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Amphibian Predator Defenses

Derek Brawner

College of Agriculture Sciences and Natural Resources

University of Tennessee - Knoxville

ObjectivesUnderstand defense

h i d bmechanisms used by amphibians throughout

their life history.• Eggs

• Larvae

• Adults

Lecture Roadmap

• Amphibians as Preyp y

• Amphibian Predators

• Amphibian Egg Defenses

• Amphibian Larvae Defenses

• Amphibian Adult Defenses

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Amphibians as Prey

• Most are small

• Very soft, thin skin

• Eggs and larvae condensed

• Very numerous

• Tasty!

Amphibian Predators

• Invertebrates

• Invertebrate parasites

• Birds

• Mammalsp

• Fish • Crocodiles

• Lizards

• Snakes

• Amphibians

Amphibian Egg Predators

Aquatic• I t b t

Terrestrial• I t b t• Invertebrates

• Caddis flies

• Leeches

• Fish

• Tadpoles

• Invertebrates

• Spiders

• Beetles

• Snakes

• Amphibians

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Egg Protection

• Guard eggsGuard eggs

• Cued hatching

• Unpalatable

Video

Guard Eggs

• Dendrobatidae

Guard Eggs

• Gymnophionay p

• Three clutches

• Suburbs of South China

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Cued hatching

• Hatching time can respond to different threats and cues

• Hatch response to snake predationp p

• Six species of Agalychnis and Pachymedusa

Cued Hatching

• 4-7 individuals of snakes

• Fasted for at least 24 hours

• Exposed hatching-competent clutches to snakes

• Found that the ability to accelerate hatching in response to risk in all spp

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Unpalatability

• Yosemite Toad eggs

• Fed to brook trout individuallyy

• No eggs were consumed

Amphibian Larvae Predators

• Fish

• Birds (wading)( g)

• Mammals

• Invertebrate

Larval Defenses

• Chemical cues

• Freezingg

• Phenotypic Plasticity

• Unpalatability

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Chemical Cues

• What are chemical cues?

• Kairomones

• Poison frogs

• Tadpole transfer

• Pheromones

• Communication

• Predator detection

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Freezing

• Swimming less when w g wpredators are present

• Reduced swimming responses when exposed to kairomones

Phenotypic Plasticity

• What is phenotypic plasticity?• Amphibian Larvae use phenotypic plasticity to adapt to the presence of a

dpredator• Height of tail fins• Parsley frog and Mediterranean painted frog vs. crawfish, mosquitofish, and

dragonfly larvae

Phenotypic Plasticity

Parsley Frog• H d t ll t ilfi h d t

Mediterranean Painted Frog• N i ifi t diff b t• Had taller tailfins when exposed to

dragonfly larvae

• Had longer tailfins when exposed to crawfish

• No significant difference between the painted frog larvae.

• Invasive species may need more time to evolve

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Unpalatability

• Tadpoles can also be unpalatable

• 8 species of tadpoles

• Rated taste on a scale of 1-5

• 1 being “tastes good”p p

• Eaten by 11 students and faculty of 1970 Tropical biography class

g g

• 2 “no taste”

• 5 “very strongly disagreeable”

Adult Amphibian Predators

• Many of the same predators

• Birds

• Mammals

• Reptiles

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Adult Amphibian Defenses

• Cryptic Coloration

• Aposematic Colorationp

• Mimicry

• Chemical Defenses

• Behavioral Defenses

Cryptic Coloration

• The first line of defense

• Ground colors• Green, yellow, red, brown, gray

• Salamanders: dark, low skin reflectance, hard to see at night

• Bright colors• Bright green

• Reflect light in near infrared

Aposematic Coloration

• Bright Colors

• Have noxious skin secretions

• Trait has evolved many times

• Fire salamander Salamandrasalamandra

• Emperor newt Tylotriot shanjing

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Mimicry

• Mimic a predator with pnoxious secretions

• Not common

Chemical Defenses

• Secretions produced by l l dgranular glands

• Often distributed throughout the body

• Wide array of compounds

• Natural compounds

• Defensive compounds

Video

Active Chemical Defenses

• Most chemical defenses are passivepassive

• Two species are known for squirting poison

• Amazonian toad Rhaebo guttatus

• Fire salamander Salamandrasalamandra

Video

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Behavioral Defenses

• Fleeing

• M ff i• Most effective

• Mount Lyell Salamander H. platycephalus

• Defensive Postures

• Physalaemus nattereri

• Unken reflex

• Showsoff bright, hidden colors

Emperor newt Tylototritonshanjing

Spanish ribbed newt Pleurodeles waltl

Hairy Frog Trichobatrachus robustus

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Behavioral Defenses

• Reviewed defensive strategies

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References

• Adams, C. K., D. Saenz, and R. N. Conner. 2011. Palatability of twelve species of anuran larvae in eastern Texas. The American Midland Naturalist 166: 211-223

• Bei, Y., S. Meng, G. Li, W. Xie, J. Li, and L. Zhang. 2012. First record of nest site and egg guarding in the caecilian Ichthyophis bannanicus (Amphibia: Gymnophiona: Ichthyophiidae). Journal of Natural History 46: 859-865.

