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Explaining why some species are disproportionately impacted by the extinction crisis is of critical importance for conservation biology as a science and for proactively protecting species that are likely to become threatened in the future. Using the most current data on threat status, population trends, and threat types for 446 primate species, we advance previous research on the determinants of extinction risk by including a wider array of phenotypic traits as predictors, filling gaps in these trait data using multiple imputation, and investigating the mechanisms that connect organismal traits to extinction risk. Our Bayesian phylogenetically controlled analyses reveal that insular species exhibit higher threat status, while those that are more omnivorous and live in larger groups have lower threat status. The same traits are not linked to risk when repeating our analyses with older IUCN data, which may suggest that the traits influencing species risk are changing as anthropogenic effects continue to transform natural landscapes. We also show that non-insular, larger-bodied, and arboreal species are more susceptible to key threats responsible for primate population declines. Collectively, these results provide new insights to the determinants of primate extinction and identify the mechanisms (i.e. threats) that link traits to extinction risk. [ABSTRACT FROM AUTHOR]

Parasites regularly switch into new host species, representing a disease burden and conservation risk to the hosts. The distribution of these parasites also gives insight into characteristics of ecological networks and genetic mechanisms of host-parasite interactions. Some parasites are shared across many species, whereas others tend to be restricted to hosts from a single species. Understanding the mechanisms producing this distribution of host specificity can enable more effective interventions and potentially identify genetic targets for vaccines or therapies. As ecological connections between human and local animal populations increase, the risk to human and wildlife health from novel parasites also increases. Which of these parasites will fizzle out and which have the potential to become widespread in humans? We consider the case of primate malarias, caused by Plasmodium parasites, to investigate the interacting ecological and evolutionary mechanisms that put human and nonhuman primates at risk for infection. Plasmodium host switching from nonhuman primates to humans led to ancient introductions of the most common malaria-causing agents in humans today, and new parasite switching is a growing threat, especially in Asia and South America. Based on a wild host-Plasmodium occurrence database, we highlight geographic areas of concern and potential areas to target further sampling. We also discuss methodological developments that will facilitate clinical and field-based interventions to improve human and wildlife health based on this eco-evolutionary perspective. [ABSTRACT FROM AUTHOR]

Characteristics of the sleep-site are thought to influence the quality and duration of primate sleep, yet only a handful of studies have investigated these links experimentally. Using actigraphy and infrared videography, we quantified sleep in four lemur species (Eulemur coronatus, Lemur catta, Propithecus coquereli, and Varecia rubra) under two different experimental conditions at the Duke Lemur Center (DLC) in Durham, NC, USA. Individuals from each species underwent three weeks of simultaneous testing to investigate the hypothesis that comfort level of the sleep-site influences sleep. We obtained baseline data on normal sleep, and then, in a pair-wise study design, we compared the daily sleep times, inter-daily activity stability, and intra-daily activity variability of individuals in simultaneous experiments of sleep-site enrichment and sleep-site impoverishment. Over 164 24-hour periods from 8 individuals (2 of each species), we found evidence that enriched sleep-sites increased daily sleep times of lemurs, with an average increase of thirty-two minutes. The effect of sleep-site impoverishment was small and not statistically significant. Though our experimental manipulations altered inter-daily stability and intra-daily variability in activity patterns relative to baseline, the changes did not differ significantly between enriched and impoverished conditions. We conclude that properties of a sleep-site enhancing softness or insulation, more than the factors of surface area or stability, influence lemur sleep, with implications regarding the importance of nest building in primate evolution and the welfare and management of captive lemurs. [ABSTRACT FROM AUTHOR]

