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Direct reciprocity was proposed by Robert Trivers as a mechanism for the evolution of cooperation. [1] If there are repeated encounters between the same two players in an evolutionary game in which each of them can choose either to "cooperate" or "defect", then a strategy of mutual cooperation may be favoured even if it pays each player, in the short term, to defect when the other cooperates.
In these examples, the source of selection on a trait coevolves with the trait itself, therefore causation is reciprocal and developmental processes potentially become relevant to evolutionary accounts. For instance, a peacock’s tail evolves through mating preferences in peahens, and those preferences coevolve with the male trait.
Direct effect in a mediation model. In the diagram shown above, the indirect effect is the product of path coefficients "A" and "B". The direct effect is the coefficient " C' ". The direct effect measures the extent to which the dependent variable changes when the independent variable increases by one unit and the mediator variable remains ...
Positive reciprocity occurs when an action committed by one individual that has a positive effect on someone else is returned with an action that has an approximately equal positive effect. [22] [23] For example, if someone mows their neighbor's lawn, the person who received this favor should then return this action with another favor such as a ...
The pygmy mammoth is an example of insular dwarfism, a case of Foster's rule, its unusually small body size an adaptation to the limited resources of its island home.. A biological rule or biological law is a generalized law, principle, or rule of thumb formulated to describe patterns observed in living organisms.
Vandenbergh effect (biology) Vaporific effect (fire) Veblen effect (consumer theory) (goods) Venturi effect (fluid dynamics) Venus effect (artistic techniques) (cognitive science) (film techniques) (mirrors) (psychology) Visual effects (computer generated imagery) Visual effects art director; Voigt effect (magnetism) (optics)
Although the behavior in these two examples is the same, the explanations are based on different sets of factors incorporating evolutionary versus physiological factors. These can be further divided, for example proximate causes may be given in terms of local muscle movements or in terms of developmental biology (see Tinbergen's four questions).
This is a unidirectional process based on the release of a specific compound by one organism that has a negative effect on another. A classic example of amensalism is the microbial production of antibiotics that can inhibit or kill other, susceptible microorganisms. A clear case of amensalism is where sheep or cattle trample grass.