The malagarasi river does not form an absolute barrier to chimpanzee movement in Western Tanzania

Barriers to chimpanzee gene flow at the south-east edge of their distribution

Populations on the edge of a species' distribution may represent an important source of adaptive diversity, yet these populations tend to be more fragmented and are more likely to be geographically isolated. Lack of genetic exchanges between such populations, due to barriers to animal movement, can not only compromise adaptive potential but also lead to the fixation of deleterious alleles. The south-eastern edge of chimpanzee distribution is particularly fragmented, and conflicting hypotheses have been proposed about population connectivity and viability. To address this uncertainty, we generated both mitochondrial and MiSeq-based microsatellite genotypes for 290 individuals ranging across western Tanzania. While shared mitochondrial haplotypes confirmed historical gene flow, our microsatellite analyses revealed two distinct clusters, suggesting two populations currently isolated from one another. However, we found evidence of high levels of gene flow maintained within each of these clusters, one of which covers an 18,000 km2 ecosystem. Landscape genetic analyses confirmed the presence of barriers to gene flow with rivers and bare habitats highly restricting chimpanzee movement. Our study demonstrates how advances in sequencing technologies, combined with the development of landscape genetics approaches, can resolve ambiguities in the genetic history of critical populations and better inform conservation efforts of endangered species.

A New Assessment of Robust Capuchin Monkey (Sapajus) Evolutionary History Using Genome-Wide SNP Marker Data and a Bayesian Approach to Species Delimitation

Robust capuchin monkeys, Sapajus genus, are among the most phenotypically diverse and widespread groups of primates in South America, with one of the most confusing and often shifting taxonomies. We used a ddRADseq approach to generate genome-wide SNP markers for 171 individuals from all putative extant species of Sapajus to access their evolutionary history. Using maximum likelihood, multispecies coalescent phylogenetic inference, and a Bayes Factor method to test for alternative hypotheses of species delimitation, we inferred the phylogenetic history of the Sapajus radiation, evaluating the number of discrete species supported. Our results support the recognition of three species from the Atlantic Forest south of the São Francisco River, with these species being the first splits in the robust capuchin radiation. Our results were congruent in recovering the Pantanal and Amazonian Sapajus as structured into three monophyletic clades, though new morphological assessments are necessary, as the Amazonian clades do not agree with previous morphology-based taxonomic distributions. Phylogenetic reconstructions for Sapajus occurring in the Cerrado, Caatinga, and northeastern Atlantic Forest were less congruent with morphology-based phylogenetic reconstructions, as the bearded capuchin was recovered as a paraphyletic clade, with samples from the Caatinga biome being either a monophyletic clade or nested with the blond capuchin monkey.

Family planning and resilience: associations found in a Population, Health, and Environment (PHE) project in Western Tanzania

Using 2016 household survey data from Tanzania, we define and measure resilience within the context of Population, Health, and Environment programming and quantify the link between resilience and family planning. We created a multicomponent model using confirmatory factor analysis in a structural equation modeling context. Factor loadings for eight defined latent factors of resilience were statistically significant (p < 0.001). We created a factor called "FP-MCH" reflecting awareness, attitudes, and access to family planning (FP) and health care services and use of maternal and child health care (MCH) facilities. Analysis, with controls, shows that a 1 standard deviation (SD) increase in FP/MCH was associated with a 0.68 SD increase in resilience (p < 0.01), suggesting that the association between FP/MCH and resilience is robust across a range of factors. Analyses showed that the association between FP/MCH is broadly related to the construct of resilience and not through any single component. This study supports the importance of including FP/MCH as part of integrated projects to enhance resilience.