Anthropogenic disturbance impacts the phylogenetic composition and diversity of ecological communities. While changes in diversity are known to dramatically change species interactions and alter disease dynamics, the effects of phylogenetic changes in host and vector communities on disease have been relatively poorly studied. Using a theoretical model, we investigated how phylogeny and extinction influence network structural characteristics relevant to disease transmission in disturbed environments. We modelled a multi-host, multi-vector community as a bipartite ecological network, where nodes represent host and vector species and edges represent connections among them through vector feeding, and we simulated vector preferences and threat status on host and parasite phylogenies. We then simulated loss of hosts, including phylogenetically clustered losses, to investigate how extinction influences network structure. We compared effects of phylogeny and extinction to those of host specificity, which we predicted to strongly increase network modularity and reduce disease prevalence. The simulations revealed that extinction often increased modularity, with higher modularity as species loss increased, although not as much as increasing host specificity did. These results suggest that extinction itself, all else being equal, may reduce disease prevalence in disturbed communities. However, in real communities, systematic patterns in species loss (e.g. favoring high competence species) or changes in abundance may counteract these effects. Unexpectedly, we found that effects of phylogenetic signal in host and vector traits were relatively weak, and only important when phylogenetic signal of host and vector traits were similar, or when these traits both varied. [ABSTRACT FROM AUTHOR]

Rates of urbanization are increasing globally, with consequences for the dynamics of parasites and their wildlife hosts. A small subset of mammal species have the dietary and behavioural flexibility to survive in urban settings. The changes that characterize urban ecology—including landscape transformation, modified diets and shifts in community composition—can either increase or decrease susceptibility and exposure to parasites. We used a meta-analytic approach to systematically assess differences in endoparasitism between mammals in urban and non-urban habitats. Parasite prevalence estimates in matched urban and non-urban mammal populations from 33 species were compiled from 46 published studies, and an overall effect of urban habitation on parasitism was derived after controlling for study and parasite genus. Parasite life cycle type and host order were investigated as moderators of the effect sizes. We found that parasites with complex life cycles were less prevalent in urban carnivore and primate populations than in non-urban populations. However, we found no difference in urban and non-urban prevalence for parasites in rodent and marsupial hosts, or differences in prevalence for parasites with simple life cycles in any host taxa. Our findings therefore suggest the disruption of some parasite transmission cycles in the urban ecological community. [ABSTRACT FROM AUTHOR]

Behaviour underpins interactions among conspecifics and between species, with consequences for the transmission of disease-causing parasites. Because many parasites lead to declines in population size and increased risk of extinction for threatened species, understanding the link between host behaviour and disease transmission is particularly important for conservation management. Here, we consider the intersection of behaviour, ecology and parasite transmission, broadly encompassing micro- and macroparasites. We focus on behaviours that have direct impacts on transmission, as well as the behaviours that result from infection. Given the important role of parasites in host survival and reproduction, the effects of behaviour on parasitism can scale up to population-level processes, thus affecting species conservation. Understanding how conservation and infectious disease control strategies actually affect transmission potential can therefore often only be understood through a behavioural lens. We highlight how behavioural perspectives of disease ecology apply to conservation by reviewing the different ways that behavioural ecology influences parasite transmission and conservation goals. This article is part of the theme issue 'Linking behaviour to dynamics of populations and communities: application of novel approaches in behavioural ecology to conservation'. [ABSTRACT FROM AUTHOR]

Abstract: Objectives: Primates vary in their sleep durations and, remarkably, humans sleep the least per 24‐hr period of the 30 primates that have been studied. Using phylogenetic methods that quantitatively situate human phenotypes within a broader primate comparative context, we investigated the evolution of human sleep architecture, focusing on: total sleep duration, rapid eye movement (REM) sleep duration, non‐rapid eye movement (NREM) sleep duration, and proportion of sleep in REM. Materials and Methods: We used two different Bayesian methods: phylogenetic prediction based on phylogenetic generalized least squares and a multistate Onrstein‐Uhlenbeck (OU) evolutionary model of random drift and stabilizing selection. Results: Phylogenetic prediction confirmed that humans sleep less than predicted for a primate of our body mass, predation risk, brain size, foraging needs, sexual selection, and diet. These analyses further revealed that humans pack an unexpectedly higher proportion of REM sleep within a shorter overall sleep duration, and do so by reducing NREM sleep (rather than increasing REM). The OU model generally confirmed these findings, with shifts along the human lineage inferred for TST, NREM, and proportion of REM, but not for REM. Discussion: We propose that the risks and opportunity costs of sleep are responsible for shorter sleep durations in humans, with risks arising from terrestrial sleep involving threats from predators and conspecifics, and opportunity costs because time spent sleeping could be used for learning, creating material objects, and socializing. [ABSTRACT FROM AUTHOR]

