Transcript 13_Antipredatory

Antipredator Behavior
“How to avoid being eaten”
avoid being seen
advertise unprofitability
be vigilant
if caught, go for broke
How not to be seen
Method 1a:
Pick a background with similar color or pattern
(minimize contrast )
Camouflage in moths
How can we experimentally determine that it works?
Pin moths to tree and see which get eaten…
Crab Spiders
Crab spiders mimic flowers to
both escape detection by
predators and to attract prey
How not to be seen
Method 1b:
Mimic some aspect of the environment (be cryptic)
How not to be seen
Method 2:
Use the environment to manipulate your pattern/color to
match environment
Caddisfly
Artificial camouflage
Decorator crabs
Crabs put algae on
their backs, which
increases their
survival
In areas with Dictyota
algae, use this
species for decoration,
but rarely food
Artificial camouflage
Decorator crabs
Crabs put algae on
their backs, which
increases their
survival
In areas with Dictyota
algae, use this
species for decoration,
but rarely food
Decorator crabs, cont.
Did this preference arise by natural selection?
All crabs in areas with Dictyota show preference.
Crabs with Dictyota have survival advantage.
Algae produces chemicals that are distasteful to
fish!
How not to be seen
Method 3:
Manipulate your pattern/color
directly to match environment.
Rapid adaptive camouflage in tropical flounders
V. S. Ramachandran and colleagues
Nature. 1996
Flounders (flat fish) can mimic backgrounds
within 2-8 seconds!
Advertise unprofitability
An alternative to hiding is to be dangerous
and let predators know.
aposematic (warning) coloration
Produce toxins – Monarch butterfly
Actually subverts
plant’s anti-herbivore
chemical defenses to
it’s own anti-predator
defenses!
Why be toxic and advertise if predators
have to eat you to learn to avoid you?
No group selection needed:
Not always killed by attack
Predators learn very quickly
Other producers of nasty chemicals:
Skunk
Bombardier beetle
Eyelash viper
Eisner and Aneshansley, 1999, PNAS
Mullerian Mimicry: 2 or more distasteful or
harmful organisms resemble each other
Monarch butterfly
Viceroy butterfly
High toxicity correlated with
diet specialization (ants).
Santos et al. 2003 PNAS
Ants appear to be the source of pumiliotoxin alkaloids.
Saporito et al. 2004. PNAS
Batesian Mimicry: defenseless species (mimic) is
protected from predation by its resemblance to a
species that is dangerous (toxic).
fly (bee mimic)
bumble bee
Need to mimic behavior too!
Texas coral snake
Kingsnake
Eastern Hognose snake
Western Hognose snake
Edible prey warning behavior:
I see you, and I can run faster than you, so do both
of us a favor and don’t even bother trying!
Stotting
behavior in
ungulates
Why do ungulates stot?
H1: Advertise unprofitability
H2: Alarm signal to offspring/others
H3: Social cohesion
H4: Confusion effect
Be vigilant – don’t get eaten
Many prey constantly watching for predators, even
while sleeping
Vigilance behavior shapes morphology – eyes on
side of head, antlers…
Effective level of vigilance increases in groups
(another lecture)
American Woodcock
“flatfish”
Antlers: grow from pedicels (bony supporting structures),
males only, shed annually (family Cervidae)
Horns: composed of a bony core covered with a sheath of
keratin, never branched (unlike antlers), occur in males and
often females (family Bovidae)
Horned lizards (genus Phrynosoma)
What to do if you’re caught?
Anything possible!
Geckos can drop
their tails when
threatened by a
predator, which is
not as bad as
death!
Death (?) screams
Why do some prey scream loudly after being
caught?
H1: It’s a response to pain receptors being
activated (proximate!)
H2: It warns conspecifics (but it says the predator
is currently busy!)
H3: It elicits parental help
H4: Screaming attracts other predators
Pike & fathead minnowsWhen captured, minnows release chemical that
attracts other predators
Presence of two pike and one minnow increased
the time to swallow the minnow, and a few times
the minnow escaped!
Cephalotes atratus
Cephalotes clypeatus
Stephen Yanoviak, Robert Dudley, and Michael Kaspari
Direct aerial descent in canopy ants. Nature. 2005