Effects of Effects of Competition on Competition on

AmbystomaAmbystoma Salamander LarvaeSalamander Larvae

Erica ReedErica ReedApril 17, April 17,

20062006BIO 299BIO 299

Adult Ambystoma opacum with eggs

Ambystoma opacum larva

Background information Background information about about AmbystomaAmbystoma

salamanderssalamanders Found in temporary woodland pondsFound in temporary woodland ponds

vernal pondsvernal ponds Breed from September to NovemberBreed from September to November Eggs are deposited between Eggs are deposited between

November and JanuaryNovember and January When the ponds fillWhen the ponds fill Eggs are attached to fallen tree Eggs are attached to fallen tree

branches in the waterbranches in the water Larval period lasts 4 to 5 monthsLarval period lasts 4 to 5 months

Background information about Background information about AmbystomaAmbystoma Salamander Salamander

LarvaeLarvae Gape-limited predatorsGape-limited predators Generalist foragersGeneralist foragers

Diet includes macroinvertebrates, Diet includes macroinvertebrates, isopods, aquatic insects, and other isopods, aquatic insects, and other amphibian larvaeamphibian larvae

Capable of phenotypic plasticityCapable of phenotypic plasticity Change in an organisms phenotype in Change in an organisms phenotype in

response to their environmentresponse to their environment

Intraspecific vs. Intraspecific vs. Interspecific CompetitionInterspecific Competition

Competition Competition between between individuals of the individuals of the same speciessame species

Effects….Effects…. SizeSize AggressionAggression ForagingForaging SurvivalSurvival

Competition Competition between different between different speciesspecies Direct interferenceDirect interference Indirect interferenceIndirect interference

Competitive speciesCompetitive species TroutTrout Rana sylvaticaRana sylvatica (Wood (Wood

Frog)Frog) Aquatic insectsAquatic insects

Diving beetle larvaeDiving beetle larvae Dragonfly naiadsDragonfly naiads

INTRASPECIFIC INTRASPECIFIC COMPETITIONCOMPETITION

Effect on SizeEffect on Size Bigger is Better…in some instancesBigger is Better…in some instances

Larger individuals are able to obtain food in greater Larger individuals are able to obtain food in greater amountsamounts

Smaller individuals are better at exploitative competitionSmaller individuals are better at exploitative competition Energy RequirementsEnergy Requirements

Larger individuals require more energy, in turn more Larger individuals require more energy, in turn more food, to keep up with everyday activitiesfood, to keep up with everyday activities

Smaller individuals can use less food to gain the required Smaller individuals can use less food to gain the required energy for everyday activitiesenergy for everyday activities

Interference Interference Larger individuals show greater aggression and push the Larger individuals show greater aggression and push the

smaller individuals aroundsmaller individuals around Size differences lead to cannibalism and intraguild Size differences lead to cannibalism and intraguild

predationpredation

Effect of AggressionEffect of Aggression Aggression is a form of direct interference within a Aggression is a form of direct interference within a

speciesspecies Increases the survival and nutrient uptake of one Increases the survival and nutrient uptake of one

individualindividual Reduces growth rate of smaller individualsReduces growth rate of smaller individuals Observed most at feeding timeObserved most at feeding time Two types…Two types…

Lunge- advancement towards another individualLunge- advancement towards another individual Bite- open mouth grabbing of another individualBite- open mouth grabbing of another individual

Often leads to cannibalismOften leads to cannibalism

INTERSPECIFIC INTERSPECIFIC COMPETITIONCOMPETITION

TroutTrout Trout were introduced in to areas where Trout were introduced in to areas where

AmbystomaAmbystoma salamanders live salamanders live Trout inhibit growth, reduce survival, and Trout inhibit growth, reduce survival, and

decrease activity of decrease activity of AmbystomaAmbystoma salamander larvaesalamander larvae

Trout can reduce or even eliminate Trout can reduce or even eliminate AmbystomaAmbystoma larvae larvae

Predation is the most likely the causePredation is the most likely the cause Trout predation also shifts larval behaviorsTrout 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 sylvaticaRana sylvatica (Wood (Wood Frogs)Frogs)

Known to feed on Known to feed on AmbystomaAmbystoma eggs and eggs and exposed larvaeexposed larvae

Wood frogs effect growth rate, time of Wood frogs effect growth rate, time of metamorphosis, and survival of larvaemetamorphosis, and survival of larvae

Wood frogs and Wood frogs and Ambystoma Ambystoma larvae feed larvae feed on much of the same resourceson much of the same resources

Wood frogs do not intentionally seek out Wood frogs do not intentionally seek out egg massesegg masses

Effects of breeding bouts and the Effects of breeding bouts and the presence or absence of presence or absence of Rana Rana

sylvaticasylvatica tadpoles tadpoles Breeding bout is the Breeding bout is the

seasonal time of egg seasonal time of egg depositsdeposits

(A) shows larval (A) shows larval survival survival

(B) shows length of (B) shows length of larval stage, or time to larval stage, or time to metamorphosismetamorphosis

(C) shows mass of (C) shows mass of AmbystomaAmbystoma larvae at larvae at metamorphosismetamorphosis Holbrook and Petranka

(2004)

Effects of Effects of Rana sylvaticaRana sylvatica density and access to egg density and access to egg

massesmasses Different densities were Different densities were

tested in different poolstested in different pools

The graph shows that The graph shows that high density of high density of Rana Rana sylvaticasylvatica causes causes decreased chance of decreased chance of survival, growth, and survival, growth, and development of development of AmbystomaAmbystoma salamander salamander larvaelarvae

Holbrook and Petranka (2004)

Predation of egg masses by Predation of egg masses by Rana sylvaticaRana sylvatica tadpoles tadpoles

Tadpoles do not Tadpoles do not intentionally seek out intentionally seek out egg massesegg masses

The predation of egg The predation of egg masses was tested in masses was tested in different food availability different food availability treatments.treatments.

