The RNA-Binding Protein PUM2 Impairs Mitochondrial Dynamics and Mitophagy During Aging.

Little information is available about how post-transcriptional mechanisms regulate the aging process. Here, we show that the RNA-binding protein Pumilio2 (PUM2), which is a translation repressor, is induced upon aging and acts as a negative regulator of lifespan and mitochondrial homeostasis. Multi-omics and cross-species analyses of PUM2 function show that it inhibits the translation of the mRNA encoding for the mitochondrial fission factor (Mff), thereby impairing mitochondrial fission and mitophagy. This mechanism is conserved in C. elegans by the PUM2 ortholog PUF-8. puf-8 knock-down in old nematodes and Pum2 CRISPR/Cas9-mediated knockout in the muscles of elderly mice enhances mitochondrial fission and mitophagy in both models, hence improving mitochondrial quality control and tissue homeostasis. Our data reveal how a PUM2-mediated layer of post-transcriptional regulation links altered Mff translation to mitochondrial dynamics and mitophagy, thereby mediating age-related mitochondrial dysfunctions.

Dopaminergic REST/NRSF is protective against manganese-induced neurotoxicity in mice.

Chronic exposure to elevated levels of manganese (Mn) may cause a neurological disorder referred to as manganism. The transcription factor REST is dysregulated in several neurodegenerative diseases, such as Alzheimer's disease and Parkinson's disease. REST upregulated tyrosine hydroxylase and induced protection against Mn toxicity in neuronal cultures. In the present study, we investigated if dopaminergic REST plays a critical role in protecting against Mn-induced toxicity in vivo using dopaminergic REST conditional knockout (REST-cKO) mice and REST loxP mice as wild-type (WT) controls. Restoration of REST in the substantia nigra (SN) with neuronal REST AAV vector infusion was performed to further support the role of REST in Mn toxicity. Mice were exposed to Mn (330 µg, intranasal, daily for 3 weeks), followed by behavioral tests and molecular biology experiments. Results showed that Mn decreased REST mRNA/protein levels in the SN-containing midbrain, as well as locomotor activity and motor coordination in WT mice, which were further decreased in REST-cKO mice. Mn-induced mitochondrial insults, such as impairment of fission/fusion and mitophagy, apoptosis, and oxidative stress, in the midbrain of WT mice were more pronounced in REST-cKO mice. However, REST restoration in the SN of REST-cKO mice attenuated Mn-induced neurotoxicity. REST's molecular target for its protection is unclear, but REST attenuated Mn-induced mitochondrial dysregulation, indicating that it is a primary intracellular target for both Mn and REST. These novel findings suggest that dopaminergic REST in the nigrostriatal pathway is critical in protecting against Mn toxicity, underscoring REST as a potential therapeutic target for treating manganism.

Hierarchically embedded scales of movement shape the social networks of vampire bats.

Social structure can emerge from hierarchically embedded scales of movement, where movement at one scale is constrained within a larger scale (e.g. among branches, trees, forests). In most studies of animal social networks, some scales of movement are not observed, and the relative importance of the observed scales of movement is unclear. Here, we asked: how does individual variation in movement, at multiple nested spatial scales, influence each individual's social connectedness? Using existing data from common vampire bats (Desmodus rotundus), we created an agent-based model of how three nested scales of movement-among roosts, clusters and grooming partners-each influence a bat's grooming network centrality. In each of 10 simulations, virtual bats lacking social and spatial preferences moved at each scale at empirically derived rates that were either fixed or individually variable and either independent or correlated across scales. We found that numbers of partners groomed per bat were driven more by within-roost movements than by roost switching, highlighting that co-roosting networks do not fully capture bat social structure. Simulations revealed how individual variation in movement at nested spatial scales can cause false discovery and misidentification of preferred social relationships. Our model provides several insights into how nonsocial factors shape social networks.

Shaping mitochondria through fed-fast and circadian cycles.

