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Type: Monograph
Published: 2017-04-11
Page range: 1–124
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The use of bioacoustics in anuran taxonomy: theory, terminology, methods and recommendations for best practice

Hessisches Landesmuseum Darmstadt, Friedensplatz 1, 64283 Darmstadt, Germany.
Senckenberg Forschungsinstitut und Naturmuseum, Senckenberganlage 25, 60325 Frankfurt am Main, Germany.
Zoological Institute, Technical University of Braunschweig, Mendelssohnstr. 4, 38106 Braunschweig, Germany. Present address: Institute of Zoology, University of Veterinary Medicine Hannover (TiHo), Bünteweg 17, 30559, Hannover, Germany
Amphibian Evolution Lab, Biology Department, Vrije Universiteit Brussel, 2 Pleinlaan, 1050 Brussels, Belgium. Department of Recent Vertebrates, Royal Belgian Institute of Natural Sciences, 29 rue Vautier, 1000 Brussels, Belgium
Laboratório de História Natural de Anfíbios Brasileiros (LaHNAB), Departamento de Biologia Animal, Instituto de Biologia (IB), Universidade Estadual de Campinas (Unicamp), 13083-970, Caixa Postal 6109, Campinas, São Paulo, Brazil.
Museum für Naturkunde, Leibniz Institute for Evolution and Biodiversity Science, Invalidenstr. 43, 10115 Berlin, Germany.
Zoologische Staatssammlung München (ZSM-SNSB), Münchhausenstr. 21, 81247 München, Germany.
Universidade Estadual Paulista (UNESP), Instituto de Biociências and Centro de Aquicultura (CAUNESP), Câmpus Rio Claro, 13506-900 Rio Claro, São Paulo, Brazil.
Museum für Naturkunde, Leibniz Institute for Evolution and Biodiversity Science, Invalidenstr. 43, 10115 Berlin, Germany.
Zoological Institute, Technical University of Braunschweig, Mendelssohnstr. 4, 38106 Braunschweig, Germany.
Amphibia Anura sound vocalization call note pulse definitions call variation call analysis call description taxonomy species delimitation

Abstract

Vocalizations of anuran amphibians have received much attention in studies of behavioral ecology and physiology, but also provide informative characters for identifying and delimiting species. We here review the terminology and variation of frog calls from a perspective of integrative taxonomy, and provide hands-on protocols for recording, analyzing, comparing, interpreting and describing these sounds. Our focus is on advertisement calls, which serve as premating isolation mechanisms and, therefore, convey important taxonomic information. We provide recommendations for terminology of frog vocalizations, with call, note and pulse being the fundamental subunits to be used in descriptions and comparisons. However, due to the complexity and diversity of these signals, an unequivocal application of the terms call and note can be challenging. We therefore provide two coherent concepts that either follow a note-centered approach (defining uninterrupted units of sound as notes, and their entirety as call) or a call-centered approach (defining uninterrupted units as call whenever they are separated by long silent intervals) in terminology. Based on surveys of literature, we show that numerous call traits can be highly variable within and between individuals of one species. Despite idiosyncrasies of species and higher taxa, the duration of calls or notes, pulse rate within notes, and number of pulses per note appear to be more static within individuals and somewhat less affected by temperature. Therefore, these variables might often be preferable as taxonomic characters over call rate or note rate, which are heavily influenced by various factors. Dominant frequency is also comparatively static and only weakly affected by temperature, but depends strongly on body size. As with other taxonomic characters, strong call divergence is typically indicative of species-level differences, whereas call similarities of two populations are no evidence for them being conspecific. Taxonomic conclusions can especially be drawn when the general advertisement call structure of two candidate species is radically different and qualitative call differences are thus observed. On the other hand, quantitative differences in call traits might substantially vary within and among conspecific populations, and require careful evaluation and analysis. We provide guidelines for the taxonomic interpretation of advertisement call differences in sympatric and allopatric situations, and emphasize the need for an integrative use of multiple datasets (bio-acoustics, morphology, genetics), particularly for allopatric scenarios. We show that small-sized frogs often emit calls with frequency components in the ultrasound spectrum, although it is unlikely that these high frequencies are of biological relevance for the majority of them, and we illustrate that detection of upper harmonics depends also on recording distance because higher frequencies are attenuated more strongly. Bioacoustics remains a prime approach in integrative taxonomy of anurans if uncertainty due to possible intraspecific variation and technical artifacts is adequately considered and acknowledged.

 

References

  1. Acevedo, M.A., Corrada-Bravo, C.J., Corrado-Bravo, H., Villanueva-Rivera, L.J. & Aide, T.M. (2009) Automated classification of bird and amphibian calls using machine learning: A comparison of methods. Ecological Informatics, 4, 206–214.
    https://doi.org/10.1016/j.ecoinf.2009.06.005

    Acevedo, M.A. & Villanueva-Rivera, L.J. (2006) Using automated digital recording systems as effective tools for the monitoring of birds and amphibians. Wildlife Society Bulletin, 34, 211–214.
    https://doi.org/10.2193/0091-7648(2006)34[211:UADRSA]2.0.CO;2

    Aide, T.M., Corrada-Bravo, C., Campos-Cerqueira, M., Milan, C., Vega, G. & Alvarez, R. (2013) Real-time bioacoustics monitoring and automated species identification. PeerJ, 1, e103.
    https://doi.org/10.7717/peerj.103

    Akmentins, M.S., Pereyra, L.C., Sanabria, E.A. & Vaira, M. (2014) Patterns of daily and seasonal calling activity of a direct-developing frog of the subtropical Andean forests of Argentina. Bioacoustics, 24, 89–99.
    https://doi.org/10.1080/09524622.2014.965217

    Alonso, R., Rodríguez, A. & Márquez, R. (2007) Guía sonora de los anfibios de Cuba. Alosa, sons de la natura, FonoZoo Barcelona, Spain. [audio CD]

    Alström, P. & Ranft, R. (2003) The use of sounds in avian systematics and the importance of bird sound archives. Bulletin of the British Ornithologists’ Club, 123A, 113–135.

    Amézquita, A. (1999) Color pattern, elevation and body size in the high Andean frog Hyla labialis. Revista de la Academia Colombiana de Ciencias Exactas Fisicas y Naturales, 23, 231–238.

    Amézquita, A., Lima, A.P., Jehle, R., Castellanos, L., Ramos, O., Crawford, A.J., Gasser, H. & Hödl, W. (2009) Calls, colours, shapes, and genes: a multi-trait approach to the study of geographic variation in the Amazonian frog Allobates femoralis. Biological Journal of the Linnean Society, 9, 826–838.
    https://doi.org/10.1111/j.1095-8312.2009.01324.x

    Amiet J.-L. (1989) Images d’amphibiens camerounais. II. L’enfouissement et la phonation bouche ouverte chez Conraua crassipes (Buchholz & Peters, 1875). Alytes, 8, 99–104.

    Amorim, M.C.P. & Hawkins, A.D. (2000) Growling for food: acoustic emissions during competitive feeding of streaked gurnard. Journal of Fish Biology, 57, 895–907.
    https://doi.org/10.1111/j.1095-8649.2000.tb02200.x

    Amorim, M.C.P., Stratoudakis, Y. & Hawkins, A.D. (2004) Sound production during competitive feeding in the grey gurnard. Journal of Fish Biology, 65, 182–184.
    https://doi.org/10.1111/j.0022-1112.2004.00443.x

    Arch, V.S., Grafe, T.U., Gridi-Papp, M. & Narins, P.M. (2009) Pure ultrasonic communication in an endemic Bornean frog. PLoS One, 4, e5413.
    https://doi.org/10.1371/journal.pone.0005413

    Arch, V.S., Grafe, T.U. & Narins, P.M. (2008) Ultrasonic signalling by a Bornean frog. Biology Letters, 4, 19–22.
    https://doi.org/10.1098/rsbl.2007.0494

    Arch, V.S. & Narins, P.M. (2009) Sexual hearing: the influence of sex hormones on acoustic communication in frogs. Hearing Research, 252, 15–20.
    https://doi.org/10.1016/j.heares.2009.01.001

    Arch, V.S., Simmons, D.D., Quiñones, P.M., Feng, A.S., Jiang, J., Stuart, B.L., Shen, J.X., Blair, C. & Narins, P.M. (2012) Inner ear morphological correlates of ultrasonic hearing in frogs. Hearing Research, 283, 70–79.
    https://doi.org/10.1016/j.heares.2011.11.006

    Arntzen, J.W., McAtear, J., Recuero, E., Ziermann, J.M., Ohler, A., van Alphen, J. & Martínez-Solano, I. (2013) Morphological and genetic differentiation of Bufo toads: two cryptic species in Western Europe (Anura, Bufonidae). Contributions to Zoology, 82, 147–169.