Rana sylvaticaRana sylvatica tadpoles tadpoles were seen to feed on egg were seen to feed on egg masses during periods masses during periods low food availabilitylow food availability

Petranka et al (1998)

Aquatic InsectsAquatic Insects

Diving Beetle LarvaeDiving Beetle Larvae Active predatorsActive predators Salamander larvae haveSalamander larvae have

Shorter snout ventsShorter snout vents Longer and deeper tailsLonger and deeper tails Weigh more than larvae Weigh more than larvae

in environments with in environments with dragonfly larvae, but less dragonfly larvae, but less than the controlthan the control

Dragonfly larvaeDragonfly larvae Sit and wait predatorsSit and wait predators Salamander larvae Salamander larvae

havehave Shorter snout ventsShorter snout vents Shorter and deeper Shorter and deeper

tailstails Weigh less than larvae Weigh less than larvae

in any of the other in any of the other environmentsenvironments

Effects of aquatic insects on Effects of aquatic insects on salamander larvaesalamander larvae

Graph shows snout Graph shows snout vent length, tail vent length, tail length and depth, length and depth, and mass of and mass of Ambystoma tigrinum Ambystoma tigrinum nebulosumnebulosum in the in the absence of aquatic absence of aquatic insects and with the insects and with the diving beetle larvae diving beetle larvae ((DytiscusDytiscus) and ) and dragonfly larvae dragonfly larvae ((AnaxAnax))

Storfer and White (2004)

Literature CitedLiterature Cited Brodman, R. 2004. Intraguild predation on congeners affects Brodman, R. 2004. Intraguild predation on congeners affects

size, aggression, and survival among Ambystoma salamander size, aggression, and survival among Ambystoma salamander larvae. Journal of Herpetology, 38: 21-26.larvae. Journal of Herpetology, 38: 21-26.

Holbrook, C.T. and J.W. Petranka. 2004. Ecological interactions Holbrook, C.T. and J.W. Petranka. 2004. Ecological interactions between between Rana sylvatica Rana sylvatica and and Ambystoma maculatumAmbystoma maculatum : : Evidence of interspecific competition and facultative intraguild Evidence of interspecific competition and facultative intraguild predation. Copeia, 4: 932-939.predation. Copeia, 4: 932-939.

Johnson, E.B., P. Bierzychudek, and H. Whiteman. 2003. Johnson, E.B., P. Bierzychudek, and H. Whiteman. 2003. Potential of prey size and type to affect foraging asymmetries Potential of prey size and type to affect foraging asymmetries in tiger salamander (in tiger salamander (Ambystoma tigrinum nebulosumAmbystoma tigrinum nebulosum) larvae. ) larvae. Canadian Journal of Zoology, 81: 1726-1735.Canadian Journal of Zoology, 81: 1726-1735.

Pearman, P.B. 2002. Interactions between Ambystoma Pearman, P.B. 2002. Interactions between Ambystoma salamander larvae: Evidence for competitive asymmetry. salamander larvae: Evidence for competitive asymmetry. Herpetologica, 58: 156-165.Herpetologica, 58: 156-165.

Petranka, J.W., A.W. Rushlow, and M.E. Hopey. 1998. Predation Petranka, J.W., A.W. Rushlow, and M.E. Hopey. 1998. Predation by tadpoles of by tadpoles of Rana sylvaticaRana sylvatica on embryos of on embryos of Ambystoma Ambystoma maculatummaculatum: Implications of ecological role reversals by Rana : Implications of ecological role reversals by Rana (predator) and Ambystoma (prey). Herpetologica, 54: 1-13.(predator) and Ambystoma (prey). Herpetologica, 54: 1-13.

Literature CitedLiterature Cited Smith, C.K. 1990. Effects of variation body size on Smith, C.K. 1990. Effects of variation body size on

intraspecific competition among larval salamanders. intraspecific competition among larval salamanders. Ecology, 71: 1777-1788.Ecology, 71: 1777-1788.

Storfer, A. and C. White. 2004. Phenotypically plastic Storfer, A. and C. White. 2004. Phenotypically plastic responses of larval tiger salamanders, Ambystoma tigrinum, responses of larval tiger salamanders, Ambystoma tigrinum, to different predators. Journal of Herpetology, 38: 612-615.to different predators. Journal of Herpetology, 38: 612-615.

Tyler, T., W. Liss, L. Ganio, G. Larson, R. Hoffman, E. Tyler, T., W. Liss, L. Ganio, G. Larson, R. Hoffman, E. Deimling, and G. Lomnicky. 1998. Interaction between Deimling, and G. Lomnicky. 1998. Interaction between introduced trout and larval salamanders (introduced trout and larval salamanders (Ambystoma Ambystoma macrodactylummacrodactylum) in high-elevation lakes. Conservation ) in high-elevation lakes. Conservation Biology, 12: 94-105.Biology, 12: 94-105.

Van Buskirk, J. and D.C. Smith. 1991. Density-dependent Van Buskirk, J. and D.C. Smith. 1991. Density-dependent population regulation in a salamander. Ecology, 72: 1747-population regulation in a salamander. Ecology, 72: 1747-1756.1756.

Yurewicz, K. 2004. A growth/mortality trade-off in larval Yurewicz, K. 2004. A growth/mortality trade-off in larval salamanders and the coexistence of intraguild predators salamanders and the coexistence of intraguild predators and prey. Oecologia, 138: 102-111. and prey. Oecologia, 138: 102-111.