Transcript Chapter 51 - Madison County Schools

Chapter 51
Social behavior
Agonistic behavior
• Ritualized contest that determines which
competitor gains access to a resource, such as
food or mates. It involves threats or actual
combat.
• The outcome of such contests may be
determined by strength, size, or the effective
use of horns, teeth, etc.
• It is most common in members of the same
species.
Agonistic behavior
• It often involves symbolic conflict and often
does not cause serious harm to either the
winner or loser in the encounter.
• It may be used to establish and defend
territories.
• It may be used to establish dominance
hierarchies.
• Example: Male eastern grey kangaroos often
“Box”
Altruism
• On occasion, some animals behave in ways
that reduce their individual fitness but
increase the fitness of other individuals in the
population.
• Example: a squirrel that sees a predator
approach often gives a high-pitched alarm call
that alerts unaware individuals to retreat to
their burrows.
Altruism
• An explanation can be seen in honeybees, where
worker females share 75% of the same genes.
When a worker honeybee stings an intruder
while defending a hive, the worker sacrifices itself
for its relatives, individuals who carry most of the
same genes as that particular worker. The
individual dies, but relatives survive to pass on
their genes, including the gene for altruistic
behavior. This concept is known as kin selection
or inclusive fitness.