2/28/2013
Amphibian Predator Defenses
Derek Brawner College of Agriculture Sciences and Natural Resources University of Tennessee - Knoxville
Objectives
Understand defense mechihanisms use dbd by amphibians throughout their life history. • Eggs • Larvae • Adults
Lecture Roadmap
• Amppyhibians as Prey • Amphibian Predators • Amphibian Egg Defenses • Amphibian Larvae Defenses • Amphibian Adult Defenses
1 2/28/2013
Amphibians as Prey
• Most are small • Very soft, thin skin • Eggs and larvae condensed • Very numerous • Tasty!
Amphibian Predators
• Invertebrates • Birds • Invertebrate parasites • Mammals • Fish • Crocodiles • Lizards • Snakes • Amphibians
Amphibian Egg Predators
Aquatic Terrestrial • ItbtInvertebrates • ItbtInvertebrates • Caddis flies • Spiders • Leeches • Beetles • Fish • Snakes • Tadpoles • Amphibians
2 2/28/2013
Egg Protection
• Guard eggs • Cued hatching • Unpalatable
Video
Guard Eggs
• Dendrobatidae
Guard Eggs
• Gyypmnophiona • Three clutches • Suburbs of South China
3 2/28/2013
Cued hatching
• Hatching time can respond to different threats and cues • Hatch resppponse to snake predation • 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
4 2/28/2013
Unpalatability
• Yosemite Toad eggs • Fed to brook trout individually • No eggs were consumed
Amphibian Larvae Predators
• Fish • Birds ((g)wading) • Mammals • Invertebrate
Larval Defenses
• Chemical cues • Freezing • Phenotypic Plasticity • Unpalatability
5 2/28/2013
Chemical Cues
• What are chemical cues? • Poison frogs • Kairomones • Tadpole transfer • Pheromones • Communication • Predator detection
6 2/28/2013
Freezing
• Swwgwimming less when predators 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 predator • Height of tail fins • Parsley frog and Mediterranean painted frog vs. crawfish, mosquitofish, and dragonfly larvae
Phenotypic Plasticity
Parsley Frog Mediterranean Painted Frog • Ha d tall er t ailfi ns wh en exposed t o • NiifitdiffNo significant difference b btetween dragonfly larvae the painted frog larvae. • Had longer tailfins when exposed • Invasive species may need more to crawfish time to evolve
7 2/28/2013
Unpalatability
• Tadpoles can also be unpalatable • Rated taste on a scale of 1-5 • 8 spppecies of tadpoles • 1 beinggg “tastes good” • Eaten by 11 students and faculty of • 2 “no taste” 1970 Tropical biography class • 5 “very strongly disagreeable”
Adult Amphibian Predators
• Many of the same predators • Birds • Mammals • Reptiles
8 2/28/2013
Adult Amphibian Defenses
• Cryptic Coloration • Aposematic Coloration • 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 Salamandra salamandra • Emperor newt Tylotriot shanjing
9 2/28/2013
Mimicry
• Mimic a predator with noxious secretions • Not common
Chemical Defenses
• Secretions produced by granulldlar glands • Often distributed throughout the body • Wide array of compounds • Natural compounds • Defensive compounds
Video
Active Chemical Defenses
• Most chemical defenses are passive • Two species are known for squirting poison • Amazonian toad Rhaebo guttatus • Fire salamander Salamandra salamandra
Video
10 2/28/2013
Behavioral Defenses
• Fleeing • Most effecti ve • Mount Lyell Salamander H. platycephalus • Defensive Postures • Physalaemus nattereri • Unken reflex
• Showsoff bright, hidden colors
Emperor newt Tylototriton shanjing
Spanish ribbed newt Pleurodeles waltl
Hairy Frog Trichobatrachus robustus
11 2/28/2013
Behavioral Defenses
• Reviewed defensive strategies
12 2/28/2013
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 (Salvelinus fontinalis) 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 E cology 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?
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