Title
Earless toads sense low frequencies but miss the high notes
Date Issued
11 October 2017
Access level
open access
Resource Type
journal article
Author(s)
Womack M.C.
Christensen-Dalsgaard J.
Coloma L.A.
Hoke K.L.
Publisher(s)
Royal Society Publishing
Abstract
Sensory losses or reductions are frequently attributed to relaxed selection. However, anuran species have lost tympanic middle ears many times, despite anurans ’ use of acoustic communication and the benefit of middle ears for hearing airborne sound. Here we determine whether pre-existing alternative sensory pathways enable anurans lacking tympanic middle ears (termed earless anurans) to hear airborne sound as well as eared species or to better sense vibrations in the environment.We used auditory brainstem recordings to compare hearing and vibrational sensitivity among 10 species (six eared, four earless) within the Neotropical true toad family (Bufonidae). We found that species lacking middle ears are less sensitive to highfrequency sounds, however, low-frequency hearing and vibrational sensitivity are equivalent between eared and earless species. Furthermore, extratympanic hearing sensitivity varies among earless species, highlighting potential species differences in extratympanic hearing mechanisms. We argue that ancestral bufonids may have sufficient extratympanic hearing and vibrational sensitivity such that earless lineages tolerated the loss of high frequency hearing sensitivity by adopting species-specific behavioural strategies to detect conspecifics, predators and prey.
Volume
284
Issue
1864
Language
English
OCDE Knowledge area
Zoología, Ornitología, Entomología, ciencias biológicas del comportamiento
Scopus EID
2-s2.0-85030763667
PubMed ID
Source
Proceedings of the Royal Society B: Biological Sciences
ISSN of the container
09628452
Sponsor(s)
Ethics. The Institutional Animal Care and Use Committee at Colorado State University approved all experiments (IACUC Protocol #12-3484A) and the Ministerio del Ambiente in Ecuador and the Servicio Forestal y de Fauna Silvestre in Peru (SERFOR) approved collection, research and export permits (electronic supplementary material, S2). Data accessibility. The hearing and vibration datasets used in this study can be found in electronic supplementary material, S3. Authors’ contributions. M.C.W. and K.L.H. contributed to the conception of the study, data collection, data analysis and writing. J.C.-D. contributed to the ABR methodological design and data collection. L.A.C. and J.C.C. contributed to the sampling design and animal collection. All authors contributed to manuscript editing and gave final approval for publication. Competing interests. We have no competing interests. Funding. This study was supported by the U.S. National Science Foundation (NSF #IOS-13503461350346 and OISE-1157779) as well as the grants-in-aid-of-research fellowship from Sigma Xi (G20111015158047) and the Danish National Research Council (grant no. 1323-00132B to J.C.D.). Acknowledgements. We thank Elicio E. Tapia (CJ), Peter Condori (MUBI) and Amanda Delgado (MHNC) who helped to obtain the wild-caught animals for this study. Special thanks to María Dolores Guarderas (CJ), Amanda Delgado and Florencia Trama (Center for Conservation and Sustainable Development, CDS, Oxapampa, Peru) for facilitating collection and transportation permits. We also thank Jennifer Stynoski for sharing her observations on conspecific communication used by earless species in this study.
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