David Jansen

Troubled waters: Water availability drives human-baboon encounters in a protected, semi-arid landscape

Biological Conservation, Oct 1, 2022

Universal gut microbial relationships in the gut microbiome of wild baboons

bioRxiv (Cold Spring Harbor Laboratory), Aug 21, 2022

Ecological relationships between bacteria mediate the services that gut microbiomes provide to th... more Ecological relationships between bacteria mediate the services that gut microbiomes provide to their hosts. Knowing the overall direction and strength of these relationships within hosts, and their generalizability across hosts, is essential to learn how microbial ecology scales up to affect microbiome assembly, dynamics, and host health. Here we gain insight into these patterns by inferring thousands of correlations in bacterial abundance between pairs of gut microbiome taxa from extensive time series data (5,534 microbiome profiles from 56 wild baboon hosts over a 13year period). We model these time series using a statistically robust, multinomial logistic-normal modeling framework and test the degree to which bacterial abundance correlations are consistent across hosts (i.e., "universal") or individualized to each host. We also compare these patterns to two publicly available human data sets. We find that baboon gut microbial relationships are largely universal: correlation patterns within each baboon host reflect a mixture of idiosyncratic and shared patterns, but the shared pattern dominates by almost 2-fold. Surprisingly, the strongest and most consistently correlated bacterial pairs across hosts were overwhelmingly positively correlated and typically belonged to the same family-a 3-fold enrichment compared to pairs drawn from the data set as a whole. The bias towards universal, positive bacterial correlations was also apparent in monthly samples from human infants, and bacterial families that had universal relationships in baboons also tended to be universal in human infants. Together, our results advance our understanding of the relationships that shape gut microbial ecosystems, with implications for microbiome personalization, community assembly and stability, and the feasibility of microbiome interventions to improve host health.

format_quoteUniversal positive bacterial correlations in gut microbiomes enhance understanding for microbiome interventions and host health improvements.format_quote

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Segmental concatenation of individual signatures and context cues in banded mongoose (Mungos mungo) close calls

BMC Biology, Dec 1, 2012

Background: All animals are anatomically constrained in the number of discrete call types they ca... more Background: All animals are anatomically constrained in the number of discrete call types they can produce. Recent studies suggest that by combining existing calls into meaningful sequences, animals can increase the information content of their vocal repertoire despite these constraints. Additionally, signalers can use vocal signatures or cues correlated to other individual traits or contexts to increase the information encoded in their vocalizations. However, encoding multiple vocal signatures or cues using the same components of vocalizations usually reduces the signals' reliability. Segregation of information could effectively circumvent this trade-off. In this study we investigate how banded mongooses (Mungos mungo) encode multiple vocal signatures or cues in their frequently emitted graded single syllable close calls. Results: The data for this study were collected on a wild, but habituated, population of banded mongooses. Using behavioral observations and acoustical analysis we found that close calls contain two acoustically different segments. The first being stable and individually distinct, and the second being graded and correlating with the current behavior of the individual, whether it is digging, searching or moving. This provides evidence of Marler's hypothesis on temporal segregation of information within a single syllable call type. Additionally, our work represents an example of an identity cue integrated as a discrete segment within a single call that is independent from context. This likely functions to avoid ambiguity between individuals or receivers having to keep track of several context-specific identity cues. Conclusions: Our study provides the first evidence of segmental concatenation of information within a single syllable in non-human vocalizations. By reviewing descriptions of call structures in the literature, we suggest a general application of this mechanism. Our study indicates that temporal segregation and segmental concatenation of vocal signatures or cues is likely a common, but so far neglected, dimension of information coding in animal vocal communication. We argue that temporal segregation of vocal signatures and cues evolves in species where communication of multiple unambiguous signals is crucial, but is limited by the number of call types produced.

