Agonistic “Tsak” call: A non-invasive tool for species diagnosis in a cryptic smallest-bodied primate, the mouse lemur?
Bioacoustics uses digital technology to record and analyse animal vocalisations to enhance our understanding of animal communication, distribution as well as biodiversity. Mouse lemurs represent the smallest-bodied extant primate radiation, are nocturnal and live in diverse Malagasy forests. This primate radiation comprises 24 genetically defined, phenotypically similar species. The conservation status of most species is barely known, but the often small geographical distribution makes them highly vulnerable to anthropogenically caused habitat disturbances. The aim of this study was to explore by a comparative and integrative bioacoustic, behavioural and genetic approach, whether the most frequently used mouse lemur calls bear species-specific signatures allowing on the long run to establish bioacoustic rapid assessment tools for surveying and monitoring species diversity in nature. We will present bioacoustic data from mouse lemurs, originating from seven different study sites in north-western and eastern Madagascar (“Bombetoka”, “Ampijoroa”, “Marosely” and “Anjiamangirana” with dry deciduous forest and “Lokobe National Park”, “Ankaramibe” and “Mantadia” with rain forest). The variation in vocalisation and its use in signalling were determined by standardised bioacoustic methods using a social encounter paradigm (N = 12 dyads/study site). Comparative data on agonistic calls between eight genetically different cryptic species: Microcebus myoxinus, M. ravelobensis, M. bongolavensis, M. danfossi, M. mamiratra, M. margotmarshae, M.murinus, and M.lehilahytsara revealed a uniform acoustic contour, but species-specific statistical distinctiveness in acoustic structure. Acoustic divergence between species is predicted by genetic distance. The studied calls do not display habitat-specific differences. Thus, findings support an acoustic diversification caused by genetic drift.