Ecological correlates of trophic status and frugivory in neotropical primates

Primates are among the most observable and best studied vertebrate order in tropical forest regions, with widespread attention dedicated to the feeding ecology of wild populations. In particular, primates play a key role as frugivores and seed‐dispersal agents for a myriad of tropical plants. Sampling effort by primatologists, however, has been unequally distributed, hampering quantitative comparisons of primate diets. We provide the first systematic review of primate diets, with an emphasis on frugivory, using a comprehensive compilation of 290 unique primate dietary studies from 164 localities in 17 countries across the entire Neotropical realm. We account for sampling effort (standardised as hours) in comparing the richness of fruiting plants recorded in primate diets, and the relative contribution of frugivory to the overall diet in relation to key life‐history traits, such as body mass. We find strong support for the long‐held hypothesis, based on Kay's Threshold, that body size imposes an upper limit on insectivory and a lower limit on folivory, and therefore that frugivory is most important at intermediate body sizes. However, the upper body mass limit of extant neotropical primates, truncated by the post‐Pleistocene megafaunal overkill, has implications for the extent of the frugivory–folivory continuum in extinct lineages. Contemporary threats faced by the largest primates serve as a further warning that the feeding ecology and diet of all neotropical primates remain severely undersampled with regard to the composition and richness of fruits consumed. Indeed, frugivorous primates expected to have the most species‐rich plant diets are amongst those most poorly sampled, exposing implications for our current understanding of primate–plant interaction networks.     

The relationship between blood and cerebrospinal fluid prolactin in nonhuman primates

We studied the relationship between plasma and cerebrospinal fluid (CSF) concentrations of prolactin (PRL) in repeated and simultaneous samples of blood and CSF from chair-restrained rhesus monkeys. Following administration of thyrotropin releasing hormone (TRH), each of 4 monkeys showed increased plasma and lumbar CSF PRL concentrations. Increases in CSF PRL concentrations were muted and delayed until 60 min after peak plasma concentrations were attained. In 3 other monkeys we compared PRL concentrations in simultaneous lateral ventricular and lumbar CSF samples. Although we found no difference in PRL concentrations under baseline conditions, a ventricular-lumbar PRL concentration gradient became apparent after TRH stimulation. These studies demonstrate that changes in plasma PRL concentrations are reflected in CSF concentrations. They suggest that a significant blood-CSF barrier exists for PRL and that PRL may enter the the CSF selectively via the ventricles.     

The enigmatic relationship between epiphyseal fusion and bone development in primates

Epiphyseal fusion in primates is a process that occurs in a regular sequence spanning a period of years and thus provides biological anthropologists with a useful marker of maturity that can be used to assess age and stage of development. Despite the many studies that have catalogued fusion timing and sequence pattern, comparatively little research has been devoted to understanding why these sequences exist in the first place. Answering this question is not necessarily intuitive; indeed, given that neither taxonomic affinities nor recent adaptations have been clearly defined, it is a challenge to explain this process in evolutionary terms. In all mammals, there is a tendency for the fusion of epiphyses at joints to occur close in sequence, and this has been proposed to relate to locomotor adaptations. Further consideration of the evidence suggests that linking locomotor behavior to sequence data alone is difficult to prove and may require a different type of evidence. Epiphyseal fusion should be considered in the context of other parameters that affect the developing skeleton, including how joint morphology relates to growth in length, as well as other possible morphological constraints. In recent years, developmental biology has been providing a better understanding of the molecular regulators of epiphyseal fusion. At some point in the near future, we may be able to link our understanding of the genetics of fusion timing to the possible selective mechanisms that are responsible for these sequences.     

Measuring the relationship between dietary quality and body size in primates

The feeding niche and the body size of any species are fundamental parameters that constrain the evolution of many other phenotypic characters. Moreover, previous work has shown that body size and diet are correlated, as a consequence of the negative allometry of metabolic rate. Unfortunately, the precise form of the association between body size and diet has never been specified, principally because no suitable cross-species measure of diet has been advanced. Here we develop a measure of diet that is sensitive over the whole spectrum of primate feeding niches, and use this measure to define the relationship between body size and diet for a sample of 72 primate species. Subsequently, we present several examples of how behavioral and ecological hypotheses can be tested by examining the extent to which particular species deviate from the general diet-body size pattern.     

