Reversible deactivation of motor cortex reveals that areas in parietal cortex are differentially dependent on motor cortex for the generation of movement.

Primates are characterized by specializations for manual manipulation, including expansion of posterior parietal cortex (PPC) and, in Catarrhines, evolution of a dexterous hand and opposable thumb. Previous studies examined functional interactions between motor cortex and PPC in New World monkeys and galagos, by inactivating M1 and evoking movements from PPC. These studies found that portions of PPC depend on M1 to generate movements. We now add a species that more closely resembles humans in hand morphology and PPC: macaques. Inactivating portions of M1 resulted in all evoked movements being reduced (28%) or completely abolished (72%) at the PPC sites tested (in areas 5L, PF, and PFG). Anterior parietal area 2 was similarly affected (26% reduced and 74% abolished) and area 1 was the least affected (12% no effect, 54% reduced, and 34% abolished). Unlike previous studies in New World monkeys and galagos, interactions between both nonanalogous (heterotopic) and analogous (homotopic) M1 and parietal movement domains were commonly found in most areas. These experiments demonstrate that there may be two parallel networks involved in motor control: a posterior parietal network dependent on M1 and a network that includes area 1 that is relatively independent of M1. Furthermore, it appears that the relative size and number of cortical fields in parietal cortex in different species correlates with homotopic and heterotopic effect prevalence. These functional differences in macaques could contribute to more numerous and varied muscle synergies across major muscle groups, supporting the expansion of the primate manual behavioral repertoire observed in Old World monkeys.NEW & NOTEWORTHY Motor cortex and anterior and posterior parietal cortex form a sensorimotor integration network. We tested the extent to which parietal areas could initiate movements independent of M1. Our findings support the contention that, although areas 2, 5L, PF, and PFG are highly dependent on M1 to produce movement, area 1 may constitute a parallel corticospinal pathway that can function somewhat independently of M1. A similar functional architecture may underlie dexterous tool use in humans.

Thalamic connections of the caudal part of the posterior parietal cortex differ from the rostral part in galagos (Otolemur garnettii).

In this study, thalamic connections of the caudal part of the posterior parietal cortex (PPCc) are described and compared to connections of the rostral part of PPC (PPCr) in strepsirrhine galagos. PPC of galagos is divided into two parts, PPCr and PPCc, based on the responsiveness to electrical stimulation. Stimulation of PPC with long trains of electrical pulses evokes different types of ethologically relevant movements from different subregions ("domains") of PPCr, while it fails to evoke any movements from PPCc. Anatomical tracers were placed in both dorsal and ventral divisions of PPCc to reveal thalamic origins and targets of PPCc connections. We found major thalamic connections of PPCc with the lateral posterior and lateral pulvinar nuclei, distinct from those of PPCr that were mainly with the ventral lateral, anterior pulvinar, and posterior nuclei. The anterior, medial, and inferior pulvinar, ventral anterior, ventral lateral, and intralaminar nuclei had fewer connections with PPCc. Dominant connections of PPCc with lateral posterior and lateral pulvinar nuclei provide evidence that unlike the sensorimotor-orientated PPCr, PPCc is more involved in visual-related functions.

Saving energy via short and shallow torpor bouts.

Maintaining a high and stable body temperature as observed in most endothermic mammals and birds is energetically costly and many heterothermic species reduce their metabolic demands during energetic bottlenecks through the use of torpor. With the increasing number of heterotherms revealed in a diversity of habitats, it becomes apparent that triggers and patterns of torpor use are more variable than previously thought. Here, we report the previously overlooked use of, shallow rest-time torpor (body temperature >30 °C) in African lesser bushbabies, Galago moholi. Body core temperature of three adult male bushbabies recorded over five months showed a clear bimodal distribution with an average active modal temperature of 39.2 °C and a resting modal body temperature of 36.7 °C. Shallow torpor was observed in two out of three males (n = 29 torpor bouts) between June and August (austral winter), with body temperatures dropping to an overall minimum of 30.7 °C and calculated energy savings of up to 10%. We suggest that shallow torpor may be an ecologically important, yet mostly overlooked energy-saving strategy employed by heterothermic mammals. Our data emphasise that torpor threshold temperatures need to be used with care if we aim to fully understand the level of physiological plasticity displayed by heterothermic species.

