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1. What smells? Developing in‐field methods to characterize the chemical composition of wild mammalian scent cues

   https://doi.org/10.1002/ece3.6224  

   Thompson, Cynthia L. ; Bottenberg, Kimberly N. ; Lantz, Andrew W. ; de Oliveira, Maria A. B. ; Melo, Leonardo C. O. ; Vinyard, Christopher J. ( April 2020 , Ecology and Evolution)

   Olfactory cues play an important role in mammalian biology, but have been challenging to assess in the field. Current methods pose problematic issues with sample storage and transportation, limiting our ability to connect chemical variation in scents with relevant ecological and behavioral contexts. Real‐time, in‐field analysisviaportable gas chromatography–mass spectrometry (GC‐MS) has the potential to overcome these issues, but with trade‐offs of reduced sensitivity and compound mass range. We field‐tested the ability of portable GC‐MS to support two representative applications of chemical ecology research with a wild arboreal primate, common marmoset monkeys (Callithrix jacchus). We developed methods to (a) evaluate the chemical composition of marmoset scent marks deposited at feeding sites and (b) characterize the scent profiles of exudates eaten by marmosets. We successfully collected marmoset scent marks across several canopy heights, with the portable GC‐MS detecting known components of marmoset glandular secretions and differentiating these from in‐field controls. Likewise, variation in the chemical profile of scent marks demonstrated a significant correlation with marmoset feeding behavior, indicating these scents’ biological relevance. The portable GC‐MS also delineated species‐specific olfactory signatures of exudates fed on by marmosets. Despite the trade‐offs, portable GC‐MS represents a viable option for characterizing olfactory compounds used by wild mammals, yielding biologically relevant data. While the decision to adopt portable GC‐MS will likely depend on site‐ and project‐specific needs, our ability to conduct two example applications under relatively challenging field conditions bodes well for the versatility of in‐field GC‐MS.

    

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2. Specificity of California mouse pup vocalizations in response to olfactory stimuli

   https://doi.org/10.1002/dev.22261  

   Wilson, Kerianne M. ; Wagner, Victoria A. ; Saltzman, Wendy ( March 2022 , Developmental Psychobiology)

   To investigate flexibility in vocal signaling by rodent pups, we examined whether olfactory stimuli influence characteristics of pup calls and how these calls may be affected by sex and litter size in California mice (Peromyscus californicus). Pups were isolated and recorded during a 3‐min baseline period followed by a 5‐min exposure to bedding containing scent from their home cage, scent from the home cage of an unfamiliar family, coyote urine, or no scent (control). Latency to call, call rate, and call characteristics (duration, frequency, and amplitude) were compared between the baseline and scent‐exposure periods and among olfactory conditions. Compared with the control condition, pups from two‐pup litters called more quietly when exposed to odor from a predator, whereas pups from three‐pup litters called more loudly. Additionally, pups showed nonsignificant tendencies to reduce call rates in response to odors from their home cage and to increase call rates when exposed to predator urine. Last, males produced higher‐frequency calls and more ultrasonic vocalizations than females. These results indicate that pup calling behavior in this species can be influenced by acute olfactory stimuli as well as litter size and sex. The flexibility of pup calling in response to these three variables potentially increases the communication value of pup calls and helps shape the parents’ responses.

    

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3. Chemical Communication in Lizards and a Potential Role for Vasotocin in Modulating Social Interactions

   https://doi.org/10.1093/icb/icab044  

   Campos, Stephanie M ; Belkasim, Selma S ( May 2021 , Integrative and Comparative Biology)

   Synopsis Lizards use chemical communication to mediate many reproductive, competitive, and social behaviors, but the neuroendocrine mechanisms underlying chemical communication in lizards are not well understood and understudied. By implementing a neuroendocrine approach to the study of chemical communication in reptiles, we can address a major gap in our knowledge of the evolutionary mechanisms shaping chemical communication in vertebrates. The neuropeptide arginine vasotocin (AVT) and its mammalian homolog vasopressin are responsible for a broad spectrum of diversity in competitive and reproductive strategies in many vertebrates, mediating social behavior through the chemosensory modality. In this review, we posit that, though limited, the available data on AVT-mediated chemical communication in lizards reveal intriguing patterns that suggest AVT plays a more prominent role in lizard chemosensory behavior than previously appreciated. We argue that these results warrant more research into the mechanisms used by AVT to modify the performance of chemosensory behavior and responses to conspecific chemical signals. We first provide a broad overview of the known social functions of chemical signals in lizards, the glandular sources of chemical signal production in lizards (e.g., epidermal secretory glands), and the chemosensory detection methods and mechanisms used by lizards. Then, we review the locations of vasotocinergic populations and neuronal projections in lizard brains, as well as sites of peripheral receptors for AVT in lizards. Finally, we end with a case study in green anoles (Anolis carolinensis), discussing findings from recently published work on the impact of AVT in adult males on chemosensory communication during social interactions, adding new data from a similar study in which we tested the impact of AVT on chemosensory behavior of adult females. We offer concluding remarks on addressing several fundamental questions regarding the role of AVT in chemosensory communication and social behavior in lizards. 

