Biology subjects

Surbeck, M.

Publications and source records attributed to Surbeck, M..

10 recordsLinked to original sources

bioRxiv2026

Ranging and territoriality in African Apes

Intergroup relations vary strikingly among African apes, with only chimpanzees showing intense, often lethal territoriality. The economic defendability hypothesis proposes that such territorial behaviour is favored where home ranges can be economically defended, as indexed by the ratio of daily travel distance to home range diameter. To test this idea, we compiled and analyzed comparable data on yearly home range size, daily travel distance and defendability indices from one population of each nonhuman African ape species and integrated these with comparable published data. We find that bonobos had substantially larger home ranges and longer daily travel distances than chimpanzees and gorillas, contradicting a prevailing assumption that bonobos experience higher or more reliable food abundance. Defendability indices were higher in chimpanzees and bonobos than in mountain gorillas, but did not differ significantly between chimpanzees, bonobos, and western gorillas. Overall, our results indicate that economic defendability alone cannot explain interspecific variation in territoriality and that our current understanding of ecological differences between the species of the genus Pan have to be revised. Possible additional factors shaping space use of neighboring groups include mate competition within groups.

animal behavior and cognition↗

bioRxiv2026

Supra-regular recursion in primate vocal sequences

Complex syntax is the widely accepted demarcation between animal and human communication. Although animal vocal systems occasionally contain pockets of syntax-like structures, their grammars are thought to be at best regular, whereas human language is supra-regular, i.e., including at least context-free computational complexity. Leveraging a new likelihood method for probabilistic formal grammars, we show that the call sequences of three phylogenetically diverse nonhuman primates (bonobos, olive colobus monkeys, common marmosets) include parts that are most likely generated by supra-regular recursive grammars, similar to human language. These findings challenge syntax as the major transition in hominid evolution and opens up prospects for alternative evolutionary scenarios.

animal behavior and cognition↗

bioRxiv2026

Targeted Chromosomal Sequencing of Wild Bonobos Identifies a Genetically Distinct Subpopulation East of the Lomami River

Bonobos (Pan paniscus), an endangered species, have for decades been genetically understudied, partly due to difficulties in obtaining high-quality samples. The study of their genome is important not only for understanding their evolution, but also for improving conservation efforts, including population management, diversity and inbreeding assessment, and tracking rescued individuals to combat illegal wildlife trafficking. Here, we use chromosome 21 target capture data from 156 non-invasively collected faecal samples from wild bonobos to perform a comprehensive analysis of their population structure. We confirm the existence of three previously suggested subpopulations identified here as Western, Central and Eastern bonobos which are defined by natural barriers of gene flow such as the Lomami River. By estimating levels of inbreeding, diversity and differentiation, we find support for isolation of mainly Western and Eastern populations and add information on the dispersal routes of their ancestors. We infer split times and separation of these populations and apply a genetic framework to geolocalize samples of unknown origin, showing that locations of their potential origin can be estimated with a precision of up to a median of [~]50 km. Our study provides valuable insight into the evolution and population structure of bonobos and reveals how rivers act as strong barriers between populations. It also offers resources for conservation efforts and highlights the need to monitor bonobo populations more closely, in particular isolated ones. ImpactBonobos have been difficult to study genetically due to their remote forest habitat and endangered status. Here we used non-invasive sampling and chromosome 21 target capture sequencing to perform the most detailed analysis to date of their population structure. We find three main subpopulations and genetic differentiation influenced by river barriers, especially with populations found on the Eastern side of the Lomami river. This data will be useful for identifying the geographic origin of confiscated samples and thus aid bonobo conservation efforts.

bioinformatics↗

bioRxiv2025

Great Ape Childhoods: Development of infant bonobos (Pan paniscus) and chimpanzees (Pan troglodytes schweinfurthii) in the wild

