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Graduate StudentDoctoral CandidateLaboratory of Dr. Peter M. Narins (Department of Ecology and Evolutionary Biology) & Center for Tropical Research

Office: Life Sciences 4835

Phone: (310) 206-8407

Laboratory of Dr. Peter M. Narins
Department of Ecology and Evolutionary Biology
University of California, Los Angeles

621 Charles E. Young Drive South, Box 951606
Los Angeles, CA 90095-1606

Center for Tropical Research
Institute of the Environment and Sustainability
University of California, Los Angeles

La Kretz Hall, Suite 300
Box 951496
Los Angeles, CA 90095-1496 USA

(310) 206-4712 phone
(310) 825-5446 fax

Research Interests

The neuroethology and underlying neurophysiology of ultrasonic communication in anuran amphibians (frogs and toads) is the focus of my dissertation research. Until recently, it was believed that only a small group of mammalian hearing “specialists” comprised of microchiropteran bats, cetaceans, and some rodents, was able to communicate in frequencies that surpass the upper-frequency limit of human sensitivity (ca. > 20 kHz). The discovery of non-mammalian vertebrates that communicate ultrasonically presents the possibility of gaining a deeper understanding of the evolutionary, ecological and morphological attributes that confer high-frequency hearing sensitivity in all vertebrate forms.

My research is focused on two Southeast Asian ranid frog species, the Chinese concave-eared torrent frog, Odorrana tormota, and the Bornean hole-in-the-head frog, Huia cavitympanum. The peripheral auditory systems of these species share a highly unusual morphological feature: the tympanic membranes (i.e., eardrums) are recessed into the skull. In contrast, the typical anuran eardrum is flush with the side of the head. Odorranaproduces calls with substantial spectral energy in the ultrasonic frequency range that has been demonstrated to serve a communicative function. Complementary electrophysiological investigations have determined that the upper-frequency hearing sensitivity of O. tormota extends to ~35 kHz. Thus, this is the first known non-mammalian vertebrate to communicate with ultrasound. The species’ recessed tympana are hypothesized to play a critical role in ultrasound reception by facilitating transmission of high-frequency sound waves through the middle-ear.

During the summer of 2007 we traveled to Sarawak, Malaysia, on the island of Borneo, and recorded the vocalizations of H. cavitympanum males with ultrasonically sensitive equipment to determine whether this species’ recessed tympana are also indicative of ultrasonic communication. We found that the Bornean frogs, like their Chinese counterparts, produce high-frequency calls with substantial ultrasonic harmonic energy. In addition, we discovered that a subset of the call repertoire of H. cavitympanum consists of purely ultrasonic signals. This is the first documentation of exclusively ultrasonic signaling in an amphibian. Acoustic playback experiments performed during the subsequent field season demonstrate that the frogs are behaviorally responsive to purely ultrasonic conspecific calls in their natural environment, providing conclusive evidence that this species uses these calls for communication. 

My behavioral research in Borneo is coupled with a multidisciplinary series of laboratory experiments designed to explore the mechanistic bases of ultrasound sensitivity in the peripheral and central auditory systems of O. tormota and H. cavitympanum. I have used electrophysiological techniques to characterize the full frequency-sensitivity range of H. cavitympanum, and found that their hearing sensitivity extends to 38 kHz. In addition, I am mapping the induction of the immediate early gene, egr-1, in the auditory midbrain of O. tormota to characterize differential neuronal activation patterns in response to audible and ultrasonic components of the conspecific call. Finally, I am employing immunohistochemical labeling and confocal microscopy to compare the inner ear and auditory hair cell morphology of these two “ultrasonic” frog species.

CTR Bird

Center for Tropical Research | UCLA Institute of the Environment and Sustainability
La Kretz Hall, Suite 300 | 619 Charles E. Young Dr. East | Los Angeles, CA 90095-1496

The Center for Tropical Research, located on the third floor of La Kretz Hall, is part of the Institute of the Environment and Sustainability at the University of California, Los Angeles. For general inquiries, contact Christa Gomez, CTR Office Manager, at 310-206-6234, or by email at Visitors are always welcome.

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