Riverine barrier effects on population genetic structure of the Hanuman langur (Semnopithecus entellus) in the Nepal Himalaya

BACKGROUND

Past climatological events and contemporary geophysical barriers shape the distribution, population genetic structure, and evolutionary history of many organisms. The Himalayan region, frequently referred to as the third pole of the Earth, has experienced large-scale climatic oscillations in the past and bears unique geographic, topographic, and climatic areas. The influences of the Pleistocene climatic fluctuations and present-day geographical barriers such as rivers in shaping the demographic history and population genetic structure of organisms in the Nepal Himalaya have not yet been documented. Hence, we examined the effects of late-Quaternary glacial-interglacial cycles and riverine barriers on the genetic composition of Hanuman langurs (Semnopithecus entellus), a colobine primate with a wide range of altitudinal distribution across the Nepalese Himalaya, using the mitochondrial DNA control region (CR, 1090 bp) and cytochrome B (CYTB, 1140 bp) sequences combined with paleodistribution modeling.

RESULTS

DNA sequences were successfully retrieved from 67 non-invasively collected fecal samples belonging to 18 wild Hanuman langur troops covering the entire distribution range of the species in Nepal. We identified 37 haplotypes from the concatenated CR + CYTB (2230 bp) sequences, with haplotype and nucleotide diversities of 0.958 ± 0.015 and 0.0237 ± 0.0008, respectively. The troops were clustered into six major clades corresponding to their river-isolated spatial distribution, with the significantly high genetic variation among these clades confirming the barrier effects of the snow-fed Himalayan rivers on genetic structuring. Analysis of demographic history projected a decrease in population size with the onset of the last glacial maximum (LGM); and, in accordance with the molecular analyses, paleodistribution modeling revealed a range shift in its suitable habitat downward/southward during the LGM. The complex genetic structure among the populations of central Nepal, and the stable optimal habitat through the last interglacial period to the present suggest that the central mid-hills of Nepal served as glacial refugia for the Hanuman langur.

CONCLUSIONS

Hanuman langurs of the Nepal Himalaya region exhibit high genetic diversity, with their population genetic structure is strongly shaped by riverine barrier effects beyond isolation by distance; hence, this species demands detailed future phylogenetic study.

Scars on plants sourced for termite fishing tools by chimpanzees: Towards an archaeology of the perishable

Chimpanzees are well-studied, but raw material acquisition for tool use is still poorly understood as sources are difficult to trace. This study pioneers the use of information that can be gleaned from plant scars made by chimpanzees while they source vegetation parts to manufacture termite fishing tools. Source plant species, raw material types and locations relative to targeted termite mounds were recorded for populations at Gombe, Issa, and Mahale in western Tanzania. Recovered bark, twig, and vine tools were traced to 29 plant species, while grass sources were indeterminable. Bark extraction scars remained detectable for months, and thus possibly for as long as the plant is alive, while twig and vine scars preserved for a few weeks only. Scars preserve better than tools, given that twice as many plant species could be linked to the former than to the latter. Some source species were exploited across all sites for the same type of tool material, while two species were sourced for different types. Compared to apes at Gombe and Mahale, Issa chimpanzees carried material from twice as far away, perhaps because the Issa habitat is more open and dry, which entails greater distances between suitable raw material sources and targeted mounds. Site-specific tools were based on different raw materials, in two cases sourced from the same species, which could suggest learned preferences for particular tool material. "Archaeology of the perishable" as pioneered in this study broadens the methodological approach of the wider field of primate archaeology to include reconstructions of past animal behavior associated with the production of plant based tools.

Mitochondrial DNA analyses and ecological niche modeling reveal post-LGM expansion of the Assam macaque (Macaca assamensis) in the foothills of Nepal Himalaya

