Search results for "Predator"
showing 10 items of 349 documents
Macroscopic Dynamic Effects of Migrations in Patchy Predator-prey Systems
1997
Abstract Different mechanisms at the behaviourial or physiological levels determine many properties of predator-prey systems at the population level. In this paper, we present a method of obtaining complex predator-prey dynamic models from models at a detailed, behaviourial level of description. We consider a multi-patch predator-prey model, the dynamics of which contains two time-scales: a fast one, associated with migrations between patches, and a slow one, on which interactions, reproduction and mortality occur. We use methods of perturbation theory in order to aggregate the multi-patch system into a reduced system of two differential equations for the total prey and predator populations…
Biological invasion and parasitism: invaders do not suffer from physiological alterations of the acanthocephalan Pomphorhynchus laevis.
2009
SUMMARYBiological invasions expose parasites to new invasive hosts in addition to their local hosts. However, local parasites are often less successful in infecting and exploiting their new hosts. This may have major consequences for the competitive ability of hosts, and finally on the fate of the parasite-host community. In Burgundy (Eastern France), the acanthocephalan parasite,Pomphorhynchus laevis, infects 2 amphipod species living in sympatry: the nativeGammarus pulexand the invasiveGammarus roeseli. WhileP. laevisaffects the behaviour and the immunity ofG. pulex,G. roeseliseems unaffected by the infection. In this study, we examined in detail the ability of the parasite to affect the …
Predatory interactions between a cyclopoid copepod and three sibling rotifer species
2002
SUMMARY 1. Cyclopoid copepod predation on rotifers affects the dynamics and structure of zooplankton communities. We address the differential vulnerability of three sympatric rotifer sibling species belonging to the Brachionus plicatilis species complex. These co-occur with their cyclopoid predator, Diacyclops bicuspidatus odessanus. 2. Using video recording and tracking, we analysed the steps in predation including attack distance, attack angle, and rotifer species swimming in the presence and absence of the predator. Our results show the greater vulnerability of B. rotundiformis (the smallest species) to D. b. odessanus predation, which is associated with a high percentage of attacks afte…
Comments on Guimarães & Sawaya. Pretending to be venomous: is a snake's head shape a trustworthy signal to a predator?
2011
Several species of non-venomous snake are known to flatten their heads when disturbed, and this behaviour has been suggested to be a mimicry of vipers (Arnold & Ovenden 2002, Hailey & Davies 1986, Young et al. 1999). Using plasticine models, Guimaraes & Sawaya (2011) tested the antipredatory function of a triangular head shape in snakes. Their article presents the first published empirical experiment testing the adaptive significance of vipers’ triangular head shape. Guimaraes & Sawaya (2011) found no support for the viper mimicry hypothesis. Accordingly, they concluded that ‘the shape of [the] head seemed not to confer advantage itself’. Although the use of plasticine models is a generally…
The complex business of survival by aposematism.
2005
The theory of warning signals dates back to Wallace but is still confusing, controversial and complex. Because predator avoidance of warningly coloured prey (aposematism) is based upon learning and reinforcement, it is difficult to understand how initially rare conspicuous forms subsequently become common. Here, we discuss several possible resolutions to this apparent paradox. Many of these ideas have been largely ignored as a result of implicit assumptions about predator behaviour and assumed lack of variation in the predators, prey and the predation process. Considering the spatial and temporal variation in and mechanisms of behaviour of both predators and prey will make it easier to unde…
The role of natural science collections in the biomonitoring of environmental contaminants in apex predators in support of the EU’s zero pollution am…
2022
Movalli, Paola et al.
Alarm calling by individual willow tits, Parus montanus
1990
Abstract Alarm responses of wild-captured individual willow tits to model sparrowhawks, Accipiter nisus, flying over a test chamber were studied. Tits did not usually give alarm calls if the apparent predator was passing nearby (at a height of 10 m), while over half of the individuals responded by alarm calling for a more distant predator (40 m). This suggests that alarm calling involves a risk to the caller. Second, there was individual variation in the responses, with older males giving the call more frequently than females or young males. The greater responsiveness of adult males may indicate that different individuals in a flock gain different benefits by warning the others. The tendenc…
Disentangling canid howls across multiple species and subspecies: Structure in a complex communication channel
2016
Wolves, coyotes, and other canids are members of a diverse genus of top predators of considerable conservation and management interest. Canid howls are long-range communication signals, used both for territorial defence and group cohesion. Previous studies have shown that howls can encode individual and group identity. However, no comprehensive study has investigated the nature of variation in canid howls across the wide range of species. We analysed a database of over 2000 howls recorded from 13 different canid species and subspecies. We applied a quantitative similarity measure to compare the modulation pattern in howls from different populations, and then applied an unsupervised clusteri…
Increased susceptibility to predation and altered anti-predator behaviour in an acanthocephalan-infected amphipod.
2007
7 pages; International audience; According to the 'parasitic manipulation hypothesis', phenotypic changes induced by parasites in their intermediate hosts are effective means of increasing trophic transmission to final hosts. One obvious prediction, although seldom tested, is that increased vulnerability of infected prey to an appropriate predator should be achieved by the parasite altering the anti-predator behaviour of its intermediate host. In this study, we tested this prediction using the fish acanthocephalan Pomphorhynchus tereticollis and the freshwater amphipod Gammarus pulex. Firstly, we estimated the relative vulnerability of infected and uninfected gammarids to predation by the b…
Infection with acanthocephalans increases the vulnerability of Gammarus pulex (Crustacea, Amphipoda) to non-host invertebrate predators.
2008
SUMMARYPhenotypic alterations induced by parasites in their intermediate hosts often result in enhanced trophic transmission to appropriate final hosts. However, such alterations may also increase the vulnerability of intermediate hosts to predation by non-host species. We studied the influence of both infection with 3 different acanthocephalan parasites (Pomphorhynchus laevis, P. tereticollis, and Polymorphus minutus) and the availability of refuges on the susceptibility of the amphipod Gammarus pulex to predation by 2 non-host predators in microcosms. Only infection with P. laevis increased the vulnerability of amphipods to predation by crayfish, Orconectes limosus. In contrast, in the ab…