Browsing by Author "Drea, CM"

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    Baby on board: olfactory cues indicate pregnancy and fetal sex in a non-human primate.
    (Biol Lett, 2015-02) Crawford, JC; Drea, CM
    Olfactory cues play an integral, albeit underappreciated, role in mediating vertebrate social and reproductive behaviour. These cues fluctuate with the signaller's hormonal condition, coincident with and informative about relevant aspects of its reproductive state, such as pubertal onset, change in season and, in females, timing of ovulation. Although pregnancy dramatically alters a female's endocrine profiles, which can be further influenced by fetal sex, the relationship between gestation and olfactory cues is poorly understood. We therefore examined the effects of pregnancy and fetal sex on volatile genital secretions in the ring-tailed lemur (Lemur catta), a strepsirrhine primate possessing complex olfactory mechanisms of reproductive signalling. While pregnant, dams altered and dampened their expression of volatile chemicals, with compound richness being particularly reduced in dams bearing sons. These changes were comparable in magnitude with other, published chemical differences among lemurs that are salient to conspecifics. Such olfactory 'signatures' of pregnancy may help guide social interactions, potentially promoting mother-infant recognition, reducing intragroup conflict or counteracting behavioural mechanisms of paternity confusion; cues that also advertise fetal sex may additionally facilitate differential sex allocation.
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    Gut Microbial Diversity and Ecological Specialization in Four Sympatric Lemur Species Under Lean Conditions
    (International Journal of Primatology, 2021-12-01) Greene, LK; Rambeloson, E; Rasoanaivo, HA; Foss, ED; Yoder, AD; Drea, CM; Blanco, MB
    The gut microbiome is gaining recognition for its role in primate nutrition, but we stand to benefit from microbiome comparisons across diverse hosts and environmental conditions. We compared gut microbiome structure in four lemur species from four phylogenetic lineages, including 9 individual mouse lemurs (Microcebus danfossi), 6 brown lemurs (Eulemur fulvus), 20 sifakas (Propithecus coquereli), and a single sportive lemur (Lepilemur grewcockorum). In northwestern Madagascar, these species are sympatric, but use different feeding strategies to cope with environmental challenges, including relying on tree gums and insects (mouse lemurs), and some vs. significant leaf matter (brown lemurs vs. sifakas and sportive lemurs). From one fecal sample collected per lemur in the dry season in the Anjajavy Forest, we determined gut microbiome diversity, variability, and membership via 16S rRNA sequencing. The lemurs harbored strongly species-specific gut microbiomes. Brown lemurs showed more diverse and generalized consortia; mouse lemurs, sifakas, and the sportive lemur had less diverse consortia with more distinct memberships. Consistent with their fallback foods, mouse lemur microbiomes included taxa putatively associated with gum and insect digestion, whereas those of sifakas and the sportive lemur showed stronger and distinct signatures of leaf fiber and secondary compound metabolism. These results point to feeding strategy, intertwined with host phylogeny, as a driver of gut microbiome composition, but highlight real-time dietary specificity as a contributing driver of microbiome diversity. While illuminating how gut microbiomes facilitate host nutrition on challenging foods, these results help explain how ecologically diverse primates living in sympatry may differentially cope with seasonal or stochastic lean times.
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    Love is in the air: Sociality and pair bondedness influence sifaka reproductive signalling
    (Animal Behaviour, 2014-01-01) Greene, LK; Drea, CM
    © 2013 The Association for the Study of Animal Behaviour.Social complexity, often estimated by group size, is seen as driving the complexity of vocal signals, but its relation to olfactory signals, which arguably arose to function in nonsocial realms, remains underappreciated. That olfactory signals also may mediate within-group interaction, vary with social complexity and promote social cohesion underscores a potentially crucial link with sociality. To examine that link, we integrated chemical and behavioural analyses to ask whether olfactory signals facilitate reproductive coordination in a strepsirrhine primate, the Coquerel's sifaka, Propithecus coquereli. Belonging to a clade comprising primarily solitary, nocturnal species, the diurnal, group-living sifaka represents an interesting test case. Convergent with diurnal, group-living lemurids, sifakas expressed chemically rich scent signals, consistent with the social complexity hypothesis for communication. These signals minimally encoded the sex of the signaller and varied with female reproductive state. Likewise, sex and female fertility were reflected in within-group scent investigation, scent marking and overmarking. We further asked whether, within breeding pairs, the stability or quality of the pair's bond influences the composition of glandular signals and patterns of investigatory or scent-marking behaviour. Indeed, reproductively successful pairs tended to show greater similarity in their scent signals than did reproductively unsuccessful pairs, potentially through chemical convergence. Moreover, scent marking was temporally coordinated within breeding pairs and was influenced by past reproductive success. That olfactory signalling reflects social bondedness or reproductive history lends support to recent suggestions that the quality of relationships may be a more valuable proxy than group size for estimating social complexity. We suggest that olfactory signalling in sifakas is more complex than previously recognized and, as in other socially integrated species, can be a crucial mechanism for promoting group cohesion and maintaining social bonds. Thus, the evolution of sociality may well be reflected in the complexity of olfactory signalling.
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    Mix it and fix it: functions of composite olfactory signals in ring-tailed lemurs.
    (R Soc Open Sci, 2016-04) Greene, LK; Grogan, KE; Smyth, KN; Adams, CA; Klager, SA; Drea, CM
    Animals communicating via scent often deposit composite signals that incorporate odorants from multiple sources; however, the function of mixing chemical signals remains understudied. We tested both a 'multiple-messages' and a 'fixative' hypothesis of composite olfactory signalling, which, respectively, posit that mixing scents functions to increase information content or prolong signal longevity. Our subjects-adult, male ring-tailed lemurs (Lemur catta)-have a complex scent-marking repertoire, involving volatile antebrachial (A) secretions, deposited pure or after being mixed with a squalene-rich paste exuded from brachial (B) glands. Using behavioural bioassays, we examined recipient responses to odorants collected from conspecific strangers. We concurrently presented pure A, pure B and mixed A + B secretions, in fresh or decayed conditions. Lemurs preferentially responded to mixed over pure secretions, their interest increasing and shifting over time, from sniffing and countermarking fresh mixtures, to licking and countermarking decayed mixtures. Substituting synthetic squalene (S)-a well-known fixative-for B secretions did not replicate prior results: B secretions, which contain additional chemicals that probably encode salient information, were preferred over pure S. Whereas support for the 'multiple-messages' hypothesis underscores the unique contribution from each of an animal's various secretions, support for the 'fixative' hypothesis highlights the synergistic benefits of composite signals.