Download 10 predator avoidance

10/16/2012
Spines and such: morphological traits suggest that predation
exerts strong selection.
Three stages in the process of predation:
Detection
Attack
Major Theme: Behavior enhancing morphology
(Why not always be a ball of spines?)
Strategies for Predator Avoidance
A. Avoid Detection
Consumption
Let’s look at predator avoidance at each
stage.
Crypsis (= Camouflage)
Cephalopods can
change their colors
to match a variety
of different
backgrounds.
Pepper moths are cryptic
only if they match
themselves against
background.*
* these are all the same moths placed against different backgrounds
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Cuttlefish match
variety of
backgrounds.
Cephalopods, like squid or octopus, can tune
colors and patterns to background against
which they rest. Even though they don’t see
in color.
Seems cognitively sophisticated.
Deception
Walking stick insects not only look like twigs
but, in the wind, sway like twigs…
They are mimicking swaying of twig!
Predators may turn the tables.
preying mantis floral
mimicry
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False Head Mimics (cont’d)
False Head Mimics
Scolopendra, our desert
centipede, has a false
head that looks like the
real one.
Predator has <50%
chance of grabbing the
right end…
If it doesn’t, it gets bit.
False head at rear of
butterfly has ‘antennae’
that move!
Attacks to the false
head result in a mouthful
of scales.
Strategies for Predator Avoidance
B. Avoid Capture and Consumption
Active Defense
Many lizards have tails
that are built to break off
easily.
Termed caudal autotomy
http://www.youtube.com/watch?v=T
sQRzRcQ3dM
Broken tail writhes
vigorously, distracting the
predator from escaping
lizard…
Grasshoppers and relatives lose legs in the same way...
Another example of convergent evolution.
Skunk sitting in its own…. pew.
Bombardier beetle
sprays attacker;
Beetle can aim spray
with precision;
Spray is irritating
benzoquinone in
boiling water.
vinegaroon
Chemical defenses are everywhere!
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hydrogen peroxide
(H2O2) and
hydroquinone in
‘reservoir’
Catalases and peroxidases in
‘reaction chamber’
When attacked, reservoir empties into reaction chamber;
Enzymes catalyze production of benzoquinone, O2, and
HEAT.
Elegant ‘design.’ But presumed to have evolved via
gradual process of natural selection.
There are a variety of species of spraying beetles
that provide for a series of intermediate stages.
O2 causes boiling solution to propel out of back end!
Stealing defenses
from prey
nudibranchs
incorporate
stinging cells called
cnidocytes from
jellyfish into their
tissues.
They are defended
from predation by
their prey…
Nematocyst discharge occurs in ca. 700
nanoseconds.
Force generated equivalent to that of bullet.
Warning Coloration (= Aposematism)
Some butterflies sequester
noxious chemicals from
host plants while feeding as
caterpillars.
Pipevine swallowtail butterfly
Poison arrow frogs
Monarch butterfly
Same strategy… must be independently evolved
=CONVERGENT EVOLUTION.
(Dendrobates spp.) are toxic,
advertising toxicity with
warning coloration, also called
aposematic coloration.
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Spotted skunk
Enhancing warning pattern by
doing handstands.
VIDEO
red eft
ladybird beetles
Do predators learn high-contrast prey
better than low-contrast prey?
lionfish
Predator:
Tenodera aridifolia
Why be conspicuous?
monarch butterfly
Prey:
Oncopeltus fasciatus
Project Leader:
Katy Prudic
Why not let the predator learn to
avoid your cryptic pattern?
Prudic, Skemp & Papaj, Behavioral Ecology 2007
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Mean No. Trials to
Criteria (+ 1 s.e.)
6
4
2
Toxic bugs painted
gray: either
conspicuous or cryptic.
Bug released at
bottom and walked
up the ramp to meet
its fate.
0
Cryptic
Conspicuous
20
15
Mean No. Days to Re10
Sampling (+ 1 s.e.)
