Post on 03-Feb-2022
8/19/2013
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Topic 20: Predators
� Who eats herps?
� Variation in predators across taxa
� Variation in predators through ontogeny
� How do herps avoid being eaten?
� Introduction to the diversity of anti-predator defenses
Who eats herps?
� Many animals
� Depends on the prey’s _______ and ________
� Birds are a major predator
� _________ – especially lizards
� Secretary birds – snake specialists
� __________ –amphibians, snakes
� Road runners -Squamates
Photos: J Dickson; www.sweetand bitter.com; wikipedia; Pough et al. 2004, Fig 15-14
Who eats herps?
� ________ are also important
� Frog-eating bat
� Honey badger
� ______________ – cobra specialists
� Rodents
Photos: C & K Begg; P Koch; Pough et al. 2004, Fig 15-14
Who eats herps?
� Invertebrates
� ____________
� ____________
� Size is particularly important
� Anolis are small
and abundant
� Many small frogs
are also vulnerable
Photos: R Keegan; Pough et al. 2004, Fig 15-14
Who eats herps?
� Other herps
� Some are generalist predators
� Some are specialists
� ______________
� Lialis
� ______________
� Heterodon
Photos: N Kley; J McDonald; Pough et al. 2004, Fig 15-14
Who eats herps?
� Predation pressure changes through ______________
� Turtles� Change size over
orders of magnitude� Shell rigidifies with age� Influence on survivorship
� High predation, broad range of predators
� Low predation, few predators
� Crocodylia� Similar pattern
Pough et al. 2004, Fig 15-15, P Richardson, ??
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Who eats herps?
� Predation changes through ontogeny
� ________________ are important
� Predators may select prey with a certain _____________
� Metamorphosing frogs may be poor at swimming and jumping…
� Thamnophis predation on Pseudacris regila �
G Nafis; Pough et al. 2004, Fig 15-16
Who eats herps?
� Different life cycle stages have different predators
� Agalychnis callidryas oviposit on leaves overhanging water
� Each life cycle stage has a different suite of predators
Photos: K Warkentin; P Weish
� Eggs � Tadpoles � Adult� Metamorphs
Who eats herps?
� Agalychnis callidryas oviposit on leaves overhanging water
Photos: K Warkentin
� Egg predators
� Snakes
� Wasps
� Ants
� Eggs can ___________ in response to vibrations from predator
� Will hatch prematurely
� http://people.bu.edu/kwarken/KWvideo.html
� Wasps target _______
� More likely to hatch prematurely and escape
� Easier to open and carry off tadpole
Who eats herps?
Photos: K Warkentin
� Tadpole predators
� Fishes
� Water striders
� Fresh water shrimp
� Early-hatched tadpoles are ____________ premature
� Can hatch after 4 days of development
� Fully developed at 7 days
� Premature tadpoles are poorer swimmers
� More difficult to escape predators
Who eats herps?
� Tadpoles can also metamorphose prematurely when predators are abundant
Photos: K Warkentin
� Metamorph predators
� Water bugs
� Spiders
� Again, decreased performance if:
� _________________
� _________________
Who eats herps?
� Adult Agalychnis callidryas are terrestrial and mobile
Photos: K Warkentin; Furrer; Pough et al. 2004 Fig 15-14
� Adult predators
� Bats
� Snakes
� Tarantulas
� Etc.
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How do herps avoid
being eaten?
� What kinds of anti-predator defenses do
you know of?
Photos: PJB
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Defenses
� _____________
� Easiest way to deal with predators is not to bump into them
� _______________
� A form of avoidance
� Camouflage
� Includes many adaptations
� Color
� Pattern
� Mimic environment
� Eliminating or enhancing shadows
Photos: T Hakonsen; M Fogden; Pough et al. 2004, Fig 15-18
Defenses
� Crypsis can also occur while ____________
Photos: Pough et al. 2004, Fig 15-14
Moving Stationary
Nerodia sipedon on
different backgrounds
Defenses
� _______________
� _____________
� Chuckwalla in crevices
� Adaptations against being pulled out
� _____________
� Jumping from danger
� All-out running away
� Running for a hiding spot
Photos: CJ Hamilton, PJB
Defenses
� ___________________
� Spines
� Can be weapons
� Can show that
something is inedible
Photos: PJB, ??
Defenses
� Signaling inedibility
� _________________
� ________________
� Frills
� Crests
� Inflating
� Opening mouth
� Flattening out
� ______________
� Hissing
� Barking
Photos: PJB; T Gamble; ER Pianka; wikipedia; Pough et al. 2004, Fig 15-24
Defenses
� Signalling inedibility
� ________________
� May be repellent to Canids
� ________________
� ________________
� All of these signal some sort of distaste
Photos: PJB; J LeClere; Pough et al. 2004, Fig 15-17
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Defenses
� Signaling inedibility
� ___________________
� Warns of toxicity
� Sometimes associated with behavior to show and hide the warning
� Unken reflex
Photos: G Nafis; DH Cummins; BP O’Connor; Pough et al. 2004, Fig 15-22
Defenses
� Mimicry� Looking like a venomous
species to signal inedibility
� _______________ mimicry� A harmless species mimics
a noxious one
� Predators should avoid both
� _______________ mimicry� Same coloration in a
number of noxious species
� Greater density of noxious individuals more effectively educates the predators
Photos: P Coin; L Brook; M Tegges
Model: Eft of Notophthalmus viridescens
Batesian Mimic
Plethodon cinereus
Mullerian Mimic Pseudotriton ruber
Defenses
� Mimicry
� Many Micrurus* are sympatric or parapatric
� Are _______________ mimics
� Pliocercus* are opisthoglyphs
� Far less toxic
� _____________ mimics of Micrurus
Pough et al. 2004, Fig 15-19
* *
*
*
* *
*
* *
*
*
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*
Defenses
� Mimicry
� Does it work?
� Brodie (1993) used a clay model approach
� Brown snake models were attacked much more despite being more camouflaged
� Tested many different Micruruspatterns
Photos: Pough et al. 2004, Fig 15-20, 15-21
Defenses
� Force
� ___________________
� Armor
� Spines
� Teeth
� Claws
� Tail
� Some have evolved for defense
� Others evolved for other purposes
Photos: PJB, M O’Shea
� ______________
� ______________
� ______________
Mechanical Defenses
� Shrike predation on Phrynosoma mcallii
� Lizards with relatively longer horns suffer less predation
� Higher expected survival with longer horns
Young et al. 2004
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Defenses
� Implications of mechanical defenses
� Bergmann et al. 2009 on Phrynosomatinae
� Losos et al. 2002 on Cordylidae� Species with longer spines
� ___________________
� Are more terrestrial
� ___________________
� Run shorter distances
Losos et al. 2002; Pough et al. 2004, Fig 4-27
Defenses
� Toxins
� ______________________
� Amphibia
� ______________________
� Viperidae
� Elapidae
� Both are often associated with behaviors
� Squirting poison
� Rattling to warn
� Various postures
Photos: Getty Images; Australian Government
Autotomy
� ____________ dropping of a body part to escape from a predator
� Can be spontaneous
� Can occur when grasped
� Salamanders
� Limbs (rare)
� Tails
� Lizards
� Tails
� All of these are ___________ after autotomy
Photos: M Thompson; AB Sheldon; Wikipedia
Autotomy
� There are costs to autotomy
� _____________________
� Loss of fat stores
� _____________________
� Change in sprint speed
� There is also considerable variation in how readily different species autotomize
Photos: K Bergmann, PJB