In the Light of Evolution Volume V: Cooperation and Conflict (2011) / Chapter Skim
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3 Kinship, Greenbeards, and Runaway Social Selection in the Evolution of Social Insect Cooperation--PETER NONACS
3 Kinship, Greenbeards, and Runaway Social Selection in the Evolution of Social Insect Cooperation--PETER NONACS
Pages 49-68
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From page 49... ...
In contrast, cooperation evolves under a wider range of conditions and to higher frequencies with genetic kin recognition as shared greenbeard traits. This "excess of niceness" matches the exist ing patterns in caste bias and reproductive skew; individuals often help others at an apparent cost to their inclusive fitness.
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From page 50... ...
. The response to these criticisms from defenders of inclusive fitness modeling and kin selection has been simultaneously vigorous and dismissive (Foster et al., 2006; Lehmann et al., 2007; West et al., 2007c, 2008; Abbot et al., 2011; Herre and Wcislo, 2011; Strassmann et al., 2011b)
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From page 51... ...
. SUCCESSES: BIASED SEX INVESTMENT RATIOS AND PARENTAGE OF MALES THROUGH WORKER POLICING Another genetic consequence of the asymmetrical relatedness patterns attributable to haplodiploidy is that with one singly mated queen (i.e., monogynous with monandry)
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From page 52... ...
. Despite these notable exceptions, extensive phylogenetic analyses support broad predictions of kin selection theory (Ratnieks et al., 2006; Wenseleers and Ratnieks, 2006b)
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From page 53... ...
. FAILURES: PATRILINE NEPOTISM IN CASTE BIAS AND REPRODUCTIVE SKEW In the eusocial Hymenoptera, sterile female workers primarily raise the offspring (Bourke and Franks, 1995)
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From page 54... ...
. MECHANISMS OF KIN SELECTION "Failure" is a semantically loaded word and should not imply that there are no evolutionary explanations for the observed outcomes in caste rearing and reproductive skew.
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From page 55... ...
Therefore, instead of relegating the solu tion as only explainable by difficult-to-test group selection, it is useful to reexamine kin selection predictions relative to the mechanistic aspects of exactly how individuals recognize or define other group mates as genetic kin. In essence, kin selection theory may accurately predict the outcomes for caste rearing and reproductive skew, but the predictions themselves may differ from earlier expectations.
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From page 56... ...
. In this context, it is seen that kin nepotism through genetic recognition differs from existing models of greenbeard nepotism not in process but simply in the number of genes involved.
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From page 57... ...
. In this scenario, falsebeard mutants can also arise that induce cooperation from greenbeard alleles but never extend help.
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From page 58... ...
For greenbeard loci, potential helpers can have either one or two greenbeard alleles (first number in pair)
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From page 59... ...
Thus, the vote of a greenbeard locus depended on b and the heterozygosity or homozygosity of the helper and helped with respect to greenbeard and matching falsebeard alleles. Different greenbeard alleles at the same locus do not help each other and would vote no.
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From page 60... ...
. Moreover, higher levels of cooperation evolved and greenbeard alleles persisted longer in the absence of mutation as the number of greenbeard loci increased across all levels of b.
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From page 61... ...
The high frequency of greenbeard alleles under many conditions results in more cooperative behavior between siblings than predicted by Hamilton's rule for any given b value. For example, even with a large FIGURE 3.2 Proportion of social pairs with loci that favor helping if individuals share the same greenbeard alleles or matching falsebeards.
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From page 62... ...
For the last 500 generations, no mutations that produce greenbeard alleles were allowed. Only the situation with seven greenbeard loci and a large level of benefit (b = 4–12)
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From page 63... ...
From the lowest to highest line in each set, the numbers of greenbeard loci are one, three, or five. For the last 500 generations, no mutations that produce greenbeard alleles were allowed.
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From page 64... ...
Similarly, reproductive skew models require that group members estimate kinship in apportioning reproductive shares. Although unstated in the models, this assumes a type of greenbeard kin recognition and may be why they fail to predict skew across groups within populations.
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From page 65... ...
Finally, when greenbeard alleles predominate at multiple loci, they will increase commonality of interest. This could result in green beard alleles forming a "voting block" as regards cooperation and depress the selective advantage of a falsebeard at any individual locus.
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From page 66... ...
Shared greenbeard alleles increase in populations and raise levels of cooperation proportional to their abun dance relative to Hamiltonian loci (Fig.
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From page 67... ...
Interestingly, unicoloniality could be categorized as work ers showing excessive cooperation by accepting and raising unrelated individuals, exactly as predicted by the model of greenbeard cooperation. The suggestion would be that if greenbeard alleles arise in a species at their recognition loci, it would be possible for such alleles to sweep through a population, carrying unicoloniality in their wake.
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From page 68... ...
Any natural system where the benefits of cooperation are primarily directed to close relatives would strongly select against genetic diversity. In contrast, cooperation could evolve with con siderably less of a tradeoff with a greenbeard kin recognition mechanism.
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