Volatile Urinary Signals of Two Nocturnal Primates, Microcebus murinus and M. lehilahytsara

Abstract

Mouse lemurs are small, nocturnal, arboreal solitary foragers and are endemic primates of Madagascar. This lifestyle and their high predation risk can explain why mouse lemurs rely heavily on olfaction for intraspecific communication. As they often use urine for this purpose, we investigated dichloromethane extracts of the urine of two mouse lemur species, the gray mouse lemur (Microcebus murinus) and the Godman's mouse lemur (M. lehilahytsara), using gas-chromatography-mass spectrometry. We detected 977 different volatile compounds of different compound classes in 22 urine extracts obtained from nine M. murinus (four males, five females) and nine M. lehilahytsara (three males, six females) individuals. We compared the volatile profiles of the sexes and species using principal component analyses and discriminant function analyses and detected a significant difference in the urinary profiles of males and females and in the profiles of M. murinus and M. lehilahytsara. These very complex sex-and species-specific signatures could be used for distance communication in the context of species recognition, for mate search and in male-male competition. Our study provides important mechanistic insights into complex chemical signaling pathways in primates that are mirrored, in the case of mouse lemurs, by their extraordinarily rich repertoire of olfactory receptors. The production of highly informative olfactory signals may be complementing the complex acoustic signaling system of these solitary foragers suggesting the existence of a multimodal communication network that should be highly beneficial for any species living in dispersed social networks.

Urine washing in urban robust capuchin monkeys (Sapajus sp.): The relation with visitors

“…In general, UW is practiced by individuals of any sex or age (Milton, 1975), but it is more commonly observed in adult males (Campos & Fedigan, 2013; Campos et al, 2007; Milton, 1975; Oppenheimer & Oppenheimer, 1973; Roeder & Anderson, 1991), which suggests that it has a social or sexual function. In this sense, UW would help to inform the status of a sender to social mates or competitors, with consequences for the individual fitness (Caspers et al, 2020). Alternatively, as adult primate males tend to be the largest animals in the groups (Fleagle, 2013), they could need more urine on hands and feet to ensure a more secure grip to the trees, as could be expected from the adherence improvement hypothesis (see below).…”

“…In fact, olfactory communication in primates, a chemical signaling that is important to transmit honest information, is more often perceived through the secretions of glands on the skin, which could be a more effective mechanism than urine for recognizing other individuals (Harcourt, 1981; Strier, 2021). In any case, since primates in general depend more on vision than on olfaction, they can rub their fur directly on substrates (Fleagle, 2013; Hirano et al, 2008), which does not necessarily require urine demarcation—although olfactory cues in urine could be important for nocturnal primates (Caspers et al, 2020; Strier, 2021).…”

Reverse Chemical Ecology Suggests Putative Primate Pheromones

“…We therefore have expressed the three SAL-MUP ortholog proteins, after restoring the human pseudogene. Using ligand-binding studies, we then have compared the biochemical behavior of these proteins in: 1) a lemur species ( Microcebus murinus ), in which chemical communication is well documented ( Caspers et al 2020 ; Kollikowski et al 2020 ), 2) an Old-World monkey ( Cercocebus atys ) belonging to the same subfamily of mandrills, which are suspected to use pheromones ( Vaglio et al 2016 ), and 3) in human, where there is so far no strong evidence for pheromonal communication. The results of our reverse chemical ecology approach have proposed macrocyclic ketones and lactones as putative pheromones for all three representative proteins, suggesting that primates have retained the use of the same volatile molecules as pheromones until the genes for their binding proteins became nonfunctional in humans and perhaps no longer used also in apes.…”