Thalamocortical and corticothalamic connections of multiple functional domains in posterior parietal cortex of galagos.

In prosimian galagos, the posterior parietal cortex (PPC) is subdivided into a number of functional domains where long-train intracortical microstimulation evoked different types of complex movements. Here, we placed anatomical tracers in multiple locations of PPC to reveal the origins and targets of thalamic connections of four PPC domains for different types of hindlimb, forelimb, or face movements. Thalamic connections of all four domains included nuclei of the motor thalamus, ventral anterior and ventral lateral nuclei, as well as parts of the sensory thalamus, the anterior pulvinar, posterior and ventral posterior superior nuclei, consistent with the sensorimotor functions of PPC domains. PPC domains also projected to the thalamic reticular nucleus in a somatotopic pattern. Quantitative differences in the distributions of labeled neurons in thalamic nuclei suggested that connectional patterns of these domains differed from each other.

Population and genetic structure of a male-dispersing strepsirrhine, Galago moholi (Primates, Galagidae), from northern South Africa, inferred from mitochondrial DNA.

The habitats of Galago moholi are suspected to be largely fragmented, while the species is thought to be expanding further into the southernmost fringe of its range, as well as into human settlements. To date, no intraspecific molecular genetic studies have been published on G. moholi. Here we estimate the genetic diversity and connectivity of populations of G. moholi using two mitochondrial gene regions, the cytochrome C oxidase subunit I gene (COI) and the displacement loop of the control region (D-loop). Samples from five localities in northern South Africa were obtained from archived collections. The two mitochondrial DNA gene regions were amplified and sequenced to provide population summary statistics, differentiation [proportion of the total genetic variation in a population relative to the total genetic variance of all the populations (FST), differentiation within populations among regions (ΦST)], genetic distance and structure. There was discernible genetic structure among the individuals, with two COI and six D-loop haplotypes belonging to two genetically different groups. There was population differentiation among regions (FST = 0.670; ΦST = 0.783; P < 0.01). However, there were low levels of differentiation among populations, as haplotypes were shared between distant populations. Adjacent populations were as divergent from each other as from distant populations. The results suggest that genetic introgression, most likely due to past migrations or recent unintentional translocations that include the animal trade, may have led to connectivity among populations.

Cortical connections of the functional domain for climbing or running in posterior parietal cortex of galagos.

Previous studies in prosimian galagos (Otolemur garnetti) have demonstrated that posterior parietal cortex (PPC) is subdivided into several functionally distinct domains, each of which mediates a specific type of complex movements (e.g., reaching, grasping, hand-to-mouth) and has a different pattern of cortical connections. Here we identified a medially located domain in PPC where combined forelimb and hindlimb movements, as if climbing or running, were evoked by long-train intracortical microstimulation. We injected anatomical tracers in this climbing/running domain of PPC to reveal its cortical connections. Our results showed the PPC climbing domain had dense intrinsic connections within rostral PPC and reciprocal connections with forelimb and hindlimb region in primary motor cortex (M1) of the ipsilateral hemisphere. Fewer connections were with dorsal premotor cortex (PMd), supplementary motor (SMA), and cingulate motor (CMA) areas, as well as somatosensory cortex including areas 3a, 3b, and 1-2, secondary somatosensory (S2), parietal ventral (PV), and retroinsular (Ri) areas. The rostral portion of the climbing domain had more connections with primary somatosensory cortex than the caudal portion. Cortical projections were found in functionally matched domains in M1 and premotor cortex (PMC). Similar patterns of connections with fewer labeled neurons and terminals were seen in the contralateral hemisphere. These connection patterns are consistent with the proposed role of the climbing/running domain as part of a parietal-frontal network for combined use of the limbs in locomotion as in climbing and running. The cortical connections identify this action-specific domain in PPC as a more somatosensory driven domain.

Northern lesser galagos (Galago senegalensis) increase the production of loud calls before and at dawn.