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Optimisation or satiation, testing diet selection rules in goats

Small Ruminant Research, Nov 1, 2007

Several hypotheses have been formulated to explain diet selection by herbivores, focusing on the ... more Several hypotheses have been formulated to explain diet selection by herbivores, focusing on the maximization of nutrient intake, the minimization of plant secondary compounds, or the satiety hypothesis. This research aimed at studying diet selection revealing which chemical characteristics of plants form the bases for dietary preferences of goats. This was done by setting up a feeding experiment with three

Synchrony and idiosyncrasy in the gut microbiome of wild baboons

Human gut microbial dynamics are highly individualized, making it challenging to link microbiota ... more Human gut microbial dynamics are highly individualized, making it challenging to link microbiota to health and to design universal microbiome therapies. This individuality is typically attributed to variation in host genetics, diets, environments, and medications, but it could also emerge from fundamental ecological forces that shape microbiota more generally. Here we leverage extensive gut microbial time series from wild baboons—hosts who experience little interindividual dietary and environmental heterogeneity—to test whether gut microbial dynamics are synchronized across hosts or largely idiosyncratic. Despite their shared lifestyles, baboon microbiome dynamics were only weakly synchronized. The strongest synchrony occurred among baboons living in the same social group, likely because group members range over the same habitat and simultaneously encounter the same sources of food and water. However, this synchrony was modest compared to each host’s personalized dynamics. Indeed, h...

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Vocal communication in the banded mongoose (Mungos mungo)

Hinweisen die potentielle Information für den Empfänger vergrössern können, ungeachtet der Gradie... more Hinweisen die potentielle Information für den Empfänger vergrössern können, ungeachtet der Gradierung vieler Rufe. Diese Fähigkeit, durch Kombinationen von akustisch unterschiedlichen Rufsegmenten oder Rufen zusätzliche Information für Empfänger zu generieren, kompensiert möglicherweise die im Vergleich zu anderen gruppenlebenden Mangustenarten reduzierte Rufanzahl. Die in dieser Arbeit enthaltenen Studien deuten weiter daraufhin, dass die Hypothese bezüglich der Evolution der vokalen Komplexität nicht nur auf die Anzahl diskreter Rufe typen bezogen werden sollte, sondern auch die Variabilität der Kombination von vokalen Einheiten berücksichtigt werden muss. Es wird vermutet, dass affiliative Kontexte bei der Untersuchung von Faktoren bezüglich der sozialen Komplexität eine hohe Relevanz besitzen. Die präsentierten Resultate schliessen sich neuesten Forschungsergebnissen an, dass zusätzliche Dimensionen der vokalen Expression in affiliativen Kontexten verbreitet sind. Bei der Untersuchung der Beziehung zwischen sozialer Komplexität und kommunikativer Komplexität sollte daher ein Fokus auf affiliative Kontexte gelegt werden. Ausserdem sollten alle Dimensionen der vokalen Variation berücksichtigt werden. General introduction General introduction General introduction Communication through vocal signals has been shown to be essential in the coordination of many behaviours in animals, such as mate attraction, parentoffspring negotiation, warning group members against danger, sharing information on food locations, vigilance, territorial defence, or maintaining group cohesion (Hauser 1996; Bradbury and Vehrencamp 1998; Seyfarth et al. 2010). Significant differences in the acoustic structure and the usage can be observed between call types. This can be due to call types differing between behavioural contexts or elicited by external events (i.e.

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Gut microbiome heritability is nearly universal but environmentally contingent

Science, 2021

Baboons inform on human gut microbiota Commensal bacteria are found throughout an organism, but i... more Baboons inform on human gut microbiota Commensal bacteria are found throughout an organism, but it is not known whether associations between gut bacteria and their host are heritable. Grieneisen et al. examined changes in the microbiomes of 585 wild baboons from fecal samples collected over 14 years (see the Perspective by Cortes-Ortiz and Amato). Almost all microbiome traits tested demonstrated some level of statistically significant heritability. Most heritability values were low but varied over time correlating with the age of the host. Baboons live in an environment similar to that postulated for early humans and have a microbiome similar to that of humans. Thus, this heritability of the microbiome may reflect similar genetic determinants in humans, for which similar datasets are not available. Science , aba5483, this issue p. 181 ; see also abj5287, p. 159

format_quote97% of microbiome phenotypes in baboons are heritable, including all community phenotypes and 93% of single-taxon phenotypes.format_quote