Human development is marked by extended immaturity, necessitating extended care throughout infancy and childhood, facilitating advanced cognitive, social, and cultural skill acquisition. Parallels of extended development are also present in our closest living relatives, bonobos (Pan paniscus) and chimpanzees (Pan troglodytes). The Self-Domestication Hypothesis (SDH) suggests that human uniqueness stems from selection against aggression. Bonobos are also considered self-domesticated, exhibiting lower aggression and greater social tolerance, which are linked to delayed development and prolonged maternal dependence compared to chimpanzees. However, systematic, quantitative comparisons of the two species developmental patterns are limited and conflicting. This study addressed this gap by examining behavioural development in bonobo and chimpanzee infants aged 0-5.5 years living in two populations (Kokolopori community, Kokolopori Bonobo Reserve, DRC, N=21; Ngogo community, Kibale National Park, Uganda, N=22) in their natural environments. We specifically focused on (i) general behaviours (travel, feeding, grooming), and (ii) spatial independence. By systematically comparing developmental data and using consistent methods, we tested whether bonobo development aligns with SDH predictions. Our results showed similar developmental trajectories, with no species differences concerning ventral riding, nipple contact, or grooming. However, we found species differences regarding travel and proximity patterns, with chimpanzees exhibiting prolonged dorsal riding, bonobos travelling independently more often and maintaining greater distances from their mothers. Age, sibling presence, and maternal parity influenced behavioural patterns, but no sex differences were observed. These findings challenge assumptions of slower bonobo maturation, and highlight the importance of systematic, collaborative research on primate behavioural diversity in natural environments.

animal behavior and cognition↗

bioRxiv2025

An updated vocal repertoire of wild adult bonobos (Pan paniscus )

While research over the last 20 years has shed important light on the vocal behaviour of our closest living relatives, bonobos and chimpanzees, a quantitative description of their full vocal repertoire is absent. Such data are critical for a holistic understanding of a species communication system and unpacking how these systems compare more broadly with other primate and non-primate species. Here we make key progress by providing the first quantitative Pan vocal repertoire, specifically for wild bonobos. Using data comprising over 1500 calls from 53 adult individuals collected over 33 months, we employ machine-learning-based random forest analyses and describe 11 acoustically distinguishable call types. We discuss issues associated with resolving vocal repertoires from wild data in great apes and highlight potential future approaches to further capture the complexity of the bonobo vocal system.

animal behavior and cognition↗

bioRxiv2023

Comparative metagenomics reveals host-specific functional adaptation of intestinal microbiota across hominids

Fine-scale knowledge of the changes in composition and function of the human gut microbiome compared that of our closest relatives is critical for understanding the evolutionary processes underlying its developmental trajectory. To infer taxonomic and functional changes in the gut microbiome across hominids at different timescales, we performed high-resolution metagenomic-based analyses of the fecal microbiome from over two hundred samples including diverse human populations, as well as wild-living chimpanzees, bonobos, and gorillas. We find human-associated taxa depleted within non-human apes and patterns of host-specific gut microbiota, suggesting the widespread acquisition of novel microbial clades along the evolutionary divergence of hosts. In contrast, we reveal multiple lines of evidence for a pervasive loss of diversity in humans populations in correlation with a high Human Development Index, including evolutionarily conserved clades. Similarly, patterns of co-phylogeny are found to be disrupted in humans. Together with identifying individual microbial taxa and functional adaptations that correlate to host phylogeny, these findings offer new and exciting insights into specific candidates playing a role in the diverging trajectories of the gut microbiome of hominids, demonstrating that repeated horizontal gene transfer and gene loss, as well as the adaptation to transient microaerobic conditions appear to have played a role in the evolution of the human gut microbiome.

evolutionary biology↗

bioRxiv2021

Failure to account for behavioral variability overestimates bonobo populations and compromises accuracy in population monitoring

Indirect wildlife population surveying largely depends upon counts of artefacts of behavior (e.g., nests or dung). Likelihood to encounter these artefacts is derived from both artefact production and decay, and variability in production behavior is considered to contribute minimally to inaccuracy in wildlife estimation. Here, we demonstrate how ignoring behavioral variability contributes to significant population misestimation, using an example of an endangered ape, the bonobo (Pan paniscus). Until now, a single estimate of nest construction rate has been used to extrapolate bonobo densities, assumed to be broadly representative of bonobo sign production behavior. We estimated nest construction rates across seasons and social groups at the Kokolopori Bonobo Reserve, DRC, and find nest construction rates in bonobos to be highly variable across populations as well as seasonal. Failure to account for this variability led to degradation in the accuracy of bonobo population estimates of abundance, accounting for a likely overestimation of bonobo numbers by 34%, and at worst as high as 80%. With this example, we demonstrate that failure to account for inter- and intra-population behavioral variation compromises the ability to estimate both relative and absolute wildlife abundances. We argue that variation in sign production is but one of several potential ways that behavioral variability can affect conservation monitoring, should be measured across contexts whenever possible, and must be considered in population estimation confidence intervals. With increasing attention to be-havioral variability as a potential tool for conservation, conservationists must also account for the impact that behavioral variability can play upon wildlife population estimation. Our results underline the importance of observational research to wildlife monitoring schemes as a critical component of conservation management. We discuss the avenues through which behavioral variability is likely to impact wildlife monitoring accuracy and precision and propose potential approaches for accounting for behavioral variability in wildlife monitoring.