Energy and metabolic homeostasis at the level of the whole body are dictated by the balance between nutrient intake/utilization, bioenergetic potential, and energy expenditure, which are tightly coupled with fed/fast cycles and circadian oscillation. Emerging literature has highlighted the importance of each of these mechanisms that are essential to maintain physiological homeostasis. Lifestyle changes predominantly associated with altered fed-fast and circadian cycles are well established to affect systemic metabolism and energetics, and hence contribute to pathophysiological states. Therefore, it is not surprising that mitochondria have emerged as being pivotal in maintaining physiological homeostasis through daily oscillations/fluctuations in nutrient inputs and light-dark/sleep-wake cycles. Moreover, given the inherent association between mitochondrial dynamics/morphology and functions, it is important to understand the phenomenological and mechanistic underpinnings of fed-fast and circadian cycles dependent remodeling of mitochondria. In this regard, we have summarized the current status of the field in addition to providing a perspective vis-a-vis the complexity of cell-autonomous and non-cell-autonomous signals that dictate mitochondrial dynamics. We also highlight the lacunae besides speculating on prospective efforts that will possibly redefine our insights into the diurnal orchestration of fission/fusion events, which are ultimately coupled to the mitochondrial output.

Sex differences in early experience and the development of aggression in wild chimpanzees.

Sex differences in physical aggression occur across human cultures and are thought to be influenced by active sex role reinforcement. However, sex differences in aggression also exist in our close evolutionary relatives, chimpanzees, who do not engage in active teaching, but do exhibit long juvenile periods and complex social systems that allow differential experience to shape behavior. Here we ask whether early life exposure to aggression is sexually dimorphic in wild chimpanzees and, if so, whether other aspects of early sociality contribute to this difference. Using 13 y of all-occurrence aggression data collected from the Kanyawara community of chimpanzees (2005 to 2017), we determined that young male chimpanzees were victims of aggression more often than females by between 4 and 5 (i.e., early in juvenility). Combining long-term aggression data with data from a targeted study of social development (2015 to 2017), we found that two potential risk factors for aggression-time spent near adult males and time spent away from mothers-did not differ between young males and females. Instead, the major risk factor for receiving aggression was the amount of aggression that young chimpanzees displayed, which was higher for males than females throughout the juvenile period. In multivariate models, sex did not mediate this relationship, suggesting that other chimpanzees did not target young males specifically, but instead responded to individual behavior that differed by sex. Thus, social experience differed by sex even in the absence of explicit gender socialization, but experiential differences were shaped by early-emerging sex differences in behavior.

Nicotine affects mitochondrial structure and function in human airway smooth muscle cells.

Exposure to cigarette smoke and e-cigarettes, with nicotine as the active constituent, contributes to increased health risks associated with asthma. Nicotine exerts its functional activity via nicotinic acetylcholine receptors (nAChRs), and the alpha7 subtype (α7nAChR) has recently been shown to adversely affect airway dynamics. The mechanisms of α7nAChR action in airways, particularly in the context of airway smooth muscle (ASM), a key cell type in asthma, are still under investigation. Mitochondria have garnered increasing interest for their role in regulating airway tone and adaptations to cellular stress. Here mitochondrial dynamics such as fusion versus fission, and mitochondrial Ca2+ ([Ca2+]m), play an important role in mitochondrial homeostasis. There is currently no information on effects and mechanisms by which nicotine regulates mitochondrial structure and function in ASM in the context of asthma. We hypothesized that nicotine disrupts mitochondrial morphology, fission-fusion balance, and [Ca2+]m regulation, with altered mitochondrial respiration and bioenergetics in the context of asthmatic ASM. Using human ASM (hASM) cells from nonasthmatics, asthmatics, and smokers, we examined the effects of nicotine on mitochondrial dynamics and [Ca2+]m. Fluorescence [Ca2+]m imaging of hASM cells with rhod-2 showed robust responses to 10 µM nicotine, particularly in asthmatics and smokers. In both asthmatics and smokers, nicotine increased the expression of fission proteins while decreasing fusion proteins. Seahorse analysis showed blunted oxidative phosphorylation parameters in response to nicotine in these groups. α7nAChR siRNA blunted nicotine effects, rescuing [Ca2+]m, changes in mitochondrial structural proteins, and mitochondrial dysfunction. These data highlight mitochondria as a target of nicotine effects on ASM, where mitochondrial disruption and impaired buffering could permit downstream effects of nicotine in the context of asthma.NEW & NOTEWORTHY Asthma is a major healthcare burden, which is further exacerbated by smoking. Recognizing the smoking risk of asthma, understanding the effects of nicotine on asthmatic airways becomes critical. Surprisingly, the mechanisms of nicotine action, even in normal and especially asthmatic airways, are understudied. Accordingly, the goal of this research is to investigate how nicotine influences asthmatic airways in terms of mitochondrial structure and function, via the a7nAChR.

