Diversité Et Distribution De La Grande Faune Mammalienne Dans Le Parc National De Moukalaba-Doudou (Sud-Ouest Du Gabon)

Le Gabon, pays d’Afrique Centrale est recouvert à plus de 80% de la forêt pourvue des zones diversifiées en paysages avec une importante biodiversité faunique et floristique. Cependant, cette biodiversité qui est mal connue dans certaines régions du pays est confrontée à plusieurs menaces. C’est dans cette optique que nous avons conduit un suivi de la faune dans la partie Nord Est du parc national de Moukalaba Doudou dont le but était de déterminer la diversité et la répartition spatiale des grands mammifères sauvages. En utilisant la méthode de line transect, nous avons installé 165 cameras traps le long de 11 transects. Les données ont été performées par le GML (Generalized Linear Models). Au total, 80410 nuits-pièges ont été réalisées. Près de 37 914 vidéos indépendantes ont été obtenues et 10 espèces de grands mammifères dont les plus observés étaient les Céphalophes bleus et rouges suivis des Chevrotains aquatiques, Eléphants et des Cercocèbes. Les résultats obtenus suggèrent que les espèces de grands mammifères sont distribuées en fonction des habitats. Les céphalophes de grande taille, le mandrill, la panthère, le chat doré, l’éléphant, et le chevrotain aquatique ont des habitats préférentiels ; par contre, le gorille, le chimpanzé, le cercocèbe à collier blanc et le céphalophe bleu ne semblent pas être affectés par l’habitat. Ce sont des espèces ubiquistes. Cependant, tous les mammifères peuvent être observés sur l’ensemble des transects. Gabon, a country in Central Africa, is covered by more than 80% of the forest, with areas diversified into landscapes with significant fauna and flora biodiversity. However, this biodiversity, which is poorly understood in certain regions of the country, faces several threats. It is with this in mind that we conducted wildlife monitoring in the northeast part of Moukalaba Doudou National Park, the aim of which was to determine the abundance and spatial distribution of large wild mammals. Using the line transect method we installed 165 cameras traps along 11 transects. The data were performed by the GML (Generalized Linear Models). A total of 80,410 trap nights were completed. Almost 37,914 independent videos were obtained and 10 species of large mammals of which the most observed were the blue and red duikers followed by aquatic Chevrotains, Elephants and Mangabeys. The results obtained suggest that large mammal species are distributed according to habitats. Large duikers, mandrill, panther, golden cat, elephant, and aquatic chevrotain have preferred habitats; however, the gorilla, the chimpanzee, the white-collared cercocebe and the blue duiker do not seem to be affected by the habitat. They are ubiquitous species. However, all mammals can be seen on all of the transects

Diet Composition and Feeding Ecology of Chimpanzees (Pan troglodytes troglodytes) in a Lowland Tropical Forest in Moukalaba-Doudou National Park, Gabon

Characterizing the diet of wild chimpanzees is fundamental to understanding ecological variation, flexibility, and adaptation within and among populations. Here, we describe the diet composition of central chimpanzees (Pan troglodytes troglodytes) in Moukalaba-Doudou National Park, southwestern Gabon. The chimpanzee diet in this area has not previously been described. Based on a macroanalysis of 809 fecal samples and 1, 119 minutes of direct observation of their foraging, we showed that they consume fewer insects and more vertebrate prey than those in other study sites. No evidence for the consumption of termites or driver ants was found. Fruits of Ficus spp. was the most frequently identified plant food and appeared in the diet of Moukalaba chimpanzees throughout the year. Chimpanzees at Moukalaba, like at other study sites, exhibit a preference for a small number of fruit species, including Ficus spp., among the foods available at any given period or area while flexibly changing the foods they eat in response to seasonal changes in fruit quantity in the habitat

Evaluation of the role of Guenons and Mangabeys in seed dispersal in Moukalaba-Doudou National Park, Gabon