• Barry, M. J. and S. Syal. 2013. Metabolic responses of tadpoles to chemical predation cues. Hydrobiologia 700: 267-276.

• Brown, J. L., E. Twomey, V. Morales, and K. Summers. 2008. Phytotelm size in relation to parental care and mating strategies in two species of Peruvian poison frogs. Behaviour 145: 1139-1165.

• Buskirk, Josh Van. 2002. Phenotypic lability and the evoluction of predator-induced plasticity in tadpoles. Evolution 56: 361-370.

• Carlos, J., M.M. Antoniazzi, V. K. Verdade, L. F. Toledo, and M. T. Rodrigues. 2011. The Amazonian Ttad Rhaebo guttatus is able to voluntarily squirt poison from the paratoid macrogrlands. Amphibia-Reptilia 32: 546-549.

• Gomez-Mestre, I., J. J. Wiends, and K. M. Warkentin. 2008. Evolution of adaptive plasticity: risk-sensitive hatching in neotropical leaf treefrogs. Ecological Monographs 78: 205-224.

• Gunzburger, M. S., and J. Travis. 2005. Critical literature review of the evidence for unpalatability of amphibian eggs and larvae. Journal of Herpetology 39: 547-571.

• Grasso, R. L., R. M. Coleman, and C. Davidsion. 2010. Palatability and antipredator response to Yosemite toads (Anaxyrus canorus) to nonnative brook trout (Salvelinusfontinalis) in the Sierra Nevada Mountains of California. Copeia 3: 457-462.

• Maag, N., L. Gehrer, D. C. Woodhams. 2012. Sink or swim: a test of tadpole behavioral responses to predator cues and potential alarm pheromones from skin secretions. Journal of Camparative Physiology 198: 841-846.

References

• Marion, Z. H., and M. E. Hay. 2011. Chemical defense of the eastern newt (Notophthalmus viridescens): variation efficiency against different consumers and in different habitats. PLoS One 6: e27581.

• Melzer, S., L. S. Davis, and P. J. Bishop. 2012. Cutaneous gland secretions of Leiopelma pakeka as a potential mechanism against rat predation. New Zealand Journal of Zoology 39: 329-339.

• Pujol-Buxo E., O. S. Sabastian, N. Garriga, and G. A. Llorente. 2012. How does the invasive/native nature of species influence tadpoles’ plastic responses to predators? Oikos 122: 19-29.

• Schulte, L. M., J. Yeager, R. Schulte, M. Veith, P. Werner, L. A. Beck, S. Lotters. 2011. The smell of success: choice of larval rearing sites by means of chemical cues in a Peruvian poison frog. Animal Behavior 81: 1147-11554.

• Stynoski J L and V R Noble 2012 To beg or to freeze: multimodal sensory integration directs behavior in a tadpole Behavioral Ecology and Sociobiology 66: 191 199• Stynoski J. L., and V. R. Noble. 2012. To beg or to freeze: multimodal sensory integration directs behavior in a tadpole. Behavioral Ecology and Sociobiology 66: 191-199.

• Toledo, L. F., I. Sazima, and C. F. B. Haddad. 2010. Behavioral defences of anurans: an overview. Ethology Ecology & Evolution 23: 1-25.

• Vockenhuber, E. A., W. Hodl, and A. Amezquita. 2009. Glass fathers do matter: egg attendance enhances embryonic survivorship in glass frog Hyalinobatrachium valerioi. Journal of Herpetology 43: 340-344.

• Warkentin, Karen M. 2011. Environmentally cued hatching across taxa: Embryos respond to risk and opportunity. Integrative and Comparative Biology 51: 14-25.

• Wassersug, Richard. 1970. On the comparative palatability of some dry-season tadpoles from Costa Rica. American Midland Naturalist 86: 101-109.

• Weygoldt, P. 2009. Evolution of parental care in dart poison frogs (Amphibia: Anura: Dendropbatidae). Journal of Zoological Systematics and Evolutionary Research 25: 51-67.

• http://news.bbc.co.uk/earth/hi/earth_news/newsid_8212000/8212623.stm

• http://webecoist.momtastic.com/2008/11/04/9-of-the-most-bizarre-animal-defense-mechanisms/

• http://amphibianrescue.org/2012/11/

• SPECIAL THANKS TO GOOGLE IMAGES FOR ALL THE PICTURES!!!!!!!!!!!!!!!!!!!

Questions?