. Much research has demonstrated how time-frequency structure of echolocation calls of different species is adapted to acoustic constraints of habitats and foraging behaviors. However, the intensity of bat calls has been largely neglected although intensity is a key factor determining echolocation range and interactions with other bats and prey. Differences in detection range, in turn, are thought to constitute a mechanism promoting resource partitioning among bats, which might be particularly important for the species-rich bat assemblages in the tropics. Here we present data on emitted intensities for 11 species from 5 families of insectivorous bats from Panamá hunting in open or background cluttered space or over water. We recorded all bats in their natural habitat in the field using a multi-microphone array coupled with photographic methods to assess the bats' position in space to estimate emitted call intensities. All species emitted intense search signals. Output intensity was reduced when closing in on background by 4–7 dB per halving of distance. Source levels of open space and edge space foragers (Emballonuridae, Mormoopidae, Molossidae, and Vespertilionidae) ranged between 122–134 dB SPL. The two Noctilionidae species hunting over water emitted the loudest signals recorded so far for any bat with average source levels of ca. 137 dB SPL and maximum levels above 140 dB SPL. In spite of this ten-fold variation in emitted intensity, estimates indicated, surprisingly, that detection distances for prey varied far less; bats emitting the highest intensities also emitted the highest frequencies, which are severely attenuated in air. Thus, our results suggest that bats within a local assemblage compensate for frequency dependent attenuation by adjusting the emitted intensity to achieve comparable detection distances for prey across species. We conclude that for bats with similar hunting habits, prey detection range represents a unifying constraint on the emitted intensity largely independent of call shape, body size, and close phylogenetic relationships.
Objective: To present the case of a female collegiate basketball player who was diagnosed with Wegener granulomatosis of the eyes and immunoglobulin A (IgA) nephropathy.\\u000aBackground: A 19-year-old female collegiate basketball player presented to a rheumatologist, urologist, and nephrologist with severe eye pain and was diagnosed with Wegener granulomatosis and IgA nephropathy. At age 20, during routine follow-up testing, urine
James E. Leone; Amie Kern; Joshua D. Williamson; Robert M. Colandreo
The spider Misumenops pallidus (Thomisidae) is commonly found in alfalfa crops. We studied its predatory preferences on potential insect prey, particularly regarding agroecosystems pests. Two kinds of tests were done under normal laboratory conditions: simultaneous presentation of prey (n = 215) and alternative prey test (n = 45). The spiders preferred insects that were mobile, small, without defensive glands and with thin exoskeletons. According to the amount of prey consumed, we established four predation levels: high (> 55%, on adult Drosophila melanogaster flies); intermediate (30%-55% on the defoliator larvae of Rachiplusia nu and adult heteropterans: Horciasinus argentinus and Halticus spegazzinii); and low (10%-30% on the chrysomelids Colapsis sp. and Diabrotica speciosa). The pentatomid Piezodorus guildinii, the curculionid Naupactus sp. and the aphid Acyrthosiphom pisum were not accepted as food. Once the spider captured a prey item it did not accept another, independently of prey item species (82% of trials). PMID:18494318
A Lagrangian method is developed to study mixing of small particles in open flows. Particle Lagrangian Coherent Structures (pLCS) are identified as transport barriers in the dynamical systems of particles. We apply this method to a planktonic predator-prey system in which moon jellyfish Aurelia aurita uses its body motion to generate fluid currents which carry their prey to the vicinity of their capture appendages. With the flow generated by the jellyfish experimentally measured and the dynamics of prey particles in the flow described by a modified Maxey-Riley equation, we use pLCS to identify the capture region in which prey can be captured. The properties of the capture region enable analysis of the effects of several physiological and mechanical parameters on the predator-prey interaction, such as prey size, escape force, predator perception, etc. The method provides a new methodology to study dynamics and mixing of small organisms in general.
Red-cockaded woodpecker; Road to Recovery. Proceedings of the 4th Red-cockaded woodpecker Symposium. Ralph Costa and Susan J. Daniels, eds. Savannah, Georgia. January, 2003. Chapter 11. Prey, Fire, and Community Ecology. Pp 633-645. Abstract: Over a 10-year period we investigated red-cockaded woodpecker (Picoides borealis) prey use, sources of prey, prey distribution within trees and stands, and how forest management decisions affect prey abundance in South Carolina, Alabama, Georgia and Florida. Cameras were operated at 31 nest cavities to record nest visits with prey in 4 locations that ranged in foraging habitat from pine stands established in old fields to an old-growth stand in South Georgia. Examination of nearly 12,000 photographs recorded over 5 years revealed that, although red-cockaded woodpeckers used over 40 arthropods for food, the majority of the nestling diet is comprised of a relatively small number of common arthropods.
We show that uloborid spiders, which lack the poison glands typical of nearly all other spiders, employ thousands of wrapping movements with their hind legs and up to hundreds of meters of silk line to make a shroud that applies substantial compressive force to their prey. Shrouds sometimes break the prey's legs, buckle its compound eyes inward, or kill it outright. The compressive force apparently results from the summation of small tensions on sticky lines as they are applied to the prey package. Behavioral details indicate that wrapping is designed to compact prey; in turn, compaction probably functions to facilitate these spiders' unusual method of feeding. This is the first demonstration that prey wrapping by spiders compacts and physically damages their prey, rather than simply restraining them. PMID:16544123
Eberhard, William G; Barrantes, Gilbert; Weng, Ju-Lin
We examined the effects of variation in swimming speed, or ‘ram speed’, on the feeding kinematics of juvenile Indo-Pacific tarpon, Megalops cyprinoides. Tarpon were filmed feeding on non-elusive prey at 500imagess?1. Prey items were offered at one end of the filming tank, the opposite end where tarpon grouped, to encourage them to use a ram strategy to capture their prey.
Predation can regulate prey numbers but predator behaviour in multiple-prey systems can complicate understanding of control\\u000a mechanisms. We investigate killer whale (Orcinus orca) predation in an ocean system where multiple marine mammal prey coexist. Using stochastic models with Monte-Carlo simulations,\\u000a we test the most likely outcome of predator selection and compare scenarios where killer whales: (1) focus predation on larger
Steven H. FergusonMichael; Michael C. S. Kingsley; Jeff W. Higdon
The prey of Antarctic fur seals, Arctocephalus gazella, was investigated through scat analysis at Marion Island from 1996 until 2000. A total of 25 different prey species were\\u000a identified from scats, of which 21 were fish, 1 crustacean and 3 cephalopods. Fish were by far the main prey item, occurring\\u000a in 96.1% of samples, followed by crustaceans (2.7%) and cephalopods
A. B. Makhado; M. N. Bester; S. P. Kirkman; P. A. Pistorius; J. W. H. Ferguson; N. T. W. Klages
We tested the widely accepted hypothesis that spotted hyaenas (Crocuta crocuta) are non-selective in their diet. The prey preference of spotted hyaena was studied in the Addo Elephant National Park (AENP),\\u000a South Africa. Diet (frequency of occurrence of prey items in the diet) was quantified through the analysis of 55 scats, and\\u000a compared with available prey. A combination of large-
Julia C. Wentworth; Craig J. Tambling; Graham I. H. Kerley
The impact of predation on prey populations has long been a focus of ecologists, but a firm understanding of the factors influencing prey selection, a key predictor of that impact, remains elusive. High levels of variability observed in prey selection may reflect true differences in the ecology of different communities but might also reflect a failure to deal adequately with uncertainties in the underlying data. Indeed, our review showed that less than 10% of studies of European wolf predation accounted for sampling uncertainty. Here, we relate annual variability in wolf diet to prey availability and examine temporal patterns in prey selection; in particular, we identify how considering uncertainty alters conclusions regarding prey selection.Over nine years, we collected 1,974 wolf scats and conducted drive censuses of ungulates in Alpe di Catenaia, Italy. We bootstrapped scat and census data within years to construct confidence intervals around estimates of prey use, availability and selection. Wolf diet was dominated by boar (61.5 ± 3.90 [SE] % of biomass eaten) and roe deer (33.7 ± 3.61%). Temporal patterns of prey densities revealed that the proportion of roe deer in wolf diet peaked when boar densities were low, not when roe deer densities were highest. Considering only the two dominant prey types, Manly's standardized selection index using all data across years indicated selection for boar (mean = 0.73 ± 0.023). However, sampling error resulted in wide confidence intervals around estimates of prey selection. Thus, despite considerable variation in yearly estimates, confidence intervals for all years overlapped. Failing to consider such uncertainty could lead erroneously to the assumption of differences in prey selection among years. This study highlights the importance of considering temporal variation in relative prey availability and accounting for sampling uncertainty when interpreting the results of dietary studies. PMID:23110122
Davis, Miranda L; Stephens, Philip A; Willis, Stephen G; Bassi, Elena; Marcon, Andrea; Donaggio, Emanuela; Capitani, Claudia; Apollonio, Marco
During predator–prey encounters, a high locomotor performance in unsteady manoeuvres (i.e. acceleration, turning) is desirable for both predators and prey. While speed increases with size in fish and other aquatic vertebrates in continuous swimming, the speed achieved within a given time, a relevant parameter in predator–prey encounters, is size independent. In addition, most parameters indicating high performance in unsteady swimming
It is suspected that phagotrophic marine protozoa might possess feeding receptors that enable them to discern the nutritional\\u000a quality of individual prey items (during prey-handling) on the basis of their cell-surface biochemistry. This article reviews\\u000a advances in our understanding of the molecular mechanisms that mediate the biorecognition and selection of nonself (microalgal)\\u000a prey items by the microplanktonic marine phagotroph Oxyrrhis
Blue jays (Cyanocitta cristata) were trained to hunt for non-cryptic moths presented in projected images. On each trial, the jays chose one of two patches to hunt in: (1) a uniform, 'non-depleting' patch with constant prey density of 0.25; or (2) a 'depleting' patch in which prey density changed during the foraging bout. In the depleting patch, the initial prey
The dietary value of a prey type varies with its nutritional status and hence with its C:N:P content. However, while stoichiometric differences between a heterotroph and its food must affect growth efficiency (GE), and thence trophic dynamics, other factors related to food quality may act as powerful modulators of predator-prey interactions. Thus, minor changes in prey stoichiometry can be associated
. ?Ratio-dependent predator–prey models are favored by many animal ecologists recently as more suitable ones for predator–prey\\u000a interactions where predation involves searching process. However, such models are not well studied in the sense that most\\u000a results are local stability related. In this paper, we consider the global behaviors of solutions of a ratio-dependent predator–prey\\u000a systems. Specifically, we shall show that ratio
Background Grass pollen is a major cause of respiratory allergy worldwide and contain a number of allergens, some of theme (Phl p 1, Phl p 2, Phl p 5, and Phl 6 from Phleum pratense, and their homologous in other grasses) are known as major allergens. The administration of grass pollen extracts by immunotherapy generally induces an initial rise in specific immunoglobulin E (sIgE) production followed by a progressive decline during the treatment. Some studies reported that immunotherapy is able to induce a de novo sensitisation to allergen component previously unrecognized. Methods We investigated in 30 children (19 males and 11 females, mean age 11.3 years), 19 treated with sublingual immunotherapy (SLIT) by a 5-grass extract and 11 untreated, the sIgE and sIgG4 response to the different allergen components. Results Significant increases (p?0.001) were detected for Phl p 1, Phl p 2, Phl p 5, and Phl p 6, while sIgE levels induced in response to Phl p 7 and Phl p 12 were low or absent at baseline and unchanged following SLIT treatment; no new sensitisation was detected. As to IgG4, significant increases were found for Phl p2 and Phl p 5, while the increase for Phl p 12 was not significant. In the control group, no significant increase in sIgE for any single allergen component was found. Conclusions These findings confirm that the initial phase of SLIT with a grass pollen extract enhances the sIgE synthesis and show that the sIgE response concerns the same allergen components which induce IgE reactivity during natural exposure.