Here we coin the term synanthrome to describe all of the species we interact with. We propose that the time is now here for The Global Synanthrome Project to describe all of our interacting species and how they have changed through time and across space. This effort must involve natural history, ecology, and evolutionary biology in addition to genomics studies that are already underway. [ABSTRACT FROM AUTHOR]

Placental invasiveness—the number of maternal tissue layers separating fetal tissues from maternal blood—is variable across mammalian species. Although this diversity is likely to be functionally important, variation in placental invasiveness remains unexplained. Here we test the hypothesis that increased risk of transplacental transmission of pathogens from the mother to the fetus promotes the evolution of non-invasive placentation, the most likely derived condition in eutherian mammals. Specifically, we predict that non-invasive placentation is associated with increased microparasite species richness relative to more invasive placental types, based on the assumption that higher numbers of microparasites in a population reflects greater risk of transplacental transmission to fetuses. As predicted, higher bacteria species richness is associated with non-invasive placentation. Protozoa species richness, however, shows the opposite pattern. Because invasive placentae facilitate the transfer of maternal antibodies to the fetus, we propose that the ancestral condition of invasive placentation is retained under selection for protection of newborns from higher risk of postnatal protozoan infection. Hence, our findings suggest that a tradeoff exists between protection against bacterial infection prenatally and protozoan infection postnatally. Future studies are needed to investigate how maternal prevalence of infection and the relative pre- versus postnatal risk of fetal infection by different microparasite groups vary among mammalian hosts in relation to placental invasiveness. [ABSTRACT FROM AUTHOR]

Increased risk of infectious disease is assumed to be a major cost of group living, yet empirical evidence for this effect is mixed. We studied whether larger social groups are more subdivided structurally. If so, the social subdivisions that form in larger groups may act as barriers to the spread of infection, weakening the association between group size and infectious disease. To investigate this 'social bottleneck' hypothesis, we examined the association between group size and four network structure metrics in 43 vertebrate and invertebrate species. We focused on metrics involving modularity, clustering, distance and centralization. In a meta-analysis of intraspecific variation in social networks, modularity showed positive associations with network size, with a weaker but still positive effect in cross-species analyses. Network distance also showed a positive association with group size when using intraspecific variation. We then used a theoretical model to explore the effects of subgrouping relative to other effects that influence disease spread in socially structured populations. Outbreaks reached higher prevalence when groups were larger, but subgrouping reduced prevalence. Subgrouping also acted as a 'brake' on disease spread between groups. We suggest research directions to understand the conditions under which larger groups become more subdivided, and to devise new metrics that account for subgrouping when investigating the links between sociality and infectious disease risk. [ABSTRACT FROM AUTHOR]

This theme issue has highlighted the links between sociality, health and fitness in a broad range of organisms, and with approaches that include field and captive studies of animals, comparative and meta-analyses, theoretical modelling and clinical and psychological studies of humans. In this concluding chapter, we synthesize the results of these diverse studies into some of the key concepts discussed in this issue, focusing on risks of infectious disease through social contact, the effects of competition in groups on susceptibility to disease, and the integration of sociality into research on life-history trade-offs. Interestingly, the studies in this issue both support pre-existing hypotheses, and in other ways challenge those hypotheses. We focus on unexpected results, including a lack of association between ectoparasites and fitness and weak results from a meta-analysis of the links between dominance rank and immune function, and place these results in a broader context. We also review relevant topics thatwere not covered fully in this theme issue, including self-medication and sickness behaviours, society-level defences against infectious disease, sexual selection, evolutionary medicine, implications for conservation biology and selective pressures on parasite traits. We conclude by identifying general open questions to stimulate and guide future research on the links between sociality, health and fitness. [ABSTRACT FROM AUTHOR]

