How populations adapt to their environment is a fundamental question in biology. Yet, we know surprisingly little about this process, especially for endangered species, such as nonhuman great apes. Chimpanzees, our closest living relatives, are particularly notable because they inhabit diverse habitats, from rainforest to woodland-savannah. Whether genetic adaptation facilitates such habitat diversity remains unknown, despite it having wide implications for evolutionary biology and conservation. By using newly sequenced exomes from 828 wild chimpanzees (388 postfiltering), we found evidence of fine-scale genetic adaptation to habitat, with signatures of positive selection in forest chimpanzees in the same genes underlying adaptation to malaria in humans. This work demonstrates the power of noninvasive samples to reveal genetic adaptations in endangered populations and highlights the importance of adaptive genetic diversity for chimpanzees.

Wild chimpanzee populations in West Africa (Pan troglodytes verus) have dramatically decreased as a direct consequence of anthropogenic activities and infectious diseases. Little information is currently available on the epidemiology, pathogenic significance, and zoonotic potential of protist species in wild chimpanzees. This study investigates the occurrence and genetic diversity of intestinal and blood protists as well as filariae in faecal samples (n = 234) from wild chimpanzees in the Dindefelo Community Nature Reserve, Senegal. PCR-based results revealed the presence of intestinal potential pathogens (Sarcocystis spp.: 11.5%; Giardia duodenalis: 2.1%; Cryptosporidium hominis: 0.9%), protist of uncertain pathogenicity (Blastocystis sp.: 5.6%), and commensal species (Entamoeba dispar: 18.4%; Troglodytella abrassarti: 5.6%). Entamoeba histolytica, Enterocytozoon bieneusi, and Balantioides coli were undetected. Blood protists including Plasmodium malariae (0.4%), Trypanosoma brucei (1.3%), and Mansonella perstans (9.8%) were also identified. Sanger sequencing analyses revealed host-adapted genetic variants within Blastocystis, but other parasitic pathogens (C. hominis, P. malariae, T. brucei, M. perstans) have zoonotic potential, suggesting that cross-species transmission between wild chimpanzees and humans is possible in areas where both species overlap. Additionally, we explored potential interactions between intestinal/blood protist species and seasonality and climate variables. Chimpanzees seem to play a more complex role on the epidemiology of pathogenic and commensal protist and nematode species than initially anticipated.

Chimpanzees (Pan troglodytes) are categorized as Endangered by the International Union for Conservation of Nature, and habitat loss due to conversion of land for agriculture is one of the major threats to wild populations of this species. This challenging scenario can lead to negative human-chimpanzee interactions, including crop feeding. Chimpanzees consume crops across their geographical range, although little is known about this behavior in savanna habitats. Here we provide new evidence of crop feeding by savanna chimpanzees. We conducted our observations at Dindefelo, a community nature reserve in southeastern Senegal. The chimpanzees were observed to feed on mango (Mangifera indica) and also on baobab (Adansonia digitata), a wild species considered a crop by local people when found in and around villages. Although local people use the fruits of these species for food and income, they tolerated crop-feeding events until recently. In 2023, a case of harassment of a crop-feeding chimpanzee in a mango orchard was witnessed, and four days later a chimpanzee corpse was found at the same place. We conclude that habitat conversion into agricultural fields, uncontrolled bush fires and extraction of wild fruits are the important factors influencing crop-feeding events at Dindefelo. Our findings highlight the need to better understand human-chimpanzee interactions in the anthropogenic landscape of Dindefelo to help mitigate negative attitudes and behaviors towards chimpanzees.

Chimpanzees use spatiotemporal cognition for fruit foraging by remembering tree locations and fruiting seasons. However, the spatiotemporal cognition behind exploiting other foods has rarely been studied. Here, we investigate whether chimpanzees use memory to exploit concealed, underground army ant nests. We analyse 679 chimpanzee visits to four nests recorded during five years (2018–2022) using camera traps in a savanna habitat. We explore if chimpanzees intentionally revisit nests, study how they detect ants, and assess ant availability and chimpanzee ant consumption. Nests are concealed, scarce, and intermittently reoccupied, yet chimpanzees eat ants frequently. We find that out of 34 identified chimpanzees who visit the nests, 23 revisit at least one. Chimpanzees visit nest sites significantly more often than similar sites without nests. Individuals revisit significantly sooner and inspect significantly longer nests where they have more recently encountered ants. The apes use sight, smell, taste, touch, and probing tools, to detect ants inside nests. We provide the first evidence suggesting that chimpanzees use spatial and episodic-like memory to exploit concealed social insects throughout multiple years. Our results expand our understanding of the cognitive strategies behind chimpanzee insectivory, suggesting it may have played an important role in the evolution of primate spatiotemporal cognition.

Percussive technology in wild chimpanzees ( Pan troglodytes ) shows significant behavioral variation across Africa. An example is baobab ( Adansonia digitata ) fruit pounding, which is only known to occur in the Bandafassi Arrondissement in the Kedougou region (Senegal) and in the Bafing area (Mali). The extent to which this proto-tool use behavior varies between populations is poorly understood. Here, we present a preliminary report of the baobab-pounding behavior of savanna chimpanzees from Dindefelo, Senegal. During the peak baobab fruiting season from November 2021 to January 2022, we obtained evidence of baobab pounding, both primate archaeological evidence (fruit remnants smeared on anvils and cracked, empty baobab shells) and camera trap recordings. We also studied chimpanzee baobab consumption using macroscopical fecal analysis. In addition, in the peak baobab fruiting season from 2019 to 2020, we opportunistically obtained hand-held camera videos of baobab pounding. Dindefelo chimpanzees opened baobab using two pounding and one non-percussive techniques. We recorded all age and sex classes performing baobab pounding, although only adolescents and adults succeeded in opening the fruit. Baobab pounding occurred on the ground (against rocks and baobab roots) and on the trees (against baobab horizontal branches). The apes held the fruit by the stem or the pericarp while cracking it against an anvil. In addition, the fecal analysis data suggest that baobab seed reingestion is common at Dindefelo. These findings expand our knowledge on the diversity of chimpanzee baobab-pounding behavior.

The current distribution of Campbell’s monkeys Cercopithecus campbelli extends from southwestern Gambia to the western Ivory Coast. In Senegal, it has only been confirmed in the western part of the country. Here, we report for the first time its presence in southeastern Senegal. We obtained camera trap footage of a Campbell’s monkey individual in the Dindefelo Community Nature Reserve located in Kedougou region, 174 km away from its known distribution range. In the footage, a single Campbell’s monkey appears alongside a group of at least nine green monkeys Chlorocebus sabaeus. We discuss different hypotheses that could explain the presence of the Campbell’s monkey in Dindefelo, and conclude that this individual may be a single migrant.