The authors examine the relative roles of vision and chemoreception and the influence of previous experience with prey on the predatory behavior of Iberian wall lizards (Podarcis hispanica). Experiment 1 compared the responses to visual, chemical, and a combination of visual and chemical cues of a familiar prey by 2 groups of lizards that had been kept in captivity for either 3 months or 21 days. Experiment 2 assessed the responses of lizards kept in the laboratory for more than 3 months to a novel prey species. The results reveal that feeding on a prey species affects the lizards' responses to chemical stimuli from that prey. The response to chemical cues of a novel prey requires a 1st-feeding experience with that prey. Lizards that have been fed the same prey species for several months cease responding to the chemical stimuli of that particular prey. PMID:14498807
The twospotted spider mite, Tetranychus urticae Koch (Acari: Tetranychidae), is an important pest of vegetables and other economically important crops. This study evaluated the functional responses and prey-stage preferences of three species of predators, a predatory gall midge, Feltiella acarisuga (Vallot) (Diptera: Cecidomyiidae), and two predatory mite species, Neoseiulus californicus (McGregor) (Acari: Phytoseiidae) and Amblyseius swirskii (AnthiasHenriot), with T. urticae as the host, under laboratory conditions. The results showed that F. acarisuga was highly effective and the two species of predacious mites were moderately effective in feeding on T. urticae eggs. Logistic regression analysis suggested Type II (convex) functional responses for all three species. However, based on the estimates of the handling time and the attacking rates, the three predators had different predation capacities. Among the three species, F. acarisuga had the highest predation on T. urticae. The maximum daily predation by a larval F. acarisuga was 50 eggs/day, followed by a female N. californicus (25.6 eggs/day) and a female A. swirskii (15.1 eggs/day). A female N. californicus produced more eggs than a female A. swirskii did when they both fed on T. urticae eggs. In addition, all three predator species had no preystage preference for either prey eggs or nymphs. The findings from this study could help select better biological control agents for effective control of T. urticae and other pests in vegetable productions. PMID:23879370
Xiao, Yingfang; Osborne, Lance S; Chen, Jianjun; McKenzie, Cindy L
West Nile Virus (WNV) antibody development and persistence were investigated in blood donors who made WNV RNA-positive (viremic) donations in 2003. Plasma samples from the index donations and follow-up serum or plasma samples were tested for WNV immunoglobulin M (IgM), IgA, and IgG by using enzyme-linked immunosorbent assays. Antibody development was investigated with 154 samples collected from 84 donors 1 to 21 days after their RNA-positive, antibody-negative, index donation. WNV IgM and IgA were first detected on day 3, and all samples collected after day 9 were WNV IgM and IgA positive; WNV IgG was first detected on day 4, and all samples collected after day 16 were positive. Antibody persistence in this donor group (index donations antibody negative) was evaluated by using 128 samples collected from 89 donors on days 22 to 440 of follow-up; 88% of samples were WNV IgM positive, 86% were WNV IgA positive, and 100% were WNV IgG positive. In linear regression analysis, trendlines for WNV IgM and IgA reached the value discriminating positive from negative results at 218 days and 232 days of follow-up, respectively. Similar WNV IgM and IgA persistence trends characterized 27 donors whose index samples were positive for WNV IgM and IgA, as well as 14 donors whose index samples were positive for WNV IgG but negative for WNV IgM. These findings show that WNV IgG emerges after WNV IgM and IgA and that both WNV IgM and IgA typically persist for at least 6 months after infection. Thus, unlike some other flavivirus infections, WNV infection is not characterized by a relatively rapid disappearance of virus-specific IgA.
Prince, Harry E.; Tobler, Leslie H.; Lape-Nixon, Mary; Foster, Gregory A.; Stramer, Susan L.; Busch, Michael P.
Predators use a variety of information sources to locate potential prey, and likewise prey animals use numerous sources of information to detect and avoid becoming the meal of a potential predator. In freshwater environments, chemosensory cues often play a crucial role in such predator/prey interactions. The importance of chemosensory information to teleost fish in marine environments is not well understood. Here, we tested whether coral reef fish predators are attracted to damage-released chemical cues from already wounded prey in order to find patches of prey and minimize their own costs of obtaining food. Furthermore, we tested if these chemical cues would convey information about status of the prey. Using y-maze experiments, we found that predatory dottybacks, Pseudochromis fuscus, were more attracted to skin extracts of damselfish, Pomacentrus amboinensis, prey that were in good condition compared to prey in poor body condition. Moreover, in both the laboratory and field, we found that predators could differentiate between skin extracts from prey based on prey size, showing a greater attraction to extracts made from prey that were the appropriate size to consume. This suggests that predators are not attracted to any general substance released from an injured prey fish instead being capable of detecting and distinguishing relatively small differences in the chemical composition of the skin of their prey. These results have implications for understanding predator foraging strategies and highlights that chemical cues play a complex role in predator-prey interactions in marine fish. PMID:21947496
Lonnstedt, Oona M; McCormick, Mark I; Chivers, Douglas P
This study was undertaken to analyze the differences in exposure and sensitization to five common environmental yeasts. The responses of IgG, IgA, and IgE to Candida albicans, C. utilis, Cryptococcus albidus, Rhodotorula rubra, and Saccharomyces cerevisiae and purified S. cerevisiae enolase were analyzed by immunoblotting (IgE-IB), and the cross-reactivity of their IgE-binding components by IgE-IB inhibition. Twenty atopic subjects, with asthma, allergic rhinitis, or atopic dermatitis were included. In skin prick tests (SPT), 12 of the patients showed simultaneous reactivity to at least two of the five yeasts, four reacted to one of the yeasts, and four had no responses. Antigens run in SDS-PAGE and transferred to nitrocellulose were probed with enzyme-labeled IgA-, IgG-, and IgE-specific antibodies. The IgE immunoblotting revealed most IgE-binding bands in C. albicans (11 bands) followed by C. utilis (eight bands), S. cerevisiae (five bands), R. rubra (five bands), and Cr. albidus (four bands). Six of the IgE-binding bands of C. albicans and C. utilis shared molecular weight, and only two bands shared molecular weight with other yeasts. These were the 46-kDa band, shared by all five yeasts, and a 13-kDa band shared by four yeasts. Prominent IgE binding was seen to a 46-kDa band of C. albicans (seven patients), C. utilis (five patients), and S. cerevisiae (one patient) and to corresponding weak bands of Cr. albidus and R. rubra (one patient). The possible cross-reactivity of the 46-kDa band was analyzed by IgE-IB inhibition and densitometry, revealing clear C. albicans inhibition of C. utilis (80%) and enolase (98%) (autoinhibition 100%). The strongest IgG responses were seen against S. cerevisiae and C. albicans. The responses were mainly against mannans of C. albicans and S. cerevisiae, suggesting that most of the exposure is to these yeasts. Yeasts with different types of exposure, from saprophytic growth on human mucous membranes to exposure by air and food, were shown to cross-react at the allergenic level. Atopic patients primarily sensitized by C. albicans and S. cerevisiae may develop allergic symptoms by exposure to other environmental yeasts due to cross-reacting IgE antibodies. PMID:9636810
Savolainen, J; Kortekangas-Savolainen, O; Nermes, M; Viander, M; Koivikko, A; Kalimo, K; Terho, E O
Circulating immune complexes containing aberrantly glycosylated IgA1 play a pivotal role in the pathogenesis of IgA nephropathy (IgAN). A portion of IgA1 secreted by IgA1-producing cells in patients with IgAN is galactose-deficient and consequently recognized by anti-glycan IgG or IgA1 antibodies. Some of the resultant immune complexes in the circulation escape normal clearance mechanisms, deposit in the renal mesangium, and induce glomerular injury. Recent studies of the origin of these aberrant molecules, their glycosylation profiles, and mechanisms of biosynthesis have provided new insight into the autoimmune nature of the pathogenesis of this common renal disease. An imbalance in the activities of the pertinent glycosyltransferases in the IgA1-producing cells favors production of molecules with galactose-deficient O-linked glycans at specific sites in the hinge region of the alpha heavy chains. By using sophisticated analytic methods, it may be possible to define biomarkers for diagnostic purposes and identify new therapeutic targets for a future disease-specific therapy. PMID:18222349
Novak, Jan; Julian, Bruce A; Tomana, Milan; Mestecky, Jiri
BACKGROUND: Adult cartilaginous fish express three immunoglobulin (Ig) isotypes, IgM, IgNAR and IgW. Newborn nurse sharks, Ginglymostoma cirratum, produce 19S (multimeric) IgM and monomeric\\/dimeric IgM1gj, a germline-joined, IgM-related VH, and very low amounts of 7S (monomeric) IgM and IgNAR proteins. Newborn IgNAR VH mRNAs are diverse in the complementarity-determining region 3 (CDR3) with non-templated nucleotide (N-region) addition, which suggests that,
Lynn L Rumfelt; Rebecca L Lohr; Helen Dooley; Martin F Flajnik
In this paper, a spatial predator-prey model with herd behavior in prey population and quadratic mortality in predator population is investigated. By the linear stability analysis, we obtain the condition for stationary pattern. Moreover, using standard multiple-scale analysis, we establish the amplitude equations for the excited modes, which determine the stability of amplitudes towards uniform and inhomogeneous perturbations. By numerical simulations, we find that the model exhibits complex pattern replication: spotted pattern, stripe pattern, and coexistence of the two. The results may enrich the pattern dynamics in predator-prey models and help us to better understand the dynamics of predator-prey interactions in a real environment.