5
0
Cryptic
Conspicuous
Prey Type
Mantid first trained to avoid a given morph, then its
retention tested.
Mantids learned conspicuous prey faster and retained
memory of aversion longer.
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Monarch butterfly is toxic,
owing to cardenolides
sequestered as caterpillars
from milkweed host plants.
Viceroy butterfly is
unrelated but also
toxic;
Jays learn to avoid patterns associated with noxious
experience.
= Mullerian mimicry
mimicry of each other
protects both better.
Having two species with same pattern may facilitate
learning experience.
mimic
Two “mimicry rings” from tropics
coral snake
mimic
Coral snakes are highly poisonous.
Once thought to serve as a model
for various harmless mimic species.
models
& Mullerian mimics
Batesian mimics*
But how can mimics benefit if
predators die from coral snake
bites?
mimic
*Batesian mimics are not harmful.
Coral snakes may mimic less poisonous relatives
in South America!
By mimicking less poisonous snakes, the coral
snake benefits from the predator’s learning
experience.
spider mimicking ant
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Dynamic mimicry
Indo-Malayan octopus
impersonates:
•
•
•
•
http://www.youtube.com/watch?v=Owelt6QKMKo&NR=1
http://www.youtube.com/watch?v=t-LTWFnGmeg&feature=related
poisonous flatfish
banded sea snakes
lionfish
jellyfish
mimic can rapidly swap between 'impersonations'
http://www.youtube.com/watch?v=H8oQBYw6xxc
“Red against yellow can kill a fellow.”
“Red against yellow can kill a fellow.”
Coral Snake Story Re-Visited
Coral Snake Story Re-Visited
1. “Mertensian mimicry”: more poisonous coral
snake may mimic less poisonous relatives.
1. “Mertensian mimicry”: more poisonous coral
snake may mimic less poisonous relatives.
2. Predators evolve innate avoidance of corallike pattern.
2. Predators evolve innate avoidance of corallike pattern.
#2 seems to be more accepted.
Ultimate Mimicry of Bad-Tasting Stuff
Why #2? Partial answer: Because coral snake dummies
attacked more where coral snake is absent.
Multiple Strategies for Predator Avoidance
Bluff: hiss & look big
Hognose snake
Backup defenses
are common.
Bird dropping mimic!
Play dead
*Look for these swallowtail caterpillars on citrus plants.
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All-in-One Strategies
Crypticity – Aposematism Tradeoff
Black swallowtail butterfly
Caterpillar is first a poop mimic
But later adopts a pattern
which is cryptic from a
distance but conspicuous
close up.
Multimodal Warning Displays
Rattlesnakes warn in both
visual modality (black &
white tail) and acoustic
modality (rattle).
Why multiple sensory
modalities?
Rattlesnakes are cryptic from side (to prey) but
conspicuous from above (to would-be predators).
Multimodal Warning Displays
When threatened, a gopher
snake mimics rattlesnakes.
It has a striped tail, makes
its head triangular, and
generates a hiss that can
sound like a rattle.
In other words, it’s a multimodal mimic.
Predator Avoidance and
Being in a Group
Whirlygig beetles and per capita risk of predation
Large groups more likely to be attacked by fish.
BUT…
per capita risk of predation goes down.
It is per capita risk that is important to consider.
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Active group defense
Prey defense is more
effective when done by
multiple individuals.
mobbing behavior
Musk oxen form a circle with heads
outwards,
soldier aphid
Sawfly larvae do something similar…
6.13 Communal defense by
sawfly larvae
Spit and Poop!
such that each individual has his back end
covered...
Dilution of risk
prey so locally abundant that local predator fauna is
satiated, which reduces per capita risk
grunion running at full moon
Butterflies puddling on damp soil…
monarchs roosting
Predation risk decreases with group size
Mmm… amino
acids…
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Confusion effect
Predators may have difficulty choosing a target out
of a tightly-packed group
Zebra
stripes
make it
even more
difficult
for a
predator
to focus
on an
individual.