Innovation across 13 ungulate species: problem solvers are less integrated in the social group and less neophobic.

Innovation is the ability to solve new problems or find novel solutions to familiar problems, and it is known to provide animals with crucial fitness benefits. Although this ability has been extensively studied in some taxa, the factors that predict innovation within and across species are still largely unclear. In this study, we used a novel foraging task to test 111 individuals belonging to 13 ungulate species-a still understudied taxon. To solve the task, individuals had to open transparent and opaque cups with food rewards, by removing their cover. We assessed whether individual factors (neophobia, social integration, sex, age, rank) and socio-ecological factors (dietary breadth, fission-fusion dynamics, domestication, group size) predicted participation and performance in the task. Using a phylogenetic approach, we showed that success was higher for less neophobic and socially less integrated individuals. Moreover, less neophobic individuals, individuals of domesticated species and having higher fission-fusion dynamics were more likely to participate in the task. These results are in line with recent literature suggesting a central role of sociality and personality traits to successfully deal with novel challenges, and confirm ungulates as a promising taxon to test evolutionary theories with a comparative approach.

FGF19 increases mitochondrial biogenesis and fusion in chondrocytes via the AMPKα-p38/MAPK pathway.

Fibroblast growth factor 19 (FGF19) is recognized to play an essential role in cartilage development and physiology, and has emerged as a potential therapeutic target for skeletal metabolic diseases. However, FGF19-mediated cellular behavior in chondrocytes remains a big challenge. In the current study, we aimed to investigate the role of FGF19 on chondrocytes by characterizing mitochondrial biogenesis and fission-fusion dynamic equilibrium and exploring the underlying mechanism. We first found that FGF19 enhanced mitochondrial biogenesis in chondrocytes with the help of ß Klotho (KLB), a vital accessory protein for assisting the binding of FGF19 to its receptor, and the enhanced biogenesis accompanied with a fusion of mitochondria, reflecting in the elongation of individual mitochondria and the up-regulation of mitochondrial fusion proteins. We then revealed that FGF19-mediated mitochondrial biogenesis and fusion required the binding of FGF19 to the membrane receptor, FGFR4, and the activation of AMP-activated protein kinase alpha (AMPKα)/peroxisome proliferator-activated receptor-gamma coactivator 1 alpha (PGC-1α)/sirtuin 1 (SIRT1) axis. Finally, we demonstrated that FGF19-mediated mitochondrial biogenesis and fusion was mainly dependent on the activation of p-p38 signaling. Inhibition of p38 signaling largely reduced the high expression of AMPKα/PGC-1α/SIRT1 axis, decreased the up-regulation of mitochondrial fusion proteins and impaired the enhancement of mitochondrial network morphology in chondrocytes induced by FGF19. Taking together, our results indicate that FGF19 could increase mitochondrial biogenesis and fusion via AMPKα-p38/MAPK signaling, which enlarge the understanding of FGF19 on chondrocyte metabolism. Video Abstract.

Vigilance has mainly a social function in a wild group of spider monkeys (Ateles geoffroyi).