Foragers base their prey-selection decisions on the information acquired by the sensory systems. In bats that use echolocation to find prey in darkness, it is not clear whether the specialized diet, as sometimes found by faecal analysis, is a result of active decision-making or rather of biased sensory information. Here, we tested whether greater horseshoe bats decide economically when to attack a particular prey item and when not. This species is known to recognize different insects based on their wing-beat pattern imprinted in the echoes. We built a simulation of the natural foraging process in the laboratory, where the bats scanned for prey from a perch and, upon reaching the decision to attack, intercepted the prey in flight. To fully control echo information available to the bats and assure its unambiguity, we implemented computer-controlled propellers that produced echoes resembling those from natural insects of differing profitability. The bats monitored prey arrivals to sample the supply of prey categories in the environment and to inform foraging decisions. The bats adjusted selectivity for the more profitable prey to its inter-arrival intervals as predicted by foraging theory (an economic strategy known to benefit fitness). Moreover, unlike in previously studied vertebrates, foraging performance of horseshoe bats was not limited by costly rejections of the profitable prey. This calls for further research into the evolutionary selection pressures that sharpened the species's decision-making capacity.
Koselj, Klemen; Schnitzler, Hans-Ulrich; Siemers, Bjorn M.
Gastropods are often the top predators in marine benthic environments, and trophic transfer is the predominant route by which metals are accumulated in these predators. In the present study, the potential influences of prey composition on the trophic transfer, accumulation, subcellular distribution and metallothionein induction of six metals (Ag, As, Cd, Cu, Pb and Zn) in a predator Nassarius siquijorensis were investigated. The snails were fed venerid clams Ruditapes philippinarum, mussels Perna viridis, oysters Crassostrea angulata or barnacles Fistulobalanus albicostatus, each differing greatly in their metal accumulation and handling patterns. N. siquijorensis showed prey-specific bioaccumulation and trophic transfer of the six metals. In general, the body burdens of metals in the viscera and muscles of N. siquijorensis increased with increasing exposure period and metal concentration in the four prey. The calculated trophic transfer factors (TTFs) of the metals in different prey varied and were the highest for clams and mussels prey, indicating that metal bioavailability from these prey was higher than that from barnacles and oysters. All the studied metals except Pb were enriched during transfer to the snails. The subcellular metal distribution in the viscera was affected by prey composition. Exposure to the four natural prey induced MTs, which may be used as a better biomarker for muscle than for viscera for metal stress. Our results imply that metals from different natural prey have different bioavailability and may help better understand the trophic transfer of metals in marine benthic food chain. PMID:23121886
Although temporal variability in the physical environment plays a major role in population fluctuations, little is known about how it drives the ecological and evolutionary dynamics of species interactions. We studied experimentally how extrinsic resource pulses affect evolutionary and ecological dynamics between the prey bacterium Serratia marcescens and the predatory protozoan Tetrahymena thermophila. Predation increased the frequency of defensive, nonpigmented prey types, which bore competitive costs in terms of reduced maximum growth rate, most in a constant-resource environment. Furthermore, the predator densities of the pulsed-resource environment regularly fluctuated above and below the mean predator densities of the constant environment. These results suggest that selection favored fast-growing competitor prey types over defensive but slower-growing prey types more often in the pulsed-resource environment (abundance of resources and low predation risk). As a result, the selection for prey defense fluctuated more in the pulsed-resource environment, leading to a weaker mean response in prey defense. At the ecological level, the evolution of prey defense weakened the relative strength of top-down regulation on prey community. This was more evident in the constant-resource environment, whereas the slow emergence of defensive prey types gradually decreased the amplitude of predator peaks in the pulsed-resource environment. Our study suggests that rapid evolution plays a smaller role in the ecological dynamics of communities dominated by resource pulses. PMID:21460542
Foragers base their prey-selection decisions on the information acquired by the sensory systems. In bats that use echolocation to find prey in darkness, it is not clear whether the specialized diet, as sometimes found by faecal analysis, is a result of active decision-making or rather of biased sensory information. Here, we tested whether greater horseshoe bats decide economically when to attack a particular prey item and when not. This species is known to recognize different insects based on their wing-beat pattern imprinted in the echoes. We built a simulation of the natural foraging process in the laboratory, where the bats scanned for prey from a perch and, upon reaching the decision to attack, intercepted the prey in flight. To fully control echo information available to the bats and assure its unambiguity, we implemented computer-controlled propellers that produced echoes resembling those from natural insects of differing profitability. The bats monitored prey arrivals to sample the supply of prey categories in the environment and to inform foraging decisions. The bats adjusted selectivity for the more profitable prey to its inter-arrival intervals as predicted by foraging theory (an economic strategy known to benefit fitness). Moreover, unlike in previously studied vertebrates, foraging performance of horseshoe bats was not limited by costly rejections of the profitable prey. This calls for further research into the evolutionary selection pressures that sharpened the species's decision-making capacity. PMID:21367788
Koselj, Klemen; Schnitzler, Hans-Ulrich; Siemers, Björn M
Predators capture prey in complex and variable environments. In the ocean, bottom-dwelling (benthic) organisms are subjected to water currents, waves, and turbulent eddies. For benthic predators that feed on small animals carried in the water (zooplankton), flow not only delivers prey, but can also shape predator-prey interactions. Benthic passive suspension feeders collect prey delivered by movement of ambient water onto capture-surfaces, whereas motile benthic predators, such as burrow-dwelling fish, dart out to catch passing zooplankton. How does the flow of ambient water affect these contrasting modes of predation by benthic zooplanktivores? We studied the effects of turbulent, wavy flow on the encounter, capture, and retention of motile zooplanktonic prey (copepods, Acartia spp.) by passive benthic suspension feeders (sea anemones, Anthopleura elegantissima). Predator-prey interactions were video-recorded in a wave-generating flume under two regimes of oscillating flow with different peak wave velocities and levels of turbulent kinetic energy ("weak" and "strong" waves). Rates of encounter (number of prey passing through a sea anemone's capture zone per time), capture (prey contacting and sticking to tentacles per time), and retention (prey retained on tentacles, without struggling free or washing off, per time) were measured at both strengths of waves. Strong waves enhanced encounter rates both for dead copepods and for actively swimming copepods, but there was so much variability in the behavior of the live prey that the effect of wave strength on encounter rates was not significant. Trapping efficiency (number of prey retained per number encountered) was the same in both flow regimes because, although fewer prey executed maneuvers to escape capture in strong waves, more of the captured prey was washed off the predators' tentacles. Although peak water velocities and turbulence of waves did not affect feeding rates of passive suspension-feeding sea anemones, increases in these aspects of flow have been shown to enhance feeding rates and efficiency of motile benthic fish that lunge out of their burrows to catch zooplankton. Faster, more turbulent flow interferes with the ability of prey to detect predators and execute escape maneuvers, and thus enhances capture rates both for passive suspension-feeding predators and for actively swimming predators. However, prey captured in the mouths of fish are not washed away by ambient flow, whereas prey captured on the tentacles of suspension feeders can be swept off before they are ingested. Therefore, the effects of flowing water on predation on zooplankton by benthic animals depend on the feeding mode of the predator. PMID:23942646
The prey choice behavior and predatory strategies of two East African assassin bugs, Scipinnia repax (Stäl 1961) and Nagusta sp. (Hemiptera: Reduviidae), were investigated in the field and the laboratory. Both of these species are from the subfamily Harpactorinae and specialize in eating spiders. They prey especially often on social jumping spiders (Salticidae) that build nest complexes (nests connected by silk) in vegetation near the shoreline of Lake Victoria. Both reduviid species associate with these nest complexes and prey on the resident salticids. Nagusta sp., but not S. repax, form groups on nest complexes with 2–3 individuals of Nagusta sometimes feeding together on a single salticid. In addition to social salticids, Nagusta sp. preys on Portia africana, an araneophagic salticid that often invades the same nest complexes. S. repax preys on salticid eggs and also on Nagusta. Although they avoid ants, Nagusta and especially S. repax prey on ant-mimicking salticids, suggesting that sensory modalities other than vision play a dominant role in prey detection.
