2/28/2013. Amphibian Predator Defenses. Objectives. Lecture Roadmap

Transcription

1 Amphibian Predator Defenses Derek Brawner College of Agriculture Sciences and Natural Resources University of Tennessee - Knoxville Objectives Understand defense mechanisms used by amphibians throughout their life history. Eggs Larvae Adults Lecture Roadmap Amphibians as Prey Amphibian Predators Amphibian Egg Defenses Amphibian Larvae Defenses Amphibian Adult Defenses 1

2 Amphibians as Prey Most are small Very soft, thin skin Eggs and larvae condensed Very numerous Tasty! Amphibian Predators Invertebrates Invertebrate parasites Fish Birds Mammals Crocodiles Lizards Snakes Amphibians Amphibian Egg Predators Aquatic Invertebrates t Caddis flies Leeches Fish Tadpoles Terrestrial Invertebrates t Spiders Beetles Snakes Amphibians 2

3 Egg Protection Guard eggs Cued hatching Unpalatable Video Guard Eggs Dendrobatidae Guard Eggs Gymnophiona Three clutches Suburbs of South China 3

4 Cued hatching Hatching time can respond to different threats and cues Hatch response 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

5 Unpalatability Yosemite Toad eggs Fed to brook trout individually No eggs were consumed Amphibian Larvae Predators Fish Birds (wading) Mammals Invertebrate Larval Defenses Chemical cues Freezing Phenotypic Plasticity Unpalatability 5

6 Chemical Cues What are chemical cues? Kairomones Pheromones Communication Predator detection Poison frogs Tadpole transfer 6

7 Freezing Swimming 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 Had taller tailfins when exposed to dragonfly larvae Had longer tailfins when exposed to crawfish Mediterranean Painted Frog No significant ifi difference between the painted frog larvae. Invasive species may need more time to evolve 7

8 Unpalatability Tadpoles can also be unpalatable 8 species of tadpoles Eaten by 11 students and faculty of 1970 Tropical biography class Rated taste on a scale of being tastes good 2 no taste 5 very strongly disagreeable Adult Amphibian Predators Many of the same predators Birds Mammals Reptiles 8

9 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

10 Mimicry Mimic a predator with noxious secretions Not common Chemical Defenses Secretions produced by granular 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

11 Behavioral Defenses Fleeing Most effective 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

12 Behavioral Defenses Reviewed defensive strategies 12

13 References Adams, C. K., D. Saenz, and R. N. Conner Palatability of twelve species of anuran larvae in eastern Texas. The American Midland Naturalist 166: Bei, Y., S. Meng, G. Li, W. Xie, J. Li, and L. Zhang First record of nest site and egg guarding in the caecilian Ichthyophis bannanicus (Amphibia: Gymnophiona: Ichthyophiidae). Journal of Natural History 46: Barry, M. J. and S. Syal Metabolic responses of tadpoles to chemical predation cues. Hydrobiologia 700: Brown, J. L., E. Twomey, V. Morales, and K. Summers Phytotelm size in relation to parental care and mating strategies in two species of Peruvian poison frogs. Behaviour 145: Buskirk, Josh Van Phenotypic lability and the evoluction of predator-induced plasticity in tadpoles. Evolution 56: Carlos, J., M.M. Antoniazzi, V. K. Verdade, L. F. Toledo, and M. T. Rodrigues The Amazonian Ttad Rhaebo guttatus is able to voluntarily squirt poison from the paratoid macrogrlands. Amphibia-Reptilia 32: Gomez-Mestre, I., J. J. Wiends, and K. M. Warkentin Evolution of adaptive plasticity: risk-sensitive hatching in neotropical leaf treefrogs. Ecological Monographs 78: Gunzburger, M. S., and J. Travis Critical literature review of the evidence for unpalatability of amphibian eggs and larvae. Journal of Herpetology 39: Grasso, R. L., R. M. Coleman, and C. Davidsion Palatability and antipredator response to Yosemite toads (Anaxyrus canorus) to nonnative brook trout (Salvelinus fontinalis) in the Sierra Nevada Mountains of California. Copeia 3: Maag, N., L. Gehrer, D. C. Woodhams Sink or swim: a test of tadpole behavioral responses to predator cues and potential alarm pheromones from skin secretions. Journal of Camparative Physiology 198: References Marion, Z. H., and M. E. Hay Chemical defense of the eastern newt (Notophthalmus viridescens): variation efficiency against different consumers and in different habitats. PLoS One 6: e Melzer, S., L. S. Davis, and P. J. Bishop Cutaneous gland secretions of Leiopelma pakeka as a potential mechanism against rat predation. New Zealand Journal of Zoology 39: Pujol-Buxo E., O. S. Sabastian, N. Garriga, and G. A. Llorente How does the invasive/native nature of species influence tadpoles plastic responses to predators? Oikos 122: Schulte, L. M., J. Yeager, R. Schulte, M. Veith, P. Werner, L. A. Beck, S. Lotters The smell of success: choice of larval rearing sites by means of chemical cues in a Peruvian poison frog. Animal Behavior 81: Stynoski J. L., and V. R. Noble To beg or to freeze: multimodal sensory integration directs behavior in a tadpole. Behavioral Ecology and Sociobiology 66: Toledo, L. F., I. Sazima, and C. F. B. Haddad Behavioral defences of anurans: an overview. Ethology Ecology & Evolution 23: Vockenhuber, E. A., W. Hodl, and A. Amezquita Glass fathers do matter: egg attendance enhances embryonic survivorship in glass frog Hyalinobatrachium valerioi. Journal of Herpetology 43: Warkentin, Karen M Environmentally cued hatching across taxa: Embryos respond to risk and opportunity. Integrative and Comparative Biology 51: Wassersug, Richard On the comparative palatability of some dry-season tadpoles from Costa Rica. American Midland Naturalist 86: Weygoldt, P Evolution of parental care in dart poison frogs (Amphibia: Anura: Dendropbatidae). Journal of Zoological Systematics and Evolutionary Research 25: SPECIAL THANKS TO GOOGLE IMAGES FOR ALL THE PICTURES!!!!!!!!!!!!!!!!!!! Questions? 13