Functional explanations for loud calling in nocturnal primates include territorial or sexual advertisement, maintenance of cohesiveness, and group coordination. It is generally accepted that loud calls of lesser galagos (genus Galago) are used for territorial advertisement and long-distance spacing. Field studies suggest that they are uttered at dusk and dawn, when the animals leave and reunite at their sleeping sites. However, empirical validation of these inferences is lacking. We conducted 16-night-long acoustic monitoring of a northern lesser galago (G. senegalensis) population in Senegal and quantified the occurrence of loud calls throughout the night. We hypothesized that significantly more of these calls would be emitted at dusk and dawn if they were used for territorial advertisement and long-distance spacing. This hypothesis was only partially supported, as we found an asymmetrical distribution of loud calls, which significantly increased only before and at dawn. The finding that the relatively early increase in vocal activity was not directly related to approaching and entering sleeping sites suggests that the northern lesser galagos' loud calls differ in function from reassembly calls described for other species of nocturnal primates. Furthermore, the early onset cannot be explained by changes in the intensity of sunlight, moonlight or starlight, which suggests that a different stimulus, most likely internal, elicits early-morning calling behavior in northern lesser galagos.

Calcaneal elongation and bone strength in leaping galagids.

OBJECTIVES: Small-bodied vertical clinging and leaping primates have elongated calcanei which enhance leap performance by optimizing leap velocity, distance, and acceleration, but at the expense of experiencing relatively large forces during takeoff and landing. This study tests the hypothesis that the elongated calcaneus of leaping galagids is adapted to resist larger and more stereotyped bending loads compared to more quadrupedal galagids. MATERIALS AND METHODS: The calcanei of 14 individuals of Otolemur and 14 individuals of Galago (three species of each genus) were µCT scanned. Calcaneal cross-sectional properties (maximum and minimum second moments of area and polar section modulus) were obtained from a slice representing the 50% position of bone segment length and dimensionless ratios were created for each variable using calcaneal cuboid facet area as a proxy for body mass. RESULTS: There were no significant differences in size-adjusted bending strength between Galago and Otolemur. Galago exhibited more elliptically shaped calcaneal cross sections, however, suggesting that its calcanei are more adapted to stereotyped loading regimes than those of Otolemur. DISCUSSION: The results suggest that the calcaneus of specialized leapers is adapted to more stereotyped loading patterns. The lack of predicted bone strength differences between Galago and Otolemur may be related to body size differences between these taxa, or it may indicate that loads encountered by Galago during naturalistic leaping are not reflected in the available experimental force data.

Species Boundaries within Morphologically Cryptic Galagos: Evidence from Acoustic and Genetic Data.

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.

Low Geographic and Subspecific Variation in the Loud Call of the Widespread and Phenotypically Cryptic Northern Lesser Galago (Galago senegalensis) Suggests Taxonomic Uniformity.

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.

Fiber type composition of epaxial muscles is geared toward facilitating rapid spinal extension in the leaper Galago senegalensis.

OBJECTIVES: We hypothesized that the vertical leaper Galago senegalensis will have epaxial extensor muscles with a fast fiber phenotype to facilitate rapid spinal extension during leaping in comparison to the slow-moving quadruped Nycticebus coucang. To test this, we determined the percentage of fiber cross-sectional area (%CSA) devoted to Type 2 fibers in epaxial muscles of G. senegalensis compared to those of N. coucang. MATERIALS AND METHODS: Immunohistochemistry was used to identify Type 1, Type 2, and hybrid fibers in iliocostalis, longissimus, and multifidus muscles of G. senegalensis (n = 3) and N. coucang (n = 3). Serial muscle sections were used to estimate and compare proportions, cross-sectional areas (CSAs), and %CSAs of Type 1, Type 2, and hybrid fibers between species. RESULTS: Epaxial muscles of G. senegalensis were comprised predominantly of Type 2 fibers with large CSAs (%CSA range ≈ 83-94%; range of mean CSA = 1,218-1,586 µm2 ). N. coucang epaxial muscles were comprised predominantly Type 1 fibers with large CSAs (%CSA range ≈ 69-77%; range of mean CSA = 983-1,220 µm2 ). DISCUSSION: The predominance of Type 2 fibers in G. senegalensis epaxial muscles facilitates rapid muscle excursion and spinal extension during leaping, and is consistent with their relatively long muscle fibers. The predominance of Type 1 fibers in N. coucang epaxial muscles may aid in maintaining stable postures during bridging and cantilevering behaviors characteristic of slow-climbing. These histochemical characteristics highlight the major divergent locomotor repertoires of G. senegalensis and N. coucang.