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A comparison of dominance rank metrics reveals multiple competitive landscapes in an animal society

Proceedings of the Royal Society B: Biological Sciences, 2020

Across group-living animals, linear dominance hierarchies lead to disparities in access to resour... more Across group-living animals, linear dominance hierarchies lead to disparities in access to resources, health outcomes and reproductive performance. Studies of how dominance rank predicts these traits typically employ one of several dominance rank metrics without examining the assumptions each metric makes about its underlying competitive processes. Here, we compare the ability of two dominance rank metrics—simple ordinal rank and proportional or ‘standardized’ rank—to predict 20 traits in a wild baboon population in Amboseli, Kenya. We propose that simple ordinal rank best predicts traits when competition is density-dependent, whereas proportional rank best predicts traits when competition is density-independent. We found that for 75% of traits (15/20), one rank metric performed better than the other. Strikingly, all male traits were best predicted by simple ordinal rank, whereas female traits were evenly split between proportional and simple ordinal rank. Hence, male and female tra...

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Costs and drivers of helminth parasite infection in wild female baboons

Journal of Animal Ecology, 2019

These apparently contradictory results probably reflect the complex nature of potential relations... more These apparently contradictory results probably reflect the complex nature of potential relationships between host physiology and parasite infection. For instance, host GC levels may rise in response to the energetic stress imposed by parasite depletion of host resources (Coop and Kyriazakis, 1999). GCs may also rise in response to activation of the immune system by helminth infections. Specifically, GCs exert anti-inflammatory and immunosuppressive effects by inhibiting the secretion of interlukin-1 (IL-1), which regulates the T-helper 2 system important for clearing helminth infections (Helmby and Grencis, 2004; Lee et al., 1988). Importantly, the immunosuppressive effects of GCs may also underlie relationships between GCs and parasitism; if elevated, GCs might reduce host resistance to infection leading to a positive relationship between GCs and helminths. On the other hand, GCs and helminths may be negatively correlated, if, for instance, females in good physical condition invest heavily in reproduction; in this case, females might exhibit high GCs and low parasite burdens because they have the resources do both (reproduce and fight parasites). In addition to investigating potential costs of infection, we sought to understand the patterns and drivers of individual infection risk. Doing so can help uncover the adaptive value of behavioral strategies and social structures, and point to selection pressures and constraints that have shaped mammalian behavior and life history. Infection risk is defined as the probability that a host acquires an infection. Variation in individual infection risk is thought to be largely reflected in existing patterns of infection in natural populations. In group-living animals, the drivers of infection risk can be categorized into three main hierarchical processes: those operating at the level of individual hosts, social groups, and the host population at large (see Fig. 1 for examples of these hierarchical processes in female baboons). These processes act through two broad mechanisms to ensure successful infection of hosts and subsequent transmission of helminth infectious stages to additional hosts: (1) host exposure to helminth infectious stages, and (2) host susceptibility, including the host's quantitative resistance to helminth infection (i.e., the ability to limit parasite burden once a host is exposed and infected). Disentangling the causal links between exposure, susceptibility, and parasite burdens is challenging, and often impossible, in observational studies. What is possible is to draw inferences about the drivers of individual variation in infection risk by correlating infection patterns with host-, group-, and population-level traits. At the host-level, traits such as age, reproductive state, sex, body mass, social

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Exorcising Grice's ghost: an empirical approach to studying intentional communication in animals

