نتایج جستجو برای: predation
تعداد نتایج: 12312 فیلتر نتایج به سال:
BACKGROUND Little is known about the impact of prey sexual dimorphism on predator-prey dynamics and the impact of sex-selective harvesting and trophy hunting on long-term stability of exploited populations. METHODOLOGY AND PRINCIPAL FINDINGS We review the quantitative evidence for sex-selective predation and study its long-term consequences using several simple predator-prey models. These mod...
Sheep predation by coyotes (Canis latrans) is a major problem for sheep producers in North America. Solutions are facilitated by a basic understanding of the trophic dynamic context of this problem, one that likely varies geographically in important qualitative ways. Little is known about vertebrate trophic dynamics in Mediterranean ecosystems, where prey are diverse and their biomass is strong...
The role predation plays in the dynamics of prey populations is controversial. Our understandings of predator-prey relationships is complicated by a multitude of factors in the environment and a general lack of knowledge of most ecological systems. Various other factors, besides predation, may regulate or limit prey populations, and various factors influence the degree to which predation affect...
Two 60 day experiments on predation behavior of leeches were conducted concurrently. In the first, medicinal leeches, Hirudo orientalis (Utevsky and Trontelj, 2005) were fed to satiation on bovine blood and subsequently transferred into two large opaque plastic containers of equal size but with differing temperatures, 6-7?C and 23-24?C, containing starved Erpobdella octoculata (L.). At the high...
A survey of studies examining crab and lobster predation on hard-shelled molluscs indicated that most predators prefer small-sized prey when offered a range of sizes. I suggest that this pattern of preference for small-sized prey can be explained by considering the mechanical cost of predation. If predation costs are assumed to be non-renewable, then the probability of exhausting them can be in...
We consider precautionary liquidity holding as counter-strategy for the entrant to protect himself from predation. Threat of predation, even if avoided in equilibrium, affects the financial contract to raise precautionary liquidity and the equilibrium outcome in the product market competition. When the incumbent’s strategy is unverifiable, the entrant with small start-up capital cannot raise la...
1. Understanding the role of predation in shaping the dynamics of animal communities is a fundamental issue in ecological research. Nevertheless, the complex nature of predator-prey interactions often prevents researchers from modelling them explicitly. 2. By using periodic Leslie-Usher matrices and a simulation approach together with parameters obtained from long-term field projects, we recons...
Bacteria of the genus Lysobacter are considered to be facultative predators that use a feeding strategy similar to that of myxobacteria. Experimental data supporting this assumption, however, are scarce. Therefore, the predatory activities of three Lysobacter species were tested in the prey spot plate assay and in the lawn predation assay, which are commonly used to analyze myxobacterial predat...
The interference of biological agents may cause behaviors such as interspecific predation, reducing their efficiencies. The interspecific predation of lacewing, Chrysoperla carnea (Steph.) and ladybeetle, Hippodamia variegata (Goeze) was investigated in the presence and absence of prey, Aphis gossypii Glover under laboratory conditions. In the presence and absence of prey, the larvae of lacew...
The introduction of predatory mammals to oceanic islands has led to the extinction of many endemic birds. Although introduced predators should favour changes that reduce predation risk in surviving bird species, the ability of island birds to respond to such novel changes remains unstudied. We tested whether novel predation risk imposed by introduced mammalian predators has altered the parental...
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