Behavioural Correlates of Lemur Scent-Marking in Wild Diademed Sifakas (Propithecus diadema) in the Maromizaha Forest (Madagascar)

Scent-marking through odours from excreta and glandular secretions is widespread in mammals. Among primates, diurnal group-living lemurs show different deployment modalities as part of their strategy to increase signal detection. We studied the diademed sifaka (Propithecus diadema) in the Maromizaha New Protected Area, Eastern Madagascar. We tested whether the scent-marking deposition occurred using a sequential rubbing of different body parts. We also tested if glands (i.e., deposition of glandular secretions) were more frequently rubbed than genital orifices (i.e., deposition of excreta) by comparing different kinds of rubbing behaviour. We then investigated if the depositor's rank and sex affected the sequence of rubbing behaviour, the height at which the scent-marking happened, and the tree part targeted. We found that glandular secretions were often deposited with urine, especially in dominant individuals. The probability of anogenital and chest marking was highest, but chest rubbing most frequently occurred in dominant males. Markings were deposited at similar heights across age and sex, and tree trunks were the most used substrate. Males exhibited long and more complex scent-marking sequences than females. Our results indirectly support the idea that diademed sifakas deploy a sex-dimorphic mixture of glandular secretions and excreta to increase the probability of signal detection by conspecifics.

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

In primates, urine washing (UW) is a behavior in which individuals intentionally deposit urine on their bodies. Social and nonsocial hypotheses have been proposed to explain the adaptive function of this behavior. For capuchins, different functions have been assigned for UW, suggesting it as a flexible behavior, but studies have been mainly in captivity. However, no investigations have been performed in urban environments, where these animals can modify their behavior. Our goal was to study UW in a semi-provisioned group of an introduced unknown robust capuchin species (Sapajus sp.) living in a tiny urban fragment in Foz do Iguaçu, Brazil, where they have contact with humans. We assessed the influence of social (sexual, agonistic, and anointing behaviors) and environmental (temperature, relative air humidity, height of the monkeys in the trees, number of people present in the fragment, and human-monkey interactions) variables, the influence of behavior before and after UW, and the influence of sex-age classes, on the frequency of UW. We observed 75 records of UW in 300 h of observations, where urine was mostly deposited on hands and passed on to feet (95%). There were no significant differences in the frequency of the behavior between sex-age classes nor in the behaviors before and after UW. Around 50% of UW took place in the late morning and we found no correlation between UW and temperature, relative air humidity, nor the heights of the monkeys in the trees. However, we found a significant association between UW and the daily number of people in the fragment, but not between UW and human-monkey interactions, anointing, agonisms, and sexual behavior. Our study increases the scope of UW flexibility by identifying the presence of visitors affecting the occurrence of this behavior. We discussed different possibilities through which people could influence the capuchins to display UW.

Reverse Chemical Ecology Suggests Putative Primate Pheromones

Pheromonal communication is widespread among living organisms, but in apes and particularly in humans there is currently no strong evidence for such phenomenon. Among primates, lemurs use pheromones to communicate within members of the same species, whereas in some monkeys such capabilities seem to be lost. Chemical communication in humans appears to be impaired by the lack or malfunctioning of biochemical tools and anatomical structures mediating detection of pheromones. Here, we report on a pheromone-carrier protein (SAL) adopting a "reverse chemical ecology" approach to get insights on the structures of potential pheromones in a representative species of lemurs (Microcebus murinus) known to use pheromones, Old-World monkeys (Cercocebus atys) for which chemical communication has been observed, and humans (Homo sapiens), where pheromones and chemical communication are still questioned. We have expressed the SAL orthologous proteins of these primate species, after reconstructing the gene encoding the human SAL, which is disrupted due to a single base mutation preventing its translation into RNA. Ligand-binding experiments with the recombinant SALs revealed macrocyclic ketones and lactones as the best ligands for all three proteins, suggesting cyclopentadecanone, pentadecanolide, and closely related compounds as the best candidates for potential pheromones. Such hypothesis agrees with the presence of a chemical very similar to hexadecanolide in the gland secretions of Mandrillus sphinx, a species closely related to C. atys. Our results indicate that the function of this carrier protein has not changed much during evolution from lemurs to humans, although its physiological role has been certainly impaired in humans.

Assessing urinary odours across the oestrous cycle in a mouse model using portable and benchtop gas chromatography-mass spectrometry

For female mammals, communicating the timing of ovulation is essential for reproduction. Olfactory communication via volatile organic compounds (VOCs) can play a key role. We investigated urinary VOCs across the oestrous cycle using laboratory mice. We assessed the oestrous stage through daily vaginal cytology and analysed urinary VOCs using headspace gas chromatography-mass spectrometry (GC-MS), testing a portable GC-MS against a benchtop system. We detected 65 VOCs from 40 samples stored in VOC traps and analysed on a benchtop GC-MS, and 15 VOCs from 90 samples extracted by solid-phase microextraction (SPME) and analysed on a portable GC-MS. Only three compounds were found in common between the two techniques. Urine collected from the fertile stages of the oestrous cycle had increased quantities of a few notable VOCs compared with urine from non-fertile stages. These VOCs may be indicators of fertility. However, we did not find significant differences in chemical composition among oestrous stages. It is possible that changes in VOC abundance were too small to be detected by our analytical methods. Overall, the use of VOC traps combined with benchtop GC-MS was the more successful of the two methods, yet portable GC-MS systems may still have utility for some in situ applications.