Vigilance is a widespread behavior that allows individuals to socially acquire information and/or effectively detect potential risks posed by predators and conspecifics. In this study, we aimed to investigate how social factors (i.e., subgroup size, number of males and immatures in the subgroup, presence of fission and fusion events, subgroup activity), individual characteristics (i.e., sex, presence of dependent offspring) and possible vulnerability to predation (i.e., being in smaller subgroups or lower in the canopy) explain variation in vigilance behavior in a wild group of spider monkeys (Ateles geoffroyi). We collected vigilance data during focal samples of all adults, subadults and juveniles of the group (N = 38), and ran generalized linear mixed models with a Bayesian approach. We found that the proportion of time both sexes spent in vigilance increased with subgroup size and during fusion events. Individuals also spent more time in vigilance when the subgroup was resting or socializing compared to other activities. Moreover, the proportion of time spent in vigilance increased in subgroups with more immatures. An alternative model with similar fit suggested that the proportion of time spent in vigilance increased in females when subgroups included more adult and subadult males. Overall, these results suggest that our study group mainly directed vigilance toward conspecifics (i.e., social vigilance), probably as a result of the relatively low predation pressure experienced, and contribute to the understanding of the multiple social factors affecting vigilance in group-living primates.

Saponins from Panax japonicus improve neuronal mitochondrial injury of aging rats.

CONTEXT: Panax japonicus is the dried rhizome of Panax japonicus C.A. Mey. (Araliaceae). Saponins from Panax japonicus (SPJ) exhibit anti-oxidative and anti-aging effects. OBJECTIVE: We evaluated the neuroprotective effects of SPJ on aging rats. MATERIALS AND METHODS: Sprague-Dawley rats (18-months-old) were randomly divided into aging and SPJ groups (n = 8). Five-month-old rats were taken as the adult control (n = 8). The rats were fed a normal chow diet or the SPJ-containing diet (10 or 30 mg/kg) for 4 months. An in vitro model was established by d-galactose (d-Gal) in the SH-SY5Y cell line and pretreated with SPJ (25 and 50 µg/mL). The neuroprotection of SPJ was evaluated via Nissl staining, flow cytometry, transmission electron microscopy and Western blotting in vivo and in vitro. RESULTS: SPJ improved the neuronal degeneration and mitochondrial morphology that are associated with aging. Meanwhile, SPJ up-regulated the protein levels of mitofusin 2 (Mfn2) and optic atrophy 1 (Opa1) and down-regulated the protein level of dynamin-like protein 1 (Drp1) in the hippocampus of aging rats (p < 0.05 or p < 0.01 vs. 22 M). The in vitro studies also demonstrated that SPJ attenuated d-Gal-induced cell senescence concomitant with the improvement in mitochondrial function; SPJ, also up-regulated the Mfn2 and Opa1 protein levels, whereas the Drp1 protein level (p < 0.05 or p < 0.01 vs. d-Gal group) was down-regulated. DISCUSSION AND CONCLUSIONS: Further research on the elderly population will contribute to the development and utilization of SPJ for the treatment of neurodegenerative disorders.

Should I stay or should I go? How activity synchronization affects fission decisions.

Group-living animals need to deal with conflicting interests to maintain cohesion. When the costs of doing so outweigh the benefits, the group may (temporarily) split into two or more subgroups. Conflicting interests can concern what activity to pursue or the direction of travel. Temporary group separation is a common feature in species with a high degree of fission-fusion dynamics. We investigated the role activity synchronization played in fission decisions in a spider monkey group living in the Otoch Ma'ax Yetel Kooh Nature Reserve, Yucatan, Mexico. For 21 months, we recorded every fission event occurring in the followed subgroup, as well as the subgroup activity. We classified the activity as 'synchronized' when at least 75% of subgroup members performed the same activity (resting, foraging, socializing or travelling); otherwise, we classified it as 'non-synchronized'. We found that fission events occurred more often when the activity was non-synchronized. In addition, when the activity was synchronized, fission events occurred more often when spider monkeys were travelling than when they were engaged in other subgroup activities. Our findings highlight the role of conflicting interests over the activity to pursue and travel direction in fission decisions.

Greetings among female chimpanzees in Mahale, Tanzania.

