Biology subjects

Robbins, M. M.

Publications and source records attributed to Robbins, M. M..

4 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↗

bioRxiv2025

Risk-taking incentives predict aggression heuristics in female gorillas

Competition is commonly reflected in aggressive interactions among groupmates, as individuals try to attain or maintain higher social ranks that can offer them better access to critical resources. In this study, we investigate the factors that can shift competitive incentives against higher- or lower-ranking groupmates, that is, more or less powerful individuals. We use a long-term behavioural dataset on five wild groups of the two gorilla species starting in 1998, and we show that most aggression is directed from higher- to lower-ranking adult females close in rank, highlighting rank-reinforcement incentives. Yet, females directed 42% of aggression to higher-ranking females than themselves. Females targeted groupmates of higher rank with increasing number of males in the group, suggesting that males might buffer female-female aggression risk. Contrarily, they targeted females of lower rank with increasing number of females in the group, potentially because this is a low risk option that females prefer when they have access to a larger pool of competitors to choose from. Lactating and pregnant females, especially those in the latest stage of pregnancy, targeted groupmates of higher rank than the groupmates that cycling females targeted, suggesting that energetic needs may motivate females to risk confrontation with more powerful rivals. Our study provides critical insights into the evolution of competitive behaviour, showing that aggression heuristics, the simple rules that animals use to guide their aggressive interactions, are not simply species-specific but also dependent on the conditions that populations and individuals experience.

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↗

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↗