In order to gain knowledge on the quantity of seed dispersed and the contribution of small diurnal primates in the ecosystem, a preliminary study  on four species of monkeys was carried out in the northeastern part of the Moukalaba-Doudou National Park in Gabon. The aim was to identify the  species of fruits which are dispersed and the animal biomass in two large groups of monkeys namely mangabeys (Cercocebus torquatus and  Lophocebus albigena) and guenons (Cercopithecus cephus and Cercopithecus nictitans). Using the reconnaissance walking method, we followed old  tracks and dung piles were collected after direct observation of the little monkeys and in the sleeping site. The dung piles were washed, and the  seeds collected were identified. A total of 104 fecal samples from the four species of monkeys were collected. Seeds from 19 species of plants  were found in the dung piles. The majority of the seeds found in droppings were seeds of Cissus dinklagei and Musanga cecropioides.  Cercopithecus nictitans dispersed seeds of more plant species than the others. All the results obtained show that the monkeys disperse an average  of 1,114 seeds per day. In this study guenons disperses more fruit than the mangabeys who have a more varied diet. These results suggest that  monkeys of Moukalaba-Doudou disperse fewer seeds compared to monkeys in other sites in Africa.   Afin d’avoir une connaissance sur la quantité de graine dispersée et la contribution des petits primates diurnes dans l’écosystème, une étude  préliminaire sur quatre espèces de singes a été réalisée dans la partie nord-est du Parc National de Moukalaba-Doudou au Gabon. L’objectif était de  connaître les espèces de fruits dispersées et la biomasse animale chez deux grands groupes de singes à savoir les mangabeys (Cercocebus  torquatus et Lophocebus albigena) et les guenons (Cercopithecus cephus et Cercopithecus nictitans). En utilisant la méthode de la marche de  reconnaissance, nous avons suivi d’anciennes pistes et les tas de fumier ont été ramassés après observation directe des petits singes et dans les  dortoirs. Les crottes ont été lavées et les graines récoltées ont été identifiées. Un total de 104 échantillons fécaux des quatre espèces de singes a été  collectés. Les graines de 19 espèces de plantes ont été trouvées dans les excréments. Cercopithecus nictitans a dispersé plus d’espèces de  graines que les autres. La majorité des graines trouvées dans les déjections étaient des graines de Cissus dinklagei et Musanga cecropioides.  L’ensemble des résultats obtenus montre que les singes dispersent en moyenne 1114 graines par jour. Dans cette étude les guenons dispersent plus  de fruits que les mangabeys qui ont une alimentation plus variée. Ces résultats suggèrent que les singes de Moukalaba-Doudou dispersent  peu de graines en comparaison aux singes d’autres sites en Afrique.&nbsp

Etude de la Relation entre l’abondance des grands mammifères frugivores et celle des fruits dans le Parc National de Moukalaba-Doudou, Gabon

Au Gabon, les travaux portant sur les relations plantes animaux demeurent encore très lacunaires. Pourtant, cette connaissance est indispensable dans la compréhension des fonctionnements des écosystèmes forestiers, mais aussi sur le comportement alimentaire des mammifères. C’est dans ce cadre qu’une étude sur l’abondance des mammifères frugivores et celles des fruits a été conduite dans le Parc National de Moukalaba Doudou. Les données sur l’abondance des mammifères ont été recueillies à l’aide des caméras pièges, le long de 11 transects de janvier 2012 à janvier 2014. Quant aux fruits, ils ont été récoltés le long de ces transects sur une bande de 1 m de large de part et d’autre du transect. Au total, 2492 fruits repartis en 100 espèces ont été recensés au cours de cette étude. Le nombre de fruits recensés a varié en fonction des biotopes prospectés et des mois. Les caméras pièges ont permis d’identifier dix espèces de mammifères frugivores présents dans cette zone. Le test de corrélation P de Pearson (R= 0,2 ; df= 10, P= 0,5) a montré que la variation entre l’abondance des mammifères et celle des fruits reste indépendante.Mots clés : Abondance, fruits, mammifères, Parc National Moukalaba-Doudou, caméra piège, Gabon

Diet Composition and Feeding Ecology of Chimpanzees (Pan troglodytes troglodytes) in a Lowland Tropical Forest in Moukalaba-Doudou National Park, Gabon

Characterizing the diet of wild chimpanzees is fundamental to understanding ecological variation, flexibility, and adaptation within and among populations. Here, we describe the diet composition of central chimpanzees (Pan troglodytes troglodytes) in Moukalaba-Doudou National Park, southwestern Gabon. The chimpanzee diet in this area has not previously been described. Based on a macroanalysis of 809 fecal samples and 1,119 minutes of direct observation of their foraging, we showed that they consume fewer insects and more vertebrate prey than those in other study sites. No evidence for the consumption of termites or driver ants was found. Fruits of Ficus spp. was the most frequently identified plant food and appeared in the diet of Moukalaba chimpanzees throughout the year. Chimpanzees at Moukalaba, like at other study sites, exhibit a preference for a small number of fruit species, including Ficus spp., among the foods available at any given period or area while flexibly changing the foods they eat in response to seasonal changes in fruit quantity in the habitat

Emergence and spread of SARS-CoV-2 lineage B.1.620 with variant of concern-like mutations and deletions.