Genetic diversity of a species is influenced by multiple factors, including the Quaternary glacial-interglacial cycles and geophysical barriers. Such factors are not yet well documented for fauna from the southern border of the Himalayan region. This study used mitochondrial DNA (mtDNA) sequences and ecological niche modeling (ENM) to explore how the late Pleistocene climatic fluctuations and complex geography of the Himalayan region have shaped genetic diversity, population genetic structure, and demographic history of the Nepalese population of Assam macaques (Macaca assamensis) in the Himalayan foothills. A total of 277 fecal samples were collected from 39 wild troops over almost the entire distribution of the species in Nepal. The mtDNA fragment encompassing the complete control region (1121 bp) was recovered from 208 samples, thus defining 54 haplotypes. Results showed low nucleotide diversity (0.0075 ± SD 0.0001) but high haplotype diversity (0.965 ± SD 0.004). The mtDNA sequences revealed a shallow population genetic structure with a moderate but statistically significant effect of isolation by distance. Demographic history analyses using mtDNA sequences suggested a post-pleistocene population expansion. Paleodistribution reconstruction projected that the potential habitat of the Assam macaque was confined to the lower elevations of central Nepal during the Last Glacial Maximum. With the onset of the Holocene climatic optimum, the glacial refugia population experienced eastward range expansion to higher elevations. We conclude that the low genetic diversity and shallow population genetic structure of the Assam macaque population in the Nepal Himalaya region are the consequence of recent demographic and spatial expansion.

Adenovirus infection in savanna chimpanzees (Pan troglodytes schweinfurthii) in the Issa Valley, Tanzania

Adenoviruses are a widespread cause of diverse human infections with recently confirmed zoonotic roots in African great apes. We focused on savanna-dwelling chimpanzees in the Issa Valley (Tanzania), which differ from those from forested sites in many aspects of behavior and ecology. PCR targeting the DNA polymerase gene detected AdV in 36.7% (69/188) of fecal samples. We detected five groups of strains belonging to the species Human mastadenovirus E and two distinct groups within the species Human mastadenovirus C based on partial hexon sequence. All detected AdVs from the Issa Valley are related to those from nearby Mahale and Gombe National Parks, suggesting chimpanzee movements and pathogen transmission.

Correction: The Malagarasi River Does Not Form an Absolute Barrier to Chimpanzee Movement in Western Tanzania

[This corrects the article DOI: 10.1371/journal.pone.0058965.].

Raw material procurement for termite fishing tools by wild chimpanzees in the Issa valley, Western Tanzania

OBJECTIVES

Chimpanzee termite fishing has been studied for decades, yet the selective processes preceding the manufacture of fishing tools remain largely unexplored. We investigate raw material selection and potential evidence of forward planning in the chimpanzees of Issa valley, western Tanzania.

MATERIALS AND METHODS

Using traditional archaeological methods, we surveyed the location of plants from where chimpanzees sourced raw material to manufacture termite fishing tools, relative to targeted mounds. We measured raw material abundance to test for availability and selection. Statistics included Chi-Squared, two-tailed Wilcoxon, and Kruskall-Wallace tests.

RESULTS

Issa chimpanzees manufactured extraction tools only from bark, despite availability of other suitable materials (e.g., twigs), and selected particular plant species as raw material sources, which they often also exploit for food. Most plants were sourced 1-16 m away from the mound, with a maximum of 33 m. The line of sight from the targeted mound was obscured for a quarter of these plants.

DISCUSSION

The exclusive use of bark tools despite availability of other suitable materials indicates a possible cultural preference. The fact that Issa chimpanzees select specific plant species and travel some distance to source them suggests some degree of selectivity and, potentially, forward planning. Our results have implications for the reconstruction of early hominin behaviors, particularly with regard to the use of perishable tools, which remain archaeologically invisible.

Neutralization properties of simian immunodeficiency viruses infecting chimpanzees and gorillas