For traits showing correlated evolution, one trait may evolve more slowly than the other, producing evolutionary lag. The species-pairs evolutionary lag test (SPELT) uses an independent contrasts based approach to detect evolutionary lag on a phylogeny. We investigated the statistical performance of SPELT in relation to degree of lag, sample size (species pairs), and strength of association between traits. We simulated trait evolution under two models: one in which trait X changes during speciation and the lagging trait Y catches up as a function of time since speciation; and another in which trait X evolves in a random walk and the lagging trait Y is a function of X at a previous time period. Type I error rates under 'no lag' were close to the expected level of 5%, indicating that the method is not prone to false-positives. Simulation results suggest that reasonable statistical power (80%) is reached with around 140 species pairs, although the degree of lag and trait associations had additional influences on power. We applied the method to two datasets and discuss how estimation of a branch length scaling parameter (κ) can be used with SPELT to detect lag. [ABSTRACT FROM AUTHOR]

Ecological associations between hosts and parasites are influenced by host exposure and susceptibility to parasites, and by parasite traits, such as transmission mode. Advances in network analysis allow us to answer questions about the causes and consequences of traits in ecological networks in ways that could not be addressed in the past.We used a network‐based framework (exponential random graph models or ERGMs) to investigate the biogeographic, phylogenetic and ecological characteristics of hosts and parasites that affect the probability of interactions among nonhuman primates and their parasites. Parasites included arthropods, bacteria, fungi, protozoa, viruses and helminths.We investigated existing hypotheses, along with new predictors and an expanded host–parasite database that included 213 primate nodes, 763 parasite nodes and 2319 edges among them. Analyses also investigated phylogenetic relatedness, sampling effort and spatial overlap among hosts.In addition to supporting some previous findings, our ERGM approach demonstrated that more threatened hosts had fewer parasites, and notably, that this effect was independent of hosts also having a smaller geographic range. Despite having fewer parasites, threatened host species shared more parasites with other hosts, consistent with loss of specialist parasites and threat arising from generalist parasites that can be maintained in other, non‐threatened hosts. Viruses, protozoa and helminths had broader host ranges than bacteria, or fungi, and parasites that infect non‐primates had a higher probability of infecting more primate species.The value of the ERGM approach for investigating the processes structing host–parasite networks provided a more complete view on the biogeographic, phylogenetic and ecological traits that influence parasite species richness and parasite sharing among hosts. The results supported some previous analyses and revealed new associations that warrant future research, thus revealing how hosts and parasites interact to form ecological networks. [ABSTRACT FROM AUTHOR]

Most wild animals face concurrent challenges by multiple infectious organisms, and immunological responses triggered by some parasites may increase susceptibility to other infectious agents. Immune-mediated interactions among parasites have been investigated among individuals in a population, but less is known about broader comparative patterns. We investigated the "macro-micro facilitation hypothesis" that higher helminth prevalence in a host species provides greater opportunities for intracellular parasites to invade, resulting in higher richness of intracellular microparasites. We obtained data on average helminth prevalence for 70 primate hosts, along with data on richness of intra- and extracellular infectious organisms. Using Bayesian phylogenetic methods, we found that primate species with higher overall helminth prevalence harbored more species of intracellular microparasites, while the positive association between helminth prevalence and extracellular microparasite species richness was weaker. The relationships held after controlling for potentially confounding variables, but associations were not found in focused tests of prevalence for six genera of well-studied helminths. The magnitude of support and effect sizes for overall helminth prevalence on intracellular microparasite species richness was similar to support for other well recognized ecological and life-history drivers of parasite species richness. Our findings therefore suggest that intrahost parasite interactions are as important as some ecological characteristics of hosts in accounting for parasite richness across host species. [ABSTRACT FROM AUTHOR]

Highlights: [•] We modeled the spread of a fecally transmitted parasite in a spatially structured population. [•] During periods of resource scarcity, groups congregated around shared resources. [•] Longer durations of resource scarcity had strong effects on infection dynamics. [•] Parasite prevalence and population decline increased with the duration of scarcity. [•] Prevalence often declined after resource scarcity and the return to the normal range, due to parasite mortality. [Copyright &y& Elsevier]