Frontal eye field in prosimian galagos: Intracortical microstimulation and tracing studies.

The frontal eye field (FEF) in prosimian primates was identified as a small cortical region, above and anterior to the anterior frontal sulcus, from which saccadic eye movements were evoked with electrical stimulation. Tracer injections revealed FEF connections with cortical and subcortical structures participating in higher order visual processing. Ipsilateral cortical connections were the densest with adjoining parts of the dorsal premotor and prefrontal cortex (PFC). Label in a region corresponding to supplementary eye field (SEF) of other primates, suggests the existence of SEF in galagos. Other connections were with ventral premotor cortex (PMV), the caudal half of posterior parietal cortex, cingulate cortex, visual areas within the superior temporal sulcus, and inferotemporal cortex. Callosal connections were mostly with the region of the FEF of another hemisphere, SEF, PFC, and PMV. Most subcortical connections were ipsilateral, but some were bilateral. Dense bilateral connections were to caudate nuclei. Densest reciprocal ipsilateral connections were with the paralamellar portion of mediodorsal nucleus, intralaminar nuclei and magnocellular portion of ventral anterior nucleus. Other FEF connections were with the claustrum, reticular nucleus, zona incerta, lateral posterior and medial pulvinar nuclei, nucleus limitans, pretectal area, nucleus of Darkschewitsch, mesencephalic and pontine reticular formation and pontine nuclei. Surprisingly, the superior colliculus (SC) contained only sparse anterograde label. Although most FEF connections in galagos are similar to those in monkeys, the FEF-SC connections appear to be much less. This suggests that a major contribution of the FEF to visuomotor functions of SC emerged with the evolution of anthropoid primates.

Galagos as avian nest predators in South Africa.

Galagos are generally regarded as dietary specialists that feed predominantly on insects and gum. The diet of the thick-tailed greater galago is more varied and also includes fruit and small vertebrates, although the latter is rare and restricted to certain populations. The southern lesser galago is seemingly a more specialist forager, but frugivory was recently reported in two separate populations, suggesting at least some dietary plasticity in this species. The species is not known to consume vertebrates. Here I report on observations of avian nest predation by both thick-tailed greater and southern lesser galagos in Roodewal State Forest Reserve in South Africa. Galagos were responsible for 56 % of nest losses captured on trail cameras. Both species consumed eggs and nestlings of six species of passerines ranging in size from recently hatched to ~30 g nestlings almost ready to fledge. The consumption of vertebrates by the southern lesser galago represents an extension of its diet, as this has not been reported before. The results suggest that eggs and nestlings comprise part of the regular diet of thick-tailed greater galagos in the study area, albeit only seasonal. The consumption of vertebrate prey by southern lesser galagos may represent the expression of latent behavior which is only expressed under certain environmental conditions, e.g., a severe drought, when its regular food base may be diminished.

Faces in the mirror, from the neuroscience of mimicry to the emergence of mentalizing.

In the current opinion paper, we provide a comparative perspective on specific aspects of primate empathic abilities, with particular emphasis on the mirror neuron system associated with mouth/face actions and expression. Mouth and faces can be very salient communicative classes of stimuli that allow an observer access to the emotional and physiological content of other individuals. We thus describe patterns of activations of neural populations related to observation and execution of specific mouth actions and emotional facial expressions in some species of monkeys and in humans. Particular attention is given to dynamics of face-to-face interactions in the early phases of development and to the differences in the anatomy of facial muscles among different species of primates. We hypothesize that increased complexity in social environments and patterns of social development have promoted specializations of facial musculature, behavioral repertoires related to production and recognition of facial emotional expression, and their neural correlates. In several primates, mirror circuits involving parietal-frontal regions, insular regions, cingulate cortices, and amygdala seem to support automatic forms of embodied empathy, which probably contribute to facial mimicry and behavioural synchrony. In humans these circuits interact with specific prefrontal and temporo-parietal cortical regions, which facilitates higher order cognitive functions such as cognitive empathy and mental state attribution. Our analysis thus suggests that the evolution of higher forms of empathy, such as mentalizing, is also linked to the coupling between the perceptual and motor system related to face processing, which may have undergone a process of exaptation during primate phylogeny.