Jackson, Robert R.; Salm, Kathryn; Nelson, Ximena J.
The purpose of this paper is, on one hand, to show the present performance of the combined final and rapid IGS global ionosphere maps (GIMs), and on the other hand to inform the geodetic community on new product - predicted IGS GIMs. In addition, information on future development of IGS ionospheric products will be also presented. Nowadays, the Ionosphere Working Group of IGS generates three types of ionospheric products: final, rapid and predicted, respectively. There are currently four IGS Associate Analysis Centres (IAACs) for the ionospheric products: CODE (Center for Orbit Determination in Europe, University of Berne, Switzerland), ESA/ESOC (European Space Operations Center of ESA, Darmstadt, Germany), JPL (Jet Propulsion Laboratory, Pasadena, U.S.A) and gAGE/UPC (Technical University of Catalonia, Barcelona, Spain). These centres provide ionosphere maps computed with different approaches. Their maps are uploaded to IGS Ionosphere Product Coordinator, who computes official IGS combined products. Since January 2008, this coordination is carried out by the GRL/UWM (Geodynamics Research Laboratory of the University of Warmia and Mazury in Olsztyn, Poland). The IGS GIMs are provided in Ionosphere Exchange (IONEX) format with spatial resolution of 5.0 degrees in longitude and 2.5 degrees in latitude, and temporal resolution of 2 hours. Latency of the final and rapid GIMs is 10 days and 1 day, respectively. In November 2009, the IGS Iono WG started to generate predicted ionospheric products 1 and 2 days in advance (requested for ESA's SMOS mission). These new IGS products are currently based on predicted ionosphere maps prepared by UPC and ESA. During period of more than 10 years of continuous IGS ionosphere operation, the techniques used by the IAACs and the strategies of combination have improved in such a way that the combined IGS GIMs are now significantly more accurate and robust. Future plans include, among others, increasing temporal resolution to 1 hour and studies on taking advantage of COSMIC occultation data.
Krankowski, Andrzej; Wielgosz, Pawel; Hernández-Pajares, Manuel; García-Rigo, Alberto
Immunoglobulin A (IgA) nephropathy is an immune-complex-mediated glomerulonephritis characterized by the presence of immunoglobulin A deposits in mesangial and paramesangial regions. The patients with IgA nephropathy present with varying clinical symptoms (eg, microhematuria with preserved renal function or progressive deterioration of renal functions resulting in end-stage renal disease). The factors involved in the pathogenetic mechanisms of IgA nephropathy include (1)
The objective was to apply the purified 38kDa protein antigen of Mycobacterium tuberculosis in ELISA to estimate the IgG, IgA and IgM antibody levels in sera and circulating immune complexes of tuberculosis patients. Sera from smear and culture positive tuberculosis patients were positive for anti 38kDa IgG, IgA and IgM antibodies, with a sensitivity of 61%, 30% and 10%, respectively,
K. R. Uma Devi; B. Ramalingam; P. J. Brennan; P. R. Narayanan; A. Raja
The regulation of IgG subclass production by polyclonally activated human B cells was investigated by using two systems previously shown to selectively suppress the generation of IgG-containing cells (CC) but not that of IgMCC or IgACC. The first one involved a brief exposure of peripheral blood mononuclear cells (PBMNC) to heat-aggregated human IgG (Agg-IgG) followed by repeated washings and culture with untreated autologous PBMNC. The second one was achieved by addition of human IgG-binding factor(s) (IgGBF) prepared by affinity chromatography from supernatants of unstimulated PBMNC. Pokeweed mitogen (PWM) and Nocardia opaca delipidated cell mitogen (NDCM) were used as polyclonal B cell activators. The latter can induce the terminal differentiation of peripheral B lymphocytes into plasma cells in the absence of helper T cells. After 6 days of culture, the number of cells containing IgM, IgG, or IgA was determined by direct immunofluorescence, and that of cells containing IgG1, IgG2, IgG3, or IgG4 was determined by indirect immunofluorescence with the use of subclass-specific monoclonal antibodies. After stimulation with PWM, exposure of PBMNC to Agg-IgG resulted in a selective diminution of the number of IgG4CC. With NDCM-stimulated cultures the same procedure induced a selective suppression of the generation of IgG2CC and IgG4CC. Conversely, the addition of IgGBF at the third day of culture was found to induce a 30 to 40% decrease in the number of cells containing each of the four IgG subclasses. Because of their differential pattern of IgG subclass suppression, Agg-IgG and IgGBF are likely to trigger distinct regulatory pathways. PMID:6610704
In this paper, we study the quenching behaviour for a system of two reaction-diffusion equations arising in the modelling of the spatio-temporal interaction of prey and predator populations in fragile environment. We first provide some sufficient conditions on the initial data to have finite time quenching. Then we classify the initial data to distinguish type I quenching and type II quenching, by introducing a delicate energy functional along with the help of some a priori estimates. Finally, we present some results on the quenching set. It can be a singleton, the whole domain, or a compact subset of the domain.
Interacting with a moving object poses a computational problem for an animal's nervous system. This problem has been elegantly solved by the dragonfly, a formidable visual predator on flying insects. The dragonfly computes an interception flight trajectory and steers to maintain it during its prey-pursuit flight. This review summarizes current knowledge about pursuit behavior and neurons thought to control interception in the dragonfly. When understood, this system has the potential for explaining how a small group of neurons can control complex interactions with moving objects. PMID:22195994
The various subsets of serum IgA were determined in 43 patients with ankylosing spondylitis to investigate the putative mucosal origin of increased IgA concentrations in this disease. Total IgA was shown to be increased and weakly correlated with the erythrocyte sedimentation rate (ESR). In contrast, although the mean concentration (but not the median) of secretory IgA (SIgA) was slightly increased, no correlation was found with total IgA nor the ESR. Moreover, molecular sieving of nine serum samples selected for their high concentrations of total IgA, and absorption with insoluble jacalin showed these immunoglobulins to be essentially monomers of the IgA1 subclass. These results are consistent with a non-secretory origin of the increase of serum IgA, which must be ascribed to the central immune system.
RationaleStriking IgE production at the root with generating antibodies against the extracellular portion of the transmembrane domain (EMPD) of IgE could be a further strategy concerning the therapy of allergic diseases.
Population sex ratios in monogamous birds are often male biased. One factor that can affect population sex ratios is sex-biased predation. However, most estimates of sex-biased predation in birds have focused on species with obvious sexual colour dimorphism or body size dimorphism. Data on sexually monomorphic birds are generally lacking. In the present study, we adopt a PCR-based sexing procedure to help test for sex-biased predation in a wintering population of western sandpipers (Calidris mauri), a shorebird that shows only subtle sexual size dimorphism. Specifically, by comparing the a priori determined sex ratio of live birds wintering at a site in western Mexico to the molecular estimate obtained from depredated birds at this same site, we were able to perform a population-specific test for sex bias in predator-induced mortality. The proportion of females estimated from living (ca. 25%) versus dead (ca. 24%) individuals was in fact not significantly different, indicating that the strong male bias in this population is not due to differential predation. However, molecular sexing of prey remains is a hitherto unexploited test of sex-biased predation in birds, and is potentially applicable to any species for which prey remains can be gathered. We discuss our results in the context of alternate ecological hypotheses for population sex biases.
Nebel, Silke; Cloutier, Alison; Thompson, Graham J
This report concerns the relative quantitation of serum polymeric IgA and polymeric IgA subclass concentrations by enzyme immunoassay (EIA). The assay relies on the specific binding of polymeric IgA to secretory component. Competition between pentameric IgM and polymeric IgA for binding to secretory component was observed. Thus, samples were adsorbed for IgM by affinity chromatography before the EIA was performed. The assay was used to determine an age-related range of serum polymeric IgA concentrations and to compare the polymeric IgA concentrations in patients with IgA nephropathy (n = 50) to those of controls (n = 50). The serum concentrations of both polymeric IgA and polymeric IgA1 increased with age reaching adult values of around 12 years of age. Polymeric IgA2 concentrations did not reach adult levels until 18 years of age. The ratio of the polymeric IgA concentration to the total serum IgA concentration was found to be significantly increased in children under 2 years of age compared with those over 4 years of age (Mann-Whitney U-test, P less than 0.01). Patients with IgA nephropathy had significantly increased concentrations of polymeric IgA (P = 0.001) and polymeric IgA1 (P = 0.001) but similar polymeric IgA2 concentrations to controls.
