Past Connectivity but Recent Inbreeding in Cross River Gorillas Determined Using Whole Genomes from Single Hairs.

The critically endangered western gorillas (Gorilla gorilla) are divided into two subspecies: the western lowland (G. g. gorilla) and the Cross River (G. g. diehli) gorilla. Given the difficulty in sampling wild great ape populations and the small estimated size of the Cross River gorilla population, only one whole genome of a Cross River gorilla has been sequenced to date, hindering the study of this subspecies at the population level. In this study, we expand the number of whole genomes available for wild western gorillas, generating 41 new genomes (25 belonging to Cross River gorillas) using single shed hairs collected from gorilla nests. By combining these genomes with publicly available wild gorilla genomes, we confirm that Cross River gorillas form three population clusters. We also found little variation in genome-wide heterozygosity among them. Our analyses reveal long runs of homozygosity (>10 Mb), indicating recent inbreeding in Cross River gorillas. This is similar to that seen in mountain gorillas but with a much more recent bottleneck. We also detect past gene flow between two Cross River sites, Afi Mountain Wildlife Sanctuary and the Mbe Mountains. Furthermore, we observe past allele sharing between Cross River gorillas and the northern western lowland gorilla sites, as well as with the eastern gorilla species. This is the first study using single shed hairs from a wild species for whole genome sequencing to date. Taken together, our results highlight the importance of implementing conservation measures to increase connectivity among Cross River gorilla sites.

The type locality of Pan troglodytes vellerosus (Gray, 1862), and implications for the nomenclature of West African chimpanzees.

We show that, in 1862, Richard Burton collected the type specimen of Pan troglodytes vellerosus not on Mount Cameroon, as has been generally assumed, but in Gabon. Therefore, P. t. vellerosus is not the correct name for the chimpanzee population of western Cameroon and southern Nigeria, if that population is taxonomically distinct. As First Reviser, we choose the name Pan troglodytes ellioti for this population of chimpanzees, based on Anthropopithecus ellioti named by Matschie [Matschie P (1914) Neue Affen aus Mittelafrika. Sitzungsber Ges Naturforsch Freunde Berlin 1914:323-342] from a specimen in the Humboldt Museum, Berlin, collected in Bascho (=Basho), Cameroon, and given to the museum in 1905.

Is the chimpanzee, Pan troglodytes, an endangered species? It depends on what "endangered" means.

I review information on the status in the wild of the robust chimpanzee, Pan troglodytes, and consider whether this evidence is consistent with the designation of P. troglodytes as Endangered in the International Union for the Conservation of Nature and Natural Resources (IUCN) Red List, and with public statements to the effect that great apes as a whole will be extinct within a few decades. Chimpanzees remain widespread in tropical Africa, occurring in a variety of forested habitats. Estimates of total surviving numbers have increased from about 200,000 in the 1980s to a maximum of almost 300,000 in 2003. However, this apparent increase comes about from new survey data, rather than representing a measured increase in actual population numbers. Infectious disease decimated several chimpanzee populations during the 1990s, and data from parts of Gabon, extrapolated to that country as a whole, suggest a major decline in great ape populations caused by disease and hunting. However, accurate data on population numbers are absent for the majority of wild chimpanzee populations. I found reports of the presence of Pan troglodytes in at least 51 national parks in at least 19 countries; some of these parks have been established very recently. Chimpanzees also occur in many non-park conservation areas. A set of large, well-protected parks could safeguard chimpanzees for the foreseeable future. Although many African parks do not function well at present, mechanisms to improve their function are understood and available. By a strict application of IUCN threat criteria, P. troglodytes can be considered Endangered, based on estimated rates of past decline and on the species' long generation time. Relatively speaking, however, P. troglodytes is less endangered than are orangutans or gorillas, and the species is unlikely to go extinct by the year 2100, especially if existing conservation measures improve. The IUCN threat-rating system has become overly complex; the system can produce results that do not accord with common sense and these results must therefore be interpreted with care.

Africa's primates in 1992: Conservation issues and options.

