Predator–prey relationships and predation rates for crustacean zooplankters from some lakes in western Canada

1970 ◽  
Vol 48 (6) ◽  
pp. 1229-1240 ◽  
Author(s):  
R. Stewart Anderson
Keyword(s):  
Prey Species ◽  
Prey Size ◽  
Relative Size ◽  
Experimental Studies ◽  
The Other ◽  
Western Canada ◽  
Potential Predator ◽  
Predator Prey ◽  
Predation Rates

Experimental studies on Diaptoimus shoshone, D. arcticus, D. nevadensis, Cyclops bicuspidatus thomasi, C. vernalis, and Branckinecta gigas show that these predatory species can capture and eat many prey species of various sizes. B. gigas probably combines raptorial with filter feeding and can eat 150 or more smaller crustaceans per day. Adult D. shoshone, D. arcticus, and D. nevadensis eat up to 12 or more cyclopoids or diaptomids per day. Rotifers are also preferred prey. Predation rates are inversely proportional to prey size. Cannibalism probably causes the uniformity in body size and instar of predaceous diaptomids in some populations, C. vernalis and C. b. thomasi can eat six or more prey animals daily, depending on the size of the prey. Predaceous diaptomids and cyclopoids will eat the same prey species at rates which are influenced more by hunger than by abundance of prey. Furthermore, each species is a potential predator on the other, where the role of predator or prey is determined by the relative size or instar of the two groups. Hence, codominance of the zooplankton by predaceous diaptomid and cyclopoid species is unlikely.

Effects of size, motility and paralysation time of prey on the quantity of venom injected by the hunting spider Cupiennius salei

1999 ◽  
Vol 202 (15) ◽  
pp. 2083-2089 ◽  
Author(s):  
H. Malli ◽  
L. Kuhn-Nentwig ◽  
H. Imboden ◽  
W. Nentwig
Keyword(s):  
Prey Species ◽  
Prey Size ◽  
Experimental Studies ◽  
Energetic Cost ◽  
Cupiennius Salei ◽  
Predator Prey ◽  
Minor Significance ◽  
Spider Cupiennius Salei ◽  
Hunting Spider ◽  
Behavioural Adaptations

Previous experimental studies have shown that neotropical wandering spiders (Cupiennius salei) inject more venom when attacking larger crickets. It has been postulated that this is a consequence of predator-prey interactions during envenomation, which increase in intensity with the size of a given prey species. The present study was designed to test this hypothesis using anaesthetized crickets of different sizes that were moved artificially. Cupiennius salei was found (1) to inject more venom the greater the intensity of the struggling movement of the crickets (prey size kept constant); (2) to inject more venom the longer the duration of the struggling movement of the crickets (prey size and intensity of movement kept constant); and (3) to inject equal amounts into crickets of different size (duration and intensity of movement kept constant). These results indicate that C. salei alters the amount of venom it releases according to the size and motility of its prey. Venom expenditure depends mainly on the extent of the interactions with the prey during the envenomation process, whereas prey size is of minor significance. The regulation of venom injection in concert with behavioural adaptations in response to various types of prey minimizes the energetic cost of venom production, thus increasing the profitability of a given prey item.

scholarly journals Effort investment in uncontrollable situations: The moderating role of motivation toward closure

2021 ◽  
Vol 45 (2) ◽  
pp. 186-196
Author(s):  
Paulina Szwed ◽  
Małgorzata Kossowska ◽  
Marcin Bukowski
Keyword(s):  
Blood Pressure ◽  
Experimental Studies ◽  
The Other ◽  
Need For Closure ◽  
Extra Effort ◽  
Moderating Role ◽  
Energy Conservation Principle ◽  
Principle Of Energy Conservation ◽  
Investment Behaviour