    Baker, M.C. (2001) Bird song research: the past 100 years. Bird Behavior, 14, 3–50.

    Baraquet, M., Grenat, P.R., Salas, N.E. & Martino, A.L. (2015) Geographic variation in the advertisement call of Hypsiboas cordobae (Anura, Hylidae). Acta Ethologica, 18, 79–86.
    https://doi.org/10.1007/s10211-014-0188-2

    Bardeli, R., Wolff, D., Kurth, F., Koch, M., Tauchert, K.H. & Frommolt, K.H. (2010) Detecting bird sounds in a complex acoustic environment and application to bioacoustic monitoring. Pattern Recognition Letters, 31, 1524–1534.
    https://doi.org/10.1016/j.patrec.2009.09.014

    Barej, M.F., Schmitz, A., Penner, J., Doumbia, J., Sandberger-Loua, L., Hirschfeld, M., Brede, C., Emmrich, M., Kouamé, N.G., Hillers, A., Gonwouo, N.L., Nopper, J., Adeba, P.J., Bangoura, M.A., Gage, C., Anderson, G. & Rödel, M.-O. (2015) Life in the spray zone – overlooked diversity in West African torrent-frogs (Anura, Odontobatrachidae, Odontobatrachus). Zoosystematics and Evolution, 91, 115–149.
    https://doi.org/10.3897/zse.91.5127

    Bee, M.A. (2003) A test of the "dear enemy effect" in the strawberry dart-poison frog (Dendrobates pumilio). Behavioral Ecology and Sociobiology, 54, 601–610.
    https://doi.org/10.1007/s00265-003-0657-5

    Bee, M.A. (2004a) Within-individual variation in bullfrog vocalizations: implications for a vocally mediated social recognition system. Journal of the Acoustic Society of America, 116, 3770–3781.
    https://doi.org/10.1121/1.1784445

    Bee, M.A. (2004b) Sound Ruler acoustical analysis: a free, open code, multi-platform sound analysis and graphing package. Bioacoustics, 14, 171–178.
    https://doi.org/10.1080/09524622.2004.9753520

    Bee, M.A., Cook, J.M., Love, E.K., O’Brian, L.R., Pettitt, B.A., Schrode, K. & Vélez, A. (2010) Assessing acoustic signal variability and the potential for sexual selection and social recognition in Boreal Chorus Frogs (Pseudacris maculata). Ethology, 116, 564–576.
    https://doi.org/10.1111/j.1439-0310.2010.01773.x

    Bee, M.A. & Gerhardt, H.C. (2001) Neighbour-stranger discrimination by territorial male bullfrogs (Rana catesbeiana): I. Acoustic basis. Animal Behaviour, 62, 1129–1140.
    https://doi.org/10.1006/anbe.2001.1851

    Bee, M.A. & Gerhardt, H.C. (2002) Individual voice recognition in a territorial frog (Rana catesbeiana). Proceedings of the Royal Society of London Series B, 269, 1443–1448.
    https://doi.org/10.1098/rspb.2002.2041

    Bee, M.A., Kozich, C.E., Blackwell, K.J. & Gerhardt, H.C. (2001) Individual variation in advertisement calls of territorial male green frogs, Rana clamitans: implications for individual discrimination. Ethology, 107, 65–84.
    https://doi.org/10.1046/j.1439-0310.2001.00640.x

    Bee, M.A. & Perrill, S.A. (1996) Responses to conspecific advertisement calls in the green frog (Rana clamitans) and their role in male-male communication. Behaviour, 133, 283–301.
    https://doi.org/10.1163/156853996X00152

    Bee, M.A., Perrill, S.A. & Owen, P.C. (2000) Male green frogs lower the pitch of acoustic signals in defense of territories: a possible dishonest signal of size? Behavioral Ecology, 11, 169–177.
    https://doi.org/10.1093/beheco/11.2.169

    Bee, M.A., Reichert, M.S. & Tumulty, J.P. (2016) Assessment and recognition of rivals in anuran contests. Advances in the Study of Behavior, 48, 161–249.
    https://doi.org/10.1016/bs.asb.2016.01.001

    Bee, M.A., Suyesh, R. & Biju, S.D. (2013a) Vocal behavior of the Ponmudi Bush Frog (Raorchestes graminirupes): repertoire and individual variation. Herpetologica, 69, 22–35.
    https://doi.org/10.1655/HERPETOLOGICA-D-11-00042

    Bee, M.A., Suyesh, R. & Biju. S.D. (2013b) The vocal repertoire of Pseudophilautus kani, a shrub frog (Anura: Rhacophoridae) from the Western Ghats of India. Bioacoustics, 22, 67–85.
    https://doi.org/10.1080/09524622.2012.712750

    Beeman, K. (1998) Digital signal analysis, editing, and synthesis. In: Hopp, S.L., Owren, M.J. & Evans, C.S. (Eds.), Animal Acoustic Communication: Sound Analysis and Research Methods. Springer Verlag, Berlin, pp. 59–103.
    https://doi.org/10.1007/978-3-642-76220-8_3

    Belanger, R. & Corkum, L. (2009) Review of aquatic sex pheromones and chemical communication in anurans. Journal of Herpetology, 43, 184–191.
    https://doi.org/10.1670/08-054R1.1

    Benevides, F.L. & Mautz, W.J. (2014) Temporal and spectral characteristics of the male Eleutherodactylus coqui two-note vocalization in Hawaii. Bioacoustics, 23, 29–38.
    https://doi.org/10.1080/09524622.2013.805308

    Bernal, X.E., Guarnizo, C. & Lüddecke, H. (2005) Geographic variation in the advertisement call and genetic structure of the Andean frog Colostethus palmatus. Herpetologica, 61, 395–408.
    https://doi.org/10.1655/04-87.1

    Bevier, C.R., Larson, K., Reilly, K. & Tat, S. (2004) Vocal repertoire and calling activity of the mink frog, Rana septentrionalis. Amphibia-Reptilia, 25, 255–264.
    https://doi.org/10.1163/1568538041975107

    Bickford, D., Iskandar, D.T. & Barlian, A. (2008) A lungless frog discovered on Borneo. Current Biology, 18, R374–R375.
    https://doi.org/10.1016/j.cub.2008.03.010

    Bickford, D., Lohman, D.J., Sodhi, N.S., Ng, P.K.L., Meier, R., Winker, K., Inram, K.K. & Das, I. (2006) Cryptic species as a window on diversity and conservation. Trends in Ecology and Evolution, 22, 148–155.
    https://doi.org/10.1016/j.tree.2006.11.004

    Bioacoustics Research Program (2011) Raven Pro: interactive sound analysis software (Version 1.4). The Cornell Lab of Ornithology, Ithaca, New York. Available from: http://www.birds.cornell.edu/raven (accessed 8 February 2017)

    Blair, W.F. (1955) Mating call and stage of speciation in the Microhyla olivacea-M. carolinensis complex. Evolution, 9, 469–480.
    https://doi.org/10.2307/2405481

    Blair, W.F. (1956a) Call difference as an isolating mechanism in southwestern toads (genus Bufo). Texas Journal of Science, 8, 87–106.

    Blair, W.F. (1956b) The mating call of hybrid toads. Texas Journal of Science, 8, 350–355.

    Blair, W.F. (1963) Acoustic behaviour of Amphibia. In: Busnel, R.G. (Ed.), Acoustic behaviour of animals. Elsevier, New York, pp. 694–708.

    Blair, W.F. (1964) Isolating mechanisms and interspecies interactions in anuran amphibians. The Quarterly Review of Biology, 39, 334–344.
    https://doi.org/10.1086/404324

    Blair, W.F. (1968) Amphibians and reptiles. In: Sebeok, T.A (Ed.), Animal communication. Indiana University Press, Bloomington, pp. 289–310.

