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PubMed1981

Comparative histochemical study of prosimian primate hindlimb muscles. I. Muscle fiber types.

The profiles of fiber types in hindlimb muscles from the tree shrew (Tupaia glis), lesser bushbaby (Galago senegalensis), and the slow loris (Nycticebus coucang) were determined using histochemical techniques. Fibers were classified as fast-twitch oxidative-glycolytic (FOG), fast-twitch glycolytic (FG), slow-twitch oxidative (SO), or fast-twitch oxidative (FO), according to reactions for alkaline-stable ATPase, acid-stable ATPase, alpha-glucan phosphorylase, reduced nicotinamide adenine dinucleotide diaphorase, succinate dehydrogenase, mitochondrial alpha-glycerophosphate dehydrogenase (MaGPDH), and beta-hydroxybutyric dehydrogenase, as well as glycogen staining by the periodic acid-Schiff technique. Prolonged dissection of numerous muscles was carried out on hindlimbs submersed in cold Tyrode's solution; such treatment had no qualitative effect on enzyme staining reactions, but it is not a suitable procedure if one wishes to stain for glycogen. Fast-twitch oxidative (FO) fibers are alkaline-stable ATPase-positive and possess low MalphaGPDH enzyme activity. These fibers have not been reported previously in any hindlimb muscles. No muscles of any species studies were homogeneous with respect to fiber type. Slow loris muscles lacked FG fibers. The majority of the muscles of the slow loris contained numerous SO fibers. The relationship between enzyme activities and locomotor pattern is discussed.

Adenosine Triphosphatases↗
PubMed1981

Comparative histochemical study of prosimian primate hindlimb muscles. II. Populations of fiber types.

The populations of fiber types in hindlimb muscles of the tree shrew (Tupaia glis), lesser bushbaby (Galago senegalensis), and the slow loris (Nycticebus coucang) were described and an attempt was made to correlate populations of fiber types and locomotor patterns. Muscle fibers were assigned to one of the following groups: fast-twitch glycolytic (FG), fast-twitch oxidative-glycolytic (FOG), and slow-twitch oxidase (SO). Histochemical techniques for the demonstration of alkaline- and acid-stable ATPase, succinic dehydrogenase, and mitochondrial alpha-glycerophosphate dehydrogenase were used in the classification of muscle fibers. Results indicated that the FG fiber type is the predominant fiber type in muscles used for jumping, the FOG fiber type is predominant in muscles used for running, and the SO fiber type occurs in high percentages in postural muscles. The SO fiber was also the most common fiber in muscles of the slow loris-a species that exhibits a slow, deliberate, sustained locomotor pattern. Intramuscular regional variations in populations were seen in some larger muscles of the tree shrew, but not in the lesser bushbaby and slow loris. Our results did not support the contentions of others that analogous muscles in different species have similar populations of fiber types.

Animals↗
PubMed2005

Social organization of the Milne-Edward's potto.

Nocturnal prosimian primates are often seen alone during their nocturnal activities, and are therefore categorized as "solitary". Recent research has shown that these animals actually possess social networks that differ among species. Here we present new information on one of the lesser studied prosimian primates, the potto, derived from fieldwork in Cameroon that employed radiotelemetry and behavioral observations. An analysis of association patterns and home-range overlaps between animals revealed that pottos associated more frequently with conspecifics than expected for a supposedly solitary primate. Certain males and females that were seen together regularly throughout the study, but were not observed to have contact with other pottos of the opposite sex, were labeled as "pairs". These pairs were found to have higher levels of association with each other than with other conspecifics. The only affiliative and sexual behaviors observed between members of the opposite sex occurred within the pairs of pottos. Although given the secretive nature of these primates, the possibility of extrapair copulations cannot be ruled out, their relatively small testis size indicates that sperm competition is not so important for this species.

Animals↗
PubMed2006

Multidirectional chromosome painting reveals a remarkable syntenic homology between the greater galagos and the slow loris.

We report on the first reciprocal chromosome painting of lorisoids and humans. The chromosome painting showed a remarkable syntenic homology between Otolemur and Nycticebus. Eight derived syntenic associations of human segments are common to both Otolemur and Nycticebus, indicative of a considerable period of common evolution between the greater galago and the slow loris. Five additional Robertsonian translocations form the slow loris karyotype, while the remaining chromosomes are syntenically equivalent, although some differ in terms of centromere position and heterochromatin additions. Strikingly, the breakpoints of the human chromosomes found fragmented in these two species are apparently identical. Only fissions of homologs to human chromosomes 1 and 15 provide significant evidence of a cytogenetic link between Lemuriformes and Lorisiformes. The association of human chromosomes 7/16 in both lorisoids strongly suggests that this chromosome was present in the ancestral primate genome.

