Predator-prey interactions

Predator-prey interactions

Predation occurs when one animal (the predator) eats another living animal (the prey) to utilize the energy and nutrients from the body of the prey for growth, maintenance, or reproduction. In the special case in which both predator and prey are from the same species, predation is called cannibalism. Sometimes the prey is actually consumed by the predator's offspring. This is particularly prevalent in the insect world. Insect predators that follow this type of lifestyle are called parasitoids, since the offspring grow parasitically on the prey provided by their mother.

Predation is often distinguished from herbivory by requiring that the prey be an animal rather than a plant or other type of organism (bacteria). To distinguish predation from decomposition, the prey animal must be killed by the predator. Some organisms occupy a gray area between predator and parasite. Finally, the requirement that both energy and nutrients be assimilated by the predator excludes carnivorous plants from being predators, since they assimilate only nutrients from the animals they consume. See Food web

Population dynamics refers to changes in the sizes of populations of organisms through time, and predator-prey interactions may play an important role in explaining the population dynamics of many species. They are a type of antagonistic interaction, in which the population of one species (predators) has a negative effect on the population of a second (prey), while the second has a positive effect on the first. For population dynamics, predator-prey interactions are similar to other types of antagonistic interactions, such as pathogen-host and herbivore-plant interactions.

Community structure refers generally to how species within an ecological community interact. The simplest conception of a community is as a food chain, with plants or other photosynthetic organisms at the bottom, followed by herbivores, predators that eat herbivores, and predators that eat other predators. This simple conception works well for some communities. Nonetheless, the role of predator species in communities is often not clear. Many predators change their ecological roles over their lifetime. Many insect predators that share the same prey species are also quite likely to kill and devour each other. This is called intraguild predation, since it is predation within the guild of predators. Furthermore, many species are omnivores, feeding at different times as either predators or herbivores. Therefore, the role of particular predator species in a community is often complex.

Predator-prey interactions may have a large impact on the overall properties of a community. For example, most terrestrial communities are green, suggesting that predation on herbivores is great enough to stop them from consuming the majority of plant material. In contrast, the biomass of herbivorous zooplankton in many aquatic communities is greater than the biomass of the photosynthetic phytoplankton, suggesting that predation on zooplankton is not enough to keep these communities green. See Population ecology

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Predator-prey interactions in two schooling fishes, Caranx ignobilis and Stolephorus purpureus.
Predator-prey interactions between Lepsiella (Bedeva) paivae (Gastropoda: Muricidae) and Katelysia scalarina (Bivalvia: Veneridae) in princess royal harbor, western Australia.
Removal of the sharks from an ecosystem has the potential to create significant changes to predator-prey interactions.
According to De Arruda Bueno & Motta-Junior (2008), a general feature of predator-prey interactions is that ambush (sit-and-wait) predators often take larger and older prey, relative to those taken by active predators.
The study, published this month in the scientific journal eLife, examines what determines the outcomes of predator-prey interactions in wild animals and how both predators and prey can best increase their chances of success.
However, predator-prey interactions can be context dependent and do not always affect the plant trophic level.
Changes in temperature as a consequence of global climate change may influence predator-prey interactions, which could alter community structure.
Why some animals use noxious scents while others live in social groups to defend themselves against predators is the question that biologists Tim Caro of the University of California, Davis and Theodore Stankowich of California State University, Long Beach and sought to answer through a comprehensive analysis of predator-prey interactions among carnivorous mammals and birds of prey.
They used previously published stable isotope datasets to reconstruct predator-prey interactions at six sites located from Alaska to western Europe.
From a conceptual viewpoint, predator-prey interactions are an important bridge between population ecology (the fluctuations in population size of a particular species in time and space) and community ecology (the interactions among species).