Abstract # 85:

Scheduled for Thursday, August 17, 2006 07:00 PM-09:00 PM: Session 8 (Regency West 1/3 ) Poster Presentation


SPECIES DIFFERENCES IN THE ACOUSTIC STRUCTURE OF ZZUSS ALARM VOCALIZATIONS OF SILKY SIFAKAS (Propithecus candidus) AND DIADEMED SIFAKAS (Propithecus diadema diadema).

J. D. Anderson1, E. R. Patel2, M. T. Irwin3 and M. J. Owren4
1University of Florida, Raleighvallen Monkey and Community Ecology Research Program, Raleighvallen Nature Reserve, Suriname, Gainesville, FL 32611, USA, 2Cornell University, Department of Psychology, Behavioral and Evolutionary Neuroscience Division, Ithaca, NY 14853, 3Interdepartmental Doctoral Program in Anthropological Sciences, Stony Brook University, Stony Brook, NY 11794, 4Georgia State University, Department of Psychology and Language Research Center, Atlanta, GA 30302-5010
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     Species differences in vocal acoustics between closely related primate species are attributable to phylogeny, body size, habitat acoustics, and social behavior. Such differences have been documented within a number of anthropoid and prosimian genera, but not lemuriform primates. Comparing the acoustic structure of zzuss vocalizations of two closely related allopatric free-ranging rainforest sifaka species in Madagascar revealed that calls of silky sifakas were noisier with fewer harmonics than those of diademed sifakas, while showing substantially higher fundamental frequencies and spectral peaks (Mann-Whitney U tests, p < 0.012). Cross-validated discriminant function analyses successfully classified the calls by species for both silky (84%) and diademed sifakas (100%). Although silky sifakas are larger than these diademed sifakas, body-size alone did not account for the observed acoustic differences. Other important factors likely include that these diademed sifakas living in disturbed habitats may be vocalizing closer to the ground, and in more open environments than silky sifakas. Contrary to the hypothesis that vocal signals that function in species recognition should show few within-species versus between-species differences (Mitani, 1996), we did not find a significant correlation between discriminant function classification and acoustic variability (r = 0.52, p = 0.15). Results offer the first quantitative evidence in lemurs of differences in the acoustic structure of vocalizations between closely related species. All acoustic differences were spectral differences, best explained by some combination of habitat acoustics, phylogeny, and social behavior.