Escape Behavior and the Aposematic Syndrome in Two Neotropical Frogs

Associations among behavioral and morphological traits are of interest to biologists because they imply functional relationships at the behavior/morphology interface. We investigated the association between escape behavior and aposematic versus cryptic coloration in two species of Neotropical frogs, namely, Craugaster fitzingeri and Oophaga pumilio. Craugaster fitzingeri is cryptically colored, whereas O. pumilio is an aposematically colored ''Poison Dart Frog.'' Specifically, we predicted that the cryptic C. fitzingeri would exhibit faster and directionally more erratic escape behavior than the aposematic O. pumilio. We tested this hypothesis by measuring escape speed and variation in turning angles of frogs in their natural habitat. Results indicated that C. fitzingeri has faster and directionally less predictable escape behavior than O. pumilio. Two evolutionary mechanisms may have linked escape behavior and coloration. One possibility is that aposematism in the dendrobatid lineage has relaxed selection and enabled a reduction in speed and unpredictability of escape behavior. A second possibility is that aposematic coloration has actively favored reduction in escape behavior, i.e., slow directionally predictable movements may enhance warning display and increase the efficacy of the aposematic signal.

Automated summary

This study investigates the association between escape behavior and aposematic versus cryptic coloration in two species of Neotropical frogs. The results show that cryptic-colored C. fitzingeri has faster and less predictable escape behavior than aposematic-colored O. pumilio. This may be due to the adaptive evolution mechanisms where aposematic coloration has relaxed selection on escape behavior, resulting in slower and more predictable movements.