Vocal activity of lesser galagos (Galago spp.) at zoos.

Almost nothing is known about the natural vocal behavior of lesser galagos living in zoos. This is perhaps because they are usually kept in nocturnal exhibits separated from the visitors by a transparent and acoustically insulating glass barrier. The aim of the present study was therefore to fill this gap in knowledge of the vocal behavior of lesser galagos from zoos. This knowledge might be beneficial because the vocalizations of these small primates can be used for species determination. We performed a 10-day-long acoustic monitoring of vocal activity in each of seven various groups of Galago senegalensis and G. moholi living at four zoos. We quantitatively evaluated the occurrence of four loud vocalization types present in both species, including the most species-specific advertisement call. We found that qualitative as well as quantitative differences exist in the vocal behavior of the studied groups. We confirmed that the observed vocalization types can be collected from lesser galagos living at zoos, and the success can be increased by selecting larger and more diverse groups. We found two distinct patterns of diel vocal activity in the most vocally active groups. G. senegalensis groups were most vocally active at the beginning and at the end of their activity period, whereas one G. moholi group showed an opposite pattern. The latter is surprising, as it is generally accepted that lesser galagos emit advertisement calls especially at dawn and dusk, i.e., at the beginning and at the end of their diel activity.

Robotic vertical jumping agility via series-elastic power modulation.

Several arboreal mammals have the ability to rapidly and repeatedly jump vertical distances of 2 m, starting from rest. We characterize this performance by a metric we call vertical jumping agility. Through basic kinetic relations, we show that this agility metric is fundamentally constrained by available actuator power. Although rapid high jumping is an important performance characteristic, the ability to control forces during stance also appears critical for sophisticated behaviors. The animal with the highest vertical jumping agility, the galago (Galago senegalensis), is known to use a power-modulating strategy to obtain higher peak power than that of muscle alone. Few previous robots have used series-elastic power modulation (achieved by combining series-elastic actuation with variable mechanical advantage), and because of motor power limits, the best current robot has a vertical jumping agility of only 55% of a galago. Through use of a specialized leg mechanism designed to enhance power modulation, we constructed a jumping robot that achieved 78% of the vertical jumping agility of a galago. Agile robots can explore venues of locomotion that were not previously attainable. We demonstrate this with a wall jump, where the robot leaps from the floor to a wall and then springs off the wall to reach a net height that is greater than that accessible by a single jump. Our results show that series-elastic power modulation is an actuation strategy that enables a clade of vertically agile robots.

The hustle and bustle of city life: monitoring the effects of urbanisation in the African lesser bushbaby.

Urbanisation has become a severe threat to pristine natural areas, causing habitat loss and affecting indigenous animals. Species occurring within an urban fragmented landscape must cope with changes in vegetation type as well as high degrees of anthropogenic disturbance, both of which are possible key mechanisms contributing to behavioural changes and perceived stressors. We attempted to elucidate the effects of urbanisation on the African lesser bushbaby, Galago moholi, by (1) recording activity budgets and body condition (body mass index, BMI) of individuals of urban and rural populations and (2) further determining adrenocortical activity in both populations as a measure of stress via faecal glucocorticoid metabolite (fGCM) levels, following successful validation of an appropriate enzyme immunoassay test system (adrenocorticotropic hormone (ACTH) challenge test). We found that both sexes of the urban population had significantly higher BMIs than their rural counterparts, while urban females had significantly higher fGCM concentrations than rural females. While individuals in the urban population fed mainly on provisioned anthropogenic food sources and spent comparatively more time resting and engaging in aggressive interactions, rural individuals fed almost exclusively on tree exudates and spent more time moving between food sources. Although interactions with humans are likely to be lower in nocturnal than in diurnal species, our findings show that the impact of urbanisation on nocturnal species is still considerable, affecting a range of ecological and physiological aspects.

