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Dilution effect
From Wikipedia, the free encyclopedia Dilution effect is the reduced, or diluted, probability of predation to a single animal when it is in a group. This is because the predator only takes a single or a limited amount of prey in each attack. More individuals watching for predators also allows each individual to spend less time watching, and more time feeding.
Herd of Gazelles
Description
Dilution effect is one of several anti-predator functions of animal aggregations that have been proposed. This function has been theorized by Turner and Pitcher as a combination of detection and attack probabilities. In the detection component of the theory, it was suggested that potential prey might benefit by living together since a predator is less likely to chance upon a single group than a scattered distribution. In the attack component, it was thought that an attacking predator is less likely to eat a particular animal when a greater number of individuals are present. In sum, an individual has an advantage if it is in the larger of two groups, assuming that the probability of detection and attack does not increase disproportionately with the size of the group.
Social Behavior
Social behavior is the interaction among individuals of the same species. Social interaction varies greatly between different species, and are subject to natural selection. Some animals interact very little with each other even when offspring is involved. Inversely, highly social species live in large group and work together to perform many tasks. Often times, social behavior of animals are adaptive, meaning that the interactions increase an animal's fitness.There are six different types of species interactions, which can be seen below:
Type of Interaction Species 1 Species 2 Predation/Parasitoidism + - Parasitism + - Mutualism + + Herbivory + - Competition - - Commensalism + 0
Group Structure
Groups of animals are seen as particular instances of social organizations, and often share similar problems as the more socially complex primates that we are. These issues usually revolve around hierarchy of power, distribution of resources, conflict management, decision making, coherent motion, etc. Despite these issues, many species continue to travel in groups.
Group travel includes: Flocking birds Herds of cow School of fish A colony of ants
Analyzing group structure and behavior is necessary in order to gain a better knowledge of individual behavior and how it is effected by social dynamics. Living in groups involves a balance of conflict and cooperation, which is mediated by the costs and benefits associated with living socially.
Group Benefits
When animals travel in groups, they receive many benefits that would otherwise not be possible when traveling alone. That is why group travel is so prominent among different species, and why the study of it is crucial to understanding population dynamics. Below is a list of the benefits animals receive from group travel:
More individuals watching for predators allows each individual to spend less time watching, and more time feeding A group may be able to fend off predators better than an individual Many individuals searching for food may be able to find rare food more easily Probability of prey capture increases Large groups attract females, making it easier to find potential mates Large groups can scatter upon attack to create confusion by dividing the attention of the predator
Group Costs
Although animals receive many benefits from traveling in groups, there are also several disadvantages from this survival strategy. They include:
Groups of animals are more conspicuous to predators The risk of parasites increases in groups; high densities can increase the rate at which diseases spread Risk of disease spread is particularly problematic in aquaculture or livestock operations, where animals are kept at high densities Food must be shared among all members of the group
References
"Birds of a Feather". terpconnect.umd.edu. Retrieved 2017-09-22. Turner, George F.; Pitcher, Tony J. (1986-08-01). "Attack Abatement: A Model for Group Protection by Combined Avoidance and Dilution". The American Naturalist. 128 (2): 228–240. ISSN 0003-0147. doi:10.1086/284556. "How Does Social Behavior Evolve? | Learn Science at Scitable". www.nature.com. Retrieved 2017-09-22. emresar. "Animal groups - ETH - Chair of Systems Design - Welcome". www.sg.ethz.ch. Retrieved 2017-09-22. "How Does Social Behavior Evolve? | Learn Science at Scitable". www.nature.com. Retrieved 2017-09-23.
External links
Dilution effect Article by Cary Institute of Ecosystem Studies
Evolution of social behavior
The Confusion Effect Journal by Royal Society Open Science