    Blair, W.F. (1974) Character displacement in frogs. American Zoologist, 14, 1119–1125.
    https://doi.org/10.1093/icb/14.4.1119

    Blumstein, D.T., Mennill, D.J., Clemins, P., Girod, L., Yao, K., Patricelli, G., Deppe, J.L., Krakauer, A.H., Clark, C., Cortopassi, K.A., Hanser, S.F., McCowan, B., Ali, A.M. & Kirschel, A.N.G. (2011) Acoustic monitoring in terrestrial environments using microphone arrays: applications, technological considerations and prospectus. Journal of Applied Ecology, 48, 758–767.
    https://doi.org/10.1111/j.1365-2664.2011.01993.x

    Boake, C.R.B. (1989) Repeatability: its role in evolutionary studies of mating behaviour. Evolutionary Ecology, 3, 173–182.
    https://doi.org/10.1007/BF02270919

    Boatright-Horowitz, S.S., Cheney, C.A. & Simmons, A.M. (1999) Atmospheric and underwater propagation of bullfrog vocalizations. Bioacoustics, 9, 57–80.
    https://doi.org/10.1080/09524622.1999.9753404

    Boeckle, M., Preininger, D. & Hödl, W. (2009) Communication in noisy environments I: acoustic signals of Staurois latopalmatus Boulenger 1887. Herpetologica, 65, 154–165.
    https://doi.org/10.1655/07-071R1.1

    Bogert, C.M. (1960) The influence of sound on the behavior of amphibians and reptiles. In: Lanyon, W.E. & Tavolga, W.N. (Eds.) Animal sounds and communication. AIBS, Washington, DC, pp. 137–320.

    Boistel, R. & Sueur, J. (1997) Comportement sonore de la femelle de Platymantis vitiensis (Amphibia, Anura) en l’absence du mâle. Comptes Rendus de l'Académie des Sciences - Séries III - Sciences de la Vie, 320, 933–941.
    https://doi.org/10.1016/s0764-4469(97)80879-7

    Bokermann W.C.A. (1974) Observações sobre desenvolvimento precoce em Sphaenorhynchus bromelicola Bok, 1966 (Anura, Hylidae). Revista Brasileira de Biologia, 34, 35–41.

    Bosch, J. & De la Riva, I. (2004) Are frog calls modulated by the environment? An analysis with anuran species from Bolivia. Canadian Journal of Zoology, 82, 880–888.
    https://doi.org/10.1139/z04-060

    Both, C. & Grant, T. (2012) Biological invasions and the acoustic niche: the effect of bullfrog calls on the acoustic signals of white banded tree frogs. Biology Letters, 8, 714–716.
    https://doi.org/10.1098/rsbl.2012.0412

    Boul, K.E., Funk, W.C., Darst, C.R., Cannatella, D.C. & Ryan, M.J. (2007) Sexual selection drives speciation in an Amazonian frog. Proceedings of the Royal Society of London B, 274, 399–406.
    https://doi.org/10.1098/rspb.2006.3736

    Bourne, G.R., Collins, A.C., Holder, A.M. & McCarthy, C.L. (2001) Vocal communication and reproductive behavior of the frog Colostethus beebei in Guyana. Journal of Herpetology, 34, 272–281.
    https://doi.org/10.2307/1566118

    Bradbury, J.W. & Vehrencamp, S.L. (2011) Principles of animal communication. Vol. 2. Sinauer Associates, Sunderland, 697 pp.

    Brenowitz, E.A., Rose, G. & Capranica, R.R. (1985) Neural correlates of temperature coupling in the vocal communication system of the gray treefrog (Hyla versicolor). Brain Research, 359, 364–367.
    https://doi.org/10.1016/0006-8993(85)91452-0

    Brepson, L., Voituron, Y. & Lengagne, T. (2013) Condition-dependent ways to manage acoustic signals under energetic constraint in a tree frog. Behavioral Ecology, 24, 488–496.
    https://doi.org/10.1093/beheco/ars189

    Bridges, A.S. & Dorcas, M.E. (2000) Temporal variation in anuran calling behavior: implications for surveys and monitoring programs. Copeia, 2000, 587–592.
    https://doi.org/10.1643/0045-8511(2000)000[0587:TVIACB]2.0.CO;2

    Briggs, V.S. (2010) Call trait variation in Morelett´s tree frog, Agalychnis moreletii, of Belize. Herpetologica, 66, 241–249.
    https://doi.org/10.1655/HERPETOLOGICA-D-09-00011.1

    Broughton, W.B. (1963) Method in bio-acoustic terminology. In: Busnel, R.G. (Ed.), Acoustic behaviour of animals, Elsevier, Amsterdam, pp. 3–24.

    Brown, W.L. & Wilson, E.O. (1956) Character displacement. Systematic Zoology, 5, 49–65.
    https://doi.org/10.2307/2411924

    Brumm, H. (2013) Animal Communication and Noise. Springer, Berlin Heidelberg, 453 pp.
    https://doi.org/10.1007/978-3-642-41494-7

    Brumm, H. & Slabbekoorn, H. (2005) Acoustic communication in noise. Advances in the Study of Behavior, 35, 151–209.
    https://doi.org/10.1016/S0065-3454(05)35004-2

    Brzoska, J. & Obert, H.-J. (1980) Acoustic signals influencing the hormone production of the testes in the grass frog. Journal of Comparative Physiology A, 140, 25–29.
    https://doi.org/10.1007/BF00613744

    Burmeister, S., Somes, C. & Wilczynski, W. (2001) Behavioral and hormonal effects of exongenous vasotocin and corticosterone in the green treefrog. General and Comparative Endocrinology, 122, 189–197.
    https://doi.org/10.1006/gcen.2001.7625

    Byrne, P. & Keogh, J. (2007) Terrestrial toadlets use chemosignals to recognize conspecifics, locate mates and strategically adjust calling behaviour. Animal Behaviour, 74, 1155–1162.
    https://doi.org/10.1016/j.anbehav.2006.10.033

    Čađenović, N., Vukov, T., Popović, E. & Ljubisavljević, K. (2013) Morphological differentiation of the common toad Bufo bufo (Linnaeus, 1758) in the central part of the Balkan Peninsula. Archives of Biological Science Belgrade, 65, 685–695.
    https://doi.org/10.2298/ABS1302685C

    Caldwell, M.S., Johnston, G.R., McDaniel, J.G. & Warkentin, K.M. (2010) Vibrational signaling in the agonistic interactions of red-eyed treefrogs. Current Biology, 20, 1012–1017.
    https://doi.org/10.1016/j.cub.2010.03.069

    Cardoso, A.J. & Heyer, W.R. (1995) Advertisement, aggressive, and possible seismic signals of the frog Leptodactylus syphax (Amphibia, Leptodactylidae). Alytes, 13, 67–76.

    Carvalho, J.E., Gomes, F.R. & Navas, C.A. (2008) Energy substrate utilization during nightly vocal activity in three species of Scinax (Anura/Hylidae). Journal of Comparative Physiology B, 178, 447–456.
    https://doi.org/10.1007/s00360-007-0236-6

    Castellano, S. & Gamba, M. (2011) Marathon callers: acoustic variation during sustained calling in treefrogs. Ethology Ecology & Evolution, 23, 329–342.
    https://doi.org/10.1080/03949370.2011.575801

    Castellano, S. & Giacoma, C. (1998) Stabilizing and directional female choice for male calls in the European green toad. Animal Behaviour, 56, 275–287.
    https://doi.org/10.1006/anbe.1998.0784

    Castellano, S., Giacoma, C. & Dujsebayeva, T. (2000) Morphometric and advertisement call geographic variation in polyploid green toads. Biological Journal of the Linnean Society, 70, 341–360.
    https://doi.org/10.1111/j.1095-8312.2000.tb00214.x

    Castellano, S., Giacoma, C., Dujsebayeva, T., Odierna, G. & Balletto, E. (1998) Morphometrical and acoustical comparison between diploid and tetraploid green toads. Biological Journal of the Linnean Society, 63, 257–281.
    https://doi.org/10.1111/j.1095-8312.1998.tb01517.x

    Castellano, S., Cuatto, B., Rosalba, R., Rosso, A. & Giacoma, C. (2002b) The advertisement call of the European treefrogs (Hyla arborea): a multilevel study of variation. Ethology, 108, 75–89.
    https://doi.org/10.1046/j.1439-0310.2002.00761.x

    Castellano, S., Tonttini, L., Giacoma, C., Lates, A. & Balletto, E. (2002a) The evolution of the release and advertisement calls in the Green Toads (Bufo viridis complex). Biological Journal of the Linnean Society, 77, 379–391.
    https://doi.org/10.1046/j.1095-8312.2002.00118.x

    Castellano, S. & Rosso, A. (2006) Variation in call temporal properties and female preferences in Hyla intermedia. Behaviour, 143, 405–424.
    https://doi.org/10.1163/156853906776240650

    Catchpole, C.K. & Slater, P.J.B. (2008) Bird Song: Biological Themes and Variations. 2nd Edition. Cambridge University Press, Cambridge, 335 pp.
    https://doi.org/10.1017/CBO9780511754791

    Cei, J.M. & Roig, V.G. (1965) The systematic status and biology of Telmatobius montanus Lataste (Amphibia, Leptodactylidae). Copeia, 1965, 421–425.
    https://doi.org/10.2307/1440989

    Channing, A., Hillers, A., Lötters, S., Rödel, M.-O., Schick, S., Conradie, W., Rödder, D., Mercurio, V., Wagner, P., Dehling, J.M., Du Preez, L.H., Kielgast, J. & Burger, M. (2013) Taxonomy of the super-cryptic Hyperolius nasutus group of long reed frogs of Africa (Anura: Hyperoliidae), with descriptions of six new species. Zootaxa, 3620 (3), 301–350.
    https://doi.org/10.11646/zootaxa.3620.3.1

    Charif, R.A., Waack, A.M. & Strickman, L.M. (2010) Raven Pro 1.4 User’s Manual. Cornell Laboratory of Ornithology, Ithaca, NY, 379 pp.