Jones, C; Mermelstein, N; Kincaid-Smith, P; Powell, H; Roberton, D
Individuals with systemic lupus erythematosus and rheumatoid arthritis are characterized by the presence of high levels of circulating IgM and IgG autoantibodies. Although IgG autoantibodies often are pathogenic, the role of IgM autoantibodies in autoimmune disease is not clear. Using mice that are unable to secrete IgM but are able to express surface IgM and IgD and to secrete other
Marianne Boes; Tara Schmidt; Kathrin Linkemann; Britte C. Beaudette; Ann Marshak-Rothstein; Jianzhu Chen
IgD is considered to be a recently evolved Ig, being previously found only in primates and rodents. Here we describe, from a teleost fish (the channel catfish, Ictalurus punctatus), a novel complex chimeric Ig heavy chain, homologous, in part, to the heavy chain (delta ) of IgD. In addition to alternative secretory or membrane-associated C termini, this chimeric molecule contains
Melanie Wilson; Eva Bengten; Norman W. Miller; L. William Clem; Louis Du Pasquier; Gregory W. Warr
Spatial coherence between predators and prey has rarely been observed in pelagic marine ecosystems. We used measures of the environment, prey abundance, prey quality, and prey distribution to explain the observed distributions of three co-occurring predator species breeding on islands in the southeastern Bering Sea: black-legged kittiwakes (Rissa tridactyla), thick-billed murres (Uria lomvia), and northern fur seals (Callorhinus ursinus). Predictions of statistical models were tested using movement patterns obtained from satellite-tracked individual animals. With the most commonly used measures to quantify prey distributions--areal biomass, density, and numerical abundance--we were unable to find a spatial relationship between predators and their prey. We instead found that habitat use by all three predators was predicted most strongly by prey patch characteristics such as depth and local density within spatial aggregations. Additional prey patch characteristics and physical habitat also contributed significantly to characterizing predator patterns. Our results indicate that the small-scale prey patch characteristics are critical to how predators perceive the quality of their food supply and the mechanisms they use to exploit it, regardless of time of day, sampling year, or source colony. The three focal predator species had different constraints and employed different foraging strategies--a shallow diver that makes trips of moderate distance (kittiwakes), a deep diver that makes trip of short distances (murres), and a deep diver that makes extensive trips (fur seals). However, all three were similarly linked by patchiness of prey rather than by the distribution of overall biomass. This supports the hypothesis that patchiness may be critical for understanding predator-prey relationships in pelagic marine systems more generally. PMID:23301063
Benoit-Bird, Kelly J; Battaile, Brian C; Heppell, Scott A; Hoover, Brian; Irons, David; Jones, Nathan; Kuletz, Kathy J; Nordstrom, Chad A; Paredes, Rosana; Suryan, Robert M; Waluk, Chad M; Trites, Andrew W
Several species of butterflyfishes (Chaetodontidae) possess extremely elongate jaws, and feed mostly by probing the benthos and biting off pieces of attached invertebrates. In contrast, Forcipiger longirostris, the longest-jawed chaetodontid, exhibits a novel pattern of prey use, feeding almost exclusively on small caridean shrimp, a mobile and highly elusive prey type that lives within the structure of coral reefs. We explored the functional basis of this novel pattern of prey use by comparing prey capture kinematics in this and four other butterflyfish species, including two other species that possess elongate jaws. High speed video recordings of feeding events on live adult brine shrimp were analyzed from individuals of five species: Forcipiger longirostris, F. flavissimus, Chelmon rostratus, Heniochus acuminatus, and Chaetodon xanthurus. We focused on a comparison among species of the relative contribution of "suction", measured as the amount of movement of the prey toward the predator's mouth, and "ram", measured as the distance moved by the predator toward the prey during the strike. All five species utilized a combination of suction and ram while feeding on brine shrimp. The contribution of suction did not differ significantly among species. However, F. longirostris exhibited a ram contribution to the strike that was more than twice that seen in any of the other species, permitting this species to initiate strikes from the greatest initial predator-prey distance. F. longirostris is known to possess a major structural novelty in the feeding mechanism that permits anterior movement of the entire jaw apparatus. The ability of this species to feed successfully on elusive prey appears to be related to exceptional jaw protrusion, resulting in greater use of ram during prey capture. This ability to protrude long, slender jaws toward the prey may allow it to move the jaws without detection within close enough proximity of the prey to then permit the effective use of suction. The use of extensive ram in this manner by small-mouthed fishes may be more widespread than previously thought. PMID:11164861
Ferry-Graham, L A.; Wainwright, P C.; Bellwood, D R.
Circulating immune complexes containing aberrantly glycosylated IgA1 play a pivotal role in the pathogenesis of IgAN. A portion of IgA1 secreted by IgA1-producing cells in patients with IgAN is galactose-deficient and consequently recognized by anti-glycan IgG or IgA1 antibodies. Some of the resultant immune complexes in the circulation escape normal clearance mechanisms, deposit in the renal mesangium, and induce glomerular injury. Recent studies of the origin of these aberrant molecules, their glycosylation profiles, and mechanisms of biosynthesis have provided new insight into the autoimmune nature of the pathogenesis of this common renal disease. An imbalance in the activities of the pertinent glycosyltransferases in the IgA1-producing cells favors production of molecules with galactose-deficient O-linked glycans at specific sites in the hinge region of the alpha heavy chains. Using sophisticated analytical methods, it may be possible to define biomarkers for diagnostic purposes and identify new therapeutic targets for a future disease-specific therapy.
Novak, Jan; Julian, Bruce A.; Tomana, Milan; Mestecky, Jiri
In the last few years many investigators have reported the recurrence of primary IgA nephropathy (IgAN) or the presence of persistent microhaematuria and/or proteinuria in family members of patients with IgAN. Our study was undertaken to investigate the relevance of abnormalities in the regulation of the IgA and IgM immune system in microhaematuric and asymptomatic family members of IgAN patients. Fifty-four out of 120 members of nine unrelated pedigrees were examined by urinalysis; polymeric IgA (pIgA), IgA rheumatoid factor (IgARF), IgA1-IgG immune complexes (IgA 1-IgG IC) and IgA 1-IgM IC, and other immunoglobulins were measured in serum samples. Moreover, we studied the production of immunoglobulins, pIgA and IgARF by peripheral blood mononuclear cells (PBMC) in basal conditions and after pokeweed mitogen (PWM) stimulation. Our data demonstrate that persistent microhaematuria was present in 24% of relatives. High serum levels of IgA, mainly pIgA and IgARF, IgA 1-IgG IC and IgA 1-IgM IC occurred in 66% of relatives. Abnormal spontaneous production of IgA by PBMC and after PWM stimulation was present in 64% of family members. Interestingly, high serum levels of IgM and abnormal production of this immunoglobulin by PBMC were observed in relatives. However, the immunological abnormalities did not correlate in any way with the presence of urinary abnormalities such as microhaematuria, which was most likely determined by an underlying glomerular alteration.
Schena, F P; Scivittaro, V; Ranieri, E; Sinico, R; Benuzzi, S; Di Cillo, M; Aventaggiato, L
Objective. To study the clinical and pathologic features of systemic lupus erythematosus (SLE) that has atypical lupus nephritis (LN) with mainly IgA deposits. Methods. We searched the SLE patients who had nephritis with mainly IgA deposits in our hospital and selected the information including clinical manifestations, laboratory tests, treatments, and prognosis. Results. From January 2009 to June 2012, 5 patients were definitely diagnosed as SLE according to both 1982 and 2009 ACR classification criteria. But renal biopsy showed that all cases had mainly IgA deposits and were free of IgG, C1q, and fibrinogen-related antigen deposits under immunofluorescent microscopy, which did not match with typical LN. There were 2 males and 3 females, aging from 31 to 64 years and with an average of (42.20 ± 13.59) years. The 5 cases had multiple-system involvements, mainly the renal system. Compared to primary IgAN, the atypical LN showed some differences: older than primary IgAN, more women than men, no previous infection history, lower incidence of serum IgA elevation, and ACL positive rate as high as 100%. Conclusion. Nephritis with mainly IgAN deposits, as an atypical LN, may be a special subtype of SLE.
Predator-prey relationships provide a classic paradigm for the study of innate animal behavior. Odors from carnivores elicit stereotyped fear and avoidance responses in rodents, although sensory mechanisms involved are largely unknown. Here, we identified a chemical produced by predators that activates a mouse olfactory receptor and produces an innate behavioral response. We purified this predator cue from bobcat urine and identified it to be a biogenic amine, 2-phenylethylamine. Quantitative HPLC analysis across 38 mammalian species indicates enriched 2-phenylethylamine production by numerous carnivores, with some producing >3,000-fold more than herbivores examined. Calcium imaging of neuronal responses in mouse olfactory tissue slices identified dispersed carnivore odor-selective sensory neurons that also responded to 2-phenylethylamine. Two prey species, rat and mouse, avoid a 2-phenylethylamine odor source, and loss-of-function studies involving enzymatic depletion of 2-phenylethylamine from a carnivore odor indicate it to be required for full avoidance behavior. Thus, rodent olfactory sensory neurons and chemosensory receptors have the capacity for recognizing interspecies odors. One such cue, carnivore-derived 2-phenylethylamine, is a key component of a predator odor blend that triggers hard-wired aversion circuits in the rodent brain. These data show how a single, volatile chemical detected in the environment can drive an elaborate danger-associated behavioral response in mammals. PMID:21690383
Ferrero, David M; Lemon, Jamie K; Fluegge, Daniela; Pashkovski, Stan L; Korzan, Wayne J; Datta, Sandeep Robert; Spehr, Marc; Fendt, Markus; Liberles, Stephen D
Predator–prey interactions are thought by many researchers to define both modern ecosystems and past macroevolutionary events. In modern ecosystems, experimental removal or addition of taxa is often used to determine trophic relationships and predator identity. Both characteristics are notoriously difficult to infer in the fossil record, where evidence of predation is usually limited to damage from failed attacks, individual stomach contents, one-sided escalation, or modern analogs. As a result, the role of predation in macroevolution is often dismissed in favor of competition and abiotic factors. Here we show that the end-Devonian Hangenberg event (359 Mya) was a natural experiment in which vertebrate predators were both removed and added to an otherwise stable prey fauna, revealing specific and persistent trophic interactions. Despite apparently favorable environmental conditions, crinoids diversified only after removal of their vertebrate consumers, exhibiting predatory release on a geological time scale. In contrast, later Mississippian (359–318 Mya) camerate crinoids declined precipitously in the face of increasing predation pressure from new durophagous fishes. Camerate failure is linked to the retention of obsolete defenses or “legacy adaptations” that prevented coevolutionary escalation. Our results suggest that major crinoid evolutionary phenomena, including rapid diversification, faunal turnover, and species selection, might be linked to vertebrate predation. Thus, interactions observed in small ecosystems, such as Lotka-Volterra cycles and trophic cascades, could operate at geologic time scales and higher taxonomic ranks. Both trophic knock-on effects and retention of obsolete traits might be common in the aftermath of predator extinction.
