Dear Marmam, Please post this. Best and thanks Peter Dear All, On behalf of Line Kyhn and coauthors, I hereby wish to draw the attention of interested readers to this recent paper in Plos One on echolocation of porpoises in a killer whale habitat: Clicking in a Killer Whale Habitat: Narrow-Band, High-Frequency Biosonar Clicks of Harbour Porpoise(Phocoena phocoena) and Dall's Porpoise (Phocoenoides dalli) Line A. Kyhn1*, Jakob Tougaard1, Kristian Beedholm2, Frants H. Jensen2, Erin Ashe3, Rob Williams3, Peter T. Madsen2 1 Department of Bioscience, Aarhus University, Aarhus, Denmark, 2 Zoophysiology, Department of Bioscience, Aarhus University, Aarhus, Denmark, 3 Sea Mammal Research Unit, Scottish Oceans Institute, University of St Andrews, St Andrews, United Kingdom Abstract Odontocetes produce a range of different echolocation clicks but four groups in different families have converged on producing the same stereotyped narrow band high frequency (NBHF) click. In microchiropteran bats, sympatric species have evolved the use of different acoustic niches and subtly different echolocation signals to avoid competition among species. In this study, we examined whether similar adaptations are at play among sympatric porpoise species that use NBHF echolocation clicks. We used a six-element hydrophone array to record harbour and Dall's porpoises in British Columbia (BC), Canada, and harbour porpoises in Denmark. The click source properties of all porpoise groups were remarkably similar and had an average directivity index of 25 dB. Yet there was a small, but consistent and significant 4 kHz difference in centroid frequency between sympatric Dall's (13763 kHz) and Canadian harbour porpoises (14162 kHz). Danish harbor porpoise clicks (13663 kHz) were more similar to Dall's porpoise than to their conspecifics in Canada. We suggest that the spectral differences in echolocation clicks between the sympatric porpoises are consistent with evolution of a prezygotic isolating barrier (i.e., character displacement) to avoid hybridization of sympatric species. In practical terms, these spectral differences have immediate application to passive acoustic monitoring. A popular account can be found here: http://www.mysciencework.com/en/MyScienceNews/10193/killer-whales-porpoise-c... A pdf copy can be found here: http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0063763 Or by emailing me: peter.madsen@biology.au.dk<mailto:peter.madsen@biology.au.dk> On behalf of the authors Peter Peter T. Madsen Zoophysiology, Department of Bioscience Aarhus University, Build. 1131, CF Mollers Alle 8000 Aarhus C, Denmark Phone: 0045 8715 6501 email: peter.madsen@biology.au.dk<mailto:peter.madsen@biology.au.dk> Web: www.marinebioacoustics.com<http://www.marinebioacoustics.com> [sender_logo]