Broadly cross-reactive neutralizing antibodies (bNabs) represent powerful tools to combat human immunodeficiency virus type 1 (HIV-1) infection. Here, we examined whether HIV-1-specific bNabs are capable of cross-neutralizing distantly related simian immunodeficiency viruses (SIVs) infecting central (Pan troglodytes troglodytes) (SIVcpzPtt) and eastern (Pan troglodytes schweinfurthii) (SIVcpzPts) chimpanzees (n = 11) as well as western gorillas (Gorilla gorilla gorilla) (SIVgor) (n = 1). We found that bNabs directed against the CD4 binding site (n = 10), peptidoglycans at the base of variable loop 3 (V3) (n = 5), and epitopes at the interface of surface (gp120) and membrane-bound (gp41) envelope glycoproteins (n = 5) failed to neutralize SIVcpz and SIVgor strains. In addition, apex V2-directed bNabs (n = 3) as well as llama-derived (heavy chain only) antibodies (n = 6) recognizing both the CD4 binding site and gp41 epitopes were either completely inactive or neutralized only a fraction of SIVcpzPtt strains. In contrast, one antibody targeting the membrane-proximal external region (MPER) of gp41 (10E8), functional CD4 and CCR5 receptor mimetics (eCD4-Ig, eCD4-Ig(mim2), CD4-218.3-E51, and CD4-218.3-E51-mim2), as well as mono- and bispecific anti-human CD4 (iMab and LM52) and CCR5 (PRO140, PRO140-10E8) receptor antibodies neutralized >90% of SIVcpz and SIVgor strains with low-nanomolar (0.13 to 8.4 nM) potency. Importantly, the latter antibodies blocked virus entry not only in TZM-bl cells but also in Cf2Th cells expressing chimpanzee CD4 and CCR5 and neutralized SIVcpz in chimpanzee CD4(+) T cells, with 50% inhibitory concentrations (IC50s) ranging from 3.6 to 40.5 nM. These findings provide new insight into the protective capacity of anti-HIV-1 bNabs and identify candidates for further development to combat SIVcpz infection.

IMPORTANCE

SIVcpz is widespread in wild-living chimpanzees and can cause AIDS-like immunopathology and clinical disease. HIV-1 infection of humans can be controlled by antiretroviral therapy; however, treatment of wild-living African apes with current drug regimens is not feasible. Nonetheless, it may be possible to curb the spread of SIVcpz in select ape communities using vectored immunoprophylaxis and/or therapy. Here, we show that antibodies and antibody-like inhibitors developed to combat HIV-1 infection in humans are capable of neutralizing genetically diverse SIVcpz and SIVgor strains with considerable breadth and potency, including in primary chimpanzee CD4(+) T cells. These reagents provide an important first step toward translating intervention strategies currently developed to treat and prevent AIDS in humans to SIV-infected apes.

Geographic distance affects dispersal of the patchy distributed greater long-tailed hamster (Tscherskia triton)

Dispersal is a fundamental process in ecology influencing the genetic structure and the viability of populations. Understanding how variable factors influence the dispersal of the population is becoming an important question in animal ecology. To date, geographic distance and geographic barriers are often considered as main factors impacting dispersal, but their effects are variable depending on different conditions. In general, geographic barriers affect more significantly than geographic distance on dispersal. In rapidly expanding populations, however, geographic barriers have less effect on dispersal than geographic distance. The effects of both geographic distance and geographic barriers in low-density populations with patchy distributions are poorly understood. By using a panel of 10 microsatellite loci we investigated the genetic structure of three patchy-distributed populations of the Greater long-tailed hamster (Tscherskia triton) from Raoyang, Guan and Shunyi counties of the North China Plain. The results showed that (i) high genetic diversity and differentiation exist in three geographic populations with patchy distributions; (ii) gene flow occurs among these three populations with physical barriers of Beijing city and Hutuo River, which potentially restricted the dispersal of the animal; (iii) the gene flow is negatively correlated with the geographic distance, while the genetic distance shows the positive correlation. Our results suggest that the effect of the physical barriers is conditional-dependent, including barrier capacity or individual potentially dispersal ability. Geographic distance also acts as an important factor affecting dispersal for the patchy distributed geographic populations. So, gene flow is effective, even at relatively long distances, in balancing the effect of geographic barrier in this study.

Termite fishing by wild chimpanzees: new data from Ugalla, western Tanzania

Chimpanzees manufacture flexible fishing probes to fish for termites in Issa, Ugalla, western Tanzania. These termite-fishing tools are similar in size and material to those used by long-studied communities of chimpanzees in western Tanzania (Pan troglodytes schweinfurthii) and in West Africa (P. t. verus), but not central African populations (P. t. troglodytes). This report adds to the patchwork of evidence of termite-fishing tool use behaviour by chimpanzees across Africa.