Sallan, Lauren Cole; Kammer, Thomas W.; Ausich, William I.; Cook, Lewis A.
There are two very different approaches to laryngeal echolocation in bats. Although most bats separate pulse and echo in time by signalling at low duty cycles (LDCs), almost 20% of species produce calls at high duty cycles (HDCs) and separate pulse and echo in frequency. HDC echolocators are sensitive to Doppler shifts. HDC echolocation is well suited to detecting fluttering targets such as flying insects against a cluttered background. We used two complementary experiments to evaluate the relative effectiveness of LDC and HDC echolocation for detecting fluttering prey. We measured echoes from fluttering targets by broadcasting artificial bat calls, and found that echo amplitude was greatest for sounds similar to those used in HDC echolocation. We also collected field recordings of syntopic LDC and HDC bats approaching an insect-like fluttering target and found that HDC bats approached the target more often (18.6% of passes) than LDC bats (1.2% of passes). Our results suggest that some echolocation call characteristics, particularly duty cycle and pulse duration, translate into improved ability to detect fluttering targets in clutter, and that HDC echolocation confers a superior ability to detect fluttering prey in the forest understory compared with LDC echolocation. The prevalence of moths in the diets of HDC bats, which is often used as support for the allotonic frequency hypothesis, can therefore be partly explained by the better flutter detection ability of HDC bats. PMID:21389198
Predator–prey relationships provide a classic paradigm for the study of innate animal behavior. Odors from carnivores elicit stereotyped fear and avoidance responses in rodents, although sensory mechanisms involved are largely unknown. Here, we identified a chemical produced by predators that activates a mouse olfactory receptor and produces an innate behavioral response. We purified this predator cue from bobcat urine and identified it to be a biogenic amine, 2-phenylethylamine. Quantitative HPLC analysis across 38 mammalian species indicates enriched 2-phenylethylamine production by numerous carnivores, with some producing >3,000-fold more than herbivores examined. Calcium imaging of neuronal responses in mouse olfactory tissue slices identified dispersed carnivore odor-selective sensory neurons that also responded to 2-phenylethylamine. Two prey species, rat and mouse, avoid a 2-phenylethylamine odor source, and loss-of-function studies involving enzymatic depletion of 2-phenylethylamine from a carnivore odor indicate it to be required for full avoidance behavior. Thus, rodent olfactory sensory neurons and chemosensory receptors have the capacity for recognizing interspecies odors. One such cue, carnivore-derived 2-phenylethylamine, is a key component of a predator odor blend that triggers hard-wired aversion circuits in the rodent brain. These data show how a single, volatile chemical detected in the environment can drive an elaborate danger-associated behavioral response in mammals.
Ferrero, David M.; Lemon, Jamie K.; Fluegge, Daniela; Pashkovski, Stan L.; Korzan, Wayne J.; Datta, Sandeep Robert; Spehr, Marc; Fendt, Markus; Liberles, Stephen D.
It is generally assumed that an individual of a prey species can benefit from an increase in the number of its group's members by reducing its own investment in vigilance. But what behaviour should group members adopt in relation to both the risk of being preyed upon and the individual investment in vigilance? Most models assume that individuals scan independently of one another. It is generally argued that it is more profitable for each group member owing to the cost that coordination of individual scans in non-overlapping bouts of vigilance would require. We studied the relationships between both individual and collective vigilance and group size in Defassa waterbuck, Kobus ellipsiprymnus defassa, in a population living under a predation risk. Our results confirmed that the proportion of time an individual spent in vigilance decreased with group size. However, the time during which at least one individual in the group scanned the environment (collective vigilance) increased. Analyses showed that individuals neither coordinated their scanning in an asynchronous way nor scanned independently of one another. On the contrary, scanning and non-scanning bouts were synchronized between group members, producing waves of collective vigilance. We claim that these waves are triggered by allelomimetic effects i.e. they are a phenomenon produced by an individual copying its neighbour's behaviour.
Interspecific threat-sensitivity allows prey to maximize the net benefit of antipredator strategies by adjusting the type and intensity of their response to the level of predation risk. This is well documented for classical prey-predator interactions but less so for intraguild predation (IGP). We examined threat-sensitivity in antipredator behaviour of larvae in a predatory mite guild sharing spider mites as prey. The guild consisted of the highly vulnerable intraguild (IG) prey and weak IG predator Phytoseiulus persimilis, the moderately vulnerable IGprey and moderate IG predator Neoseiulus californicus and the little vulnerable IGprey and strong IG predator Amblyseius andersoni. We videotaped the behaviour of the IGprey larvae of the three species in presence of either a low- or a high-risk IG predator female or predator absence and analysed time, distance, path shape and interaction parameters of predators and prey. The least vulnerable IGprey A. andersoni was insensitive to differing IGP risks but the moderately vulnerable IGprey N. californicus and the highly vulnerable IGprey P. persimilis responded in a threat-sensitive manner. Predator presence triggered threat-sensitive behavioural changes in one out of ten measured traits in N. californicus larvae but in four traits in P. persimilis larvae. Low-risk IG predator presence induced a typical escape response in P. persimilis larvae, whereas they reduced their activity in the high-risk IG predator presence. We argue that interspecific threat-sensitivity may promote co-existence of IG predators and IGprey and should be common in predator guilds with long co-evolutionary history. PMID:23104106
The zebrafish is an emerging model for comparative immunology and biomedical research. In contrast to the five heavy chain isotype system of mice and human (IgD, IgM, IgA, IgG, IgE), zebrafish harbor gene segments for IgD, IgM, and novel heavy chain isotype called IgZ/T which appears restricted to bony fishes. The purpose of this study was to design and validate a suite of quantitative real time RT-PCR protocols to measure IgH expression in a vertebrate model which has considerable promise for modeling both pathogenic infection and chronic conditions leading to immune dysfunction. Specific primers were designed and following verification of their specificty, relative expression levels of IgD, IgM, and IgZ/T were measured in triplicate for zebrafish raised under standard laboratory conditions. During embryonic stages, low levels of each heavy chain isotype (IgH) were detected with each increasing steadily between 2 and 17 weeks post fertilization. Overall IgM>IgZ>IgD throughout zebrafish development with the copy number of IgM being several fold higher than that of IgD or IgZ/T. IgD exon usage was also characterized, as its extremely long size and presence of a stop codon in the second IgD exon in zebrafish, raised questions as to how this antibody might be expressed. Zebrafish IgD was found to be a chimeric immunoglobulin, with the third IgD exon spliced to the first IgM constant exon thereby circumventing the first and second IgD exons. Collectively, the qRT-PCR results represent the first comparative profile of IgD, IgM, IgZ/T expression over the lifespan of any fish species and the primers and assay parameters reported should prove useful in enabling researchers to rapidly quantify changes in IgH expression in zebrafish models of disease where altered IgH expression is manifested. PMID:21820179
Zimmerman, Anastasia M; Moustafa, Farah M; Romanowski, Kryzstof E; Steiner, Lisa A
The zebrafish is an emerging model for comparative immunology and biomedical research. In contrast to the five heavy chain isotype system of mice and human (IgD, IgM, IgA, IgG, IgE), zebrafish harbor gene segments for IgD, IgM, and novel heavy chain isotype called IgZ/T which appears restricted to bony fishes. The purpose of this study was to design and validate a suite of quantitative real time RT-PCR protocols to measure IgH expression in a vertebrate model which has considerable promise for modelling both pathogenic infection and chronic conditions leading to immune dysfunction. Specific primers were designed and following verification of their specificty, relative expression levels of IgD, IgM, and IgZ/T were measured in triplicate for zebrafish raised under standard laboratory conditions. During embryonic stages, low levels of each heavy chain isotype (IgH) were detected with each increasing steadily between 2 and 17 weeks post fertilization. Overall IgM>IgZ>IgD throughout zebrafish development with the copy number of IgM being several fold higher than that of IgD or IgZ/T. IgD exon usage was also characterized, as its extremely long size and presence of a stop codon in the second IgD exon in zebrafish, raised questions as to how this antibody might be expressed. Zebrafish IgD was found to be a chimeric immunoglobulin, with the third IgD exon spliced to the first IgM constant exon thereby circumventing the first and second IgD exons. Collectively, the qRT-PCR results represent the first comparative profile of IgD, IgM, IgZ/T expression over the lifespan of any fish species and the primers and assay parameters reported should prove useful in enabling researchers to rapidly quantify changes in IgH expression in zebrafish models of disease where altered IgH expression is manifested.
Zimmerman, Anastasia M.; Moustafa, Farah M.; Romanowski, Kryzstof E.; Steiner, Lisa A.
Stegodyphus mimosarumof the African savanna form communal nests consisting of few to several hundred individuals and co-operate in nest construction and maintenance, brood care and prey capture. We tested large and small individuals for differential responses to different prey risk types. To date, there has been no conclusive evidence of tasking in these or other social spiders. If tasking occurs,
Cheron Ainsworth; Rob Slotow; Tanza Crouch; Yael Lubin
Laboratory experiments demonstrated that the spiderChiracanthium mildei\\u000a L. Koch. shows a functional response to increasing density of its prey: larvae ofSpodoptera littoralis (Boisd.). A sigmoid curve was found to represent the preying rate.