AbstractAccording to the principle of energy-conservation principle, effort investment is usually reduced in situations that are perceived as uncontrollable. This is because when success is recognized as impossible, any effortful actions are no longer justified. However, we predicted that individual differences in uncertainty tolerance, i.e., the need for closure (NFC), may moderate effort investment in uncontrollable situations. We tested this prediction in two experimental studies in which we exposed participants with differing levels of NFC to uncontrollable events, and indexed effort through the assessment of systolic blood pressure (SBP) responses. As predicted, in the uncontrollability (vs. controllability) condition, effort investment decreased significantly among low- but not high-NFC participants. Since gaining certainty and achieving closure is not a critical epistemic goal for low-NFC individuals, exerting extra effort to gain certainty is therefore no longer justified. On the other hand, high-NFC participants do not withhold their efforts, as they are highly motivated to obtain certainty. These results may help to account for contradictory findings in effort-investment behaviour and add substantively to the literature concerning motivation toward closure.

scholarly journals Modelling and parameter inference of predator–prey dynamics in heterogeneous environments using the direct integral approach

2017 ◽  
Vol 14 (126) ◽  
pp. 20160525 ◽  
Author(s):  
Itai Dattner ◽  
Ezer Miller ◽  
Margarita Petrenko ◽  
Daniel E. Kadouri ◽  
Edouard Jurkevitch ◽  
...  
Keyword(s):  
Experimental Studies ◽  
Estimation Procedure ◽  
Integral Approach ◽  
Parameter Estimates ◽  
Heterogeneous Environments ◽  
Prey Refuge ◽  
Parameter Inference ◽  
Direct Integral ◽  
Predator Prey

Most bacterial habitats are topographically complex in the micro scale. Important examples include the gastrointestinal and tracheal tracts, and the soil. Although there are myriad theoretical studies that explore the role of spatial structures on antagonistic interactions (predation, competition) among animals, there are many fewer experimental studies that have explored, validated and quantified their predictions. In this study, we experimentally monitored the temporal dynamic of the predatory bacterium Bdellovibrio bacteriovorus , and its prey, the bacterium Burkholderia stabilis in a structured habitat consisting of sand under various regimes of wetness. We constructed a dynamic model, and estimated its parameters by further developing the direct integral method, a novel estimation procedure that exploits the separability of the states and parameters in the model. We also verified that one of our parameter estimates was consistent with its known, directly measured value from the literature. The ability of the model to fit the data combined with realistic parameter estimates indicate that bacterial predation in the sand can be described by a relatively simple model, and stress the importance of prey refuge on predation dynamics in heterogeneous environments.

scholarly journals Comparison and analysis of two forms of harvesting functions in the two-prey and one-predator model

2019 ◽  
Vol 2019 (1) ◽  
Author(s):  
Xinxin Liu ◽  
Qingdao Huang
Keyword(s):  
Prey Species ◽  
Equilibrium Points ◽  
Maximum Sustainable Yield ◽  
Predator Prey ◽  
Prey System ◽  
Existence And Stability ◽  
Predator Model ◽  
Model Equations ◽  
The Given

AbstractA new way to study the harvested predator–prey system is presented by analyzing the dynamics of two-prey and one-predator model, in which two teams of prey are interacting with one team of predators and the harvesting functions for two prey species takes different forms. Firstly, we make a brief analysis of the dynamics of the two subsystems which include one predator and one prey, respectively. The positivity and boundedness of the solutions are verified. The existence and stability of seven equilibrium points of the three-species model are further studied. Specifically, the global stability analysis of the coexistence equilibrium point is investigated. The problem of maximum sustainable yield and dynamic optimal yield in finite time is studied. Numerical simulations are performed using MATLAB from four aspects: the role of the carrying capacity of prey, the simulation about the model equations around three biologically significant steady states, simulation for the yield problem of model system, and the comparison between the two forms of harvesting functions. We obtain that the new form of harvesting function is more realistic than the traditional form in the given model, which may be a better reflection of the role of human-made disturbance in the development of the biological system.