    Che, J., Chen, H.M., Yang, J.X., Jin, J.Q., Jiang, K., Yuan, Z.Y., Murphy, R.W. & Zhang, Y.P. (2012) Universal COI primers for DNA barcoding amphibians. Molecular Ecology Resources, 12, 247–258.
    https://doi.org/10.1111/j.1755-0998.2011.03090.x

    Christensen-Dalsgaard, J., Ludwing, T.A. & Narins, P.M. (2002) Call diversity in an Old World treefrog: level dependence and latency of acoustic responses. Bioacoustics, 13, 21–35.
    https://doi.org/10.1080/09524622.2002.9753484

    Chu, J., Marler, C.A. & Wilczynski, W. (1998) The effects of arginine vasotocin on the calling behavior of male cricket frogs in changing social contexts. Hormones and Bahavior, 34, 248–261.
    https://doi.org/10.1006/hbeh.1998.1479

    Clarke, E., Reichard, U.H. & Zuberbühler, K. (2006) The syntax and meaning of wild gibbon songs. PLoS One, 1, e73.
    https://doi.org/10.1371/journal.pone.0000073

    Cocroft, R., Morales, V.R. & McDiarmid, R.W. (2001) Frogs of Tambopata, Peru. Cornell Laboratory of Ornithology, Macaulay library of naturals sounds, New York, USA. [audio CD]

    Cocroft, R.B. & Ryan, M.J. (1995) Patterns of advertisement call evolution in toads and chorus frogs. Animal Behaviour, 49, 283–303.
    https://doi.org/10.1006/anbe.1995.0043

    Colleye, O. & Parmentier, E. (2012) Overview on the diversity of sounds produced by clownfishes (Pomacentridae): importance of acoustic signals in their peculiar way of life. PLoS One, 7, e49179.
    https://doi.org/10.1371/journal.pone.0049179

    Collias, N.E. (1960) An ecological and functional classification of animal sounds. In: Lanyon, W.E. & Tavolga, W.N. (Eds.), Animal sounds and communication. Intelligencer Printing Company, Washington, D.C., pp. 368–391.

    Cooley, J.R. (2007) Decoding asymmetries in reproductive character displacement. Proceedings of the Academy of Natural Sciences of Philadelphia, 156, 89–96.
    https://doi.org/10.1635/0097-3157(2007)156[89:DAIRCD]2.0.CO;2

    Cowlishaw, G. (1992) Song function in gibbons. Behaviour, 121, 131–153.
    https://doi.org/10.1163/156853992X00471

    Coyne, J. & Orr, H.A. (2004) Speciation. Sinauer Associates, Massachusetts, 545 pp.

    Crawford, A.J., Cruz, C., Griffith, E., Ross, H., Ibáñez, R., Lips, K.R., Driskell, A.C., Bermingham, E. & Crump, P. (2013) DNA barcoding applied to ex situ tropical amphibian conservation programme reveals cryptic diversity in captive populations. Molecular Ecology Resources, 13, 1005–1018.

    Crawford, A.J., Lips, K.R. & Bermingham, E. (2010) Epidemic disease decimates amphibian abundance, species diversity, and evolutionary history in the highlands of central Panama. Proceedings of the National Academy of Sciences of the U.S.A., 107, 13777–13782.
    https://doi.org/10.1073/pnas.0914115107

    Cugler, D.C., Medeiros, C.B. & Toledo, L.F. (2011) Managing animal sounds - some challenges and research directions. Proceedings V eScience Workshop-XXXI Brazilian Computer Society Conference, 2011, 174.

    Cunnington, G.M. & Fahrig, L. (2010) Plasticity in the vocalizations of anurans in response to traffic noise. Acta Oecologica, 36, 463–470.
    https://doi.org/10.1016/j.actao.2010.06.002

    Davis, M.S. (1987) Acoustically mediated neighbor recognition in the North American bullfrog, Rana catesbeiana. Behavioral Ecology and Sociobiology, 21, 185–190.
    https://doi.org/10.1007/BF00303209

    Davies, N.B. & Halliday, T.R. (1978) Deep croaks and fighting assessment in toads, Bufo bufo. Nature, 274, 683–685.
    https://doi.org/10.1038/274683a0

    Davies, N.B., Krebs, J.R. & West, S.A. (2012) An Introduction to Behavioural Ecology. 4th Edition. Wiley-Blackwell, Chichester, 520 pp.

    Dawson, B. & Ryan, M.J. (2009) Early experience leads to changes in the advertisement calls of male Physalaemus pustulosus. Copeia, 2009, 221–226.
    https://doi.org/10.1643/CE-07-254

    Dayrat, B. (2005) Toward integrative taxonomy. Biological Journal of the Linnean Society, 85, 407–415.
    https://doi.org/10.1111/j.1095-8312.2005.00503.x

    de Araújo, C.B., Marcondes Machado, L.O. & Vielliard, J.M.E. (2011) Vocal repertoire of the Yellow-Faced Parrot (Alipiopsitta xanthops). The Wilson Journal of Ornithology, 123, 603–608.
    https://doi.org/10.1676/10-102.1

    De Jongh, H.J. & Gans, C. (1969) On the mechanism of respiration in the bullfrog, Rana catesbeiana: a reassessment. Journal of Morphology, 127, 259–290.
    https://doi.org/10.1002/jmor.1051270302

    De la Nuez, D. (2007) Variación intraespecífica de la llamada de anuncio y aspectos eto-ecológicos de la conducta vocal de Eleutherodactylus glamyrus (Anura: Leptodactylidae). BSc. Thesis., Universidad de La Habana, Havana, 86 pp.

    De Sá, F.P., Zina, J. & Haddad, C.F.B. (2016) Sophisticated communication in the Brazilian torrent frog Hylodes japi. PLoS One, 11, e0145444.
    https://doi.org/10.1371/journal.pone.0145444

    Delgado, D.B. & Haddad, C.F.B. (2015) Calling activity and vocal repertoire of Hypsiboas prasinus (Anura, Hylidae), a treefrog from the Atlantic forest of Brazil. Herpetologica, 71, 88–95.
    https://doi.org/10.1655/HERPETOLOGICA-D-13-00071

    Depraetere, M., Pavoine, S., Jiguet, F., Gasc, A., Duvail, S. & Sueur, J. (2012) Monitoring animal diversity using acoustic indices: implementation in a temperate woodland. Ecological Indicators, 13, 46–54.
    https://doi.org/10.1016/j.ecolind.2011.05.006

    De Queiroz, K. (1998) The general lineage concept of species, species criteria, and the process of speciation: a conceptual unification and terminological recommendations. In: Howard, D.J. & Berlocher, S.H. (Eds.), Endless forms: Species and speciation. Oxford University Press, New York, pp. 57–75.

    De Queiroz, K. (2007) Species concepts and species delimitation. Systematic Biology, 56, 879–886.
    https://doi.org/10.1080/10635150701701083

    Dobzhansky, T. (1937) Genetics and the Origin of Species. Columbia University Press, New York, 364 pp.

    Dobzhansky, T. (1940) Speciation as a stage in evolutionary divergence. American Naturalist, 74, 312–321.
    https://doi.org/10.1086/280899

    Docherty, S., Bishop, P.J. & Passmore, N.I. (2000) Consistency of calling performance in male Hyperolius marmoratus marmoratus: implications for male mating success. African Journal of Herpetology, 49, 43–52.
    https://doi.org/10.1080/21564574.2000.9650015

    Dodd, C.K. Jr. (2013) Frogs of the United States and Canada. 2 Vols. Johns Hopkins University Press, Baltimore, xxvii + 962 pp.

