Mating Systems Conflict

Agonistic Behavior A term dealing with conflict situations among conspecifics for a resource Animals can be competing for food, water, shelter, mates, nest sites, etc. Competition involves exploitation (passive use of resources) and interference (aggressive defense of resources).

Competition Ideal free distribution. A model which assumes that the animals involved have all the information there is about the way in which resources are distributed in the environment. (see figure 16.2 p. 283). No aggression is involved and the resources are passively exploited to the best benefit of all. Usually, however, animals are not passive with respect to the way in which they control access to resources and interference competition and resource defense results.

Terms involved in usage of space by animals Home range. The area in which an animal lives. Not always easy to determine because some animals wander to new areas and stay there. Usually determined as the range in which it is found 95 percent of the time. Core area. The area within the home range in which the animal spends most of its time. Individuals distance or personal space.

Territory A virtually exclusively occupied area that is defended. Size depends upon the animal and the resource being defended. Usually the territory includes food source. Takes energy to patrol the territory and signal its boundaries by scent marketing, singing and making other displays, so why do it? Turns out to be easier than fighting

Territory When a resource is limited and uniformly distributed, territories develop. A clumped unpredictable resource usually is not worth defending. Territories that do develop in such areas are very small. Red winged, polygynous blackbirds have large territories where food source is relatively unconcentrated and predictable, whereas tricolored are the opposite and have very small territories.

Territory So animals will be territorial when the cost of defending an area pays off. If defending the resource results in enough decrease in competition to make it worthwhile, the resource will be defended. If the resource is so good that there is enough for everyone, it does not pay to defend it. If the resource is so small and scattered that the cost of defense is less than the profit gained, the resource is not worth defending.

Territory(leks) Leks are areas where males display for the purpose of courting. Here the dispute is over the best spot to perform the courtship ritual. Females choose and mating is promiscuous.

Dominance hierarchies Involves situations in which one animal controls the behavior of another. Dominance can involve pecking orders, and the more complex hierarchies of primates. Advantages can involve greater access to food and mates, but having to maintain dominance can be a problem.

Cannibalism and infanticide In lions, langur monkeys and other groups males kill off young when they take over a harem. Rodents often eat their young when conditions get overcrowded. Embryo reabsorption also occurs in rodents and lagomorphs. Bird siblings, e.g. white footed boobies, are killed by older stronger birds..

Why is everyone not killing everyone? Displays have evolved to limit agonistic behavior. Game theory models. Hawks vs. doves. Results in evolutionary stable strategies (ESS). Resource holders generally win. They are hawks. Size can make a difference. Predictions differ when neither individual has an advantage.

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