Photosynthetic (PN) and dark respiration rate (RD) were measured in two species of aquatic carnivorous plants, Aldrovanda vesiculosa and Utricularia australis, growing with or without prey in an outdoor growth experiment. After 7–14 days, the positive growth effect of feeding on prey (apical growth rate, plant size, branching) was evident in both species. Tissue N content in young leaf whorls
We determined whether a marine diving bird, the rhinoceros auklet, Cerorhinca monocerata, used different foraging behaviour and collected different prey items for its young than when feeding itself. Foraging behaviour was determined by conducting visual scans, and prey items were sampled by collecting fish delivered to chicks and by collecting fish where auklets were self-feeding, which was verified by two
Prey species show specific adaptations that allow recognition, avoidance and defense against predators. For many mammalian species this includes sensitivity towards predator-derived odors. The typical sources of such odors include predator skin and fur, urine, feces and anal gland secretions. Avoidance of predator odors has been observed in many mammalian prey species including rats, mice, voles, deer, rabbits, gophers, hedgehogs,
Raimund Apfelbach; Caroline D. Blanchard; Robert J. Blanchard; R. Andrew Hayes; Iain S. McGregor
|Presents a laboratory investigation to demonstrate that habitat structure promotes increased organism abundance and species diversity by reducing predator effects on prey abundance. Investigates the effects of goldfish (Carassius auratus) predators on Gammarus sp. (an amphipod) and Daphnia magna (a cladoceran) prey in the absence and presence of…
We investigated the spatial scales at which seabirds aggregate and associate with prey over the continental shelf off southwest Vancouver Island, British Columbia. Bird densities and hydroacoustic measures of prey abundance were recorded in all seasons from 1993 to 1995 from a vessel moving along fixed strip transects (mean distance 93 km; minimum spatial units 250 m). We used the
Alan E. Burger; Christine L. Hitchcock; Gail K. Davoren
Many carnivorous arthropods can use chemical information from plants to locate their herbivorous prey. The composition of blends of herbivore-induced plant volatiles can vary with plant and herbivore species and thus carnivores are confronted with variable information about the presence of their prey. Such environmental variation is expected to favour learning. We investigated the learning ability of the predatory mite
To evaluate the current diet of alewives Alosa pseudoharengus and interactions with their prey in light of recent changes in Lake Michigan, we determined the seasonal diet and prey selectivity of large (>100 mm total length) and small (<100 mm) alewives in southeastern Lake Michigan. Selectivity and diet were evaluated on a biomass basis for alewives collected near Muskegon, Michigan,
Predator-prey interactions were studied among a small prey fish (the johnny darter Etheostoma nigrum) and two predators (crayfish Orconectes rusticus and smallmouth bass Micropterus dolomieui) with complementary foraging behaviors. When only smallmouth bass were present, darters reduced activity to 6% of control rates and spent most of the time hiding under tile shelters. When only crayfish were present, darter activity
We investigated foraging behaviour of larval dragonflies Aeshna juncea in order to examine the significance of prey density and body size in predator-prey dynamics. A. juncea were offered separately three size-classes of Daphnia magna at low and high densities. The data were collected with direct observations of the foraging individuals. We found that large A. juncea larvae could better enhance
Patterns of prey size selectivity were quantified in the field for two species of marine microcarnivorous fish, Embiotoca jacksoni and Embiotoca lateralis (Embiotocidae) to test Scott and Murdoch's (1983) size spectrum hypothesis. Two mechanisms accounted for observed selectivity: the relative size of a fish in relation to its prey, and the type of foraging behavior used. Juvenile E. jacksoni were
An important study in multi-agent systems is the development of cooperative behavior between agents that have a shared goal. In this paper, an example of the predator-prey problem is studied in which four predator agents, using the reinforcement learning method, in an attempt to collectively achieve the task of surrounding one prey agent. First, we describe the structure of the
The paper describes two cooperating strategies among several homogeneous agents to reach a given target. In our case we used the prey-predators paradigm in which a set of agents (predators) have the purpose to reach a target (prey). The problem is addressed as an optimization problem that has been faced with two different algorithms (a genetic algorithm and a particle
The diets of pinnipeds have often been used to study their ecology and resource dynamics and in ecosystem monitoring. Scat analysis is now the most widely used method of inferring the diets of pinnipeds. Using a mathemati- cal model the present study explores the expected biases in prey occurrence that are related to prey mass, proportion of loss of remains,
The hypotheses that vegetation structural diversity and prey availability determine alpha diversity were examined for scrub- and meadow-inhabiting web spider species assemblages along elevational gradients in Costa Rica and California. Prey availabilities were estimated by sticky trap catches, using only the orders and size classes of insects actually captured by the spiders. The measured component of vegetation structural diversity was
Movements of wide-ranging top predators can now be studied effectively using satellite and archival telemetry. However, the motivations underlying movements remain difficult to determine because trajectories are seldom related to key biological gradients, such as changing prey distributions. Here, we use a dynamic prey landscape of zooplankton biomass in the north-east Atlantic Ocean to examine active habitat selection in the plankton-feeding basking shark Cetorhinus maximus. The relative success of shark searches across this landscape was examined by comparing prey biomass encountered by sharks with encounters by random-walk simulations of ‘model’ sharks. Movements of transmitter-tagged sharks monitored for 964 days (16?754?km estimated minimum distance) were concentrated on the European continental shelf in areas characterized by high seasonal productivity and complex prey distributions. We show movements by adult and sub-adult sharks yielded consistently higher prey encounter rates than 90% of random-walk simulations. Behavioural patterns were consistent with basking sharks using search tactics structured across multiple scales to exploit the richest prey areas available in preferred habitats. Simple behavioural rules based on learned responses to previously encountered prey distributions may explain the high performances. This study highlights how dynamic prey landscapes enable active habitat selection in large predators to be investigated from a trophic perspective, an approach that may inform conservation by identifying critical habitat of vulnerable species.
Sims, David W; Witt, Matthew J; Richardson, Anthony J; Southall, Emily J; Metcalfe, Julian D
Because some native ungulates have lived without top predators for generations, it has been uncertain whether runaway predation would occur when predators are newly restored to these systems. We show that landscape features and vegetation, which influence predator detection and capture of prey, shape large-scale patterns of predation in a newly restored predator-prey system. We analysed the spatial distribution of
Matthew J. Kauffman; Nathan Varley; Douglas W. Smith; Daniel R. Stahler; Daniel R. MacNulty; Mark S. Boyce
Movements of wide-ranging top predators can now be studied effectively using satellite and archival telemetry. However, the motivations underlying movements remain difficult to determine because trajectories are seldom related to key biological gradients, such as changing prey distributions. Here, we use a dynamic prey landscape of zooplankton biomass in the north-east Atlantic Ocean to examine active habitat selection in the plankton-feeding basking shark Cetorhinus maximus. The relative success of shark searches across this landscape was examined by comparing prey biomass encountered by sharks with encounters by random-walk simulations of 'model' sharks. Movements of transmitter-tagged sharks monitored for 964 days (16754 km estimated minimum distance) were concentrated on the European continental shelf in areas characterized by high seasonal productivity and complex prey distributions. We show movements by adult and sub-adult sharks yielded consistently higher prey encounter rates than 90% of random-walk simulations. Behavioural patterns were consistent with basking sharks using search tactics structured across multiple scales to exploit the richest prey areas available in preferred habitats. Simple behavioural rules based on learned responses to previously encountered prey distributions may explain the high performances. This study highlights how dynamic prey landscapes enable active habitat selection in large predators to be investigated from a trophic perspective, an approach that may inform conservation by identifying critical habitat of vulnerable species. PMID:16720391
Sims, David W; Witt, Matthew J; Richardson, Anthony J; Southall, Emily J; Metcalfe, Julian D
Unique to South-east Asia, Lao People's Democratic Republic contains extensive habitat for tigers and their prey within a multiple-use protected area system covering 13% of the country. Although human population density is the lowest in the region, the impact of human occurrence in protected areas on tiger Panthera tigris and prey populations was unknown. We examined the effects of human-
A. Johnson; C. Vongkhamheng; M. Hedemark; T. Saithongdam
Marine plastic pollution affects seabirds that mistake it for prey or incidentally ingest it with prey. Northern Fulmars (Fulmarus glacialis) and seabirds that feed at the water's surface ingest the most plastic. This can cause health issues, including satiety that possibly leads to inefficient foraging. The objectives of this study were to examine fulmar body condition, identify cephalopod diet and
Relationships of wolves (Canis lupus) and ungulates were studied in the Polish part of Biaowieza Primeval Forest with high densities of prey. The number of wolves ranged from 7 to 19, and the number of packs ranged from 2 to 4. Average densities were 2.3 wolves\\/ 100 km 2. Red deer (Cervus elaphus) was the main prey of wolves. Roe
W?odzimierz J?drzejewski; Bogumi?a J?drzejewska; Henryk Okarma; Krzysztof Schmidt; Karol Zub; Marco Musiani
1.The response of the echolocating bat,Megaderma lyra, was tested to different kinds of prey in an outdoor cage. The bats caught larger flying insects (moths, beetles, grasshoppers, and cockroaches) on the wing and also picked up arthropods (solifugid spiders, beetles and cockroaches) and small vertebrates (mice, fishes, frogs and geckoes) from the ground. After touching the prey with the muzzle,
Differential predation pressure and the probability of predation on a Batesian mimicry complex and on alternative prey were estimatedin a field experiment. The mimicry complex was composed of a noxious model (Eleodes obscura (Say)) and a palatable mimic (Stenomorpha marginata (LeConte)). House crickets (Acheta domesticus) (Linn.) were used as alternative prey. The experiment was conducted for 23 nights in August
Between 1997 and 2000, an outbreak of skin lesions and observations of emaciated striped bass, Morone saxatilis (Walbaum), in upper Chesapeake Baywere attributed to a perceived shortage of its main prey , Atlantic menhaden, Brevoortia tyrannus Latrobe. Abundance estimates, Atlantic menhaden consumption per recruit analysis (modified yield-per-recruit), bioenergetics analysis and predator-prey theory were combined to explore whether an imbalance between
