16-levels of selection Flashcards
what old group selection idea did VC Wynne Edwards propose?
reproductive self restraint to avoid over exploitation of resources
what ideas demolished ideas of group selection? + give 2 examples
inclusive fitness theory
- George Williams
- RIchard Dawkins “selfish gene” 1976
why are the conditions for old group selection unlikely to be met in nature?
selfish nature of selection selecting for selfish behaviour
what is the old group selection model in theory? + what may be considered more powerful?
group selection can work if some groups die out faster than others but individuals usually die at faster rate than groups so individual selection more powerful
what must occur for group selection to work?
isolated so selfish individuals cant migrate into coop groups
- predicts selfish groups would go extinct so coop would spread
- BUT these are unrealistic conditions
give 3 new group selectionists:
- EO Wilson
- Martin Nowak (leader)
- David Sloan Wilson
what is the multi level selection concept + by who?
Wilson
selection doesnt just operate on genes or individuals but also at the group level
what are the 3 main points for the theoretical argument for multilevel selection?
- populations are divided into trait groups/demes (less discrete than old group selection models)
- selection acts for/ against cooperative traits within groups
- groups mix together before splitting into new groups + to next round of selection
when may groups cooperate more and when less?
coop: more
selfish: less
what do individuals organise themselves into groups according to?
the possession of certain traits
- cooperators tend to associate with coop individuals + selfish to other selfish individuals
- coop traits spread when between group selection stronger than within group selection
what 3 things is coop in new groups favoured by?
- increasing group benefits (b)
- reducing individual cost (c)
- reducing within group genetic variance relative to between group genetic variance (r)
what are new group selection models mathematically equivalent to?
hamilton’s rule for evo of altruism rb > c (inclusive fitness theory)
once individuals are assorted according to traits what is reduced?
within group genetic variance relative to population as a whole
if new group selection + inclusive fitness models are mathematically equivalent are they also equally useful? (5)
no
- IFT tells us the quantity which is maximised by NS under all conditions
- inclusive fitness can be increased individually or by helping kin
- NS acts on inclusive fitness
- new group selection models tell us when cooperation might evolve but only under certain narrow conditions
- new group selection theory has low generality + may work in theory but cannot explain a lot of phenomena
what is the empirical study of the social spider A.studiosus by Pruitt + Goodnight 2014? (9)
- spiders in groups coop to build collective web
- docile + aggressive phenotypes that are site specific + influence reproductive success
- mix of phenotypes argued to be group level trait not individual
- limited dispersal
- artificial colonies were introduced to diff sites (native or foreign)
- outcome matched what was expected for mix of social phenotypes
- site specific selection at group level
- colonikes aimed to match what was seen in native site
- suggested group trait locally adapted
why was there scepticism for the empirical study of the social spider A.studiosus by Pruitt + Goodnight 2014? (3)
- individual selection not investigated
- successful groups could = successful individuals
- genetic basis of group trait unknown
advocates of group selection cite studies such as Gordon et al 2013 ant colony study- what was found (2) + why were results found to be inconsistent with individual level selection? (1)
- ant colonies show collective restraint in foraging that does not affect colony survival
- a colony’s foraging behaviour may be inherited by daughters colonies
- IFT should be used as theoretical framework to understand evolution of behaviour rather than group selection models
what is v limited in nature?
conditions for group selection
why can IFT be considered more useful than group models?
give us the quantity that NS maximises
what do advocates of group selection often appear to have?
an agenda of denial
Nowak et al 2010: insufficient empirical evidence for IFT
according to Marshall 2011 what is the dominant explanation for the evo of social behaviour + what do other theories suggest?
IFT
other theories suggest group selection also responsible
according to Marshall 2011 what do some studies are for why group selection could be considered to have?
more general framework as IFT cant deal with strong selection
according to Marshall 2011 what is hamiltons rule a summary of?
the direction of selection based on IF
according to Marshall 2011 what can be used to estimate relatedness?
pedigree
according to Marshall 2011 what is greenbeard altruism?
conditionally directing altruism to other bearers of an altruistic trait
according to Marshall 2011 what gave rise to hamiltons rule?
Inclusive fitness