    Dubnov, S. (2004) Generalization of spectral flatness measure for non-Gaussian linear processes. IEEE Signal Processing Letters, 11, 698–701.
    https://doi.org/10.1109/LSP.2004.831663

    Dudley, R. & Rand, A.S. (1991) Sound production and vocal sac inflation in the Túngara frog, Physalaemus pustulosus (Leptodactylidae). Copeia, 1991, 460–470.
    https://doi.org/10.2307/1446594

    Dudley, R. & Rand, A.S. (1992) Underwater sound production in a Neotropical anuran, Physalaemus pustulosus (Leptodactylidae). Bioacoustics, 4, 211–216.
    https://doi.org/10.1080/09524622.1992.9753222

    Duellman, W.E. (1963) Importance of breeding call in amphibian systematics. Proceedings of the International Congress of Zoology, 16, 106–110.

    Duellman, W.E. & Trueb, L. (1994) Biology of Amphibians. The Johns Hopkins University Press, Baltimore, 670 pp.

    Du Preez, L. & Carruthers, V. (2009) A complete Guide to the Frogs of Southern Africa. Struik Nature, Cape Town, 488 pp. [with audio CD]

    Dyson, M.L., Reichert, M.S. & Halliday, T. (2013) Contests in amphibians. In: Hardy, I.C. W. & Briffa, M. (Eds), Animal contests. Cambridge University Press, Cambridge, pp. 228–257.
    https://doi.org/10.1017/cbo9781139051248.013

    Edds-Walton, P.L. (1997) Acoustic communication signals of mysticete whales. Bioacoustics, 8, 47–60.
    https://doi.org/10.1080/09524622.1997.9753353

    Elliott, L., Gerhardt, C. & Davidson, C. (2009) The Frogs and Toads of North America: A Comprehensive Guide to their Identification, Behavior and Calls. Houghton Mifflin Harcourt, Boston, 344 pp. [with audio CD]

    Emerson, S.B. & Boyd, S.K. (1999) Mating vocalizations of female frogs: control and evolutionary mechanisms. Brain, Behavior and Evolution, 53, 187–197.
    https://doi.org/10.1159/000006594

    Emerson, S.B. & Hess, D.L. (1996) The role of androgens in opportunistic breeding tropical frogs. General and Comparative Endocrinology, 103, 220–230.
    https://doi.org/10.1006/gcen.1996.0113

    Emerson, S.B. & Hess, D.L. (2001) Glucocorticoids, androgens, testis mass, and the energetics of vocalization in breeding male frogs. Hormones and Behavior, 39, 59–69.
    https://doi.org/10.1006/hbeh.2000.1635

    Erdtmann, L.K. & Lima,A.P. (2013) Environmental effects on anuran call design: what we know and what we need to know. Ethology Ecology & Evolution, 25, 1–11.
    https://doi.org/10.1080/03949370.2012.744356

    Ey, E. & Fischer, J. (2009) The “acoustic adaptation hypothesis” - a review of the evidence from birds, anurans and mammals. Bioacoustics, 19, 21–48.
    https://doi.org/10.1080/09524622.2009.9753613

    Faria, D.C. do C., Signorelli, L., de Morais, A.R., Bastos, R.P. & Maciel, N.M. (2013) Geographic structure and acoustic variation in populations of Scinax squalirostris (A. Lutz, 1925) (Anura: Hylidae). North-Western Journal of Zoology, 9, 329–336.

    Feng, A.S., Arch, V.S., Yu, Z., Yu, X.-J., Xu, Z.M. & Shen, J.X. (2009a) Neighbor–stranger discrimination in Concave-eared Torrent Frogs, Odorrana tormota. Ethology, 115, 851–856.
    https://doi.org/10.1111/j.1439-0310.2009.01666.x

    Feng, A.S. & Narins, P.M. (2008) Ultrasonic communication in concave-eared torrent frogs (Amolops tormotus). Journal of Comparative Physiology A, 194, 159–167.
    https://doi.org/10.1007/s00359-007-0267-1

    Feng, A.S., Narins, P.M., Xu, C.H., Lin, W.Y., Yu, Z.L., Qiu, Q., Xu, Z.M. & Shen, J.X. (2006) Ultrasonic communication in frogs. Nature, 440, 333–336.
    https://doi.org/10.1038/nature04416

    Feng, A.S., Riede, T., Arch, V.S., Yu, Z., Xu, Z.-M., Yu, X.-J. & Shen, J.-X. (2009b) Diversity of the vocal signals of Concave-eared Torrent Frogs (Odorrana tormota): evidence for individual signatures. Ethology, 115, 1015–1028.
    https://doi.org/10.1111/j.1439-0310.2009.01692.x

    Forester, D.C. (1973) Mating call as a reproductive isolating mechanism between Scaphiopus bombifrons and S. hammondii. Copeia, 1973, 60–67.
    https://doi.org/10.2307/1442358

    Forrest, T.G. (1994) From sender to receiver: propagation and environmental effects on acoustic signals. American Zoologist, 34, 644–654.
    https://doi.org/10.1093/icb/34.6.644

    Forti, L.R., Costa, W.P., Martins, L.B., Nunes-de-Almeida, C.H.L. & Toledo, L.F. (2016) Advertisement call and genetic structure conservatism: good news for an endangered Neotropical frog. PeerJ, 4, e2014.
    https://doi.org/10.7717/peerj.2014

    Forti, L.R., Márquez, R. & Bertoluci, J. (2015) Advertisement call of Dendropsophus microps (Anura: Hylidae) from two populations of southeastern Brazil. Zoologia, 32, 187–194.
    https://doi.org/10.1590/S1984-46702015000300002

    Forti, L.R., Martins, F.A.M. & Bertoluci, J. (2012) Advertisement call and geographical variation in call features of Dendropsophus berthalutzae (Anura: Hylidae) from the Atlantic Rainforest of southeastern Brazil. Zootaxa, 3310, 66–68.

    Fouquet, A., Gilles, A., Vences, M., Marty, C., Blanc, M. & Gemmell, N.J. (2007) Underestimation of species richness in Neotropical frogs revealed by mtDNA analyses. PLoS One, 2, e1109.
    https://doi.org/10.1371/journal.pone.0001109

    Fouquet, A., Martinez, Q., Zeidler, L., Courtois, E.A., Gaucher, P., Blanc, M., Lima, J.D., Marques Souza, S., Rodrigues, M.T. & Kok, P.J.R. (2016) Cryptic diversity in the Hypsiboas semilineatus species group (Amphibia, Anura) with the description of a new species from the eastern Guiana Shield. Zootaxa, 4084 (1), 79–104.
    https://doi.org/10.11646/zootaxa.4084.1.3

    Fouquette, M.J. (1975) Speciation in chorus frogs. I. Reproductive character displacement in the Pseudacris nigrita complex. Systematic Zoology, 24, 16–22.
    https://doi.org/10.2307/2412694

    Friedl, T.W.P. (2006) Individual male calling pattern and male mating success in the European Treefrog (Hyla arborea): is there evidence for directional or stabilizing selection on male calling behaviour? Ethology, 112, 116–126.
    https://doi.org/10.1111/j.1439-0310.2005.01132.x

    Friedl, T.W.P. & Klump G.M. (2002) The vocal behaviour of male European treefrogs (Hyla arborea): implications for inter- and intrasexual selection. Behaviour, 139, 113–136.
    https://doi.org/10.1163/15685390252902319

    Frommolt, K.-H. (1999) Sidebands – facts and artifacts. Bioacoustics, 10, 219–224.
    https://doi.org/10.1080/09524622.1999.9753432

    Frommolt, K.-H. & Tauchert, K.-H. (2014) Applying bioacoustic methods for long-term monitoring of a nocturnal wetland bird. Ecological Informatics, 21, 4–12.
    https://doi.org/10.1016/j.ecoinf.2013.12.009

    Frommolt, K.H., Kaufmann, M., Mante, S. & Zadow, M. (2008) Die Lautäußerungen der Knoblauchkröte (Pelobates fuscus) und Möglichkeiten einer akustischen Bestandserfassung der Art. Rana, Special Issue, 5, 101–112.