Biological reviews of the Cambridge Philosophical Society, Jan 2, 2016

Language's intentional nature has been highlighted as a crucial feature distinguishing it fro... more Language's intentional nature has been highlighted as a crucial feature distinguishing it from other communication systems. Specifically, language is often thought to depend on highly structured intentional action and mutual mindreading by a communicator and recipient. Whilst similar abilities in animals can shed light on the evolution of intentionality, they remain challenging to detect unambiguously. We revisit animal intentional communication and suggest that progress in identifying analogous capacities has been complicated by (i) the assumption that intentional (that is, voluntary) production of communicative acts requires mental-state attribution, and (ii) variation in approaches investigating communication across sensory modalities. To move forward, we argue that a framework fusing research across modalities and species is required. We structure intentional communication into a series of requirements, each of which can be operationalised, investigated empirically, and must...

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Comparing proportional and ordinal dominance ranks reveals multiple competitive landscapes in an animal society

Across group-living animals, linear dominance hierarchies lead to disparities in access to resour... more Across group-living animals, linear dominance hierarchies lead to disparities in access to resources, health outcomes, and reproductive performance. Studies of how dominance rank affects these outcomes typically employ one of several dominance rank metrics without examining the assumptions each metric makes about its underlying competitive processes. Here we compare the ability of two dominance rank metrics—ordinal rank and proportional or ‘standardized’ rank—to predict 20 distinct traits in a well-studied wild baboon population in Amboseli, Kenya. We propose that ordinal rank best predicts outcomes when competition is density-dependent, while proportional rank best predicts outcomes when competition is density-independent. We found that for 75% (15/20) of the traits, one of the two rank metrics performed better than the other. Strikingly, all male traits were better predicted by ordinal than by proportional rank, while female traits were evenly split between being better predicted ...

format_quoteOrdinal rank better predicts competition for social and mating partners across sexes, revealing competitive processes.format_quote

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Multi-scale predictors of parasite risk in wild male savanna baboons (Papio cynocephalus)

Behavioral Ecology and Sociobiology, 2019

Several factors are thought to shape male parasite risk in polygynous and polygynandrous mammals,... more Several factors are thought to shape male parasite risk in polygynous and polygynandrous mammals, including male-male competition, investment in potentially immunosuppressive hormones, and dispersal. Parasitism is also driven by processes occurring at larger scales, including host social groups and populations. To date, studies that test parasite-related costs of male behavior at all three scales-individual hosts, social groups, and the host population-remain rare. To fill this gap, we investigated multi-scale predictors of helminth parasitism in 97 male savanna baboons (Papio cynocephalus) living in the Amboseli ecosystem in Kenya over a 5-year span. Controlling for multi-scale processes, we found that many of the classic indicators of male mating effort-high dominance rank, testosterone, and glucocorticoids-did not predict helminth infection risk. However, we identified two parasite-related costs associated with male behavior: (i) socially connected males exhibited higher Trichuris trichiura egg counts and greater parasite species richness than socially isolated males and (ii) males with stable group residency exhibited higher parasite species richness than males who frequently dispersed to new social groups. At the population level, males harbored more parasites following periods of drought than rainfall. Lastly, parasites exhibited positive covariance suggesting that infection risk increases if a host already harbors one or more parasite taxa. These results indicate that multi-scale processes are important in driving male parasite risk and that some aspects of male behavior are costly. Together, our results provide an unusually holistic perspective on the drivers of parasite risk in the context of male behaviors and life histories. Significance statement Infection by gastrointestinal helminths can have major consequences for host fitness, especially in the context of male mating effort. Multi-scale processes-from the host to its social group and population-are important for understanding key drivers of parasitism. We leveraged long-term data from one of the longest running behavioral ecology studies of a wild primate population in the world, the well-studied Amboseli baboon population in Kenya. We found that traditional indicators of male mating effort (attaining high dominance rank, high testosterone and glucocorticoids) did not predict parasitism. However, male social connectedness to females, competitive group demography, and harsh weather were all associated with higher parasitism. Because socially connected males faced the highest parasite risk, males may face a tradeoff between male-female relationships and parasitism. Our results show how processes at multiple scales contribute to variation in male parasite risk.