Selfish herd
Prey use each others as shields. Animals attempt
to move to the center of the group.
Leopard seal
Adelie penguin
Average per capita risk can actually be greater
than if animals spread themselves out.
sheep fitted with GPS unit
http://www.youtube.com/watch?v=o54zO30lnas
Sheep show selfish herd behavior in response
to a herding dog.
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Group vigilance and early detection
Vigilance for predators may be facilitated by
being in groups.
Better advertisement
Being in a group may better
advertise a warning patter.
Standing head to tail helps
zebras cover their behinds.
Being in a group may provide a
more effective learning
experience for predator.
The ‘many eyes’ strategy
permits any one individual
to spend more time
foraging and less time on
vigilance
Goshawk has
less success as
flock gets
larger.
Group advantage is due to better vigilance.
Vervet Alarm Calls
Vervets make three different kinds of alarm calls,
according to kind of predator.
Alarm calls
Birds and mammals utter calls that
signal predator threat to others
Predator Effect on Listeners
Belding’s ground squirrel
Alarm pheromones
Insects and fish emit chemical
signals that signal predator
threat.
Eagle
Snake
Look up and run to
bushes
Look down at ground
Leopard
Run and climb trees
Alarm pheromone of
honey bee
Sometimes signal simply alerts individuals who then
flee; sometimes signal elicits a group defense.
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Diana’s monkeys have
separate alarm calls for
leopards and crownedhawk eagles.
African hornbills respond to the alarm calls for
eagles (which are hornbill predators) but not
the alarm call for eagles.
Campbell’s monkey males link
sounds together, making for a
rich repertoire.
Hok! given in response to eagle.
Hok oo! given in response to almost any disturbance
in the canopy, including eagles, neighboring groups of
monkeys, squirrel, etc.
Figure 1. Spectrographic illustrations of the different loud call types produced by male Campbell's monkeys
in different contexts.
Ouattara K, Lemasson A, Zuberbühler K (2009) Campbell's Monkeys Use Affixation to Alter Call Meaning. PLoS ONE 4(11): e7808.
doi:10.1371/journal.pone.0007808
http://www.plosone.org/article/info:doi/10.1371/journal.pone.0007808
Audio S1 ‘‘Hok’’ calls are almost exclusively associated with
crowned eagle presence.
Found at: doi:10.1371/journal.pone.0007808.s001 (0.05 MB
WAV)
Audio S2 ‘‘Hok-oo’’ are given to a range of disturbances within
the canopy, including eagles, the presence of neighbouring
groups
and, on a few occasions, to a flying squirrel. While producing
these
calls, males adopt a threat posture, combined with flashing their
eyelids, sometimes combined with a short dash towards the
disturbance.
Found at: doi:10.1371/journal.pone.0007808.s002 (0.06 MB
WAV)
Audio S3 ‘‘Krak’’ calls are exclusively given after detecting a
leopard.
Found at: doi:10.1371/journal.pone.0007808.s003 (0.09 MB
WAV)
Audio S4 ‘‘Krak-oo’’ function as a general alert call and can be
given to almost any disturbance.
Found at: doi:10.1371/journal.pone.0007808.s004 (0.09 MB
WAV)
Audio S5 ‘‘Wak-oo’’ calls are given to the same events as ‘‘hokoo’’ calls (eagles, other flying animals, Diana monkey eagle
alarms), but not to neighbours.
Found at: doi:10.1371/journal.pone.0007808.s005 (0.14 MB
WAV)
Audio S6 ‘‘Boom’’ calls are given to non-predatory contexts,
such as a falling branch or tree, to initiate or halt group travel,
during disputes with neighbours, and to any unusual vocal
excitation with the group.
Found at: doi:10.1371/journal.pone.0007808.s006 (0.20 MB
WAV)
Composition of call sequences in different behavioral contexts. “Alarm”
indicates leopard or eagle alarm calls given by sympatric Diana monkeys.
Ouattara K et al. PNAS 2009;106:22026-22031
©2009 by National Academy of Sciences
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