Environmental Factors Influencing Wood Frog (Lithobates sylvaticus)
Tadpole Size in a Glaciated Landscape
Background
 L. sylvaticus populations are a significant contributor in maintaining
food webs; therefore L. sylvaticus is important to maintain a
functional wetland.
 Isolated ephemeral wetlands are critical habitat for amphibians in a
forested landscape.
 Body size is a key feature in the life history of amphibians.
 Amphibian body size and growth is related to several environmental
characteristics including temperature (Berven 1982; Ryser 1996),
food resources (Berven and Chadra 1988), predation, and other
environmental characteristics (reviewed in Morrison and Hero
2003).
S. Kilibarda, A. Smith, J. Church, and
A. Little
University of Wisconsin—Stout
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Methods
Four minnow traps per pond (Fig. 1)
24 hour sample period
Snout-vent length (SVL) (Fig. 2)
Chippewa Moraine State Recreation Area (Fig. 3)
40 ephemeral ponds
16 permanent wetlands
One sample period in May 2013
Purpose
 Evaluate environmental variables as they relate to tadpole body size.
 Investigate how L. sylvaticus might be affected by the local
environment, landscape characteristics, and climate change.
Figure 1. An ephemeral pond sampling site. Four minnow traps were set in
varying habitat. Each star represents the location of water chemistry
measurements.
Figure 2. Measuring method. Tadpoles body size was
measured from the tip of the snout to the vent.
Literature Cited
Results
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Figure 3. Map of Wisconsin. Study area was
located in Chippewa County.
Out of the 40 ephemeral ponds surveyed,
20 contained L. sylvaticus tadpoles
Mean body size was larger in tadpoles
sampled from permanent wetlands (Fig.
6)
pH was the only environmental variable
positively correlated with SVL (Fig. 7)
Berven, K.A. 1982. The genetic basis of altitudinal variation in the wood frog Rana
sylvatica. II. An experimental analysis of larval development. Oecologia, 52:
360-369.
Berven, K.A. and Chadra, B.G. 1988. The relationship among egg size, density and
food level on larval development in the wood frog (Rana sylvatica
Oecologia, 75: 67-72.
Morrison, C. and J. Hero. 2003. Geographic variation in life-history
characteristics of amphibians: a review. Journal of Animal Ecology, 72:
270-279.
Ryser, J. 1996. Comparative life histories of a low- and a high-elevation population
of the common frog Rana temporaria. Amphibia–Reptilia, 17: 183–195.
Stoler, A.B. and R.A. Relyea. 2011 Living in the litter: the influence of leaf litter on
wetland communities. Oikos, 120: 862-867.
Figure 6. Mean SVL (+/- 1 SE) of tadpoles in ephemeral and
permanent wetlands. SVL was significantly larger in permanent
wetlands (p<0.01)
Discussion
Figure 7. Correlation of SVL and pH. SVL was significantly
correlated with pH (r2 = 0.30). Red data points represent ephemeral
ponds. Blue data points represent permanent wetlands.
 Factors associated with pH are most likely litter inputs and geological
characteristics. Studies examining types of leaf litter have indicated that tadpole size
may be determined by tree species in the wetland (Stoler and Reylea 2011).
 Potential sources for body size difference includes wetland duration, resources,
predator community, water temperatures, and competition.
 While our study focused on L. sylvaticus, it is important to realize the potential
implications of our results on other members of the biological community that eat
and are eaten by L. sylvaticus.
Acknowledgements
 We thank Ashley Kijowski, Megen Hines, Adam Cameron, Pam Gehant, and Leta
Ganrude for help with collecting data
 Brenda Rederer and Rod Gont, WI DNR Ice Age Interpretive Center provided
logistical assistance
 The University of Wisconsin-Stout College of Science, Technology, Engineering,
and Mathematics, and the Department of Biology provided support for this
project.
 This material is based upon work supported by the National Science Foundation
under Grant 1256142. Any opinions, findings, and conclusions or
recommendations expressed in this material are those of the authors and do
not necessarily reflect the views of the National Science Foundation.