Effects of Competition on Ambystoma Salamander Larvae Erica Reed April 17, 2006 BIO 299

Adult Ambystoma opacum with eggs Ambystoma opacum larva

Background information about Ambystoma salamanders Found in temporary woodland ponds Found in temporary woodland ponds vernal ponds vernal ponds Breed from September to November Breed from September to November Eggs are deposited between November and January Eggs are deposited between November and January When the ponds fill When the ponds fill Eggs are attached to fallen tree branches in the water Eggs are attached to fallen tree branches in the water Larval period lasts 4 to 5 months Larval period lasts 4 to 5 months

Background information about Ambystoma Salamander Larvae Gape-limited predators Gape-limited predators Generalist foragers Generalist foragers Diet includes macroinvertebrates, isopods, aquatic insects, and other amphibian larvae Diet includes macroinvertebrates, isopods, aquatic insects, and other amphibian larvae Capable of phenotypic plasticity Capable of phenotypic plasticity Change in an organisms phenotype in response to their environment Change in an organisms phenotype in response to their environment

Intraspecific vs. Interspecific Competition Competition between individuals of the same species Competition between individuals of the same species Effects…. Effects…. Size Size Aggression Aggression Foraging Foraging Survival Survival Competition between different species Competition between different species Direct interference Indirect interference Competitive species Competitive species Trout Rana sylvatica (Wood Frog) Aquatic insects Diving beetle larvae Dragonfly naiads

INTRASPECIFIC COMPETITION

Effect on Size Bigger is Better…in some instances Bigger is Better…in some instances Larger individuals are able to obtain food in greater amounts Larger individuals are able to obtain food in greater amounts Smaller individuals are better at exploitative competition Smaller individuals are better at exploitative competition Energy Requirements Energy Requirements Larger individuals require more energy, in turn more food, to keep up with everyday activities Larger individuals require more energy, in turn more food, to keep up with everyday activities Smaller individuals can use less food to gain the required energy for everyday activities Smaller individuals can use less food to gain the required energy for everyday activities Interference Interference Larger individuals show greater aggression and push the smaller individuals around Larger individuals show greater aggression and push the smaller individuals around Size differences lead to cannibalism and intraguild predation Size differences lead to cannibalism and intraguild predation

Effect of Aggression Aggression is a form of direct interference within a species Aggression is a form of direct interference within a species Increases the survival and nutrient uptake of one individual Increases the survival and nutrient uptake of one individual Reduces growth rate of smaller individuals Reduces growth rate of smaller individuals Observed most at feeding time Observed most at feeding time Two types… Two types… Lunge- advancement towards another individual Lunge- advancement towards another individual Bite- open mouth grabbing of another individual Bite- open mouth grabbing of another individual Often leads to cannibalism Often leads to cannibalism

INTERSPECIFIC COMPETITION

Trout Trout were introduced in to areas where Ambystoma salamanders live Trout were introduced in to areas where Ambystoma salamanders live Trout inhibit growth, reduce survival, and decrease activity of Ambystoma salamander larvae Trout inhibit growth, reduce survival, and decrease activity of Ambystoma salamander larvae Trout can reduce or even eliminate Ambystoma larvae Trout can reduce or even eliminate Ambystoma larvae Predation is the most likely the cause Predation is the most likely the cause Trout predation also shifts larval behaviors Trout predation also shifts larval behaviors Larvae shift to nocturnal feeding Larvae shift to nocturnal feeding Decreased food consumption and feeding efficiency Decreased food consumption and feeding efficiency

Rana sylvatica (Wood Frogs) Known to feed on Ambystoma eggs and exposed larvae Known to feed on Ambystoma eggs and exposed larvae Wood frogs effect growth rate, time of metamorphosis, and survival of larvae Wood frogs effect growth rate, time of metamorphosis, and survival of larvae Wood frogs and Ambystoma larvae feed on much of the same resources Wood frogs and Ambystoma larvae feed on much of the same resources Wood frogs do not intentionally seek out egg masses Wood frogs do not intentionally seek out egg masses

Effects of breeding bouts and the presence or absence of Rana sylvatica tadpoles Breeding bout is the seasonal time of egg deposits Breeding bout is the seasonal time of egg deposits (A) shows larval survival (A) shows larval survival (B) shows length of larval stage, or time to metamorphosis (B) shows length of larval stage, or time to metamorphosis (C) shows mass of Ambystoma larvae at metamorphosis (C) shows mass of Ambystoma larvae at metamorphosis Holbrook and Petranka (2004)

Effects of Rana sylvatica density and access to egg masses Different densities were tested in different pools Different densities were tested in different pools The graph shows that high density of Rana sylvatica causes decreased chance of survival, growth, and development of Ambystoma salamander larvae The graph shows that high density of Rana sylvatica causes decreased chance of survival, growth, and development of Ambystoma salamander larvae Holbrook and Petranka (2004)

