Olof Leimar, Department of Zoology, Stockholm University
Biology and game theory
Where are we now and how did we come here?
A biologist’s perspective
The Logic of Animal Conflict
Maynard Smith & Price (1973)
Mule deer males fighting Arabian oryx males fighting
“reducing intra-specific damage”
Julian Huxley (1966). Ritualization of behaviour in animals and man.
The logic of asymmetric contests
Maynard Smith & Parker (1976)
Papilio zelicaon male Hilltopping P. zelicaon male
“The resident always wins”
Davies (1978). Territorial defence in the speckled wood butterfly (Pararge aegeria)
Typical habitat for speckled wood butterflies
Does the resident always win?
Does the resident always win?
The role of motivation
Christer Wiklund
Bergman, Olofsson & Wiklund (2010) Contest outcome in a territorial butterfly
Polymorphism and morph determination
Papilio dardanus
model mimic
Papilio dardanus
model
model
mimic
mimic Papilio dardanus
Batesian mimicry
Polymorphism
The Dobzhansky - Cain & Sheppard - Fisher polymorphism debate
Dobzhansky (1951) Genetics and the origin of species
Genetic polymorphism as such is frequently
adaptive Theo. Dobzhansky
Cain & Sheppard (1954) The theory of adaptive polymorphism
"This interesting theory may be correct, but it is not clear what is meant by one population being more highly adapted than another to a particular environment"
Arthur Cain
A precursor of the group selection debate
Fisher concluded the debate
Dobzhansky is right, but the idea traces back to
"a little-known book of nearly a hundred years ago, called The Origin of Species"
Fisher regarded polymorphism as an adaptive strategy
"one way of making this intelligible is by the analogy of games of skill, or to speak somewhat more
pretentiously, of the Theory of Games"
Fisher (1958) Polymorphism and natural selection
"I would not have alluded to this storm in a tea-cup, but for the circumstance that I mean to put forward some ideas on this problem of the possible adaptive value of polymorphisms"
The “Darwin joke”
Phenotype determination
Schwander & Leimar (unpubl.)
Phenotype determination
Schwander & Leimar (unpubl.)
Sex determination
Bulmer & Bull (1982). Models of polygenic sex determination and sex ratio control
Ouachita map turtle Baby
Sex determination
Van Dooren & Leimar (2003). The evolution of environmental and genetic sex determination in fluctuating environments.
Mechanisms of sex determination
Quinn et al. (2007). Temperature sex reversal implies sex gene dosage in a reptile.
Central bearded dragon lizard
Climate-driven population divergence in sex-determining systems
Pen et al. (2007)
Snow skink
Five rules for the evolution of cooperation
Nowak (2006)
From a biologist’s perspective some things are missing
• Biological markets
• Sanctions and partner choice
• By-product benefits
• Pseudoreciprocity
• Common interest
Leimar & Hammerstein (2010).
Cooperation for direct fitness benefits.
Sanctions in legume rhizobium mutualism
Bacteria fix atmospheric nitrogen inside root nodules of leguminous plants
What if the bacteria do not fix nitrogen?
Experiments suggest that the plant then re-allocates its resources
(Kiers et al. 2003)
Recent work claims that the role of sanctions is small (Marco et al. 2009)
Comment
Sanctions are best understood as a by-product
of an action that is of direct interest to the actor
Cleaning mutualism: by-product benefits
There are immediate benefits (food and removal of ectoparasites) for the partners
Ant-lycaenid mutualism: pseudoreciprocity
Lycaenid larvae invest in sweet secretion – ants forage and protect their food resource
Mycorrhizae: exchange of organic carbon and
mineral nutrients between plants and fungi
Could it work like human trading and exchange?
Mutual investments in by-product benefits
Leimar & Connor (2003) Bever et al (2009)