Animals↗
PubMed2006

Polycystic nephropathy in slender lorises (Loris lydekkerianus).

In a colony of slender lorises, 20 deaths that occurred over a period of 11 years were investigated postmortem. Juvenile/adult polycystic nephropathy was observed in one newborn and 13 adult slender lorises. Although polycystic kidney disease (PKD) in humans and other animals is known to be inherited, it is not clear whether kidney alterations in slender lorises are genetically transmitted, stress related, or induced by microbiological influences.

Animals↗
PubMed2006

Social lives of adult Mysore slender lorises (Loris lydekkerianus lydekkerianus).

Despite the persistent use of the word "solitary" to describe nocturnal primate social behavior, increasing numbers of studies are revealing sophisticated levels of social interactions among nocturnal primates. This study explores the relationships among 11 adult Mysore slender lorises (Loris lydekkerianus lydekkerianus) studied over 10(1/2) months in Tamil Nadu, India. When all observations regarding dependent offspring are excluded, the animals spent on average 38% of their activity in various forms of neutral, affiliative, and agonistic behaviors. Affiliative behaviors were the most common type of social interaction, and males in general were more social than females. Low values for Cole's index (CI) of association emphasize that females rarely interacted with same-sex conspecifics, but commonly interacted with males. In turn, males also formed strong affiliative relationships with other adult males. This index also indicates that levels of affiliation are strongest among animals that share sleeping sites. The Hinde index (HI) suggests that males control proximity to females more than the reverse. A female's tolerance of multiple males in her home range and at a sleeping site may be related to high spatial variability of food resources. Such resources may constrain females with costly reproductive strategies (up to two sets of twins per annum) to a small home range. With their larger home ranges, males may be able to monopolize females by initiating social interactions, and also provide a benefit to females by contributing to parental care.

Animals↗
PubMed2007

Comparative penile morphology of East African galagos of the genus Galagoides (family Galagidae): implications for taxonomy.

Recent studies on the comparative penile morphology of galagos have revealed complex patterns that vary among both genera and species, and help with species identification. So far the penile morphologies of 14 galago species have been described and an identification key has been proposed. The present study extends and revises previous work. Wild Galagoides cocos, G. granti, G. zanzibaricus and G. rondoensis from the Eastern Arc Mountains and coastal forests of Tanzania and Kenya were live-trapped, and one species (G. orinus) was examined using a museum specimen. Penile morphology was photographed, traced, and described qualitatively. All of the mature males had penile spines. Spines were absent or indistinct in immature males of all of the species. The penile morphologies of G. cocos, G. granti, and G. zanzibaricus are similar in their overall distribution and type of spines, but differ in the shape of the glans penis. Both G. orinus and G. rondoensis have divergent penile morphologies compared to all other galagos, and are probably phylogenetically distinct. The results support other recent morphological and behavioral studies that consider these five galagos to be distinct species. The evolution of the baculum and spines is thought to be linked to sexual selection in multimale mating systems, but the mechanisms involved are not entirely understood. Adult male G. rondoensis appear to display the penile spines by exposing the distal section of the penis.

Animals↗
PubMed2007

Histomorphology of the mandibular condylar cartilage in greater galagos (Otolemur spp.).

The functional morphology of the primate craniomandibular complex and temporomandibular joint (TMJ) components is frequently discussed in terms of gross skeletal structure. At the histomorphologic level, however, the TMJ has only been studied in Old World anthropoids. The present study is designed to describe the microanatomy of the condylar cartilage of the TMJ in two closely related species of greater galago: the exudativorous Otolemur crassicaudatus and the frugivorous O. garnettii. TMJs with intact joint capsules were harvested from adult, cadaveric specimens of these species (four O. crassicaudatus and five O. garnettii). The samples were decalcified, processed for paraffin sectioning, and sectioned at 10-18 microm in the coronal plane. The samples were then stained with hematoxylin/eosin, Gomori trichrome, and Alcian blue, and examined with a photomicroscope. Generally, condylar cartilage in O. crassicaudatus was thickest both laterally and centrally, while O. garnettii had the relatively thickest cartilage laterally. Both species displayed a superficial articular zone, a middle proliferative zone, and a deeply located hypertrophic zone in the condylar cartilage. O. crassicaudatus typically had the greatest cell density in each of these zones. In addition, O. crassicaudatus had focal concentrations of Alcian blue laterally and centrally, while O. garnettii had the greatest reactivity in the central portion only. These results suggest that O. crassicaudatus may be specialized to resist greater compressive force at the TMJ condylar cartilage in specific regions of the mandibular condyle.

