Transcript Chapter 14 Animal aggregations.ppt

• Competition
for resources
– Carcass
sharing in
burying
beetles
• Disease
• Cuckoldry
• Dogma for colonial breeding
– Limited options force coloniality
• Data from a number of
spp. fail to support dogma
• The “many eyes”
hypothesis
– Chaotic dynamics
– Why not cheat?
• Dilution effects
– In breeding
synchrony
• Confusion effects
• Group defense
• Abiotic factors
– Monarchs
– Penguins
• The geometry
of the selfish
herd
– The “domain
of danger”
• How does selfish
herding apply to
immobile
aggregations?
– Breeding colonies
– Anchored animals
• In herons, colonial
exposed nesting is
unstable
• Allee effects
– Hunting in
lions
– Dam building
in beavers
• Food sharing
– Vampire bats
• Ward and Zahavi’s information center
– Applies to large, ephemeral food sources
•
•
Schooling fish
Carrion
– Key point
•
•
Benefits go to followers
Reciprocity required
–
What if followers don’t ask?
• The recruitment center
– Returning animals actively recruit for own benefit
– Benefits of group foraging
•
Predation, competition, etc.
• ICH or RCH?
• Seabirds were
colonial first,
then became
marine
• Is food finding
a secondary
benefit of
coloniality?
• Not selection for
coloniality, but
selection for X
which resulted
in coloniality
• The Ideal Free
Distribution and
aggregation
• Social attraction
might be an EES
for purposes of
habitat choice
– Copy choices
made by
successful
breeders
– Avoid weighing
all costs and
benefits
• Females drive
aggregation by
preferring social
mates who are
physically close
to desirable sex
partners
– “Hidden leks”