Sensory drive tested in the sister-species Microcebus griseorufus and M. murinus

Madagascar’s mouse lemurs ( Microcebus ) comprise a diverse clade of cryptic species, which were historically discriminated using genetic data, distribution, as well as diagnostic mating calls. However, the mating calls are well described only for a small number of mouse lemur species. Focussing on two closely related Microcebus taxa, we hypothesised that environment-driven change in communication signal, or sensory drive, contributed to this diversity. In order to test this hypothesis, we characterised the courtship of Microcebus griseorufus . We used ultrasonic recordings and sound transmission trials to compare the attenuation of male mating trills of M. griseorufus and sympatric M. murinus in their respective preferred habitats. Differences in habitat had an influence on the reverberation, also affecting the call, with M. griseorufus mating call presenting more modulations than the simpler call of M. murinus . Our results confirm that mating calls are selected in response to environmental conditions and local habitat, as formulated by the sensory drive hypothesis. Trill attenuation also explains mating call differences (complex or simple) leading to interspecific variation predicted in the recognition concept of species.