Animals↗
PubMed2007

Interspecific analysis of covariance structure in the masticatory apparatus of galagos.

The primate masticatory apparatus (MA) is a functionally integrated set of features, each of which performs important functions in biting, ingestive, and chewing behaviors. A comparison of morphological covariance structure among species for these MA features will help us to further understand the evolutionary history of this region. In this exploratory analysis, the covariance structure of the MA is compared across seven galago species to investigate 1) whether there are differences in covariance structure in this region, and 2) if so, how has this covariation changed with respect to size, MA form, diet, and/or phylogeny? Ten measurements of the MA functionally related to bite force production and load resistance were obtained from 218 adults of seven galago species. Correlation matrices were generated for these 10 dimensions and compared among species via matrix correlations and Mantel tests. Subsequently, pairwise covariance disparity in the MA was estimated as a measure of difference in covariance structure between species. Covariance disparity estimates were correlated with pairwise distances related to differences in body size, MA size and shape, genetic distance (based on cytochrome-b sequences) and percentage of dietary foods to determine whether one or more of these factors is linked to differences in covariance structure. Galagos differ in MA covariance structure. Body size appears to be a major factor correlated with differences in covariance structure among galagos. The largest galago species, Otolemur crassicaudatus, exhibits large differences in body mass and covariance structure relative to other galagos, and thus plays a primary role in creating this association. MA size and shape do not correlate with covariance structure when body mass is held constant. Diet also shows no association. Genetic distance is significantly negatively correlated with covariance disparity when body mass is held constant, but this correlation appears to be a function of the small body size and large genetic distance for Galagoides demidoff. These exploratory results indicate that changing body size may have been a key factor in the evolution of the galago MA.

Animals↗
PubMed2007

Cranial ontogeny, diet, and ecogeographic variation in African lorises.

A series of 22 craniodental measurements were obtained for the three subspecies of potto (Perodicticus) and angwantibos (Arctocebus). To describe patterns of variation in Perodicticus, a discriminant function analysis (DFA) was performed with adult data. To investigate the ecogeographic correlates of size variation in Perodicticus, adult cranial dimensions were compared with field data on latitudinal and longitudinal coordinates for available specimens as well as altitudinal data for a more limited sample. Ontogenetic series for larger-bodied Perodicticus and smaller-bodied Arctocebus were compared to test the hypothesis that inter- and intrageneric variation in skull form results from the differential extension/truncation of shared patterns of relative growth, and to assess morphological variation in the masticatory complex of sister taxa with differing dietary habits. Analyses of relative growth indicate that skull proportions in Perodicticus subspecies are largely ontogenetically scaled. In comparisons between Perodicticus and Arctocebus, most facial dimensions also are ontogenetically scaled, with all but one of the seven divergent comparisons (interorbital breadth) representing a feature of the masticatory apparatus. The DFA provided independent support for prior classifications of Perodicticus into three taxa. Size differentiation in African lorises appears to be correlated with altitudinal variation (Bergmann's Rule) as well as character displacement. The smallest pottos, P. p. potto, occupy low-lying coastal habitats in western Africa, whereas the larger, eastern forms inhabit higher, presumably colder elevations. The largest potto, P. p. edwardsi, is sympatric throughout most of its range with the smallest and most insectivorous African lorises (Arctocebus). A basis for intrageneric taxonomic variation in Perodicticus is supported by such nonclinal size variation, as well as divergences in the ontogeny of masticatory proportions corresponding to interspecific variation in dietary proclivities.

Africa↗
PubMed2007

Not all lorises are slow: rapid arboreal locomotion in Loris tardigradus of southwestern Sri Lanka.

The unique slow-climbing quadrupedalism of Asian lorises has been the subject of numerous studies; however, qualitative observations of more rapid locomotion have occasionally been reported. Field studies of the red slender loris have revealed the habitual use of unexpectedly high-speed locomotion by the so-called "sloth of the primate world." Novel video footage permitted the first quantitative kinematic analysis of rapid quadrupedalism in wild lorises. Observations revealed that this previously unexplored behavior is far from infrequent, with 26% of red slender loris locomotor activity being dedicated to high-velocity arboreal quadrupedalism. This locomotor pattern may represent a primitive retention of the rapid, scrambling quadrupedalism that is observed in other strepsirhines, or it may constitute a more recent specialization of this smallest loris taxon.