Most emerging infectious diseases (EIDs) in humans have arisen from animals. Identifying high-risk hosts is therefore vital for the control and surveillance of these diseases. Viewing hosts as connected through the parasites they share, we use network tools to investigate predictors of parasitism and sources of future EIDs. We generated host-parasite networks that link hosts when they share a parasite, using nonhuman primates as a model system because-owing to their phylogenetic proximity and ecological overlap with humans-they are an important source of EIDs to humans. We then tested whether centrality in the network of host species-a measurement of the importance of a given node (i.e., host species) in the network-is associated with that host serving as a potential EID source. We found that centrality covaries with key predictors of parasitism, such as population density and geographic range size. Importantly, we also found that primate species having higher values of centrality in the primate-parasite network harbored more parasites identified as EIDs in humans and had parasite communities more similar to those found in humans. These relationships were robust to the use of different centrality metrics and to multiple ways of controlling for variation in how well each species has been studied (i.e., sampling effort). Centrality may therefore estimate the role of a host as a source of EIDs to humans in other multispecific host-parasite networks. [ABSTRACT FROM AUTHOR]

The authors comment on a global health crisis involving the spread of drug-resistant strains of a wide range of microorganisms, affecting people of all ages. They say that the inappropriate prescription of antimicrobial drugs, frequent use of antibiotics in agriculture, and failure by patients to complete courses of prescribed antibiotics are all responsible for the evolution of resistance.

Parasitism is widely viewed as the primary cost of sociality and a constraint on group size, yet studies report varied associations between group size and parasitism. Using the largest database of its kind, we performed a meta-analysis of 69 studies of the relationship between group size and parasite risk, as measured by parasitism and immune defenses. We predicted a positive correlation between group size and parasitism with organisms that show contagious and environmental transmission and a negative correlation for searching parasites, parasitoids, and possibly vector-borne parasites (on the basis of the encounter-dilution effect). Overall, we found a positive effect of group size (r p 0.187) that varied in magnitude across transmission modes and measures of parasite risk, with only weak indications of publication bias. Among different groups of hosts, we found a stronger relationship between group size and parasite risk in birds than in mammals, which may be driven by ecological and social factors. A metaregression showed that effect sizes increased with maximum group size. Phylogenetic meta-analyses revealed no evidence for phylogenetic signal in the strength of the group size-parasitism relationship. We conclude that group size is a weak predictor of parasite risk except in species that live in large aggregations, such as colonial birds, in which effect sizes are larger. [ABSTRACT FROM AUTHOR]

Sleep duration, quality, and rest-activity pattern—a measure for inferring circadian rhythm—are influenced by multiple factors including access to electricity. Recent findings suggest that the safety and comfort afforded by technology may improve sleep but negatively impact rest-activity stability. According to the circadian entrainment hypothesis, increased access to electric lighting should lead to weaker and less uniform circadian rhythms, measured by stability of rest-activity patterns. Here, we investigate sleep in a Maya community in Guatemala who are in a transitional stage of industrialization. We predicted that (i) sleep will be shorter and less efficient in this population than in industrial settings, and that (ii) rest-activity patterns will be weaker and less stable than in contexts with greater exposure to the natural environment and stronger and more stable than in settings more buffered by technologic infrastructure. Our results were mixed. Compared to more industrialized settings, in our study population sleep was 4.87% less efficient (78.39% vs 83.26%). We found no significant difference in sleep duration. Rest-activity patterns were more uniform and less variable than in industrial settings (interdaily stability = 0.58 vs 0.43; intradaily variability = 0.53 vs 0.60). Our results suggest that industrialization does not inherently reduce characteristics of sleep quality; instead, the safety and comfort afforded by technological development may improve sleep, and an intermediate degree of environmental exposure and technological buffering may support circadian rhythm strength and stability. [ABSTRACT FROM AUTHOR]

