Biology subjects

Caillaud, D.

Publications and source records attributed to Caillaud, D..

3 recordsLinked to original sources

bioRxiv2026

Non-invasive genomic sampling uncovers novel connectivities and origins of confiscated gorillas

BackgroundGorillas are a group of African great apes with two species and four subspecies that are currently critically endangered or endangered. Previous studies that analysed the genetics of wild gorillas from non-invasive samples, such as faeces or hair, analysed short mitochondrial or nuclear markers, which may not reflect the wider nuclear genome. Recent technical advances in target capture hybridisation, enrich the endogenous DNA content of non-invasive samples, allowing contiguous genomic regions to be sequenced. ResultsHere, we generated georeferenced genetic data from faecal and hair samples of 280 wild gorillas, sampled from three of the four gorilla subspecies, across large parts of their present-day distributions. With this expanded representation of gorilla genetic diversity in the wild, we detected three population clusters in western lowland gorillas, with the Sangha River and its affluents acting as significant barriers to gene flow. We reconstructed patterns of past population connectivity between western lowland gorillas in the north-eastern distribution range and Cross River gorillas, which may have been facilitated by a migration corridor also used by the Central and Nigeria-Cameroon chimpanzee subspecies. Finally, we predicted the geographic origins of wild-born gorillas, achieving a mean prediction error of 65 km, with a population-level resolution for mountain gorillas and some populations of western lowland gorillas. ConclusionOur work characterises fine-scale population structure in western lowland gorillas, which will be informative for future conservation strategies. This proof of concept in predicting geographic locations of wild gorillas, will be useful for future applications to geolocalise trafficked or rescued gorillas.

evolutionary biology↗

bioRxiv2025

Terrain ruggedness and human activities influence the distribution of Grauer's gorillas and eastern chimpanzees in the Tayna Nature Reserve, Democratic Republic of Congo

The Albertine Rift Hotspot in east-central Africa is one of the most biodiverse regions in the world. It hosts a number of conservation-priority species, including Critically Endangered Grauers gorillas and Endangered eastern chimpanzees. Yet, prolonged insecurity in the region has made wildlife monitoring and conservation challenging. This is particularly true of the northeastern limits of the range of Grauers gorillas, where wide stretches of unprotected forest could harbor behaviorally and genetically unique peripheral populations of great apes and other species. Here, we developed a rapid wildlife survey method to map population distributions and monitor the impact of various human activities in the Tayna Nature Reserve in eastern Democratic Republic of Congo. Despite a lack of surveys since the early 2000s, we find that Grauers gorillas and eastern chimpanzees, as well as a number of smaller-bodied species, have persisted in Tayna. Observations of gorilla and chimpanzee signs were highly heterogeneous. They were less dense near human settlements and artisanal mines and peaked in areas with rugged terrain. The association with rugged terrain may be a result of historical anthropogenic pressure, behavioral avoidance of human activities, and/or ecological preference. Maintaining connectivity between patches of suitable great ape habitat will be critical for long-term great ape conservation in the Albertine Rift region. Our findings also demonstrate the utility of priority species monitoring driven by local communities for conservation initiatives.

ecology↗

bioRxiv2022

Isolated Grauer's gorilla populations differ in diet and gut microbiome

The animal gut microbiome has been implicated in a number of key biological processes, ranging from digestion to behavior, and has also been suggested to facilitate local adaptation. However, studies in wild animals rarely compare multiple populations that differ ecologically, which is the level at which local adaptation may occur. Further, few studies simultaneously characterize diet and the gut microbiome from the same sample, despite the likely presence of co-dependencies. Here, we investigate the interplay between diet and gut microbiome in three geographically isolated populations of the critically endangered Grauers gorilla, which we show to be genetically differentiated. We find population- and social group-specific dietary and gut microbial profiles and co-variation between diet and gut microbiome, despite the presence of core microbial taxa. There was no detectable effect of age, sex, or genetic relatedness on the microbiome. Diet differed considerably across populations, with the high-altitude population consuming a lower diversity of plants compared to low-altitude populations, consistent with food plant availability constraining diet. The observed pattern of covariation between diet and gut microbiome is likely a result of long-term social and ecological factors. Our study suggests that the gut microbiome is sufficiently plastic to support flexible food selection and hence contribute to local adaptation.

ecology↗