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4. The importance of scale in comparative microbiome research: New insights from the gut and glands of captive and wild lemurs

   https://doi.org/10.1002/ajp.22974  

   Greene, Lydia K. ; Bornbusch, Sally L. ; McKenney, Erin A. ; Harris, Rachel L. ; Gorvetzian, Sarah R. ; Yoder, Anne D. ; Drea, Christine M. ( April 2019 , American Journal of Primatology)

   Research on animal microbiomes is increasingly aimed at determining the evolutionary and ecological factors that govern host–microbiome dynamics, which are invariably intertwined and potentially synergistic. We present three empirical studies related to this topic, each of which relies on the diversity of Malagasy lemurs (representing a total of 19 species) and the comparative approach applied across scales of analysis. In Study 1, we compare gut microbial membership across 14 species in the wild to test the relative importance of host phylogeny and feeding strategy in mediating microbiome structure. Whereas host phylogeny strongly predicted community composition, the same feeding strategies shared by distant relatives did not produce convergent microbial consortia, but rather shaped microbiomes in host lineage‐specific ways, particularly in folivores. In Study 2, we compare 14 species of wild and captive folivores, frugivores, and omnivores, to highlight the importance of captive populations for advancing gut microbiome research. We show that the perturbational effect of captivity is mediated by host feeding strategy and can be mitigated, in part, by modified animal management. In Study 3, we examine various scent‐gland microbiomes across three species in the wild or captivity and show them to vary by host species, sex, body site, and a proxy of social status. These rare data provide support for the bacterial fermentation hypothesis in olfactory signal production and implicate steroid hormones as mediators of microbial community structure. We conclude by discussing the role of scale in comparative microbial studies, the links between feeding strategy and host–microbiome coadaptation, the underappreciated benefits of captive populations for advancing conservation research, and the need to consider the entirety of an animal's microbiota. Ultimately, these studies will help move the field from exploratory to hypothesis‐driven research.

    

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5. Identifying social behaviours related to disease transmission in banded mongoose from accelerometer data

   https://doi.org/10.1002/2688-8319.12228  

   Van de Vuurst, Paige ; Alexander, Kathleen A. ( July 2023 , Ecological Solutions and Evidence)

   Current methods for identifying and predicting infectious disease dynamics in wildlife populations are limited. Pathogen transmission dynamics can be complex, influenced by behavioural interactions between and among hosts, pathogens and their environments. These behaviours may also be influenced directly by observers, with observational research methods being limited to habituated species. Banded mongooseMungos mungoare social, medium size carnivores infected with the novel tuberculosis pathogenMycobacterium mungi. This pathogen is principally transmitted during normal olfactory communication behaviours. Banded mongoose behavioural responses to humans change over the landscape, limiting the use of direct observational approaches in areas where mongoose are threatened and flee.

   The accelerometers in bio‐logging devices have been used previously to identify distinct behaviours in wildlife species, providing a tool to quantifying specific behaviours in ecological studies. We deployed Axy‐5X model accelerometers (TechnoSmArt) on captive mongoose to determine whether accelerometers could be used to identify key mongoose behavioural activities previously associated withM. mungitransmission.

   After two collaring periods, we determined that three distinct behavioural activities could be identified in the accelerometer data: bipedal vertical vigilance, running and scent marking activity; behaviours that have been shown to vary across land type in the banded mongoose.

   Results from this work advance current data analytics and provide modifications to data analysis works flows, updating and expanding upon current methodologies. We also provide preliminary evidence of successful mathematical classification of the target behaviours, supporting the future use of these devices. Methods applied here may allow model estimates ofM. mungitransmission in free‐ranging mongoose to be refined with possible application to other systems where direct observation approaches have limited application.

    

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