Transcript E6 altruisitc examples

Discuss two nonhuman examples of
altruistic behavior
and discuss in terms
of evolution
Ryuya & Samata
Altruism
• behavior by an animal that is not beneficial or may
be harmful to itself but that benefits others of its
species
• examples: birds, bats, bees
Evolution
• the process by which different kinds of living
organisms are thought to have developed and
diversified from earlier forms during the history of the
earth
Warning call of birds
• A form of altruism called reciprocal altruism, where
a organism temporary reduces its fitness, while
temporary raising the fitness of another
Advantage in terms of
evolution and survival
• Decreases the chances that the bird giving the call,
and the bird being targeted will be eaten
Vampire Bats
(Desmondus rotundus)
• Reciprocal altruism
o Benefitting non-relatives at a cost to themselves
• Vampire bats show familial altruism for kin selection
• Genetic basis for familial altruism
o Extended to non-relatives under conditions where there is no exploitation
(starvation, etc)
o Can occur for bats who experience repeated encounters resulting in
recognition of individuality
• Altruism is equal to what has been given before
o Recognition and punishment of cheaters
• Bats roost together for many years
• Successfully obtain blood meal an average of only
1/3 of the nights
o Risk of starvation if body weight falls below 80% of normal weight
• After feeding, sharing blood with nonrelatives may
increase
o Number of repeated encounters increases
o Previous encounters have been altruistic by both individuals
o Recipient is close to starvation weight
• Benefits to the recipient exceed the costs to the
donor
o Donor regurgitation costs 6 hours of time
o Recipient of regurgitation gains 18 hours of time
Works Cited
• http://www.merriamwebster.com/dictionary/altruism
• http://www.merriamwebster.com/dictionary/evolution
• http://www.newscientist.com/data/images/ns/cms
/dn15083/dn15083-1_680.jpg
• http://intranet.canacad.ac.jp:3445/BiologyIBHL2/ad
min/versions.html?pageid=5058