Multimodal Communication in the Panamanian Golden Frog (Atelopus Zeteki)
Publication Type: |
Thesis |
Year of Publication: |
2008 |
Authors: |
Joni McCullar Criswell |
Publication/Journal: |
Evolution, Ecology, and Organismal Biology Graduate Program |
Publisher: |
Ohio State University |
Keywords: |
amphibians, anuran, dissertation/thesis, multimodal communication, semaphores |
Abstract:
Animals may combine different types of signals (e.g. acoustic, visual, etc.) for multimodal communication. Anuran amphibians (frogs and toads) are well known for their use of acoustic signals in communication. Some anurans also may use visual signals for this purpose. The genus Atelopus (family Bufonidae) produces conspicuous movements of the forelimb and forefoot (semaphores) and provides an excellent opportunity to study multimodal (acoustic and visual) communication in an anuran amphibian.
Results of experiments using model frogs that can produce semaphores suggest that vocalizations and semaphoring actions do indeed function together in biomodal communication in A. zeteki. Target males produced significantly more behavioral responses when acoustic and visual signals were combined compared to signals presented individually. Results of these experiments suggest that semaphores may be important in providing information on the position of males. Data suggest that A. zeteki (which lacks a tympanic middle ear) is relatively ineffective at localizing sound sources, and that visual semaphore signals may facilitate the location of a vocalizing territorial male. Although semaphores occur in communication in A. zeteki, male frogs responded almost equally well to any type of model motion and not just the specific semaphore action. The semaphore is a modified stepping action, and potentially represents an exaptation for functioning in territorial communication occurring between resident and intruding males.
Studies examined the pattern of co-occurrence of semaphores and pulsed vocalizations in male A. zeteki. Signals were more likely to be followed by the same type of signal, and time delays between signals were quite variable. Analysis of the pattern of co-occurrence of semaphores and vocalizations did not provide any additional insight into the role of these signals in multimodal communication.
Field observations established that juvenile A. zeteki also actively semaphore. In fact, semaphoring rates of juveniles were significantly higher than those of adults. However no clear function of juvenile semaphoring was apparent from the field observations.
Tests also examined the potential use of other types of visual signals (vocal sac inflation and body color pattern) in this species. However, no evidence was found that such potential visual signals modify the territorial behavior of male A. zeteki.