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  • Author or Editor: Vincent Nijman x
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Great progress has been made in unravelling the evolutionary history of Asian colobines, largely through the use of dated molecular phylogenies based on multiple markers. The Presbytis langurs are a case in point, with more allopatric species being identified, recognition of Presbytis thomasi from Sumatra rather than P. potenziani from the Mentawai Islands as being the most basal species of the group, and the discovery that P. rubicunda from Borneo is nested among the Sumatran species and only made it to Borneo in the last 1.3 million years. Based on variation in mitochondrial d-loop, it has recently been argued that Malaysia’s P. femoralis femoralis is actually P. neglectus neglectus. Unfortunately, despite being available, sequences from the type locality, Singapore, were excluded from the analysis, and none of the newly generated sequences was deposited in GenBank. I manually reconstructed these sequences, which allowed me to present a molecular phylogeny that includes 8 additional sequences from West Malaysia and Singapore. P. neglectus from Malaysia and P. femoralis from Singapore form one monophyletic clade, with minimal divergence. I conclude that recognition of P. neglectus is erroneous and the name is a junior synonym of P. femoralis. Colobine taxonomy and systematics have advanced, and continue to advance, mostly by considering evidence from a wide range of individuals, species and data sets (molecular, behavioural and morphological) rather than focusing on single molecular markers from 1 or 2 species from one small geographic area. For an orderly taxonomic debate where evidence can be evaluated and reinterpreted it is essential that newly generated sequences are deposited in public repositories.

In: Folia Primatologica
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Grizzled langurs, Presbytis comata, a largely sexually monomorphic species, are reported to occur in populations where either the majority of groups comprise 1 adult male with 1 adult female, or where groups comprise 1 adult male with multiple females. As such, they may have a monandrous mating system. I investigated whether 1-male/1-female groups indeed form a significant part of the species' social system, and whether habitat variation (forest fragment size, distance to the forest edge, altitude) affects social organization. I found the species from sea level to 2,565 m above sea level in groups from 1 to 13 individuals. I recorded mostly 1-male/multifemale groups with offspring or, alternatively, all-male groups. Two out of 55 groups comprised 1-male/1-female groups with offspring. Group size was negatively correlated with altitude and forest fragment size, and positively correlated with increasing distance from the forest edge. Altitudinal variation in group sizes was driven mainly by fewer adult females being present in groups at higher elevations; the number of adult males (almost invariably 1), subadults, juveniles, and infants, as well as the infant/adult female ratio, showed little altitudinal variation. One-male/1-female groups have been recorded repeatedly over a 25-year period in a high-altitude population on Mt. Patuha, West Java, but even here, on average, three fifths of the groups comprise 1 adult male with multiple females. At high-altitude sites, P. comata may indeed have a monandrous mating system, but at lower elevations it seems similar to that of other Presbytis langurs.

In: Folia Primatologica
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The colobine monkey Presbytis comata is confined to the rain forests of West and Central Java, Indonesia. In order to determine its distribution, a review of the literature, evidence from the study of museum specimens, and the results of recent surveys are presented. Recent surveys in the central parts of the island indicate that P. comata is still present on four volcanic mountain complexes, viz. Mt. Sawal, Mt. Slamet, Mts. Dieng, and Mt. Lawu. The present paper gives the results of the surveys combined with a review of its distribution. Altitudinal and habitat preferences, and the conservation status of the species are discussed.

Free access
In: Bijdragen tot de Dierkunde
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The Javan gibbon Hylobates moloch is confined to the last remnants of rainforest on the island of Java, Indonesia. As of 2002, the species has been recorded in 29 forest areas, and the wild population is conservatively estimated at 4100-4500 individuals. Over 95% of the gibbons are in populations of >100 individuals, and the four largest areas support populations of >500 individuals each. In 2003, 56 Javan gibbons were maintained at eight Indonesian zoos, 15 at four Indonesian wildlife rescue centres, with five potential breeding pairs. There is no evidence that the species has bred successfully in captivity in Indonesia. Outside the range country, 48 Javan gibbons were maintained at ten institutions in nine countries, with six breeding pairs. The total ex-situ population is some 120 individuals, the majority of which is wild-caught. At present most initiatives relating to the conservation of the Javan gibbon have targeted small isolated forest areas and the ex-situ population, whereas in-situ protection of the largest populations in the wild has been largely ignored. Significant populations are currently found in unprotected forests. The large captive population of Javan gibbons within Indonesia allows, with improved co-operation, to set up an integrated captive- breeding programme. This should, not be seen, however, as a means to improve the conservation status of the wild Javan gibbons, which needs to be achieved through protection of remaining habitat, but could be used for improving the prevailing low levels of conservation awareness in Java.