Distinct SARS-CoV-2 lineages, discovered through various genomic surveillance initiatives, have emerged during the pandemic following unprecedented reductions in worldwide human mobility. We here describe a SARS-CoV-2 lineage - designated B.1.620 - discovered in Lithuania and carrying many mutations and deletions in the spike protein shared with widespread variants of concern (VOCs), including E484K, S477N and deletions HV69Δ, Y144Δ, and LLA241/243Δ. As well as documenting the suite of mutations this lineage carries, we also describe its potential to be resistant to neutralising antibodies, accompanying travel histories for a subset of European cases, evidence of local B.1.620 transmission in Europe with a focus on Lithuania, and significance of its prevalence in Central Africa owing to recent genome sequencing efforts there. We make a case for its likely Central African origin using advanced phylogeographic inference methodologies incorporating recorded travel histories of infected travellers

Effects of competition on tree radial-growth vary in importance but not in intensity along climatic gradients

Summary 1. Plant interactions play a central role in regulating plant communities and this role can be altered by abiotic stress. With increasing stress, ecological theory predicts that the role of competition decreases whilst that of facilitation increases. Such predictions have been tested with short-term plant removal experiments using two distinct indices evaluating the role of plant interactions: the intensity (absolute impact) and the importance (impact relative to that of other abiotic constraints) of plant interactions. 2. Using data on individual tree radial growth from more than 17 000 forest plots covering the habitat conditions of 16 species in the Alps and the Jura mountains of France, we show that non-manipulative estimates of plant interactions provide an alternative to this experimental approach. We developed a Bayesian neighbourhood growth competition model to test theoretical predictions about plant–plant interactions with a much larger spatio-temporal scope and set of study species than classically used in experimental studies of plant–plant interactions. 3. Our analyses revealed that competition – measured as neighbours effects on adult tree growth – varies in importance but not in intensity along two major bioclimatic gradients (degree-day sum and water availability). Observed patterns of competition importance differed between shade-tolerant and shade-intolerant tree species. First, the mean importance of competition was found to be much higher for shade-intolerant species. Second, for shade-intolerant species the importance of competition remained high even at low crowding indices (i.e. at a low competitor density), whereas for shade-tolerant species competition only became important at high crowding indices. 4. Synthesis. Our non-manipulative approach to the study of plant–plant interactions allows analysing interactions among many species over large climatic gradients. Our results clearly demonstrate that a quantitative estimation of density dependence effects is key to understanding how plant–plant interactions vary along abiotic gradients. Growth predictions derived from our model can easily be integrated with other results on tree regeneration and mortality in individual-based models to investigate how plant–plant interactions drive tree population and community dynamics under varying climatic conditions

Local people enhance our understanding of Afrotropical frugivory networks.

International audienceAfrotropical forests are undergoing massive change caused by defaunation, i.e., the human-induced decline of animal species,1 most of which are frugivorous species.1,2,3 Frugivores' depletion and their functional disappearance are expected to cascade on tree dispersal and forest structure via interaction networks,4,5,6,7 as the majority of tree species depend on frugivores for their dispersal.8 However, frugivory networks remain largely unknown, especially in Afrotropical areas,9,10,11 which considerably limits our ability to predict changes in forest dynamics and structures using network analysis.12,13,14,15 While the academic workforce may be inadequate to fill this knowledge gap before it is too late, local ecological knowledge appears as a valuable source of ecological information and could significantly contribute to our understanding of such crucial interactions for tropical forests.16,17,18,19,20,21 To investigate potential synergies between local ecological knowledge and academic knowledge,20,21 we compiled frugivory interactions linking 286 trees to 100 frugivore species from the academic literature and local ecological knowledge coming from interviews of Gabonese forest-dependent people. Here, we showed that local ecological knowledge on frugivory interactions was substantial and original, with 39% of these interactions unknown by science. We demonstrated that combining academic and local ecological knowledge affects the functional relationship linking frugivore body mass to seed size, as well as the network structure. Our results highlight the benefits of bridging knowledge systems between academics and local communities for a better understanding of the functioning and response to perturbations of Afrotropical forests