Greeting behaviors have been reported in several primate species, although their forms and context may vary across species. Chimpanzees (Pan troglodytes) greet each other in various ways when they meet; however, many recent studies of greetings in chimpanzees have mostly focused on pant grunt vocalizations, which are often viewed as equivalent to submissive signals. As most greetings in chimpanzees are directed toward adult males, either from other males or females, relatively few studies have focused on female-female greetings. Thus, the primary aim of this study was to describe the greetings (not limited to pant grunts) between chimpanzee females in the Mahale Mountains National Park based on long-term observational data. I observed 405 female-female greeting events (10.9 instances per 100 observation hours [obsn. h]) between 1994 and 2018, of which 242 were pant grunts (6.5 instances per 100 obsn. h); 42.3% of greetings were nonaudible, such as tactile or gestural greetings. Most pant grunts were directed toward older females; females under 20 years of age were generally responsible for this trend, as they were the most frequent greeters among females and tended to perform pant grunts toward older females. Nonetheless, among females 20 years of age or older, pant grunts from an older to a younger female were not rare (37%). Compared to previous studies in Mahale, pant grunts between females were an order of magnitude less than those directed toward males. There may also be a large difference in the frequencies of female-female pant grunts across study sites, which may be attributed to differences in female gregariousness.

Spatio-temporal variation in the wintering associations of an alpine bird.

Many animals make behavioural changes to cope with winter conditions, being gregariousness a common strategy. Several factors have been invoked to explain why gregariousness may evolve during winter, with individuals coming together and separating as they trade off the different costs and benefits of living in groups. These trade-offs may, however, change over space and time as a response to varying environmental conditions. Despite its importance, little is known about the factors triggering gregarious behaviour during winter and its change in response to variation in weather conditions is poorly documented. Here, we aimed at quantifying large-scale patterns in wintering associations over 23 years of the white-winged snowfinch Montifringilla nivalis nivalis. We found that individuals gather in larger groups at sites with harsh wintering conditions. Individuals at colder sites reunite later and separate earlier in the season than at warmer sites. However, the magnitude and phenology of wintering associations are ruled by changes in weather conditions. When the temperature increased or the levels of precipitation decreased, group size substantially decreased, and individuals stayed united in groups for a shorter time. These results shed light on factors driving gregariousness and points to shifting winter climate as an important factor influencing this behaviour.

Sociability increases survival of adult female giraffes.

Studies increasingly show that social connectedness plays a key role in determining survival, in addition to natural and anthropogenic environmental factors. Few studies, however, integrated social, non-social and demographic data to elucidate what components of an animal's socio-ecological environment are most important to their survival. Female giraffes (Giraffa camelopardalis) form structured societies with highly dynamic group membership but stable long-term associations. We examined the relative contributions of sociability (relationship strength, gregariousness and betweenness), together with those of the natural (food sources and vegetation types) and anthropogenic environment (distance from human settlements), to adult female giraffe survival. We tested predictions about the influence of sociability and natural and human factors at two social levels: the individual and the social community. Survival was primarily driven by individual- rather than community-level social factors. Gregariousness (the number of other females each individual was observed with on average) was most important in explaining variation in female adult survival, more than other social traits and any natural or anthropogenic environmental factors. For adult female giraffes, grouping with more other females, even as group membership frequently changes, is correlated with better survival, and this sociability appears to be more important than several attributes of their non-social environment.

Research Highlight: Social dispersal in giraffes.

Research Highlight: Bond, M. L., Lee, D. E., Ozgul, A., Farine, D. R., & König, B. (2021). Leaving by staying: Social dispersal in giraffes. Journal of Animal Ecology, https://doi.org/10.1111/1365-2656.13582. Dispersal is a key ecological and evolutionary process, which shows marked variability between and within species. The social and kinship structure of species fundamentally affects the patterns and types of dispersal, but information on how animals with fission-fusion group dynamics disperse is missing. Bond et al. provide novel data on natal dispersal of giraffe calves in relation to their dynamic multilayered social system, showing that individuals from both sexes can disperse socially, by switching association with different social groups, without leaving their natal area. The results highlight that traditional spatial-only measures of dispersal, such as dispersal distance, may be inadequate for social species with overlapping social units.

Insights into the functional aspects of poly(ADP-ribose) polymerase-1 (PARP-1) in mitochondrial homeostasis in Dictyostelium discoideum.

