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Altruism

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David Sloan Wilson – 1st expert on this subject based on the ideXlab platform

  • Population viscosity and the evolution of Altruism
    Journal of Theoretical Biology, 2000
    Co-Authors: Joshua Mitteldorf, David Sloan Wilson

    Abstract:

    The term population viscosity refers to limited dispersal, which increases the genetic relatedness of neighbors. This effect both supports the evolution of Altruism by focusing the altruists’ gifts on relatives of the altruist, and also limits the extent to which Altruism may emerge by exposing clusters of altruists to stiffer local competition. Previous analyses have emphasized the way in which these two effects can cancel, limiting the viability of Altruism. These papers were based on models in which total population density was held fixed. We present here a class of models in which population density is permitted to fluctuate, so that patches of altruists are supported at a higher density than patches of non-altruists. Under these conditions, population viscosity can support the selection of both weak and strong Altruism. (C) 2000 Academic Press.

  • Altruism, tit for tat and ‘outlaw’ genes
    Evolutionary Ecology, 1994
    Co-Authors: Lee Alan Dugatkin, David Sloan Wilson, Livingston Farrand, Richard T. Wilkens

    Abstract:

    In a prior study we combined game theory and inclusive fitness models to examine whether the guarded Altruism that can evolve among non-relatives (tit for tat, TFT) might also evolve among close relatives, supplanting unconditional Altruism. In most cases, TFT replaced unconditional Altruism in family-structured models. Even when TFT is selected at a single locus, however, by withholding Altruism from non-reciprocating relatives it may qualify as an ‘outlaw’ from the standpoint of modifier genes at other loci. Here we examine this possibility with a series of haploid, two-locus models in which a modifier gene transforms TFT into unconditional Altruism. The modifier allele spreads to fixation whenever Hamilton’s Rule is satisfied, resulting in an unconditional altruist replacing the TFT strategy. As such, TFT may be regarded as an outlaw vulnerable to suppression by alleles at other loci.

Lee Alan Dugatkin – 2nd expert on this subject based on the ideXlab platform

  • Altruism, tit for tat and ‘outlaw’ genes
    Evolutionary Ecology, 1994
    Co-Authors: Lee Alan Dugatkin, David Sloan Wilson, Livingston Farrand, Richard T. Wilkens

    Abstract:

    In a prior study we combined game theory and inclusive fitness models to examine whether the guarded Altruism that can evolve among non-relatives (tit for tat, TFT) might also evolve among close relatives, supplanting unconditional Altruism. In most cases, TFT replaced unconditional Altruism in family-structured models. Even when TFT is selected at a single locus, however, by withholding Altruism from non-reciprocating relatives it may qualify as an ‘outlaw’ from the standpoint of modifier genes at other loci. Here we examine this possibility with a series of haploid, two-locus models in which a modifier gene transforms TFT into unconditional Altruism. The modifier allele spreads to fixation whenever Hamilton’s Rule is satisfied, resulting in an unconditional altruist replacing the TFT strategy. As such, TFT may be regarded as an outlaw vulnerable to suppression by alleles at other loci.

  • Nepotism vs Tit-For-Tat, or, why should you be nice to your rotten brother?
    Evolutionary Ecology, 1991
    Co-Authors: D. S. Wilson, Lee Alan Dugatkin

    Abstract:

    It is well known that interactions among relatives facilitate the evolution of altruistic behaviours. Game theoretic models show, however, that guarded Altruism (such as Tit-For-Tat) can evolve among non-relatives when individuals interact many times and ‘cheating’ behaviours can be punished. Strangely, no one has yet asked whether the guarded Altruism that evolves among non-relatives might also evolve among close relatives, supplanting unconditional altriusm. We present a series of one-locus sexual haploid models in which Tit-For-Tat, unconditional altruists and selfish individuals interact in groups of full siblings. Tit-For-Tat frequently (but not always) replaced unguarded Altruism, in which case the strategic ‘rules’ for interacting with kin vs non-kin are identical. Even when Tit-For-Tat is selected at a single locus, however, by withholding Altruism for non-reciprocating relatives it may qualify as an ‘outlaw’ from the standpoint of modifier genes at other loci.

Joshua Mitteldorf – 3rd expert on this subject based on the ideXlab platform

  • Population viscosity and the evolution of Altruism
    Journal of Theoretical Biology, 2000
    Co-Authors: Joshua Mitteldorf, David Sloan Wilson

    Abstract:

    The term population viscosity refers to limited dispersal, which increases the genetic relatedness of neighbors. This effect both supports the evolution of Altruism by focusing the altruists’ gifts on relatives of the altruist, and also limits the extent to which Altruism may emerge by exposing clusters of altruists to stiffer local competition. Previous analyses have emphasized the way in which these two effects can cancel, limiting the viability of Altruism. These papers were based on models in which total population density was held fixed. We present here a class of models in which population density is permitted to fluctuate, so that patches of altruists are supported at a higher density than patches of non-altruists. Under these conditions, population viscosity can support the selection of both weak and strong Altruism. (C) 2000 Academic Press.