Coevolutionary relationship between striatum size and social play in nonhuman primates

The striatum is a region of the brain specifically tied to the experience and anticipation of pleasure, reward, appropriate behavioral sequencing, cognition, learning, and social modulation. Furthermore, the striatum is connected neurologically and functionally to other brain regions associated with the exhibition of social play, such as the neocortex, cerebellum, and limbic system. For these reasons, the striatum is especially interesting to researchers of play behavior. Moreover, the caudate-putamen area of the striatum has been specifically implicated in laboratory studies of social play behavior. This study uses the phylogenetic comparative method of independent contrasts to test for an evolutionary relationship between striatum volume and a measure of social play in nonhuman primates. Relative volume of the primate striatum correlates with rate of social, but not nonsocial, play behavior across species, suggesting a coevolution of traits. The pleasurable and procedural aspects of social play behavior may be mediated in part by the striatum and further to its connection to dopaminergic pathways in the primate brain.     

The global distribution of frugivory in birds

Aim To examine patterns of avian frugivory across clades, geography and environments. Location Global, including all six major biogeographical realms (Afrotropics, Australasia, Indo‐Malaya, Nearctic, Neotropics and Palaearctic). Methods First, we examine the taxonomic distribution of avian frugivory within orders and families. Second we evaluate, with traditional and spatial regression approaches, the geographical patterns of frugivore species richness and proportion. Third, we test the potential of contemporary climate (water–energy, productivity, seasonality), habitat heterogeneity (topography, habitat diversity) and biogeographical history (captured by realm membership) to explain geographical patterns of avian frugivory. Results Most frugivorous birds (50%) are found within the perching birds (Passeriformes), but the woodpeckers and allies (Piciformes), parrots (Psittaciformes) and pigeons (Columbiformes) also contain a significant number of frugivorous species (9–15%). Frugivore richness is highest in the Neotropics, but peaks in overall bird diversity in the Himalayan foothills, the East African mountains and in some areas of Brazil and Bolivia are not reflected by frugivores. Current climate explains more variance in species richness and proportion of frugivores than of non‐frugivores whereas it is the opposite for habitat heterogeneity. Actual evapotranspiration (AET) emerges as the best single climatic predictor variable of avian frugivory. Significant differences in frugivore richness and proportion between select biogeographical regions remain after differences in environment (i.e. AET) are accounted for. Main conclusions We present evidence that both environmental and historical constraints influence global patterns of avian frugivory. Whereas water–energy dynamics possibly constrain frugivore distribution via indirect effects on food plants, regional differences in avian frugivory most likely reflect historical contingencies related to the evolutionary history of fleshy fruited plant taxa, niche conservatism and past climate change. Overall our results support an important role of co‐diversification and environmental constraints on regional assembly over macroevolutionary time‐scales.     

Linkage relationship between the genes for thymidine kinase and galactokinase in different primates.

In this study we investigated the expression of primate galactokinase in somatic cell hybrids between a thymidine kinase-deficient mouse cell line and two different primate cell lines, one of which was derived from African green monkey kidney cells and the other from chimpanzee fibroblasts. All the African green monkey-mouse hybrid clones, selected in HAT medium, expressed monkey galactokinase activity and contained a monkey chromosome similar to a human E-group chromosome. When these clones were backselected in medium containing 5-bromodeoxyuridine, both this chromosome and the monkey galactokinase activity were lost. All the hybrid clones between mouse and chimpanzee cells, which were selected in HAT medium, contained the chimpanzee chromosome 17 and expressed chimpanzee galactokinase activity. These results indicate that the linkage relationship between galactokinase and thymidine kinase has been maintained in 3 divergent primate species--man, chimpanzee, and Old World monkey.     

