Transcript Effects of Competition on Ambystoma Salamander Larvae

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
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Found in temporary woodland ponds
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Breed from September to November
Eggs are deposited between November
and January
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vernal ponds
When the ponds fill
Eggs are attached to fallen tree branches in
the water
Larval period lasts 4 to 5 months
Background information about
Ambystoma Salamander Larvae
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Gape-limited predators
Generalist foragers
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Diet includes macroinvertebrates, isopods,
aquatic insects, and other amphibian larvae
Capable of phenotypic plasticity
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Change in an organisms phenotype in
response to their environment
Intraspecific vs. Interspecific
Competition
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Competition between
individuals of the
same species
Effects….
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Size
Aggression
Foraging
Survival
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Competition between
different species
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Direct interference
Indirect interference
Competitive species
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Trout
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Rana sylvatica (Wood
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Frog)
Aquatic insects
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Diving beetle larvae
Dragonfly naiads
INTRASPECIFIC
COMPETITION
Effect on Size
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Bigger is Better…in some instances
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Energy Requirements
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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
Interference
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Larger individuals are able to obtain food in greater amounts
Smaller individuals are better at exploitative competition
Larger individuals show greater aggression and push the
smaller individuals around
Size differences lead to cannibalism and intraguild
predation
Effect of Aggression
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Aggression is a form of direct interference within a
species
Increases the survival and nutrient uptake of one
individual
Reduces growth rate of smaller individuals
Observed most at feeding time
Two types…
 Lunge- advancement towards another individual
 Bite- open mouth grabbing of another individual
Often leads to cannibalism
INTERSPECIFIC
COMPETITION
Trout
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Trout were introduced in to areas where
Ambystoma salamanders live
Trout inhibit growth, reduce survival, and
decrease activity of Ambystoma salamander
larvae
Trout can reduce or even eliminate Ambystoma
larvae
Predation is the most likely the cause
Trout predation also shifts larval behaviors
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Larvae shift to nocturnal feeding
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Decreased food consumption and feeding efficiency
Rana sylvatica (Wood Frogs)
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Known to feed on Ambystoma eggs and
exposed 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 do not intentionally seek out egg
masses
Effects of breeding bouts and the presence
or absence of Rana sylvatica tadpoles
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Breeding bout is the
seasonal time of egg
deposits
(A) shows larval survival
(B) shows length of
larval stage, or time to
metamorphosis
(C) shows mass of
Ambystoma larvae at
metamorphosis
Holbrook and Petranka (2004)
Effects of Rana sylvatica density
and access to egg masses
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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
Holbrook and Petranka (2004)
Predation of egg masses by Rana
sylvatica tadpoles
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Tadpoles do not
intentionally seek out egg
masses
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
Petranka et al (1998)
Aquatic Insects
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Diving Beetle Larvae
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Active predators
Salamander larvae have
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Shorter snout vents
Longer and deeper tails
Weigh more than larvae in
environments with
dragonfly larvae, but less
than the control
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Dragonfly larvae
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Sit and wait predators
Salamander larvae have
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Shorter snout vents
Shorter and deeper tails
Weigh less than larvae
in any of the other
environments
Effects of aquatic insects on
salamander larvae
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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
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Brodman, R. 2004. Intraguild predation on congeners affects size,
aggression, and survival among Ambystoma salamander larvae.
Journal of Herpetology, 38: 21-26.
Holbrook, C.T. and J.W. Petranka. 2004. Ecological interactions
between Rana sylvatica and Ambystoma maculatum : Evidence of
interspecific competition and facultative intraguild predation. Copeia,
4: 932-939.
Johnson, E.B., P. Bierzychudek, and H. Whiteman. 2003. Potential of
prey size and type to affect foraging asymmetries in tiger salamander
(Ambystoma tigrinum nebulosum) larvae. Canadian Journal of
Zoology, 81: 1726-1735.
Pearman, P.B. 2002. Interactions between Ambystoma salamander
larvae: Evidence for competitive asymmetry. Herpetologica, 58: 156165.
Petranka, J.W., A.W. Rushlow, and M.E. Hopey. 1998. 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
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Smith, C.K. 1990. Effects of variation body size on intraspecific
competition among larval salamanders. Ecology, 71: 1777-1788.
Storfer, A. and C. White. 2004. Phenotypically plastic responses of
larval tiger salamanders, Ambystoma tigrinum, to different
predators. Journal of Herpetology, 38: 612-615.
Tyler, T., W. Liss, L. Ganio, G. Larson, R. Hoffman, E. Deimling, and
G. Lomnicky. 1998. Interaction between introduced trout and larval
salamanders (Ambystoma macrodactylum) in high-elevation lakes.
Conservation Biology, 12: 94-105.
Van Buskirk, J. and D.C. Smith. 1991. Density-dependent
population regulation in a salamander. Ecology, 72: 1747-1756.
Yurewicz, K. 2004. A growth/mortality trade-off in larval
salamanders and the coexistence of intraguild predators and prey.
Oecologia, 138: 102-111.