BACKGROUND INFORMATION: Poly(ADP-ribose) Polymerase-1 (PARP-1) is predominantly a nuclear protein and involved in various cellular processes like DNA repair, cell death, development, chromatin modulation etc. PARP-1 utilizes NAD+ and adds negatively charged PAR moieties on the target proteins. Over-activation of PARP-1 has been shown to cause energy crisis mediated cell death in which mitochondrial homeostasis is also affected. Moreover, the presence of mitochondrial NAD+ pools highlights the role of PARP-1 in mitochondria. The aim of present study is to understand the physiological role of PARP-1 in regulating mitochondrial functioning by varying the levels of PARP-1 in Dictyostelium discoideum. Intra-mitochondrial PARylation was analyzed by indirect immunofluorescence. Further, the effect of altered levels of PARP-1 i.e. overexpression, downregulation, knockout and its chemical inhibition was studied on mitochondrial respiration, reactive oxygen species (ROS) levels, ATP production, mitochondrial fission-fusion, mitochondrial morphology and mitochondrial DNA (mtDNA) content of D. discoideum. RESULTS: Our results show intra-mitochondrial PARylation under oxidative stress. Altered levels of PARP-1 caused impairment in the mitochondrial respiratory capacity, leading to elevated ROS levels and reduced ATP production. Moreover, PARP-1 affects the mitochondrial morphology and mtDNA content, alters the mitochondrial fission-fusion processes in lieu of preventing cell death under physiological conditions. CONCLUSION: The current study highlights the physiological role of PARP-1 in mitochondrial respiration, its morphology, fission-fusion processes and mtDNA maintenance in D. discoideum. SIGNIFICANCE: This study would provide new clues on the PARP-1's crucial role in mitochondrial homeostasis, exploring the therapeutic potential of PARP-1 in various mitochondrial diseases.

Home range, sleeping site use, and band fissioning in hamadryas baboons: Improved estimates using GPS collars.

Variation in spatial and temporal distribution of resources drives animal movement patterns. Links between ecology and behavior are particularly salient for the multilevel society of hamadryas baboons, in which social units cleave and coalesce over time in response to ecological factors. Here, we used data from GPS collars to estimate home range size and assess temporal patterns of sleeping site use in a band of hamadryas baboons in Awash National Park, Ethiopia. We used GPS data derived from 2 to 3 collared baboons over three 8-12-month collaring intervals to estimate annual and monthly home ranges using kernel density estimators (KDEs) and minimum convex polygons (MCPs). The 95% KDE home range was 64.11 km2 for Collaring Interval I (July 2015-March 2016), 85.52 km2 for Collaring Interval II (October 2016-October 2017), 76.43 km2 for Collaring Interval III (July 2018-May 2019), and 75.25 km2 across all three collaring intervals. MCP home ranges were 103.46 km2 for Collaring Interval I, 97.90 km2 for Collaring Interval II, 105.22 km2 for Collaring Interval III, and 129.33 km2 overall. Ninety-five percent KDE home range sizes did not differ across months, nor correlate with temperature or precipitation, but monthly MCP home ranges increased with monthly precipitation. Our data also revealed a southward home range shift over time and seven previously unknown sleeping sites, three of which were used more often during the wet season. Band cohesion was highest during dry months and lowest during wet months, with fissioning occurring more frequently at higher temperatures. One pair of collared individuals from Collaring Interval III spent 95% of nights together, suggesting they were members of the same clan. Our results both suggest that previous studies have underestimated the home range size of hamadryas baboons and highlight the benefits of remote data collection.

Effects of fasting on collective movement and fission-fusion dynamics in both homogeneous and heterogeneous shoals of a group-living cyprinid fish species.