Open Access
In: Contributions to Zoology
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Hose’s leaf monkey Presbytis hosei is endemic to Borneo and occurs only in tall forest. In recent decades Borneo has lost a large part of its forest cover, mostly in low-lying coastal regions. Large intact tracts of forest remain in the interior, but these are by and large inhabited by tribes that subsist in part by hunting. The combined effects of habitat disturbance and hunting on the densities and biomass of Hose’s leaf monkey were studied in Kayan Mentarang National Park in Borneo’s far interior. Over four months, data on densities and hunting were collected by transect walks in four forest types. Hose’s leaf monkeys were hunted to deter crop-raiding, for their meat, and to obtain bezoar stones (visceral secretions used in traditional medicine). Hose’s leaf monkeys occurred in single male groups of 7-8 individuals in densities from 0.8 to 2.3 groups km-2. Densities of Hose’s leaf monkeys were positively correlated with certain vegetation characteristics, e.g. tree height and height of first bough, and negatively correlated with distance to the nearest village. Biomass of Hose’s leaf monkeys declined considerably as a result of habitat disturbance and hunting from 92 kg km-2 in primary hill forest inside the reserve to 38 kg km-2 in old secondary forest and 31 kg km-2 in young secondary forest near villages. A review of the few studies conducted on the effects of habitat disturbance and hunting on Hose’s leaf monkeys reveal inconsistent trends in biomass and density responses.

Open Access
In: Contributions to Zoology
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As one of the fundamental units of ecology and biogeography, the geographic distribution of the endemic and threatened ebony leaf monkey Trachypithecus auratus (E. Geoffroy Saint-Hilaire, 1812) on the islands of Java, Bali, and Lombok (Indonesia) has been assessed. All localities where the species has been collected are listed, and forty-two areas (each in itself consisting of numerous smaller sites) where the species has been recorded are discussed. The species occurs in a large variety of forest types, including mangrove, beach, and freshwater swamp forest; everwet lowland and hill forest; dry decidious forest; montane forest up to 3,000 - 3,500 m a.s.l.; and in some forest plantations (teak Tectona grandis, rasamala Altingia excels, acacia Acacia spp). In East Java, certain populations are dimorphic, containing, besides the more common melanic individuals, also erythristic individuals. This erythristic pelage morph only occurs in the easternmost part of Java of which the line between Mt. Penanggunang and the surroundings of Mojokerto running southwards, via Wonosalam and Blitar, to Mts Kidul roughly forms the western boundary. Localities where individuals of the erythristic pelage morph have been collected or observed are given.

Open Access
In: Contributions to Zoology

Small populations of several species of the groundwater dwelling amphipod genus Ingolfiella are found in caves, wells, seabottoms, beaches and riverbed interstitial habitats. To gain insight in the socio-ecology of these elusive species, we used data from collected specimens to explore the relationships between sexratios, display of secondary sexual characters and other morphological features, and habitat use. We extracted data on the sex ratios and the presence-absence of secondary sexual characters of 13 species from the literature and through examination of museum material. We found a clearly skewed sex ratio with a preponderance of females, both in the individual species as in the genus as a whole. However, sex ratio and the display of secondary sexual characters were not correlated, nor did these characters correlate with the amount of sexual dimorphism. It remains unknown why so many ingolfiellids have evolved these costly features.

Open Access
In: Contributions to Zoology

Given its complex zoogeography and large number of islands insular Southeast Asia makes an excellent subject for studying the interrelationships of species richness, island area and isolation. The islands are merely highpoints of an immense shallow continental shelf which during Pleistocene glacial periods was exposed periodically as dry land connecting the now isolated islands with one another. The area is home to a large number of primate taxa, including many endemic to the region (Nasalis, Presbytis, Pongo, Symphalangus, Simias, Tarsius). Worldwide, the number of described (extant) species of primates has doubled in the last two decades partially as a result of applying a different species concept (viz. Phylogenetic Species Concept PSC as opposed to the Biological Species Concept BSC). According to Isaac et al. (Trends in Ecology and Evolution 19: 464-469, 2004) this ‘taxonomic inflation’ will influence the outcome of macroecological studies. We studied the species-area relationships in Primates on 118 islands in insular Southeast Asia, and used two taxonomies (PSC and BSC). The number of primate species (PSC 37 species, BSC 23 species) is highly significantly related to surface area of the islands, and the slope of the curve is similar for both PSC and BSC species (z = 0.13). Species ‘newly’ described under the PSC are not only from large islands but also smaller ones hence affecting neither intercept nor the slope of the curve. Area alone was a much better predictor for primate species richness than models that included other macroecological variables (latitude, longitude, altitude, distance to mainland, greatest depth between island and mainland, distance to neighbouring islands). Degree of isolation has little influence on species number but both longitude and latitude are inversely correlated with the number of species per island, suggesting that species numbers decrease in a northerly and easterly direction. The low z-values suggest that for primates the islands of Southeast Asia are perhaps less isolated than previously recognised.

Open Access
In: Contributions to Zoology

Global biogeography and phylogeography have gained importance as research topics in zoology, as attested by the steady increase in the number of journals devoted to this topic and the number of papers published. Yet, in a globalising world, with species reintroductions, invasions of alien species, and large-scale extinctions, unravelling the true biogeographic relationships between areas and species may become increasingly difficult. We present an introduction to the symposium ‘Biogeography: explaining and predicting species distributions in space and time’ held in Amsterdam in 2007, and the resulting papers as published in this special issue, including papers on crustaceans, birds and mammals.

Open Access
In: Contributions to Zoology