Strengthened insectivory in a temperate fragmented forest

Habitat fragmentation modifies ecological patterns and processes through changes in species richness and abundance. In the coastal Maulino forest, central Chile, both species richness and abundance of insectivorous birds increases in forest fragments compared to continuous forest. Through a field experiment, we examined larvae predation in fragmented forests. Higher richness and abundance of birds foraging at forest fragments translated into more insect larvae preyed upon in forest fragments than in continuous forest. The assessed level of insectivory in forest fragments agrees with lower herbivory levels in forest fragments. This pattern strongly suggests the strengthening of food interactions web in forest fragments of coastal Maulino forest.Electronic Supplementary Material Supplementary material is available for this article at and is accessible for authorized users.     

The direct and indirect effects of insectivory by birds in two contrasting Neotropical forests

A goal among community ecologists is to predict when and where trophic cascades occur. For example, several studies have shown that forest birds can limit arthropod abundances on trees, but indirect effects of bird predation (i.e. decreased arthropod damage to trees) are not always observed and their context is not well understood. Because productivity is one factor that is expected to influence trophic cascades, we compared the extent to which birds indirectly limit herbivore damage to trees in two lowland Neotropical forests that differed in seasonality of leaf production and rainfall. We compared the effects of bird predation on local arthropod densities and on damage to foliage through a controlled experiment using bird exclosures in the canopy and understory of two forests. We found that birds decreased local arthropod densities and leaf damage in the canopy of the drier site during periods of high leaf production, but not in the wetter forest where leaf production was low and sporadic throughout the year. Birds had no effect on arthropod abundances and leaf damage in the understory where leaf production and turnover rates were low. In support of these experimental interpretations, although we observed that arthropod densities were similar at the two sites, bird densities and the rate at which birds captured arthropods were greater at the drier, seasonally productive site. The influence of top-down predation by birds in limiting herbivorous insects appears to be conditional and most important when the production and turnover of leaves are comparatively high.Electronic Supplementary Material Supplementary material is available for this article at     

The direct and indirect effects of insectivory by birds in two contrasting Neotropical forests

A goal among community ecologists is to predict when and where trophic cascades occur. For example, several studies have shown that forest birds can limit arthropod abundances on trees, but indirect effects of bird predation (i.e. decreased arthropod damage to trees) are not always observed and their context is not well understood. Because productivity is one factor that is expected to influence trophic cascades, we compared the extent to which birds indirectly limit herbivore damage to trees in two lowland Neotropical forests that differed in seasonality of leaf production and rainfall. We compared the effects of bird predation on local arthropod densities and on damage to foliage through a controlled experiment using bird exclosures in the canopy and understory of two forests. We found that birds decreased local arthropod densities and leaf damage in the canopy of the drier site during periods of high leaf production, but not in the wetter forest where leaf production was low and sporadic throughout the year. Birds had no effect on arthropod abundances and leaf damage in the understory where leaf production and turnover rates were low. In support of these experimental interpretations, although we observed that arthropod densities were similar at the two sites, bird densities and the rate at which birds captured arthropods were greater at the drier, seasonally productive site. The influence of top-down predation by birds in limiting herbivorous insects appears to be conditional and most important when the production and turnover of leaves are comparatively high. Figure legends were missing in the original article published under Plant Animal Interactions, Oecologia (2005) 143: 106–166. The complete article is repeated here. The online version of the original article can be found at     

Functional morphology of the lemuriform wrist joints and the relationship between wrist morphology and positional behavior in arboreal primates

