rapid evolution of antipredator responses do pacific treefrog populations differ in their response...
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![Page 1: Rapid Evolution of Antipredator Responses Do Pacific Treefrog Populations Differ in Their Response to an Introduced Predator? David Paoletti Advisor: Dr](https://reader030.vdocuments.net/reader030/viewer/2022032523/56649d7e5503460f94a61971/html5/thumbnails/1.jpg)
Rapid Evolution ofAntipredator Responses
Do Pacific Treefrog Populations Differ in Their Response to an Introduced
Predator?
David Paoletti
Advisor: Dr. Andrew Blaustein
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Loss of Biodiversity
• Declining globally across all taxa
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Amphibian Population Declines
Various Factors Contribute:• UV radiation• Disease• Habitat Loss• Pollution• Over-harvesting• Introduced Species
Oregon Spotted Frog
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Introduced Species
Many plant and animal species have become successfully established in foreign environments.
Zebra Mussel
Himalayan Blackberry
Cane Toad
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Introduced Species
Brook Trout(Salvelinus fontinalus)
Focal Species
Pacific Treefrog(Hyla regilla)
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Antipredator Behaviors
Most amphibian larvae rely on waterborne chemical cues to detect a potential threat. Upon detection, an individual may respond in several ways:
• Camouflage• Refuge use• Decrease in activity
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Allopatric vs.Sympatric Populations
ALLOPATRY
SYMPATRY
Frogs Fish
Frogs+Fish
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Allopatric vs.Sympatric Populations
Previous studies have shown that a population may evolve to avoid a newly introduced predator.
• Kiesecker and Blaustein, 1997
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I Thought I Smelled Something…
HYPOTHESIS:Allopatric treefrog populations will not
exhibit antipredator behaviors. Sympatric treefrog populations will
recognize trout as potential predators and thus change their behavior accordingly.
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Collection
H. regilla egg masses were collected from natural populations in the Cascade Mountains.
One from a lake with brook trout (allopatric).One from a trout-free habitat (sympatric).
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Susan’s Pond
Trout-free habitat
Three Creeks Lake
Last stockedin 1961
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Experimental Design
Allopatric Population
Sympatric Population
Control Group(No chemical cue)
Control Group(No chemical cue)
Predator Chemical Cue
Predator Chemical Cue
Alternate Chemical Cue
Alternate Chemical Cue
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Methods
• 15 minute acclimation period• Individuals spot-checked every ten minutes for two hours and any change in position was recorded
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MethodsObservations were conducted in a
laboratory setting. Activity levels for each group were recorded and analyzed.
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Predictions
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Movement
ANOVA- P<0.001 cue effect P=0.016 pop. effect
*
•Predator cue significantly decreased movement
•Tadpoles from the allopatric population moved significantly less often
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Distance
ANOVA- P<0.001 cue effect P=0.05 pop. effect
*
•Both populations decreased distance traveled in the presence of predator cues
•Tadpoles from the allopatric population traveled less distance
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Predicted Results Actual Results
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Conclusions
Sympatric AND allopatric populations reduce activity in the presence of a predator
Treefrog populations exhibit antipredator behaviors in the presence of a perceived threat, regardless of prior experience
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Rapid Evolution?
No evidence…No evidence…•MetapopulationMetapopulation•Ancestral populations previously Ancestral populations previously exposed to predatorexposed to predator
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Acknowledgements
Howard Hughes Medical Institute and Undergraduate Research, Innovation, Scholarship and Creativity (URISC)
Kevin Ahern and Andy Blaustein
Blaustein Lab:Dr. Tiffany GarciaBetsy Bancroft Anna JollesJohn Romansic Erin
Scheessele