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Organisms, Groups and Superorganism

Organisms, Groups and Superorganism. Sex and Death: An Introduction to Philosophy of Biology. 8.1 Interactors Identifying Interactors – Copidosoma Floridanum Example. 8.1 Interactors Identifying Interactors – Copidosoma Floridanum Example.

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Organisms, Groups and Superorganism

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  1. Organisms, Groups and Superorganism Sex and Death: An Introduction to Philosophy of Biology

  2. 8.1 InteractorsIdentifying Interactors – Copidosoma Floridanum Example

  3. 8.1 InteractorsIdentifying Interactors – Copidosoma Floridanum Example

  4. 8.1 InteractorsIdentifying Interactors – Copidosoma Floridanum Example

  5. 8.1 InteractorsIdentifying Interactors – Copidosoma Floridanum Example

  6. 8.1 InteractorsIdentifying Interactors – Copidosoma Floridanum Example

  7. 8.1 InteractorsIdentifying Interactors – Copidosoma Floridanum Example • Should we think of all the clones as a single interactor or as individuals? • If they are individuals, how can such suicidal behaviour evolve?

  8. 8.1 InteractorsHierarchical Conception of Evolution • Organisms are only one level of organization • Organized groups may also be relevant to evolution • Main motivation for HCE is that it can explain the challenge of altruism

  9. Yet many organisms seem to show altruism 8.2 The Challenge of AltruismWhy altruism? • Selection should favour selfish behaviour

  10. 8.2 The Challenge of AltruismThree possible explanations 1. Error/imperfect adaption to the environment 2. Altruism is an illusion 3. Selection on the collectives

  11. 8.3 Group Selection: Take 1Wynne-Edwards • Reproductive contstraint as central example of altruism • Reproductive constraint evolved through group selection: • Groups that don‘t show reproductive constraint go extinct and are replaced by groups that do

  12. 8.3 Group Selection: Take 1Challenges • Altruism is an Illusion • Kin Selection/Inclusive Fitness • Individiuals can promote the projection of its genes into the future not just by reproducing itself but also by helping close relatives (similar genes) to reproduce  Self sacrifice can be selfish

  13. 8.3 Group Selection: Take 1Subversion from Within • Selfish individual in an altruistic group has a higher fitness than an altruistic individual • Individual selection favours egoism • Individual selection has shorter generation time and higher variety than group selection • Individual selection should outperform group selection

  14. Wilson introduced the idea of trait groups 8.4 Group Selection: Take 2Trait Groups • group of organisms that each feel the influence of the others with respect to some trait

  15. 8.4 Group Selection: Take 2Trait Groups as Unit of Selection • Wilson: Trait group is a unit of selection • Trait group selection can overpower individual selection, even though selfish individuals are fitter than altruistic ones in both selfish and altruistic groups (Simpson‘s paradox)

  16. 8.4 Group Selection: Take 2Simpson‘s Paradox • Application of Simpson‘s paradox • Fitness(altruist individual) < Fitness(selfish individual) in both selfish and altruistic groups • Fitness(altrustic groups) > Fitness(selfish groups) • Can lead to Avg. Fitness(altruist) > Avg. Fitness(egoist) in combined groups • If most altruists are in an altruistic group

  17. 8.4 Group Selection: Take 2Wilson‘s Response to Kin Selection • Kin selection is a special case of trait group selection • Genetic relatedness only relevant as it generates the correlation between having a trait and being in the same group with others having this trait

  18. 8.4 Group Selection: Take 2Wilson‘s/Sober‘s Response to Reciprocal Altruism • Reciprocating individuals form a trait group • Reciprocal altruism evolves as reciprocating groups outperform other groups

  19. 8.5 Population Structured EvolutionChallenges to group selection: Are Trait Groups really Interactors? • Are trait groups really interactors? • Alternative view: Groups are rather part of the environment (broad individualism) • Authors argue that broad individualism and (trait) group selection are equivalent

  20. 8.5 Population Structured EvolutionOne True Story? • Group selection: altruism evolves because altruistic groups are more productive and group selection can outweight individualselection • Broad individualism: altruistic individual is fitter than the 'freeloader' because it is more likely to live in an altruistic group

  21. 8.5 Population Structured EvolutionOne True Story cont‘d • Both views recognize importance of groups and that an individual‘s fitness depends both on the character of the group they are a member of as well as its own behaviour • Both views are equivalent formulations of population structured selection.

  22. Some collective individuals are enough like an organism to be a real composite interactor, a 'superorganism' 8.6 Organisms and SuperorganismsSuperorganisms • Organisms are objectively interactors

  23. 8.6 Organisms and SuperorganismsDefining/Identifiying Superorganisms • Two suggestions how superorganisms could be identified: • physical cohesion • reproductive fate is irrevocably tied to that of others • However, the nature of superorganisms is not well understood

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