There are about 60 species of African primates, and over 50% of these are generally considered to be vulnerable to extinction. Planning for the conservation of these primates, and the objective assessment of the degree of endangerment faced by different species and subspecies is hampered, however, by poorly resolved taxonomy and inadequate data on geographic distributions, ecology, and population biology. The African primate species at most imminent risk of extinction may be Sclater's guenon, threatened by forest destruction and hunting in an area of Nigeria with a very dense human population. The most endangered African subspecies may be Bouvier's red colobus, whose continued existence in Congo is uncertain. The taxonomic position of each of these monkeys is debated. Their predicaments illustrate some general phenomena: almost all threatened African primates are forest dwellers; habitat destruction and/or hunting are the major threats to the survival of forest primates; endangerment is the result of an interaction of external threats with features intrinsic to particular primates. The African primates most widely used in biomedical research are savanna-zone species that are not generally endangered at present, although there are disturbingly high levels of trapping in certain countries. Ideally, all Africa's primates would be protected by a network of large reserves, but in a few cases such a conservation strategy may not be a viable option; population manipulations may become important management tools, and these manipulations may be aided by new techniques developed by reproductive biologists. © 1994 Wiley-Liss, Inc.

Association between olive colobus (Procolobus verus), Diana guenons (Cercopithecus diana), and other forest monkeys in Sierra Leone.

Close association between olive colobus (Procolous verus) and other monkeys (especially Cercopithecus species) has been observed throughout the range of P. verus in the forest zone of West Africa. To investigate the basis of this association, we made new observations in Sierra Leone, concentrated at Tiwai Island. We obtained data on the association patterns of monkeys over a large area of the island from line-transect samples, and studied association behavior via long-term observational sampling of habituated groups of olive colobus and Diana monkeys (C. diana). During transect sampling, olive colobus always were seen less than 50 m from monkeys of other species, especially Cercopithecus. In studies of habituated groups, we found that one groups of olive colobus associated closely with a larger groups of Diana monkeys for more than 3 years. Members of the two groups were within 50 m of each other on over 80% of scan samples; the two groups shared the same range, but foraged in different parts of the canopy and had little dietary overlap; association was maintained by the behavior of the colobus. The olive colobus was the only Tiwai monkey species seen less than 50 m from members of a secon Diana study group more frequently than expected, although in this case the two species were associated during less than 12% of samples. In both cases, we detected month-to-month variation in association frequency. We suggest that olive colobus has a strong tendency to associate with other monkeys as part of an evolved strategy; that observed association patterns depend on the ranging habits and group dispersion patterns of the other species in the area; and that this strategy evolved because it reduces predation risk for a small-bodied monkey that forages in small, dispersed groups.

Food selection by the South Indian leaf-monkey, Presbytis johnii, in relation to leaf chemistry.

The leaf-monkey Presbytis johnii has been found to exhibit considerable selectivity in its dietary utilization of mature foliage in a rain-forest habitat. To investigate the basis of this selectivity and to examine the hypothesis that the observed selection is related to the digestibility and toxicity of the available foliage, chemical analyses have been made on 16 of the most important tree species in the monkey's habitat. It has been found that the most heavily used items, which form a staple part of the diet of P. johnii, are characterized by a low fibre content and a very low condensed tannin content. However, neither class of compound is an absolute feeding deterrent as minor, but still significant, mature leaf food items contain considerable amounts of both. It is suggested that the feeding deterrents in these minor items, which may be ingested to supply specific dietary requirements, can perhaps be tolerated because of their dilution in the gut by the dietary staples. An examination of the pepsin/cellulase digestibility of available mature foliage showed that the staple food items tended to be highly digestible. Little correlation has been found between alkaloid content and food selection and it is suggested that the colobine forestomach microflora has the ability to detoxify at least some alkaloids. Additional data on mature leaf petioles and young leaves suggest that the high ratio of cell-sap to cell-wall in these items, and their related high digestibility, explain the high relative abundance of these items in the P. johnii diet.