PSYCH 1XX3 Lecture Notes - Ground Squirrel, Gene-Centered View Of Evolution, Kin Recognition

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Published on 14 Apr 2013
School
McMaster University
Department
Psychology
Course
PSYCH 1XX3
Professor
Evolution 2
Introduction to Social Behaviours
Organisms evolved to maximize their fitness and reproductive success. Many examples in
humans and social animals where individuals appear to behave altruistically; helping others to a
cost to themselves.
Examples: bees spend their lives in the service of the colony helping to raise eggs laid by the
Queen and many bees often die defending their colony from predators. Also, in Belding’s
ground squirrels, individuals will frequently give alarm calls to warn others that there is a
predator in the area, giving everyone a chance to flee and hide. However, the “whistle blower
draws attention to itself, alerting the predator to its exact location. Finally, humans cooperate
by helping their family, friends and strangers.
Evolution acts at the level of genes and those genes that contribute to an individual’s fitness will
consequently get replicated more often, increasing in frequency in successive generations.
“Selfish gene”
Natural Selection will favour the genes that best serve their own interest.
Types of Social Behaviours
Cooperation- working together to help both the other person as well as themselves.
Cost < Benefit
For the good of the gene only
Good of the Group?= if you happen to be lucky enough to discover some food others might
come over and eat some too. But more often, a bird ill end up being the lucky one; even though
you’ll have some food taken from you on occasion, you’ll also have opportunities to take food
from others when they find it first.
The foraging-vigilance trade-off= while one of the birds is searching for food, they are more
vulnerable to predators by having their head down; so the other bird will be vigilant.
Altruism- Behaviour in which the actor incurs a cost to provide a benefit to a recipient.
Not Altruism- Foraging/ vigilance in groups; not altruism because actor gains directly from
behaviour.
An individual that behaves altruistically decreases its own fitness by definition, whereas an
individual that behaves selfishly won’t.
Lemmings- live in the far North, myth about suicidal population control.
Inclusive Fitness
Eusocial Hymenoptera- includes all ants, some bees and some wasps. Most individuals spend
their lives serving the colony without reproducing.
Inclusive Fitness- genes for altruism are successful when they involve helping individuals that
are an identical copy to themselves (passing down their genes; as if reproducing themselves).
Relatedness- the probability that the actor and recipient share the gene in question; the gene
that leads its bearer to be helpful.
Relatedness to mother/father= 0.5; 50% that she passed a certain gene onto her offspring.
Kin Recognition
In organisms with limited migration following maturity, neighbours are most likely to be close
kin.
One simple rule is to be altruistic towards individuals that are spatially close to you; in this way
individuals do not need to “recognize” kin.
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Document Summary

Organisms evolved to maximize their fitness and reproductive success. Many examples in humans and social animals where individuals appear to behave altruistically; helping others to a cost to themselves. Examples: bees spend their lives in the service of the colony helping to raise eggs laid by the. Queen and many bees often die defending their colony from predators. Also, in belding"s ground squirrels, individuals will frequently give alarm calls to warn others that there is a predator in the area, giving everyone a chance to flee and hide. However, the whistle blower draws attention to itself, alerting the predator to its exact location. Finally, humans cooperate by helping their family, friends and strangers. Evolution acts at the level of genes and those genes that contribute to an individual"s fitness will consequently get replicated more often, increasing in frequency in successive generations. Natural selection will favour the genes that best serve their own interest.

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