The Processing of Musical Prosody by Musical and Nonmusical Children

1992 ◽  
Vol 10 (1) ◽  
pp. 93-125 ◽  
Author(s):  
Claire Gérard ◽  
Catherine Auxiette
Keyword(s):  
Cognitive Processes ◽  
Musical Training ◽  
Experimental Studies ◽  
Surface Structures ◽  
The Other ◽  
Music Production ◽  
Simple Sentences ◽  
Verbal Production ◽  
Better Than

The surface structures of music and speech should coincide in musical prosody. Two processing systems have thus to be integrated, one devoted to the surface structure of speech, the other to that of music. This article is in two parts: a review of data on speech and music production and hearing, and two experimental studies on the synchronization between a rhythm and spoken sounds. In the first part, a comparison between some intensity and timing parameters that characterize the unfolding of spoken strings and of musical sequences is presented. Data from studies on performers (speakers, musicians) and listeners are compared with regard to spontaneous rates, location and duration of pauses, duration of sounds, and periodic occurrence of accents. In the second part, the ability to control the correspondence between taps and words is examined. Two experimental studies on 6-year-old children focus on the role of musical training. The reproductions of simple rhythms and simple sentences or onomatopoeias were analyzed as well as the coordination between a rhythmic sequence of taps and a spoken string. Young musicians succeeded better than nonmusicians of the same age in the synchronization between their verbal production and their motor accompaniment, mainly because they more markedly anticipated the musical string in which they integrated the spoken sounds subsequently. The results are discussed in relation to the acoustic, motor, and cognitive processes involved in the coordination of the two temporal strings.

Ontogenetic niche feeding partitioning in juvenile of white sea catfish Genidens barbus in estuarine environments, southern Brazil

2008 ◽  
Vol 89 (4) ◽  
pp. 839-848 ◽  
Author(s):  
Manuel Mendoza-Carranza ◽  
João Paes Vieira
Keyword(s):  
Prey Species ◽  
White Sea ◽  
Prey Size ◽  
Age Distribution ◽  
Similarity Index ◽  
Large Fish ◽  
Southern Brazil ◽  
Predator Prey ◽  
Feeding Groups ◽  
Regression Quantile

Ontogenetic diet changes (prey species richness and size) in juveniles of white sea catfish (Genidens barbus) were tested in three southern Brazilian estuaries: Mampituba (29°12′S), Tramandaí (30°02′S), Chuí (33°44′S). Cluster analysis revealed that white sea catfish juvenile populations in the three estuaries are composed of two feeding groups. These two feeding groups are coincident with a bimodal size–age distribution of the juveniles of white sea catfish. In small catfish (5 to 10 cm TL) copepods were the most numerous prey (Chuí = 86.66%N, Tramandaí = 85.52%N and Mampituba = 52.34%N). In large catfish (10 to 20 cm TL) the most abundant and frequent prey was fish (Chuí: 73.19%N and 74.56%FO; Tramandaí: 85.92%N and 73.33%FO; Mampituba: 52.34%N and 61.54%FO). The Morisita overlap index among small and large fish was low in all estuaries; high values of Morisita's similarity index were observed among same size catfish groups. In all cases, no differences were observed among prey bio-volume curves of same size predator groups (small, F = 0.41, P = 0.65; large, F = 2.19, P = 0.11). In all estuaries, prey size increased significantly with increasing predator size. The 90th regression quantile estimated with most precision the predator–prey size relationship.

Experimental studies on acarine predator–prey interactions: effects of temporal changes in the environment on searching behaviour, predation rates, and fecundity (Acarina: Phytoseiidae)

1982 ◽  
Vol 60 (12) ◽  
pp. 2992-3000 ◽  
Author(s):  
Eldon S. Eveleigh ◽  
D. A. Chant
Keyword(s):  
Experimental Studies ◽  
Phytoseiulus Persimilis ◽  
Temporal Changes ◽  
Patchy Environment ◽  
Changing Environment ◽  
Searching Behaviour ◽  
Predator Prey ◽  
Prey Distribution ◽  
Predation Rates