A comparative study of carpal joint structure and function in six Malagasy lemuriforms was undertaken to test predicted morphoclines in carpal joint morphology between pronograde and orthograde arboreal primates. Patterns of movement at the wrist during locomotion were observed and described for the lemuriform species Lemur fulvus and Propithecus verreauxi. Lemur fulvus, which assumes a pronograde posture during locomotion, extends and pronates the wrist during the support phase of quadrupedal walking and running stride cycles. Furthermore, the forearm of this species exhibits some transverse movement across the proximal wrist joint during the support phase. In contrast, the indriid Propithecus maintains the hand and wrist in a flexed and partially supinated position during vertical clinging and suspensory postures. Habitual quadrupedal and vertical postures in Malagasy primates are in turn related to very different patterns of carpal joint morphology and articular mechanics. Those lemurs which are predominantly pronograde share a series of structural features related to stabilizing the antebrachiocarpal joint during extension and mediolateral deviation and the midcarpal joint during pronation: an intraarticular labrum is present on the inner portion of the radiocarpal ligament, the radiocarpal articular surface is quite flat dorsoventrally, the capitate-trapezoid embrasure is expanded dorsally, and development of the radial and ulnar styloids is more pronounced. The wrists of Propithecus, Avahi, and Lepilemur (vertical clingers) differ from those of quadrupedal lemuriforms in possessing a suite of morphological features related to stabilizing the wrist during antebrachiocarpal flexion and midcarpal supination: the radiocarpal articular surface is deeply curved and tilted anteriorly, the dorsal radiocarpal ligament is very broad, thick, and fibrous, the hamate's triquetral facet is directed proximodistally, and the capitate-trapezoid embrasure is dorsally constricted and expanded palmarly. These observed contrasts in carpal form and function are used to define further the morphological features related to orthograde posture in several lineages of arboreal primates. © 1996 Wiley-Liss, Inc.     

The trade-off between number and size of offspring in humans and other primates

Life-history theory posits a fundamental trade-off between number and size of offspring that structures the variability in parental investment across and within species. We investigate this 'quantity-quality' trade-off across primates and present evidence that a similar trade-off is also found across natural-fertility human societies. Restating the classic Smith-Fretwell model in terms of allometric scaling of resource supply and offspring investment predicts an inverse scaling relation between birth rate and offspring size and a (-1/4) power scaling between birth rate and body size. We show that these theoretically predicted relationships, in particular the inverse scaling between number and size of offspring, tend to hold across increasingly finer scales of analyses (i.e. from mammals to primates to apes to humans). The advantage of this approach is that the quantity-quality trade-off in humans is placed into a general framework of parental investment that follows directly from first principles of energetic allocation.     

The role of frugivory in the diversification of bats in the Neotropics

Aim Ecological interactions are among the most important biotic factors influencing the processes of speciation and extinction. Our aim was to test whether diversification rates of New World Noctilionoidea bats are associated with specialization for frugivory, and how this pattern differs between the mainland and the West Indies. Location The New World. Methods We reconstructed a time‐calibrated molecular phylogenetic hypothesis for the New World genera of the superfamily Noctilionoidea. We compiled data on diet, morphology, geographical distribution and number of ecoregions in which each genus occurs. Then, using the phylogenetic tree constructed, we tested whether diversification was driven by diet (animalivorous and sanguinivorous versus nectarivorous and frugivorous) and specialization for frugivory. Afterwards, we conducted phylogenetic comparative analyses to identify correlates of species richness and net diversification rates. Results The diversification rate was higher in mutualistic than in antagonistic clades in mainland and Antillean biogeographical scenarios, but only strictly frugivorous clades showed a markedly higher diversification rate than the rest of the genera. Geographical range and number of ecoregions were positively associated with species richness and diversification rate in continental and insular lineages. Lower body mass, lower forearm length and specialization for frugivory were significantly positively correlated with higher diversification rates in continental lineages, whereas these parameters were negatively correlated in Antillean lineages. Main conclusions The direction of the relationship of intrinsic factors (specialization for frugivory and body size) with diversification of noctilionoid bats depends on the biogeographical context, whereas the direction of the relationship of extrinsic factors (geographical range and number of ecoregions) with diversification is consistent in both mainland and the West Indian lineages.     

The relationship between growth and allometry

The asymptotic allometric equations are derived by considering the relative growth of different physiological and anatomical quantities. The growth rate is assumed to be proportional to the value of the quantity, where the proportion coefficient depends on time. The allometric exponents are calculated for some organs of man and compared with the experimental values for primates. The exponents are generally time-dependent during the growth. The effect of the choice of the origin of time axis on the asymptotic allometric exponents is studied.     

微生态失调与感染

微生态失调与感染的关系极为密切。引起感染的微生物不一定是致病菌或病原体,微生态失调后,正常微生物群易位或易主也可以引起感染。从微生态的视角去审视感染的发生、发展和结局,将会为感染病的防治提供新的思路。