    Frost, D. (2017) Amphibian Species of the World: an Online Reference. Version 6.0 (11 January 2017). Electronic Database. American Museum of Natural History, New York, USA. Available from: http://research.amnh.org/herpetology/amphibia/index.html (accessed 8 February 2017)

    Funk, W.C., Caminer, M. & Ron, S.R. (2012) High levels of cryptic species diversity uncovered in Amazonian frogs. Proceedings of the Royal Society of London B, 279, 1806–1814.
    https://doi.org/10.1098/rspb.2011.1653

    Funk, W.C., Cannatella, D.C. & Ryan, M.J. (2009) Genetic divergence is more tightly related to call variation than landscape features in the Amazonian frogs Physalaemus petersi and P. freibergi. Journal of Evolutionary Biology, 22, 1839–1853.
    https://doi.org/10.1111/j.1420-9101.2009.01795.x

    Gambale, P.G. & Bastos, R.P. (2014) Vocal repertoire and bioacoustic analyses in Physalaemus cuvieri (Anura, Leptodactylidae) from southern Brazil. Herpetological Journal, 24, 31–34.

    Gambale, P.G., Signorelli, L. & Bastos, R.P. (2014) Individual variation in the advertisement calls of a Neotropical treefrog (Scinax constrictus). Amphibia-Reptilia, 3, 271–281.
    https://doi.org/10.1163/15685381-00002949

    Ganchev, T.D., Jahn, O., Marques, M.I., Figueiredo, J.M. de & Schuchmann, K.-L. (2015) Automated acoustic detection of Vanellus chilensis lampronotus. Expert Systems with Applications, 42, 6098–6111.
    https://doi.org/10.1016/j.eswa.2015.03.036

    Gans, C. (1973) Sound production in the Salientia: mechanism and evolution of the emitter. American Zoologist, 13, 1179–1194.
    https://doi.org/10.1093/icb/13.4.1179

    Gardner, E.A. & Graves, B.M. (2005) Responses of resident male Dendrobates pumilio to territory intruders. Journal of Herpetology, 39, 248–253.
    https://doi.org/10.1670/95-04A

    Gasc, A., Sueur, J., Pavoine, S., Pellens, R. & Grandcolas, P. (2013) Biodiversity sampling using a global acoustic approach: contrasting sites with microendemics in New Caledonia. PLoS One, 8, e65311.
    https://doi.org/10.1371/journal.pone.0065311

    Gasser, H., Amézquita, A. & Hödl, W. (2009) Who is calling? Intraspecific call variation in the aromobatid frog Allobates femoralis. Ethology, 115, 596–607.
    https://doi.org/10.1111/j.1439-0310.2009.01639.x

    Gayou, D.C. (1984) Effects of temperature on the mating call of Hyla versicolor. Copeia, 1984, 733–738.
    https://doi.org/10.2307/1445157

    Gehara, M., Crawford, A.J., Orrico, V.G.D., Rodríguez, A., Lötters, S., Fouquet, A., Barrientos, L.S., Brusquetti, F., De la Riva, I., Ernst, R., Gagliardi Urrutia, G., Glaw, F., Guayasamin, J.M., Hölting, M., Jansen, M., Kok, P.J.R., Kwet, A., Lingnau, R., Lyra, M., Moravec, J., Pombal Jr., J.P., Rojas-Runjaic, F.J.M., Schulze, A., Señaris, J.C., Solé, M., Trefaut Rodriguez, M., Twomey, E., Haddad, C.F.B., Vences, M. & Köhler, J. (2014) High levels of diversity uncovered in a widespread nominal taxon: continental phylogeography of the Neotropical tree frog Dendropsophus minutus. PLoS One, 9, e103958.
    https://doi.org/10.1371/journal.pone.0103958

    Gergus, E.W.A., Reeder, T.W. & Sullivan, B.K. (2004) Geographic variation in Hyla wrightorum: advertisement calls, allozymes, mtDNA, and morphology. Copeia, 2004, 758–769.
    https://doi.org/10.1643/CG-04-061R

    Gergus, E.W.A., Sullivan, B.K. & Malmos, K.B. (1997) Call variation in the Bufo microscaphus complex: implications for species boundaries and the evolution of mate recognition. Ethology, 103, 979–989.
    https://doi.org/10.1111/j.1439-0310.1997.tb00140.x

    Gerhardt, H.C. (1974) The vocalizations of some hybrid treefrogs: acoustic and behavioral analyses. Behaviour, 49, 130–151.
    https://doi.org/10.1163/156853974X00435

    Gerhardt, H.C. (1975) Sound pressure levels and sound radiation patterns of the vocalizations of some North American frogs and toads. Journal of Comparative Physiology, 102, 1–12.
    https://doi.org/10.1007/BF00657481

    Gerhardt, H.C. (1978) Temperature coupling in the vocal communication system of the gray tree frog, Hyla versicolor. Science, 199, 992–994.
    https://doi.org/10.1126/science.199.4332.992

    Gerhardt, H.C. (1982) Sound pattern recognition in some North American treefrogs (Anura: Hylidae): implications for mate choice. American Zoologist, 22, 581–595.
    https://doi.org/10.1093/icb/22.3.581

    Gerhardt, H.C. (1988) Acoustic properties used in call recognition in frogs and toads. In: Fritzsch, B., Ryan, M.J., Wilczynski, W., Hetherington, T.E. & Walkowiak, W. (Eds.), The Evolution of the Amphibian Auditory System. Wiley, New York, pp. 455–483.

    Gerhardt, H.C. (1991) Female mate choice in treefrogs: static and dynamic acoustic criteria. Animal Behaviour, 42, 615–635.
    https://doi.org/10.1016/S0003-3472(05)80245-3

    Gerhardt, H.C. (1994a) The evolution of vocalization in frogs and toads. Annual Reviews of Ecology and Systematics, 25, 293–324.
    https://doi.org/10.1146/annurev.es.25.110194.001453

    Gerhardt, H.C. (1994b) Reproductive character displacement of female mate choice in the grey treefrog, Hyla chrysoscelis. Animal Behaviour, 47, 959–969.
    https://doi.org/10.1006/anbe.1994.1127

    Gerhardt, H.C. (1998) Acoustic signals of animals: recording, field measurements, analysis and description. In: Hopp, S.L., Owren, M.J. & Evans, C.S. (Eds.), Animal Acoustic Communication: Sound Analysis and Research Methods. Springer, Berlin, pp. 1–23.
    https://doi.org/10.1007/978-3-642-76220-8_1

    Gerhardt, H.C. (2012) Evolution of acoustic communication: a multi-level analysis of signal variation. Bioacoustics, 21, 9–11.
    https://doi.org/10.1080/09524622.2011.647469

    Gerhardt, H.C. (2013) Geographic variation in acoustic communication: reproductive character displacement and speciation. Evolutionary Ecology Research, 15, 605–632.

    Gerhardt, H.C. & Davis, M.S. (1988) Variation in the coding of species identity in the advertisement calls of Litoria verreauxi (Anura: Hylidae). Evolution, 42, 556–565.
    https://doi.org/10.2307/2409039

    Gerhardt, H.C., Dyson, M.L. & Tanner, S.D. (1996) Dynamic properties of the advertisement calls of gray tree frogs: patterns of variability and female choice. Behavioral Ecology, 7, 7–18.
    https://doi.org/10.1093/beheco/7.1.7

    Gerhardt, H.C., Guttman, S.I. & Karlin, A.A. (1980) Natural hybrids between Hyla cinerea and Hyla gratiosa: Morphology, vocalization and electrophoretic analysis. Copeia, 1980, 577–584.
    https://doi.org/10.2307/1444432

    Gerhardt, H.C. & Huber, F. (2002) Acoustic Communication in Insects and Frogs: Common Problems and Diverse Solutions. University of Chicago Press, Chicago, 542 pp.

    Gerhardt, H.C. & Schwartz, J.J. (1995) Interspecific interactions in anuran courtship. In: Heatwole, H. & Sullivan, B.K. (Eds.), in Amphibian Biology. Vol. 2. Social Behaviour. Surrey Beatty and Sons, Chipping Norton, New South Wales, pp. 603–632.

    Giacoma, C., Zugolaro, C. & Beani, L. (1997) The advertisement calls of the green toad (Bufo viridis): variability and role in mate choice. Herpetologica, 53, 454–464.

    Giaretta, A.A., Vo, P., Herche, J., Tang, J.N. & Gridi-Papp, M. (2015) Reinterpreting features of the advertisement call of Dermatonotus muelleri (Boettger, 1885; Anura, Microhylidae). Zootaxa, 3972 (4), 595–598.
    https://doi.org/10.11646/zootaxa.3972.4.11

    Gingras, B., Boeckle, M., Herbst, C.T. & Fitch, W.T. (2013) Call acoustics reflect body size across four clades of anurans. Journal of Zoology, 289, 143–150.
    https://doi.org/10.1111/j.1469-7998.2012.00973.x

    Given, M.F. (1996) Intensity modulation of advertisement calls in Bufo woodhousii fowleri. Copeia, 1996, 970–977.
    https://doi.org/10.2307/1447660

    Glaw, F. & Köhler, J. (1998) Amphibian species diversity exceeds that of mammals. Herpetological Review, 29, 11–12.