We examined the effects of temporal changes in the environment on the searching behaviour, predation rates, and fecundity of Phytoseiulus persimilis and Amblyseius degenerans in the laboratory. Phytoseiulus persimilis demonstrated an ability to respond quickly to changes in prey distribution in a patchy environment and maintained its searching efficiency despite these changes. In contrast, A. degenerans was rather insensitive to temporal changes in prey distribution and when it found a profitable patch its visits to other patches were restricted. Thus, this species was unable to maintain its searching efficiency in the changing environment. Phytoseiulus persimilis distributed its progeny in relation to the distribution of prey in the changing environment and avoided oviposition in patches without prey, whereas A. degenerans showed no such discrimination. The fecundity of both species was not adversely affected by changes in prey distribution although their fecundity was lower than when all of the prey were in a single patch and their dispersal was restricted.

scholarly journals The Mechanism of Embolic Watershed Infarction: Experimental Studies

1990 ◽  
Vol 17 (4) ◽  
pp. 395-398 ◽  
Author(s):  
M.S. Pollanen ◽  
J.H.N. Deck
Keyword(s):  
Particle Size ◽  
Size Range ◽  
Experimental Studies ◽  
Limited Range ◽  
The Other ◽  
Main Trunk ◽  
Branch Size ◽  
Watershed Infarction ◽  
Watershed Infarcts

ABSTRACT:The mechanism for the preferential distribution of emboli to cerebral arterial bordcrzone regions, known to cause some watershed infarcts was studied. We hypothesized that emboli of a specific size range are selectively directed to the arterial borderzones due to the tendency of emboli to bypass the small arterial branches which emerge proximal to major borderzones. To test this hypothesis we perfused the brains of cadavers with suspensions of 90-210 µm glass microspheres and chemically extracted the particles from various arterial territories and a watershed zone. Particles in the 150-210 µm size range were found to be preferentially distributed to the watershed zone whereas particles less than 150 µm in size were randomly dispersed in leptomeningeal arteries of all vascular regions. To assess the role of branch size on the concentration of emboli at bifurcations, we perfused artificial analogs of evenly and unevenly branching bifurcations with suspensions of 90-150 µm and 150-210 µm particles. Branching cylinders with symmetrical branches contained the same concentration of particles, independent of particle size. In contrast, when one branch was one-quarter the size of the other, the concentration of 150-210 µm particles in the asymmetric branch was approximately 65% of the main trunk. Particles 90-150 µm in size were evenly distributed despite variation in branch size. These results indicate that emboli, of a limited range of size, may be selectively propagated to the distal ramifications of subarachnoid arteries located in the watershed zone rather than diverging into small calibre branches which arise along the way.

scholarly journals At Least Bias Is Bipartisan: A Meta-Analytic Comparison of Partisan Bias in Liberals and Conservatives

2019 ◽  
Author(s):  
Peter Ditto ◽  
Brittany Liu ◽  
Cory J Clark ◽  
Sean Wojcik ◽  
Eric Chen ◽  
...  
Keyword(s):  
Experimental Studies ◽  
Strong Support ◽  
Scientific Discourse ◽  
Political Conflict ◽  
The Other ◽  
The Political ◽  
Partisan Bias ◽  
Political Beliefs ◽  
Symmetry Hypothesis

Both liberals and conservatives accuse their political opponents of partisan bias, but is there empirical evidence that one side of the political aisle is indeed more biased than the other? To address this question, we meta-analyzed the results of 51 experimental studies, involving over 18,000 participants, that examined one form of partisan bias— the tendency to evaluate otherwise identical information more favorably when it supports one’s political beliefs or allegiances than when it challenges those beliefs or allegiances. Two hypotheses based on previous literature were tested: an asymmetry hypothesis (predicting greater partisan bias in conservatives than in liberals) and a symmetry hypothesis (predicting equal levels of partisan bias in liberals and conservatives). Mean overall partisan bias was robust (r = .245), and there was strong support for the symmetry hypothesis: Liberals (r = .235) and conservatives (r = .255) showed no difference in mean levels of bias across studies. Moderator analyses reveal this pattern to be consistent across a number of different methodological variations and political topics. Implications of the current findings for the ongoing ideological symmetry debate and the role of partisan bias in scientific discourse and political conflict are discussed.

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