Infectious disease plays a major role in the lives of wild primates, and the past decade has witnessed significant strides in our understanding of primate disease ecology. In this review, I briefly describe some key findings from phylogenetic comparative approaches, focusing on analyses of parasite richness that use the Global Mammal Parasite Database. While these studies have provided new answers to fundamental questions, new questions have arisen, including questions about the underlying epidemiological mechanisms that produce the broader phylogenetic patterns. I discuss two examples in which theoretical models have given us new traction on these comparative questions. First, drawing on findings of a positive association between range use intensity and the richness of helminth parasites, we developed a spatially explicit agent-based model to investigate the underlying drivers of this pattern. From this model, we are gaining deeper understanding of how range use intensity results in greater exposure to parasites, thus producing higher prevalence in the simulated populations-and, plausibly, higher parasite richness in comparative analyses. Second, I show how a model of disease spread on social networks provides solid theoretical foundations for understanding the effects of sociality and group size on parasitism across primate species. This study further revealed that larger social groups are more subdivided, which should slow the spread of infectious diseases. This effect could offset the increased disease risk expected in larger social groups, which has yet to receive strong empirical support in our comparative analyses. In addition to these examples, I discuss the need for more meta-analyses of individual-level phenomena documented in the field, and for greater linkage between theoretical modeling and field research. Am. J. Primatol. 74:497-509, 2012. © 2012 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

Unique among animals, humans eat a diet rich in cooked and nonthermally processed food. The ancestors of modern humans who invented food processing (including cooking) gained critical advantages in survival and fitness through increased caloric intake. However, the time and manner in which food processing became biologically significant are uncertain. Here, we assess the inferred evolutionary consequences of food processing in the human lineage by applying a Bayesian phylogenetic outlier test to a comparative dataset of feeding time in humans and nonhuman primates. We find that modern humans spend an order of magnitude less time feeding than predicted by phylogeny and body mass (4.7% vs. predicted 48% of daily activity). This result suggests that a substantial evolutionary rate change in feeding time occurred along the human branch after the human-chimpanzee split. Along this same branch, Homo erectus shows a marked reduction in molar size that is followed by a gradual, although erratic, decline in H. sapiens. We show that reduction in molar size in early Homo (H. habilis and H. rudolfensis) is explicable by phylogeny and body size alone. By contrast, the change in molar size to H. erectus, H. neanderthalensis, and H. sapiens cannot be explained by the rate of craniodental and body size evolution. Together, our results indicate that the behaviorally driven adaptations of food processing (reduced feeding time and molar size) originated after the evolution of Homo but before or concurrent with the evolution of H. erectus, which was around 1.9 Mya. [ABSTRACT FROM AUTHOR]

Mammals are infected by a wide array of gastrointestinal parasites, including parasites that also infect humans and domesticated animals. Many of these parasites are acquired through contact with infectious stages present in soil, feces or vegetation, suggesting that ranging behavior will have a major impact on their spread. We developed an individual-based spatial simulation model to investigate how range use intensity, home range overlap, and defecation rate impact the spread of fecally transmitted parasites in a population composed of social groups (i.e., a socially structured population). We also investigated the effects of epidemiological parameters involving host and parasite mortality rates, transmissibility, disease- related mortality, and group size. The model was spatially explicit and involved the spillover of a gastrointestinal parasite from a reservoir population along the edge of a simulated reserve, which was designed to mimic the introduction pathogens into protected areas. Animals ranged randomly within a "core" area, with biased movement toward the range center when outside the core. We systematically varied model parameters using a Latin hypercube sampling design. Analyses of simulation output revealed a strong positive association between range use intensity and the prevalence of infection. Moreover, the effects of range use intensity were similar in magnitude to effects of group size, mortality rates, and the per-contact probability of transmission. Defecation rate covaried positively with gastrointestinal parasite prevalence. Greater home range overlap had no positive effects on prevalence, with a smaller core resulting in less range overlap yet more intensive use of the home range and higher prevalence. Collectively, our results reveal that parasites with fecal-oral transmission spread effectively in socially structured populations. Future application should focus on parameterizing the model with empirically derived ranging behavior for different species or populations and data on transmission characteristics of different infectious organisms. [ABSTRACT FROM AUTHOR]

