Vocal range and ultraviolet-induced photoluminescence in gliding mammals and their relatives

Gliding is only present in six extant groups of mammals – interestingly,
despite divergent evolutionary histories, all mammalian gliders are
strictly nocturnal. Gliding mammals also seem to have relatively high
rates of ultrasound use and ultraviolet-induced photoluminescence (UVP) in
contrast with their close relatives. Therefore, we hypothesized that,
despite diverging lineages, gliding mammals use similar modes of cryptic
communication compared to their non-gliding counterparts. We developed two
datasets containing the vocal range (minimum-maximum of the dominant
harmonic; kHz) and UVP of 73 and 82 species, respectively; we report five
novel vocal repertoires and 57 novel observations of the presence or
absence of UVP. We complemented these datasets with information about body
size, diel activity patterns, habitat openness, and sociality to explore
possible covariates related to vocal production and UVP. We found that the
maximum of the dominant harmonic was significant higher in gliding mammals
when vocalizing than their non-gliding relatives. Additionally, we found
that nocturnality was the only significant predictor of UVP, consistent
with the previous hypothesis that luminophores primarily drive UVP in
mammal fur. In contrast, however, we did not find UVP ubiquitous in
nocturnal mammals, suggesting that some unknown process may contribute to
variation in this trait.