Lecture 6- Cooperation.doc - Lecture 6 Cooperation...

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Lecture 6- Cooperation Inclusive Fitness We have mostly been talking about direct fitness Selfish Genes Natural selection results in ‘selfish’ behaviours All that matters is the reproductive output of an individual by passing on individual genes to the next generation Self-interest of genes o Natural selection results in increase of best replicators o A gene that assists other genes in replicating will not increase in number How can helping behaviour evolve? The idea that it is the genes that matter: passing on genetic material through generations All that matters is reproductive output of an individual o This is the view of evolution Individual genes moving to the next generation is important o But then how can helping behaviours possibly evolve? Why would someone sacrifice their own fitness to help another if it means they wont pass their genes on to the next generation Altruism Behaviour that increases Reproductive Success of another individual at a cost to oneself Genes that promote self-sacrifice won’t be passed on to future generations as they are sacrificing their own reproductive output o If someone has this gene, they cant pass this gene on to future generations because they are sacrificing their reproductive output Thus, can’t evolve via natural selection... Helping However, cooperation and helping not uncommon How to resolve the paradox? o Nepotism helping those who are related to us o Idea of helping relatives Altruism? Helping behaviour directed to relatives is typically regarded as nepotism, not altruism “…I help out an older woman…” o You may think you are nice o If they said I helped out an older women by cleaning… and it was my mother, you may be less impressed Have an intuitive idea that helping others depends on how related we are Alarm Calling Belding’s ground squirrels Individuals alarm call warns others of predator o Callers more likely to be eaten – so what do they gain? Is this altruistic?
This seems altruistic! What is this person giving the call getting from this? Belding’s Ground Squirrels They are getting fitness benefit through their relatives Males disperse and leave to another area when reaching maturity, and females settle near home You have large populations of related females in the same area Closely related females live nearby and are protected by the male’s alarm call Thus when an animal engages in an alarm call, it may be sacrificing itself but it is protecting its female relatives Alarm calling more likely in: o Older female animals that have gotten past reproductive peak so that their young female relatives are more likely to survive predation How can we figure out when something is altruistic or nepotistic? Calculate r Coefficient of Relatedness ( r ) Measure of proportion of shared genetic material in the genome o Ranges from 0 o r = 0 would represent genetic relationship b/w unrelated individuals, and r = 1 represents identical twins o 0 is the baseline for humans sharing genetic material

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