Holarctic Marmots as a factor of Biodiversity.
Rumiantsev V.Yu;, Nikol'skii A.A. & Brandler O.V. eds.,
3d Conference on Marmots (Cheboksary, Russia, 25-30 August 1997),
Moscow ABF 1997, 216p.
A TEST OF THE ACOUSTIC ADAPTATION HYPOTHESIS IN MARMOTS
J.C. Daniel, D.T. Blumstein
Department of Systematics and Ecology, University of Kansas
Animal communication requires the transmission of signals from a signaler to a receiver. Over distance, biologically important sounds may attenuate (i.e., experience amplitude loss), degrade (i.e., change acoustic structure), and compete with background noise. Thus, we might expect selection to modify the structure of long-distance signals to maximize their transmission in different habitats - "the acoustic adaptation hypothesis." A specific prediction of the acoustic adaptation hypothesis is that long-distance signals are expected to change less during transmission through native than through foreign habitats. We tested this prediction using the alarm calls of four species of marmots - Marmota flaviventris, M. olympus, M. caligata, M. monax. The four species live in different habitats and produce species-specific
long-distance alarm vocalizations. We broadcast and re-recorded representative alarm calls of the four species in each species' habitat at four distances
from a source. Re-recorded, and therefore degraded alarm calls, were compared to undegraded calls using spectrogram correlation. If each species' alarm call transmits best in its own environment, we would expect a significant interaction between species' habitat and species' call type. We tested this hypothesis with a two-way MANOVA, where we modeled transmission fidelity as a function of habitat and call type at each of the four distances. Although we found significant overall differences in the transmission properties of each habitat, and we found significant overall differences in the transmission properties of each call type, we found no significant interaction between habitat and call type. We therefore found no evidence to support the acoustic adaptation hypothesis for these marmot species. Factors other than maximizing long distance transmission through the environment may be important in the evolution of species-specific marmot alarm calls.
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