    Glaw, F., Köhler, J., De la Riva, I., Vieites, D.R. & Vences, M. (2010) Integrative taxonomy of Malagasy treefrogs: combination of molecular genetics, bioacoustics and comparative morphology reveals twelve additional species of Boophis. Zootaxa, 2383, 1–82.

    Glaw, F. & Vences, M. (1991) Bioacoustic differentiation in painted frogs (Discoglossus). Amphibia-Reptilia, 12, 385–394.
    https://doi.org/10.1163/156853891X00031

    Glaw, F. & Vences, M. (1994) A Fieldguide to the Amphibians and Reptiles of Madagascar. Second Edition. Vences & Glaw Verlag, Cologne, 496 pp.

    Goense, J.B.M. & Feng, A.S. (2005) Seasonal changes in frequency tuning and temporal processing in single neurons in the frog auditory midbrain. Journal of Neurobiology, 65, 22–36.
    https://doi.org/10.1002/neu.20172

    Goicoechea, N., De la Riva, I. & Padial, J.M. (2010) Recovering phylogenetic signal from frog mating calls. Zoologica Scripta, 39, 141–154.
    https://doi.org/10.1111/j.1463-6409.2009.00413.x

    Goutte, S., Dubois, A. & Legendre, F. (2013) The importance of ambient sound level to characterise anuran habitat. PLoS One, 8, e78020.
    https://doi.org/10.1371/journal.pone.0078020

    Grafe, T.U. (1995) Graded aggressive calls in the African painted reed frog Hyperolius marmoratus (Hyperoliidae). Ethology, 101, 67–81.
    https://doi.org/10.1111/j.1439-0310.1995.tb00346.x

    Grafe, T.U., Preininger, D., Sztatecsny, M., Kasah, R., Dehling, J.M., Proksch, S. & Hödl, W. (2012) Multimodal communication in a noisy environment: a case study of the Bornean rock frog Staurois parvus. PLoS One, 7, e37965.
    https://doi.org/10.1371/journal.pone.0037965

    Grafe, T.U., Schmuck, R. & Linsenmair, K.E. (1992) Reproductive energetics of the African reed frogs, Hyperolius viridiflavus and Hyperolius marmoratus. Physiological Zoology, 20, 153–171.
    https://doi.org/10.1086/physzool.65.1.30158244

    Grafe, T.U. & Thein, J. (2001) Energetics of calling and metabolic substrate use during prolonged exercise in the European treefrog Hyla arborea. Journal of Comparative Physiology B, 171, 69–76.
    https://doi.org/10.1007/s003600000151

    Grant, P.R. (1972) Convergent and divergent character displacement. Biological Journal of the Linnean Society, 4, 39–68.
    https://doi.org/10.1111/j.1095-8312.1972.tb00690.x

    Greenfield, M.D. (2006) Honesty and deception in animal signals. In: Lucas, J.R. & Simmons, L.W. (Eds.), Essays in Animal Behaviour: Celebrating 50 Years of Animal Behaviour. Academic Press, London, pp. 279–298.

    Greenewalt, C.H. (1968) Bird song: Acoustic and Physiology. Smithsonian Institute Press, Washington, DC, 496 pp.

    Grenat, P.R. & Martino, L. (2013) The release call as a diagnostic character between cryptic related species Odontophrynus cordobae and O. americanus (Anura: Cycloramphidae). Zootaxa, 3635 (5), 583–586.
    https://doi.org/10.11646/zootaxa.3635.5.8

    Gridi-Papp, M. (2003) SoundRuler, acoustic analysis and graphing. Sourceforge. Available from: http://soundruler.sourceforge.net (accessed 3 November 2016)

    Gridi-Papp, M. (2008) The structure of vocal sounds produced with the mouth closed or with the mouth open in treefrogs. Journal of the Acoustical Society of America, 123, 2895–2902.
    https://doi.org/10.1121/1.2897001

    Gridi-Papp, M., Rand, A.S. & Ryan, M.J. (2006) Animal communication: complex call production in the Túngara frog. Nature, 441, 38.
    https://doi.org/10.1038/441038a

    Gruber, S.L., Silva, A.P., Haddad, C.F.B. & Kasahara, S. (2013) Cytogenetic analysis of Phyllomedusa distincta Lutz, 1950 (2n = 2x = 26), P. tetraploidea Pombal and Haddad, 1992 (2n = 4x = 52), and their natural triploid hybrids (2n = 3x = 39) (Anura, Hylidae, Phyllomedusinae). BMC Genetics, 14, 75.
    https://doi.org/10.1186/1471-2156-14-75

    Guerra, M.A. & Ron, S.R. (2008) Mate choice and courtship signal differentiation promotes speciation in an Amazonian frog. Behavioral Ecology, 19, 1128–1135.
    https://doi.org/10.1093/beheco/arn098

    Guillot, G., Renaud, S., Ledevin, R., Michaux, J. & Claude, J. (2012) A unifying model for the analysis of phenotypic, genetic, and geographic data. Systematic Biology, 61, 897–911.
    https://doi.org/10.1093/sysbio/sys038

    Haddad, C.F.B. & Cardoso, A.J. (1992) Elección del macho por la hembra de Hyla minuta (Amphibia: Anura). Acta Zoologica Lilloana, 41, 81–91.

    Haddad, C.F.B., Cardoso, A.J. & Castanho, L.M. (1990) Hibridação natural entre Bufo ictericus e Bufo crucifer (Amphibia: Anura). Revista Brasileira de Biologia, 50, 739–744.

    Haddad, C.F.B., Giovanelli, J.G.R., Giasson, L.O.M. & Toledo, L.F. (2005) Sound Guide of the Atlantic Rain Forest Anurans. Lab. Herpetologia, UNESP, Rio Claro, SP, 14 pp. [audio CD with an explanatory booklet]

    Haddad, C.F.B., Pombal, J.P. & Batistic, R.F. (1994) Natural hybridization between diploid and tetraploid species of leaf-frogs, genus Phyllomedusa (Amphibia). Journal of Herpetology, 28, 425–430.
    https://doi.org/10.2307/1564953

    Hafner, S.D. & Katz, J. (2014) Package ‘monitoR’. Acoustic Template Detection in R. CRAN. Available from: http://www.uvm.edu/rsenr/vtcfwru/R/?Page=monitoR/ monitoR.htm (accessed 3 November 2016)

    Halliday, T.R. (1977) The courtship of European newts: an evolutionary perspective. In: Taylor, D.H. & Guttman, S.I. (Eds.), The Reproductive Biology of Amphibians. Plenum Press, New York, pp. 185–232.
    https://doi.org/10.1007/978-1-4757-6781-0_6

    Hanken, J. (1999) Why are there so many new amphibian species when amphibians are declining? Trends in Ecology and Evolution, 14, 7–8.
    https://doi.org/10.1016/S0169-5347(98)01534-1

    Hanna, D.E.L., Wilson, D.R., Blouin-Demers, G. & Mennill, D.J. (2014) Spring peeper (Pseudacris crucifer) modify their call structure in response to noise. Current Zoology, 60, 438–448.
    https://doi.org/10.1093/czoolo/60.4.438

    Hawlitschek, O., Morinière, J., Dunz, A., Franzen, M., Rödder, D., Glaw, F. & Haszprunar, G. (2016): Comprehensive DNA barcoding of the herpetofauna of Germany. Molecular Ecology Resources, 16, 242–253.
    https://doi.org/10.1111/1755-0998.12416

    Heyer, W.R. (1994) Recording frog calls. In: Heyer, W.R., Donnelly, M.A., McDiarmid, R.W., Hayek, L.A.C. & Foster, M.S. (Eds.), Measuring and Monitoring Biological Diversity. Standard Methods for Amphibians. Smithsonian Institution Press, Washington DC, pp. 285–287.

    Heyer, W.R., Rand, A.S., Da Cruz, C.A.G., Peixoto, O.L. & Nelson, C.E. (1990) Frogs of Boracéia. Arquivos de Zoología, 1, 237–410.