Animals↗
PubMed2002

Variability of metapodials in primates with rudimentary digits: Ateles geoffroyi, Colobus guereza, and Perodicticus potto.

A tenet of evolutionary theory is that, within a species, phenotypic variability is inversely related to the intensity of stabilizing selection. A corollary is that a rudimentary or vestigial structure should be highly variable. This relationship between rudimentation and variability, however, may simply be part of a continuum, as several studies have shown that variability and size of a structure are inversely related. This study tests whether the first metacarpal (MC1) in Ateles geoffroyi and Colobus guereza and the second metacarpal (MC2) in Perodicticus potto are highly variable in their lengths relative to their other metapodials. The former two species have rudimentary thumbs, and the latter species has a rudimentary index finger. Fourteen other species of primates are included in the comparison. The results show that MC1 in A. geoffroyi and C. guereza and MC2 in P. potto are the relatively shortest first and second metapodials, respectively, in this sample of primates. However, an intraspecific analysis shows that neither MC1 in A. geoffroyi and C. guereza nor MC2 in P. potto is significantly more variable than the other metapodials. Nevertheless, an interspecific analysis shows that MC1 in A. geoffroyi and C. guereza is relatively the most variable among the first metapodials (i.e., MC1 and first metatarsal) in this study. MC2 in P. potto, however, is of relatively low variability compared with the other primates. These contrasting results are interpreted in terms of the developmental and evolutionary biology of digits.

Adaptation, Physiological↗
PubMed2003

Spacing system of the Mysore slender loris (Loris lydekkerianus lydekkerianus).

Loris lydekkerianus lydekkerianus has been shown to have a promiscuous copulatory pattern, to maintain social networks via frequent loud calls, to interact socially throughout the night with all age classes, and to sleep socially. Though these behaviors point towards a multimale social system, no study of their spacing system has yet been provided to support this view. From October 1997-August 1998, I conducted a study of the Mysore slender loris in Ayyalur, India. During 1,400 field hours, data were collected on range use of 3 adult females, 3 adult males, 1 subadult female, and 1 subadult male. Lorises slept in groups averaging 4 individuals, composed of an adult female, her offspring, and 1-2 adult and subadult males. Sleeping sites for three groups were located within 1.9 ha in the center of the study area. The minimum convex polygon in hectares encompassing each animal's range was determined, as well as overlap among home ranges of individual lorises. Average home range sizes were: adult males, 3.6 ha +/- 0.09; subadult/smaller males, 1.17 ha +/- 0.26; and adult and subadult females, 1.59 ha +/- 0.24. Male ranges overlapped with at least 2-3 other adult males (0.72 ha +/- 0.23). Female ranges overlapped slightly with at least 2 other female ranges (0.22 ha +/- 0.25). Male ranges overlapped those of at least 3 females (0.82 ha +/- 0.51). Patterns of home range and sleeping site support previous suggestions of a multimale social system, similar to aye ayes and some galagos.

Animals↗
PubMed2005

Mechanical significance of femoral head trabecular bone structure in Loris and Galago evaluated using micromechanical finite element models.

Work on the interspecific and intraspecific variation of trabecular bone in the proximal femur of primates demonstrates important architectural variation between animals with different locomotor behaviors. This variation is thought to be related to the processes of bone adaptation whereby bone structure is optimized to the mechanical environment. Micromechanical finite element models were created for the proximal femur of the leaping Galago senegalensis and the climbing and quadrupedal Loris tardigradus by converting bone voxels from high-resolution X-ray computed tomography scans of the femoral head to eight-noded brick elements. The resulting models had approximately 1.8 million elements each. Loading conditions representing takeoff phase of a leap and more generalized load orientations were applied to the models, and the models were solved using the iterative "row-by-row" matrix-vector multiplication algorithm. The principal strain and Von Mises stress results for the leaping model were similar for both species at each load orientation. Similar hip joint reaction forces in the range of 4.9 x to 12 x body weight were calculated for both species under each loading condition, but the hip reaction values estimated for Loris were higher than predicted based on locomotor behavior. These results suggest that functional adaptation to hip joint loading may not fully explain the differences in femoral head trabecular bone structure in Galago and Loris. The finite element method represents a unique and useful tool for analyzing the functional adaptation of trabecular bone in a diversity of animals and for reconstructing locomotor behavior in extinct taxa.

Animals↗