animal behavior and cognition↗

bioRxiv2021

Evaluating the efficacy of a consumer-centric method for ecological sampling: Using bonobo (Pan paniscus) feeding patterns as an instrument for tropical forest characterization

O_LICharacteristics of food availability and distribution are a key component of a species ecology. Objective measurement of food resources, such as vegetation plot sampling, do not consider aspects of selection by the consumer and therefore may produce imprecise measures of availability. Further, in most animal ecology research, traditional ecological surveying often is time-intensive and supplementary to ongoing behavioral observation. We propose a method to integrate ecological sampling of an animals environment into existing behavioral data collection systems by using the consumer as the surveyor. Here, we introduce the consumer-centric method (CCM) of assessing resource availability for its ability to measure food resource abundance, distribution, and dispersion. This method catalogues feeding locations observed during behavioral observation and uses aggregated data to characterize these ecological metrics. C_LIO_LIWe evaluated the CCM relative to traditional vegetation plot surveying using accumulated feeding locations across three years visited by a tropical frugivore, the bonobo (Pan paniscus), and compared it with data derived from over 200 vegetation plots across their 50km2+ home range. C_LIO_LIWe demonstrate that food species abundance estimates derived from the CCM are comparable to those derived from traditional vegetation plot sampling after approximately 600 observation days or 60 spatially explicit feeding locations. The agreement between the methods further improved when accounting for aspects of consumer selectivity in objective vegetation plot sampling (e.g., size minima). Estimates of density from CCM correlated with plot-derived estimates and were relatively insensitive to home range inclusion and other species characteristics, but were sensitive to sampling frequency (e.g., consumption frequency). Agreement between the methods in relative distribution of resources performed better across species than expected by chance, although measures of dispersion correlated poorly. C_LIO_LIWe demonstrate that while providing a robust measure to quantify local food availability, the CCM has an advantage over traditional sampling methods as it incorporates sampling biases relevant to the consumer. Therefore, as this method can be incorporated into existing observational data collection and does not require additional ecological surveying, it serves as a promising method for behavioral ecological data collection for animal species who re-use space and consume immobile food items. C_LI

ecology↗

bioRxiv2020

Behavioural diversity of bonobo prey preference as a potential cultural trait

The importance of cultural processes to behavioural diversity, especially in our closest living relatives, is central for revealing the evolutionary origins of human culture. Whereas potential cultural traits are extensively investigated in chimpanzees, our other closest living relative, the bonobo, is often overlooked as a candidate model. Further, a prominent critique to many examples of proposed animal cultures is premature exclusions of environmental confounds known to shape behavioural phenotypes. We addressed these gaps by investigating variation in prey preference expression between neighbouring bonobo groups that associate and share largely overlapping home ranges. We find specific group preference for duiker or anomalure hunting that are otherwise unexplained by variation in spatial usage of hunt locations, seasonality or sizes of hunting parties. Our findings demonstrate that group-specific behaviours emerge independently of the local ecology, indicating that hunting techniques in bonobos may be culturally transmitted. We suggest that the tolerant intergroup relations of bonobos offer an ideal context to explore drivers of behavioural phenotypes, the essential investigations for phylogenetic constructs of the evolutionary origins of culture.Competing Interest StatementThe authors have declared no competing interest.View Full Text

animal behavior and cognition↗

bioRxiv2020

Primate phageomes are structured by superhost phylogeny and environment

The evolutionary origins of human-associated bacteriophage communities are poorly understood. To address this question, we examined fecal phageomes of 23 wild non-human primate taxa, including multiple representatives of all the major primate radiations, and find relatives of the majority of human-associated phages. Primate taxa have distinct phageome compositions that exhibit a clear phylosymbiotic signal, and phage-superhost co-divergence is detected for 44 individual phages. Within species, neighboring social groups harbor evolutionarily and compositionally distinct phageomes, structured by superhost social behavior. However, captive non-human primate phageomes are more similar to humans than their wild counterparts, revealing replacement of wild-associated phages with human-associated ones. Together, our results suggest that potentially labile primate-phage associations persisted across millions of years of evolution, potentially facilitated by transmission between groupmates. One Sentence SummaryRelatives of human-associated phages in wild primates reveal ancient but dynamic superhost-phage associations shaped by social transmission.

microbiology↗