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Troubled waters: Water availability drives human-baboon encounters in a protected, semi-arid landscape

Biological Conservation

Optimisation or satiation, testing diet selection rules in goats

Small Ruminant Research, 2007

Several hypotheses have been formulated to explain diet selection by herbivores, focusing on the ... more Several hypotheses have been formulated to explain diet selection by herbivores, focusing on the maximization of nutrient intake, the minimization of plant secondary compounds, or the satiety hypothesis. This research aimed at studying diet selection revealing which chemical characteristics of plants form the bases for dietary preferences of goats. This was done by setting up a feeding experiment with three

Segmental concatenation of individual signatures and context cues in banded mongoose (Mungos mungo) close calls

BMC Biology, 2012

Background: All animals are anatomically constrained in the number of discrete call types they ca... more Background: All animals are anatomically constrained in the number of discrete call types they can produce. Recent studies suggest that by combining existing calls into meaningful sequences, animals can increase the information content of their vocal repertoire despite these constraints. Additionally, signalers can use vocal signatures or cues correlated to other individual traits or contexts to increase the information encoded in their vocalizations. However, encoding multiple vocal signatures or cues using the same components of vocalizations usually reduces the signals' reliability. Segregation of information could effectively circumvent this trade-off. In this study we investigate how banded mongooses (Mungos mungo) encode multiple vocal signatures or cues in their frequently emitted graded single syllable close calls. Results: The data for this study were collected on a wild, but habituated, population of banded mongooses. Using behavioral observations and acoustical analysis we found that close calls contain two acoustically different segments. The first being stable and individually distinct, and the second being graded and correlating with the current behavior of the individual, whether it is digging, searching or moving. This provides evidence of Marler's hypothesis on temporal segregation of information within a single syllable call type. Additionally, our work represents an example of an identity cue integrated as a discrete segment within a single call that is independent from context. This likely functions to avoid ambiguity between individuals or receivers having to keep track of several context-specific identity cues. Conclusions: Our study provides the first evidence of segmental concatenation of information within a single syllable in non-human vocalizations. By reviewing descriptions of call structures in the literature, we suggest a general application of this mechanism. Our study indicates that temporal segregation and segmental concatenation of vocal signatures or cues is likely a common, but so far neglected, dimension of information coding in animal vocal communication. We argue that temporal segregation of vocal signatures and cues evolves in species where communication of multiple unambiguous signals is crucial, but is limited by the number of call types produced.

format_quoteThis research presents the first evidence of segmental concatenation within a non-human vocalization, integrating identity cues independently of context.format_quote

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Optimisation or satiation, testing diet selection rules in goats

Small Ruminant …, 2007

Several hypotheses have been formulated to explain diet selection by herbivores, focusing on the ... more Several hypotheses have been formulated to explain diet selection by herbivores, focusing on the maximization of nutrient intake, the minimization of plant secondary compounds, or the satiety hypothesis. This research aimed at studying diet selection revealing which chemical characteristics of plants form the bases for dietary preferences of goats. This was done by setting up a feeding experiment with three

Exorcising Grice's ghost: an empirical approach to studying intentional communication in animals

by Sonja Koski, David Jansen, Florence Gaunet, Sabine Stoll, Ines Goncalves, Balthasar Bickel, Markus Böckle, and Thibaud Gruber

Language's intentional nature has been highlighted as a crucial feature distinguishing it from ot... more Language's intentional nature has been highlighted as a crucial feature distinguishing it from other communication systems. Specifically, language is often thought to depend on highly structured intentional action and mutual mindreading by a communicator and recipient. Whilst similar abilities in animals can shed light on the evolution of intentionality, they remain challenging to detect unambiguously. We revisit animal intentional communication and suggest that progress in identifying analogous capacities has been complicated by (i) the assumption that intentional (that is, voluntary) production of communicative acts requires mental-state attribution, and (ii) variation in approaches investigating communication across sensory modalities. To move forward, we argue that a framework fusing research across modalities and species is required. We structure intentional communication into a series of requirements, each of which can be operationalised, investigated empirically, and must be met for purposive, intentionally communicative acts to be demonstrated. Our unified approach helps elucidate the distribution of animal intentional communication and subsequently serves to clarify what is meant by attributions of intentional communication in animals and humans.

