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  • Author or Editor: Simon K. Bearder x
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Vocalizations of Senegal and South African lesser bushbabies were compared with respect to their acoustic properties analysed from spectrograms and oscillograms. Homologous calls could be identified within comparable functional categories. Considerable similarities were revealed in most of the noisy vocalizations associated with aggressive, defensive or anxiety and alarm behaviour. Striking divergences were detected, however, in almost all of the tonal or harmonic call types given in association with contact or contact-seeking, defensive or alarm behaviour. The results provide strong support for the separation of the two forms into distinct species, Galago senegalensis and Galago moholi.

In: Folia Primatologica

This paper provides a checklist and summary of what is currently known of the variation in infant contact, sleeping site preference and aspects of social cohesion in the nocturnal primates of Africa. Genera and species are compared, based on previously unpublished field observations and a review of the literature. There is a clear pattern of similarity between the species within each genus and distinct differences between genera. Species in the same genus tend to be ecologically equivalent and replace each other allopatrically, whereas species in different genera are more likely to be sympatric, with up to 6 species living together. Maximum sympatry within genera is found in Otolemur and Galagoİdes, where species are ecologically divergent. This may reflect an ancient origin of species within these genera or suggest that further taxonomic revision is required at the generic level. Some data are recorded for the first time for species that have only recently been separated (cryptic species), but some taxa remain very poorly known. It is concluded that field studies are still at an elementary stage and further research with radio tracking is urgently needed in the face of rapidly declining habitats.

In: Folia Primatologica

Like other nocturnal primates, many species of galago (Galagidae) are phenotypically cryptic, making their taxonomic status difficult to resolve. Recent taxonomic work has disentangled some of the confusion. This has resulted in an increase in the number of recognised galago species. The most widespread galago species, and indeed the most widespread nocturnal primate, is the northern lesser galago (Galago senegalensis) whose geographic range stretches >7,000 km across Africa. Based on morphology, 4 subspecies are currently recognised: G. s. senegalensis, G. s. braccatus, G. s. sotikae and G. s. dunni. We explore geographic and subspecific acoustic variation in G. senegalensis, testing three hypotheses: isolation by distance, genetic basis, and isolation by barrier. There is statistical support for isolation by distance for 2 of 4 call parameters (fundamental frequency and unit length). Geographic distance explains a moderate amount of the acoustic variation. Discriminant function analysis provides some degree of separation of geographic regions and subspecies, but the percentage of misdesignation is high. Despite having (putative) parapatric geographic ranges, the most pronounced acoustic differences are between G. s. senegalensis and G. s. dunni. The findings suggest that the Eastern Rift Valley and Niger River are significant barriers for G. senegalensis. The acoustic structures of the loud calls of 121 individuals from 28 widespread sites are not significantly different. Although this makes it unlikely that additional unrecognised species occur within G. senegalensis at the sites sampled, vast areas of the geographic range remain unsampled. We show that wide-ranging species do not necessarily exhibit large amounts of variation in their vocal repertoire. This pattern may also be present in nocturnal primates with smaller geographic ranges.

In: Folia Primatologica

Describing primate biodiversity is one of the main goals in primatology. Species are the fundamental unit of study in phylogeny, behaviour, ecology and conservation. Identifying species boundaries is particularly challenging for nocturnal taxa where only subtle morphological variation is present. Traditionally, vocal signals have been used to identify species within nocturnal primates: species-specific signals often play a critical role in mate recognition, and they can restrict gene flow with other species. However, little research has been conducted to test whether different “acoustic forms” also represent genetically distinct species. Here, we investigate species boundaries between two putative highly cryptic species of Eastern dwarf galagos (Paragalago cocosand P. zanzibaricus). We combined vocal and genetic data: molecular data included the complete mitochondrial cytochrome b gene (1,140 bp) for 50 samples across 11 localities in Kenya and Tanzania, while vocal data comprised 221 vocalisations recorded across 8 localities. Acoustic analyses showed a high level of correct assignation to the putative species (approx. 90%), while genetic analyses identified two separate clades at the mitochondrial level. We conclude that P. cocos and P. zanzibaricus represent two valid cryptic species that probably underwent speciation in the Late Pliocene while fragmented in isolated populations in the eastern forests.

In: Folia Primatologica