organisms, groups and superorganism
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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. - PowerPoint PPT PresentationTRANSCRIPT
Organisms, Groups and Superorganism
Sex and Death: An Introduction to Philosophy of Biology
8.1 InteractorsIdentifying Interactors – Copidosoma Floridanum Example
8.1 InteractorsIdentifying Interactors – Copidosoma Floridanum Example
8.1 InteractorsIdentifying Interactors – Copidosoma Floridanum Example
8.1 InteractorsIdentifying Interactors – Copidosoma Floridanum Example
8.1 InteractorsIdentifying Interactors – Copidosoma Floridanum Example
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?
8.1 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
8.2 The Challenge of AltruismWhy altruism?
Selection should favour selfish behaviour
Yet many organisms seem to show altruism
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
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
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
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
8.4 Group Selection: Take 2Trait Groups
Wilson introduced the idea of trait groups
– group of organisms that each feel the influence of the others with respect to some trait
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)
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
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
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
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
8.5 Population Structured EvolutionOne True Story?
Group selection: altruism evolves because altruistic groups are more productive and group selection can outweight individual selection
Broad individualism: altruistic individual is fitter than the 'freeloader' because it is more likely to live in an altruistic group
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.
8.6 Organisms and SuperorganismsSuperorganisms
Organisms are objectively interactors
Some collective individuals are enough like an organism to be a real composite interactor, a 'superorganism'
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