GOD SAVE THE QUEENBiology 342 Fall 2011Physiological & Environmental Effects on Hierarchical Rank in Ants. |
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Adaptive Value: -Adaptive value is the extent to which a trait, behavior, or characteristic positively influences the evolutionary fitness of an individual There is adaptive value in living as a colony if the benefits of doing so outweigh the costs (see Phylogeny page for details) -the allele for the altruistic behavior displayed by the sterile or “eusocial” workers can spread even in competition with a gene that promotes only personal reproduction. This is due to indirect fitness. -The indirect Fitness theory on the adaptive value of social behavior: indirect fitness is fitness achieved by helping non-descendent kin survive. This involves altruistic behavior towards relatives: siblings, cousins, etc. While altruistic behavior may reduce the fitness of the altruistic individual, these fitness costs are outweighed by the indirect fitness gains of insuring the survival of non-descendent kin, i.e. the offspring of relative. Even though queen ants live longer than workers, the indirect benefits of ensuring the fitness of the queens offspring (who are genetically related to the workers) outweigh the costs of trying to break away from the colony and founding a new one, i.e. trying to ensure their own individual reproductive fitness. Self-sacrificing individuals almost always are assisting close relatives Mutualism theory on the adaptive value of social behavior: The other theory of social behavior relevant for ant colonies is mutualism, in which members of a species help each other for each of their own mutual benefit. This latter theory can explain cooperation among castes, but cooperation between castes, specifically altruistic behavior of the sterile workers towards the queen ant can be explained by the theory of indirect fitness. History:
-Nearby colonies are less aggressive towards each other than colonies that live far away from each other. This suggests there is adaptive value to having new queens moving only a short distance away from their colonies to establish new ones, that being friendly, low fitness cost relationships with their neighbors as opposed to high aggressive territorial relationships which incur fitness costs. -Transaction theory: organized social groups are arenas in which dominants and subordinates “negotiatie” their reproductive rights within the group. An example of this is the “concessions model” in which the dominant group member concedes some amount of reproduction rights to lower-ranking individuals in order to maintain a certain degree of advantage for the subordinates to stay within the colony.
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