    Heyer, W.R. & Reid, Y.R. (2003) Does advertisement call variation coincide with genetic variation in the genetically diverse frog taxon currently known as Leptodactylus fuscus (Amphibia: Leptodactylidae)? Anais da Academia Brasileira de Ciências, 75, 39–54.
    https://doi.org/10.1590/S0001-37652003000100006

    Higgie, M., Chenoweth, S. & Blows, M.W. (2000) Natural selection and the reinforcement of mate recognition. Science, 290, 519–521.
    https://doi.org/10.1126/science.290.5491.519

    Hirschmann, W. & Hödl, W. (2006) Visual signaling in Phrynobatrachus krefftii Boulenger, 1909 (Anura: Ranidae). Herpetologica, 62, 18–27.
    https://doi.org/10.1655/04-06.1

    Höbel, G. & Gerhardt, H.C. (2003) Reproductive character displacement in the communication system of green treefrogs (Hyla cinerea). Evolution, 57, 894–904.
    https://doi.org/10.1111/j.0014-3820.2003.tb00300.x

    Hödl, W. & Amézquita, A. (2001) Visual signalling in anuran amphibians. In: Ryan, M.J. (Ed.), Anuran Communication. Smithsonian Institution Press, Washington DC, pp. 121–141.

    Hödl, W. & Gollmann, G. (1986) Distress calls in Neotropical frogs. Amphibia-Reptilia, 7, 11–21.
    https://doi.org/10.1163/156853886X00226

    Hoffman, E. & Blouin, M. (2000) A review of colour and pattern polymorphisms in anurans. Biological Journal of the Linnean Society, 70, 633–665.
    https://doi.org/10.1111/j.1095-8312.2000.tb00221.x

    Hoffmann, F. & Kloas, W. (2012) Estrogens can disrupt amphibian mating behavior. PLoS One, 7, e32097.
    https://doi.org/10.1371/journal.pone.0032097

    Hoffmann, A. & Reyer, H.U. (2013) Genomic effects on advertisement call structure in diploid and triploid hybrid waterfrogs (Anura, Pelophylax esculentus). BMC Ecology, 13, 47.
    https://doi.org/10.1186/1472-6785-13-47

    Hoskin, C.J., Higgie, M., McDonald, K.R. & Moritz, C. (2005) Reinforcement drives rapid allopatric speciation. Nature, 437, 1353–1356.
    https://doi.org/10.1038/nature04004

    Howard, D.J. (1993) Reinforcement: origin, dynamics & fate of an evolutionary hypothesis. In: Harrison, R.G. (Ed.), Hybrid Zones and the Evolutionary Process. Oxford University Press, New York, pp. 46–69.

    Howard, R.D. & Young, J.R. (1998) Individual variation in male vocal traits and female mating preferences in Bufo americanus. Animal Behaviour, 55, 1165–1179.
    https://doi.org/10.1006/anbe.1997.0683

    Huang, C.-J., Yang, Y-J., Yang, D.-X. & Chen, Y.-J. (2009) Frog classification using machine learning techniques. Expert Systems with Applications, 36, 3737–3743.
    https://doi.org/10.1016/j.eswa.2008.02.059

    Humfeld, S.C. (2013) Condition-dependent signaling and adoption of mating tactics in an amphibian with energetic displays. Behavioral Ecology, 25, 520–530.
    https://doi.org/10.1093/beheco/art024

    Hunt, F.V. (1955) Acoustic vs Acoustical. Journal of the Acoustical Society of America, 27, 975.
    https://doi.org/10.1121/1.1908102

    Irisarri, I., Vences, M., San Mauro, D., Glaw, F. & Zardoya, R. (2011) Reversal to air-driven sound production revealed by a molecular phylogeny of tongueless frogs, family Pipidae. BMC Evolutionary Biology, 11, 114.
    https://doi.org/10.1186/1471-2148-11-114

    Jackson, L. (1996) Sidebands − artefacts or facts? Bioacoustics, 7, 163–164.
    https://doi.org/10.1080/09524622.1996.9753325

    Jang, Y. (2008) Asymmetry in reproductive character displacement. Journal of Ecology and Field Biology, 31, 255–260.
    https://doi.org/10.5141/jefb.2008.31.4.255

    Jang, Y., Hahm, E.H., Lee, H.-J., Park, S., Won, Y.-J. & Choe, J.C. (2011) Geographic variation in advertisement calls in a tree frog species: gene flow and selection hypotheses. PLoS One, 6, e23297.
    https://doi.org/10.1371/journal.pone.0023297

    Jansen, M., Bloch, R., Schulze, A. & Pfenninger, M. (2011) Integrative inventory of Bolivia’s lowland anurans reveals hidden diversity. Zoologica Scripta, 40, 567–583.
    https://doi.org/10.1111/j.1463-6409.2011.00498.x

    Jansen, M., Masurowa, A. & O´Hara, R.B. (2016b) Temporal variation, duty cycle and absolute calling effort during sustained calling of Leptodactylus mystacinus (Anura: Leptodactylidae). Salamandra, 52, 328–336.

    Jansen, M., Plath, M., Brusquetti, F. & Ryan, M. (2016a) Asymmetric frequency shift in advertisement calls of sympatric frogs. Amphibia-Reptilia, 37, 137–152.
    https://doi.org/10.1163/15685381-00003038

    Jehle, R. & Arak, A. (1998) Graded call variation in the Asian cricket frog Rana nicobariensis. Bioacoustics, 9, 35–48.
    https://doi.org/10.1080/09524622.1998.9753378

    Jim, J. & Caramaschi, U. (1979) Uma nova espécie de Hyla da região de Botucatu, São Paulo, Brasil (Amphibia, Anura). Revista Brasileira de Biologia, 40, 717–719.

    Jones, G. & Barlow, K.E. (2003) Cryptic species of echolocating bats. In: Thomas, J.A., Moss, C. & Vater, M. (Eds.), Echolocation in Bats and Dolphins. University of Chicago Press, pp. 345–349.

    Kaefer, I.L. & Lima, A.P. (2012) Sexual signals of the Amazonian frog Allobates paleovarzensis: geographic variation and stereotypy of acoustic traits. Behaviour, 149, 15–33.
    https://doi.org/10.1163/156853912X623757

    Kaefer, I.L., Tsuji-Nishikido, B.M. & Lima, A.P. (2012) Beyond the river: underlying determinants of population acoustic signal variability in Amazonian direct-developing Allobates (Anura: Dendrobatoidea). Acta Ethologica, 15, 187–194.
    https://doi.org/10.1007/s10211-012-0126-0

    Kaffenberger, N., Wollenberg, K.C., Köhler, J., Glaw, F., Vieites, D.R. & Vences, M. (2011) Molecular phylogeny and biogeography of Malagasy frogs of the genus Gephyromantis. Molecular Phylogenetics and Evolution, 62, 555–560.
    https://doi.org/10.1016/j.ympev.2011.09.023

    Keister, A.R. (1977) Communication in amphibians and reptiles. In: Sebeok, T.A. (Ed.), How Animals Communicate. Indiana University Press, Bloomington, pp. 519–544.

    Kelley, D.B. (2004) Vocal communication in frogs. Current Opinions in Neurobiology, 14, 751–757.
    https://doi.org/10.1016/j.conb.2004.10.015

    Kikuyama, S., Nakada, T., Toyoda, F., Iwata, T., Yamamoto, K. & Conlon, J.M. (2005) Amphibian pheromones and endocrine control of their secretion., Annals of the New York Academy of Sciences, 1040, 123–130.
    https://doi.org/10.1196/annals.1327.015

    Kime, N.M., Ryan, M.J. & Wilson, P.S. (2013) A bond graph approach to modeling the anuran vocal production system. Journal of the Acoustic Society of America, 133, 4133–4144.
    https://doi.org/10.1121/1.4802743

    Kime, N.M., Turner, W.R. & Ryan, M.J. (2000) The transmission of advertisement calls in Central American frogs. Behavioral Ecology, 11, 71–83.
    https://doi.org/10.1093/beheco/11.1.71

    Kime, N.M., Whitney, T.K., Davis, E.S. & Marler, C.A. (2007) Arginine vasotocin promotes calling behavior and call changes in male Túngara frogs. Brain Behavior and Evolution, 69, 254–265.
    https://doi.org/10.1159/000099613

    Kingston, T. & Rossiter, S.J. (2004) Harmonic-hopping in Wallacea's bats. Nature, 429, 654–657.
    https://doi.org/10.1038/nature02487

    Klomberg, K.F. & Marler, C.A. (2000) The neuropeptide arginine vasotocin alters male call characteristics involved in social interactions in the grey treefrog, Hyla versicolor. Animal Behaviour, 59, 807–812.
    https://doi.org/10.1006/anbe.1999.1367

    Klump, G.M. & Gerhardt, H.C. (1987) Use of non-arbitrary acoustic criteria in mate choice by female gray tree frogs. Nature, 326, 286–288.
    https://doi.org/10.1038/326286