Predation of egg masses by Rana sylvatica tadpoles Tadpoles do not intentionally seek out egg masses Tadpoles do not intentionally seek out egg masses The predation of egg masses was tested in different food availability treatments. The predation of egg masses was tested in different food availability treatments. Rana sylvatica tadpoles were seen to feed on egg masses during periods low food availability Rana sylvatica tadpoles were seen to feed on egg masses during periods low food availability Petranka et al (1998)

Aquatic Insects Diving Beetle Larvae Diving Beetle Larvae Active predators Active predators Salamander larvae have Salamander larvae have Shorter snout vents Shorter snout vents Longer and deeper tails Longer and deeper tails Weigh more than larvae in environments with dragonfly larvae, but less than the control Weigh more than larvae in environments with dragonfly larvae, but less than the control Dragonfly larvae Dragonfly larvae Sit and wait predators Salamander larvae have Shorter snout vents Shorter and deeper tails Weigh less than larvae in any of the other environments

Effects of aquatic insects on salamander larvae Graph shows snout vent length, tail length and depth, and mass of Ambystoma tigrinum nebulosum in the absence of aquatic insects and with the diving beetle larvae (Dytiscus) and dragonfly larvae (Anax) Graph shows snout vent length, tail length and depth, and mass of Ambystoma tigrinum nebulosum in the absence of aquatic insects and with the diving beetle larvae (Dytiscus) and dragonfly larvae (Anax) Storfer and White (2004)

Literature Cited Brodman, R Intraguild predation on congeners affects size, aggression, and survival among Ambystoma salamander larvae. Journal of Herpetology, 38: Brodman, R Intraguild predation on congeners affects size, aggression, and survival among Ambystoma salamander larvae. Journal of Herpetology, 38: Holbrook, C.T. and J.W. Petranka Ecological interactions between Rana sylvatica and Ambystoma maculatum : Evidence of interspecific competition and facultative intraguild predation. Copeia, 4: Holbrook, C.T. and J.W. Petranka Ecological interactions between Rana sylvatica and Ambystoma maculatum : Evidence of interspecific competition and facultative intraguild predation. Copeia, 4: Johnson, E.B., P. Bierzychudek, and H. Whiteman Potential of prey size and type to affect foraging asymmetries in tiger salamander (Ambystoma tigrinum nebulosum) larvae. Canadian Journal of Zoology, 81: Johnson, E.B., P. Bierzychudek, and H. Whiteman Potential of prey size and type to affect foraging asymmetries in tiger salamander (Ambystoma tigrinum nebulosum) larvae. Canadian Journal of Zoology, 81: Pearman, P.B Interactions between Ambystoma salamander larvae: Evidence for competitive asymmetry. Herpetologica, 58: Pearman, P.B Interactions between Ambystoma salamander larvae: Evidence for competitive asymmetry. Herpetologica, 58: Petranka, J.W., A.W. Rushlow, and M.E. Hopey Predation by tadpoles of Rana sylvatica on embryos of Ambystoma maculatum: Implications of ecological role reversals by Rana (predator) and Ambystoma (prey). Herpetologica, 54: Petranka, J.W., A.W. Rushlow, and M.E. Hopey Predation by tadpoles of Rana sylvatica on embryos of Ambystoma maculatum: Implications of ecological role reversals by Rana (predator) and Ambystoma (prey). Herpetologica, 54: 1-13.

Literature Cited Smith, C.K Effects of variation body size on intraspecific competition among larval salamanders. Ecology, 71: Smith, C.K Effects of variation body size on intraspecific competition among larval salamanders. Ecology, 71: Storfer, A. and C. White Phenotypically plastic responses of larval tiger salamanders, Ambystoma tigrinum, to different predators. Journal of Herpetology, 38: Storfer, A. and C. White Phenotypically plastic responses of larval tiger salamanders, Ambystoma tigrinum, to different predators. Journal of Herpetology, 38: Tyler, T., W. Liss, L. Ganio, G. Larson, R. Hoffman, E. Deimling, and G. Lomnicky Interaction between introduced trout and larval salamanders (Ambystoma macrodactylum) in high-elevation lakes. Conservation Biology, 12: Tyler, T., W. Liss, L. Ganio, G. Larson, R. Hoffman, E. Deimling, and G. Lomnicky Interaction between introduced trout and larval salamanders (Ambystoma macrodactylum) in high-elevation lakes. Conservation Biology, 12: Van Buskirk, J. and D.C. Smith Density-dependent population regulation in a salamander. Ecology, 72: Van Buskirk, J. and D.C. Smith Density-dependent population regulation in a salamander. Ecology, 72: Yurewicz, K A growth/mortality trade-off in larval salamanders and the coexistence of intraguild predators and prey. Oecologia, 138: Yurewicz, K A growth/mortality trade-off in larval salamanders and the coexistence of intraguild predators and prey. Oecologia, 138: