amphibian predator defenses
TRANSCRIPT
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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?