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Optimisation or satiation, testing diet selection rules in goats

by David Jansen and Kevin Kirkman

Small Ruminant Research, Feb 15, 2007

Several hypotheses have been formulated to explain diet selection by herbivores, focusing on the ... more Several hypotheses have been formulated to explain diet selection by herbivores, focusing on the maximization of nutrient intake, the minimization of plant secondary compounds, or the satiety hypothesis. This research aimed at studying diet selection revealing which chemical characteristics of plants form the bases for dietary preferences of goats. This was done by setting up a feeding experiment with three different combinations of tree species Acacia karroo, A. nilotica and A. sieberana. The chemical characteristics of these three Acacia species were used to predict diet selection. To test the validity of the satiety hypothesis, goats were placed on a conditioning diet of one of the three species. We found a clear preference for A. karroo and an avoidance of A. nilotica when these two were offered to the goats. In trials where A. nilotica was present, tannin minimization was the best explaining diet selection rule. In trials where A. nilotica was not present, however, tannin minimization was not the best explanation. Our ﬁndings suggest that tannins are not avoided but kept below a certain threshold. Below this threshold, goats based their dietary choices on other chemical characteristics of the Acacia species. Acid detergent ﬁbre (ADF) minimization could then best explain preferences in trials with Acacia karroo and A. sieberana that have generally low tannin content. Goats did not maximize nutrient intake or digestibility, and we found no support for the satiety hypothesis.

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Segmental concatenation of individual signatures and context cues in banded mongoose (Mungos mungo) close calls

BMC Biology, Dec 3, 2012

Background All animals are anatomically constrained in the number of discrete call types they ca... more Background
All animals are anatomically constrained in the number of discrete call types they can produce. Recent studies suggest that by combining existing calls into meaningful sequences, animals can increase the information content of their vocal repertoire despite these constraints. Additionally, signalers can use vocal signatures or cues correlated to other individual traits or contexts to increase the information encoded in their vocalizations. However, encoding multiple vocal signatures or cues using the same components of vocalizations usually reduces the signals' reliability. Segregation of information could effectively circumvent this trade-off. In this study we investigate how banded mongooses (Mungos mungo) encode multiple vocal signatures or cues in their frequently emitted graded single syllable close calls.

Results
The data for this study were collected on a wild, but habituated, population of banded mongooses. Using behavioral observations and acoustical analysis we found that close calls contain two acoustically different segments. The first being stable and individually distinct, and the second being graded and correlating with the current behavior of the individual, whether it is digging, searching or moving. This provides evidence of Marler's hypothesis on temporal segregation of information within a single syllable call type. Additionally, our work represents an example of an identity cue integrated as a discrete segment within a single call that is independent from context. This likely functions to avoid ambiguity between individuals or receivers having to keep track of several context-specific identity cues.

Conclusions
Our study provides the first evidence of segmental concatenation of information within a single syllable in non-human vocalizations. By reviewing descriptions of call structures in the literature, we suggest a general application of this mechanism. Our study indicates that temporal segregation and segmental concatenation of vocal signatures or cues is likely a common, but so far neglected, dimension of information coding in animal vocal communication. We argue that temporal segregation of vocal signatures and cues evolves in species where communication of multiple unambiguous signals is crucial, but is limited by the number of call types produced.

Keywords: vocal signature; vocal cue; syllable; close call; segregation of information; graded calls; banded mongoose; segmental concatenation

format_quoteEvidence of segmental concatenation in non-human vocalizations shows discrete identity cues integrated within calls, minimizing ambiguity in individual recognition.format_quote

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