Background: Most hypotheses on population limitation of small mammals and their predators come from studies carried out in northern latitudes, mainly in boreal ecosystems. In such regions, many predators specialize on voles and predator- prey systems are simpler compared to southern ecosystems where predator communities are made up mostly of generalists and predator-prey systems are more complex. Determining food limitation
Juan A. Fargallo; Jesús Martínez-Padilla; Javier Vińuela; Guillermo Blanco; Ignasi Torre; Pablo Vergara; Liesbeth De Neve
While numerous studies have examined the effects of increased primary production on higher trophic levels, most studies have focused primarily on the grazing food web and have not considered the importance of alternate prey channels. This has happened despite the fact that fertilization not only increases grazing herbivore abundance, but other types of consumers such as detritivores that serve as alternate prey for generalist predators. Alternate prey channels can sustain generalist predators at times when prey abundance in the grazing food web is low, thus increasing predator densities and the potential for trophic cascades. Using arthropod data from a fertilization experiment, we constructed a hierarchical Bayesian model to examine the direct and indirect effects of plant production and alternate prey channels on predators in a salt marsh. We found that increased plant production positively affected the density of top predators via effects on lower trophic level herbivores and mesopredators. Additionally, while the abundance of algivores and detritivores positively affected mesopredators and top predators, respectively, the effects of alternate prey were relatively weak. Because previous studies in the same system have found that mesopredators and top predators rely on alternate prey such as algivores and detritivores, future studies should examine whether fertilization shifts patterns of prey use by predators from alternate channels to the grazing channel. Finally, the hierarchical Bayesian model used in this study provided a useful method for exploring trophic relationships in the salt marsh food web, especially where causal relationships among trophic groups were unknown. PMID:23604861
Prey capture by the orb-web spider, Argiope aurantia Lucas 1833, depends on the type of the web-site selected. I analyzed A. aurantia web sites in open field and adjacent forest edge habitats to identify habitat features associated with web characteristics and prey capture. In the open field, the use of herbs or grass for web attachment was associated with smaller
Multiple predator species feeding on a common prey can lead to higher or lower predation than would be expected by simply combining their individual effects. Such emergent multiple predator effects may be especially prevalent if predators share feeding habitat. Despite the prevalence of endophagous insects, no studies have examined how multiple predators sharing an endophytic habitat affect prey or predator
Brian H. Aukema; Murray K. Clayton; Kenneth F. Raffa
Prey capture success and foraging mode were studied in brown trout Salmo trutta at temperatures ranging from 5.7 to 14.0° C. At low temperatures, there was a positive correlation between prey capture success and the proportion of time that the fish spent holding feeding stations. This correlation was not found at temperatures >10° C. PMID:22747825
Summary 1. Humans are increasingly influencing global climate and regional predator assem- blages, yet a mechanistic understanding of how climate and predation interact to affect fluctuations in prey populations is currently lacking. 2. Here we develop a modelling framework to explore the effects of different predation strategies on the response of age-structured prey populations to a changing climate. 3. We
By discarding inedible body parts of prey at greater distances from a central place, a central place forager can reduce the cost of prey transport and thus increase net rate of energy delivery. This hypothesis was tested in a specialist predator, the Merlin (Falco columbarius). Fifteen male Merlins were radio-tracked in Saskatoon (Canada) for this study. Merlins were more likely
Ecosystems are being altered on a global scale by the extirpation of top predators. The ecological effects of predator removal have been investigated widely; however, predator removal can also change natural selection acting on prey, resulting in contemporary evolution. Here we tested the role of predator removal on the contemporary evolution of trophic traits in prey. We utilized a historical
Eric P. Palkovacs; Ben A. Wasserman; Michael T. Kinnison; Howard Browman
The U.S. Forest Service manages most southwestern ponderosa pine (Pinu sponderos a) for forest structure s designed to increase abundance of prey for northern goshawks (Accipiter gentili s). The rationale for this strategy i s a hypothesis that goshawk populations are limited by prey abundance. However, Beier and Drennan (199 7 ) foun d that during the breeding season goshawks
The U.S. Forest Service recently recommended managing forests to increase the abundance of prey for Northern Goshawks (Accipiter gentilis) in the southwestern United States. However, empirical data are needed to indicate whether goshawks select foraging habitat based on prey abundance, on the presence of forest structures that favor their hunting strategy, or both. During the 1993 and 1994 breeding seasons,
The evolution of aquatic prey-capture strategies in snakes has been suggested as a model system for the study of con- vergence. However, hypotheses of correlated evolution of prey-capture strategy with different aspects of foraging niche have never been tested quantitatively. Whereas a considerable amount of data is available for North American species, data for European species are scarce. In this
|Predator-prey dynamics are an important concept in ecology, often serving as an introduction to the field of community ecology. However, these dynamics are difficult for students to observe directly. We describe a methodology that employs model caterpillars made of clay to estimate rates of predator attack on a prey species. This approach can be…
Curtis, Rachel; Klemens, Jeffrey A.; Agosta, Salvatore J.; Bartlow, Andrew W.; Wood, Steve; Carlson, Jason A.; Stratford, Jeffrey A.; Steele, Michael A.
Toothed whales echolocating in the wild generate clicks with low repetition rates to locate prey but then produce rapid sequences of clicks, called buzzes, when attempting to capture prey. However, little is known about the factors that determine clicking rates or how prey type and behaviour influence echolocation-based foraging. Here we study Blainville's beaked whales foraging in deep water using a multi-sensor DTAG that records both outgoing echolocation clicks and echoes returning from mesopelagic prey. We demonstrate that the clicking rate at the beginning of buzzes is related to the distance between whale and prey, supporting the presumption that whales focus on a specific prey target during the buzz. One whale showed a bimodal relationship between target range and clicking rate producing abnormally slow buzz clicks while attempting to capture large echoic targets, probably schooling prey, with echo duration indicating a school diameter of up to 4.3?m. These targets were only found when the whale performed tight circling manoeuvres spending up to five times longer in water volumes with large targets than with small targets. The result indicates that toothed whales in the wild can adjust their echolocation behaviour and movement for capture of different prey on the basis of structural echo information.
Johnson, M; Hickmott, L.S; Aguilar Soto, N; Madsen, P.T
The effect of bean and maize vegetation on the abundance of prey, predators, and predation rate in larvae of the Mexican bean beetle (Epilachna varivestis Mulsant (Coleoptera: Coccinellidae)) was investigated. Prey and predator densities were determined when bean and maize plants were grown alone (monocultures) and when bean plants were intercropped with tall or short maize plants (dicultures). On bean
A stage-structured predator–prey system (stage structure for both predator and prey) with discrete time delay has been presented in this paper. By analyzing the model and using the standard comparison theorem, the sufficient conditions are derived for permanence of the system and non-permanence of predators.
The flatworm Platydemus manokwari (Tricladida: Rhynchodemidae) preys on various species of land snail, and its introduction to areas outside of its native\\u000a range is thought to have caused the extinction of native land snails on several Pacific islands. Platydemus manokwari occurs in areas where land snails have been absent since its invasion, suggesting that the flatworm can prey on animals
The Laysan teal (Anas laysanensis) is an endangered dabbling duck endemic to the Hawaiian Archipelago but currently restricted to a single breeding population on Laysan Island. We studied its diet using fecal analysis and behavioral observations. Laysan teal fecal samples (N=118) contained prey items in 15 primary prey categories with a mean of ?.? (range 0-?) taxa per sample. Sixty-two
MICHELLE H. REYNOLDS; JOHN W. SLOTTERBACK; JEFFREY R. WALTERS
Synopsis The spatio-temporal availability to, and use of terrestrial (allochthonous) prey by, a subset of the fish assemblage of a Virginia piedmont stream were investigated during spring and summer. Terrestrial invertebrates were most abundant in drift nets, but least common in fish stomachs, during April. In contrast, during August, terrestrial prey dominated the diet of the major cyprinid fish,Notropis ardens,
Movement is an important element of prey defense ensembles. The adaptive advantages of either remainingmotionless or rapid escape are clear. In contrast, putative benefits are unclear for sluggish movement of aposematic prey that are neither fleeing nor avoiding detection of pre- dators. Nonetheless, sluggish movement is common in aposematic insects. Our central hypothesis is that sluggish movement evolved in part
JOHN D. HATLE; BRENT A. SALAZAR; DOUGLAS W. WHITMAN
Movement is an important element of prey defense ensembles. The adaptive advantages of either remaining motionless or rapid escape are clear. In contrast, putative benefits are unclear for sluggish movement of aposematic prey that are neither fleeing nor avoiding detection of predators. Nonetheless, sluggish movement is common in aposematic insects. Our central hypothesis is that sluggish movement evolved in part
John D. Hatle; Brent A. Salazar; Douglas W. Whitman
We used direct observations to quantify prey types, prey delivery rate, and adult and nestling behavior at nests of Red-shouldered Hawks (Buteo lineatus) in suburban southwestern Ohio. Twenty-one nests were observed for a total of 256 hr in 1997-2001. Small mammals made up the ...
The exceptionally high speed at which syngnathid fishes are able to rotate their snout towards prey and capture it by suction is potentially caused by a catapult mechanism in which the energy previously stored in deformed elastic elements is suddenly released. According to this hypothesis, tension is built up in tendons of the post-cranial muscles before prey capture is initiated.
Sam Van Wassenbergh; James A. Strother; Brooke E. Flammang; Lara A. Ferry-Graham; Peter Aerts
In this paper we propose a predator–prey model with logistic growth in the prey population that includes an SIS parasitic infection in the predator population, with the assumption that the predator has an alternative source of food. For simplicity we initially work with a model involving the fractions of the predator which are susceptible and those infected and then translate