Population differences in responses of red-legged frogs to introduced bullfrogs - Rana aurora

Ecology, Sept, 1997 by Joseph M. Kiesecker, Andrew R. Blaustein

TABLE 1. (A) Results of MANOVA for overall effects of Rana
catesbeiana tadpoles and Rana aurora population type
(synoptic/allotopic) on R. aurora behavior. (B) Results of
discriminant function analysis (DFA) of activity and shelter use.

A) Experiment 1, MANOVA

Source                       F           df             P

Constant                  5365.63      2, 143     [less than]0.001
Population                   7.14     14, 286     [less than]0.001
Bullfrog                    89.60      2, 143     [less than]0.001
Bullfrog x Population        9.86     14, 286     [less than]0.001

B) Experiment 1, DFA

             Standardized
             discriminant       Total
              function        structure
Behavior     coefficient      coefficient             P

Activity       0.908             0.746        [less than]0.001
Shelter        0.882             0.962        [less than]0.001

Note: Response variables are the number of times a Rana aurora
tadpole crossed the center line (activity) and the number of R.
aurora tadpoles under the shelter.

The spread of exotic species is a global phenomenon that poses critical problems for many ecosystems. This study demonstrates the importance of understanding the behavioral and context-dependent responses of prey to predators, and how they can influence the outcome of interactions between species. This is especially true in systems where species are in decline, and where there have been introductions of exotic species.

ACKNOWLEDGMENTS

We thank Cheri Miller and Brian Edmond for providing technical assistance, and D. Grant Hokit, Will Kant, Amy Kane, Jonas Henderson, Harvey Pell, and Frank Miller for helpful discussions regarding experimental design. Doug Chivers, Erica Wildy, Jill DeVito, Adolfo Marco, David Reznick, David Skelly, and an anonymous reviewer provided helpful suggestions on this manuscript. Thanks to Dave Debou and the staff at E.E. Wilson Wildlife Refuge for all the help they provided. Funding was provided by the Department of Zoology Research Funds and the National Science Foundation (DEB-9423333 to A. R. Blaustein).

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