Epaxial muscle fiber architecture favors enhanced excursion and power in the leaper Galago senegalensis.

Galago senegalensis is a habitual arboreal leaper that engages in rapid spinal extension during push-off. Large muscle excursions and high contraction velocities are important components of leaping, and experimental studies indicate that during leaping by G. senegalensis, peak power is facilitated by elastic storage of energy. To date, however, little is known about the functional relationship between epaxial muscle fiber architecture and locomotion in leaping primates. Here, fiber architecture of select epaxial muscles is compared between G. senegalensis (n = 4) and the slow arboreal quadruped, Nycticebus coucang (n = 4). The hypothesis is tested that G. senegalensis exhibits architectural features of the epaxial muscles that facilitate rapid and powerful spinal extension during the take-off phase of leaping. As predicted, G. senegalensis epaxial muscles have relatively longer, less pinnate fibers and higher ratios of tendon length-to-fiber length, indicating the capacity for generating relatively larger muscle excursions, higher whole-muscle contraction velocities, and a greater capacity for elastic energy storage. Thus, the relatively longer fibers and higher tendon length-to-fiber length ratios can be functionally linked to leaping performance in G. senegalensis. It is further predicted that G. senegalensis epaxial muscles have relatively smaller physiological cross-sectional areas (PCSAs) as a consequence of an architectural trade-off between fiber length (excursion) and PCSA (force). Contrary to this prediction, there are no species differences in relative PCSAs, but the smaller-bodied G. senegalensis trends towards relatively larger epaxial muscle mass. These findings suggest that relative increase in muscle mass in G. senegalensis is largely attributable to longer fibers. The relative increase in erector spinae muscle mass may facilitate sagittal flexibility during leaping. The similarity between species in relative PCSAs provides empirical support for previous work linking osteological features of the vertebral column in lorisids with axial stability and reduced muscular effort associated with slow, deliberate movements during anti-pronograde locomotion.

Spicing up the menu: evidence of fruit feeding in Galago moholi.

The African lesser bushbaby, Galago moholi, is described as a food specialist, feeding exclusively on small arthropods and gum primarily from Acacia karroo trees. We studied a population of G. moholi in a highly fragmented habitat in the southernmost part of its natural distributional range in South Africa. In this habitat, we opportunistically observed bushbabies feeding on fruits of the winter fruiting tree, Pappea capensis. Plot counts of tree composition revealed that although the dominant tree species in the area belonged to the genus Acacia, A. karroo trees were widely absent and gum could only be found in small quantities on other Acacia species. The analysis of P. capensis fruits showed high levels of protein, fat, and energy content, making the fruits a potentially important food source for G. moholi during winter when insect availability is low. Our observation is the first documented case of fruit feeding in G. moholi, suggesting that the species is not a food specialist as previously reported but can supplement its diet with fruit when available.

Nonshivering thermogenesis in the African lesser bushbaby, Galago moholi.

The capacity for nonshivering thermogenesis (NST) plays an important role during arousal from torpid states. Recent data on heterotherms inhabiting warmer regions, however, suggest that passive rewarming reduces the need of metabolic heat production during arousal significantly, leading to the question: to what extent do subtropical or tropical heterotherms depend on NST? The African lesser bushbaby, Galago moholi, enters torpid states as an emergency response only, but otherwise stays normothermic throughout the cold and dry winter season. In addition, this species shows unusual rewarming difficulties during arousal from torpor on cold days. We therefore examined the seasonal adjustments of the capacity for NST of naturally acclimatized G. moholi by stimulation with noradrenaline (NA) injection. Dissection of two adult female bushbabies revealed that G. moholi possesses brown adipose tissue, and NA treatment (0.5 mg kg(-1), s.c.) induced a significant elevation in oxygen consumption compared with control (saline) injection. However, the increase in oxygen consumption following injection of NA was not significantly different between winter and summer. Our results show that the ability to produce heat via NST seems to be available throughout the year and that G. moholi is able to change NST capacity within a very short time frame in response to cold spells. Together with results from studies on other (Afro-)tropical heterotherms, which also indicate low or even absent seasonal difference in NST capacity, this raises the question of whether the definition of NST needs to be refined for (Afro-)tropical mammals.