The present study aimed to reveal the effect of fasting (21 days) on collective movement and interaction dynamics in both homogeneous (eight members fed a commercial diet or deprived of food) and heterogeneous (four fed + four starved members) shoals of juvenile qingbo (Spinibarbus sinensis). The authors of this study measured the shoaling behaviour in both a commonly used rectangular open arena with no spatial complexity and a radial arm maze. When measured in the open arena, the starved shoals had a faster swimming speed and acceleration rate and a longer interindividual distance than the fed shoals, possibly because of the elevated foraging motivation. Nonetheless, the values of the heterogeneous groups were similar to those of the fed groups. Furthermore, in contrast to the fish in homogeneous shoals, the starved fish in heterogeneous shoals showed a slower acceleration rate and speed than fed members in heterogeneous shoals. These results, combined with the relationships of variables at the among- and within-shoal levels, suggested that starved fish limited their motion in heterogeneous shoals to maintain group cohesion but that the fed fish contributed more to maintaining shoal structure, possibly because of the higher energy expenditure required for movement changes. When monitored in a radial arm maze, starved shoals showed more fission-fusion episodes without sacrificing group cohesion, as they adaptively adjusted the frequency and duration of each majority choice. The among-shoal variation revealed that the heterogeneous groups showed less variation in the open arena but more variation in the radius maze than did the homogeneous groups. This difference might arise because dominant members have opposite effects on shoal behaviour and consensus decisions. In conclusion, the present study showed opposite effects of feeding states on collective behaviour between homogeneous and heterogeneous shoals, possibly because of the complicated interactions among members with different energy storage levels and foraging motivations. Furthermore, the heterogeneous groups showed a difference between shoal behaviour in the open area and exploration in the radial arm maze. Future studies manipulating the personality composition of starved and fed members of heterogeneous groups might yield interesting results.

Group Composition and Social Structure of Red-Shanked Doucs (Pygathrix nemaeus) at Son Tra Nature Reserve, Vietnam.

Multilevel societies, consisting of multiple one-male multi-female units, are relatively rare among primates, but are more widespread in the odd-nosed colobines than other taxa. Multilevel societies are found particularly in snub-nosed monkeys (Rhinopithecus)and have been debated in studies of proboscis monkeys (Proboscis). While it has been suggested that douc langurs (Pygathrix) may also form multilevel societies, the limited data available make the details of their social organization unclear. We aimed to establish a more comprehensive picture of the social organization of red-shanked doucs (Pygathrix nemaeus) and to address the question of whether this species forms multilevel societies, specifically collections of multiple distinct one-male units hereafter termed "bands." We collected 259 h of behavioral data at Son Tra Nature Reserve in Vietnam from February 2010 to May 2011. The mean band size was approximately 18 individuals. Bands were comprised of approximately 2.7 units, and each unit contained approximately 6.5 individuals. Units had an average sex ratio of 1.0:1.6. We observed fission and fusion behaviors which were not correlated with phenological or weather measures. Activity budget data showed that fission and fusion behaviors between units were positively correlated with activity. Both vocalizations and vigilance increased when units engaged in fission. Based on this evidence, P. nemaeus at Son Tra Nature Reserve appear to engage in daily fission-fusion activity which does not vary between seasons. Additionally, our data suggest that these primates may form multilevel societies made up of distinct units. However, future data including proximity pattern analyses are necessary for confirmation.

Sex-Segregated Range Use by Black-and-White Ruffed Lemurs (Varecia variegata) in Ranomafana National Park, Madagascar.

Ranging behavior is one important strategy by which nonhuman primates obtain access to resources critical to their biological maintenance and reproductive success. As most primates live in permanent social groups, their members must balance the benefits of group living with the costs of intragroup competition for resources. However, some taxa live in more spatiotemporally flexible social groups, whose members modify patterns of association and range use as a method to mitigate these costs. Here, we describe the range use of one such taxon, the black-and-white ruffed lemur (Varecia variegata), at an undisturbed primary rain forest site in Ranomafana National Park, Madagascar, and characterize sex differences in annual home range area, overlap, and daily distances traveled. Moreover, we characterize seasonal variability in range use and ask whether ranging behaviors can be explained by either climatic or reproductive seasonality. We found that females used significantly larger home ranges than males, though sexes shared equal and moderate levels of home range overlap. Overall, range use did not vary across seasons, although within sexes, male range use varied significantly with climate. Moreover, daily path length was best predicted by day length, female reproductive state, and sex, but was unrelated to climate variables. While the patterns of range use and spatial association presented here share some similarities with "bisexually bonded" community models described for chimpanzees, we argue that ruffed lemurs best conform to a "nuclear neighborhood" community model wherein nuclear (core) groups share the highest levels of home range overlap, and where these groups cluster spatially into adjacent "neighborhoods" within the larger, communally defended territory.