The spatiotemporal distribution of females is thought to drive variation in mating systems, and hence plays a central role in understanding animal behavior, ecology and evolution. Previous research has focused on investigating the links between female spatiotemporal distribution and the number of males in haplorhine primates. However, important questions remain concerning the importance of spatial cohesion, the generality of the pattern across haplorhine and strepsirrhine primates, and the consistency of previous findings given phylogenetic uncertainty. To address these issues, we examined how the spatiotemporal distribution of females influences the number of males in primate groups using an expanded comparative dataset and recent advances in Bayesian phylogenetic and statistical methods. Specifically, we investigated the effect of female distributional factors (female number, spatial cohesion, estrous synchrony, breeding season duration and breeding seasonality) on the number of males in primate groups. Using Bayesian approaches to control for uncertainty in phylogeny and the model of trait evolution, we found that the number of females exerted a strong influence on the number of males in primate groups. In a multiple regression model that controlled for female number, we found support for temporal effects, particularly involving female estrous synchrony: the number of males increases when females are more synchronously receptive. Similarly, the number of males increases in species with shorter birth seasons, suggesting that greater breeding seasonality makes defense of females more difficult for male primates. When comparing primate suborders, we found only weak evidence for differences in traits between haplorhines and strepsirrhines, and including suborder in the statistical models did not affect our conclusions or give compelling evidence for different effects in haplorhines and strepsirrhines. Collectively, these results demonstrate that male monopolization is driven primarily by the number of females in groups, and secondarily by synchrony of female reproduction within groups. [ABSTRACT FROM AUTHOR]

With their striking predilection for perching on African ungulates and eating their ticks, yellow-billed ( Buphagus africanus) and red-billed oxpeckers ( B. erythrorhynchus) represent one of the few potentially mutualistic relationships among vertebrates. The nature of the oxpecker-ungulate relationship remains uncertain, however, because oxpeckers are known to consume ungulate tissues, suggesting that the relationship between oxpeckers and ungulates may also be parasitic. To examine this issue further, we obtained data on oxpecker preferences for different ungulate species, the abundance of ticks on these ungulates, and ungulate hide thickness. In support of the mutualism hypothesis, we found that both species of oxpeckers prefer ungulate hosts that harbor a higher abundance of ticks. We found no evidence that hide thickness-a measure of the potential for parasitism by oxpeckers-predicts oxpecker preferences for different ungulate species. Oxpeckers also prefer larger-bodied ungulates, possibly because larger animals have more ticks, provide a more stable platform upon which to forage, or support more oxpeckers feeding simultaneously. However, the preference for ungulates with greater tick abundance was independent of host body mass. These results support the hypothesis that the relationship between oxpeckers and ungulates is primarily mutualistic. [ABSTRACT FROM AUTHOR]

All mammals thus far studied sleep, yet important questions remain concerning the ecological factors that influence sleep patterns. Here, we developed an evolutionary individual-based model to investigate the effect of predation pressure on prey sleep. We investigated three ecological conditions, including one that assumed a dynamic interaction between predator and prey behaviour. In condition 1, we found that monophasic predators (i.e. with one sleep bout per 24h) select for monophasic prey that sleep perfectly out of phase with predators. In condition 2, predators were monophasic but the safety of prey varied as a function of their activity (sleeping versus awake). In this condition, the prey adjusted their sleeping behaviour to lower the risk of predation. Finally, in condition 3, we modelled a more dynamic interaction between predator and prey, with predator activity dependent on prey activity in the previous hour. In this scenario, the prey adjusted their behaviour relative to one another, resulting in either greater or lesser synchrony in prey as a function of predator searching behaviour. Collectively, our model demonstrates that predator behaviour can have a strong influence on prey sleep patterns, including whether prey are monophasic or polyphasic (i.e. with many sleep bouts per 24h). The model further suggests that the timing of sleep relative to predator behaviour may depend strongly on how other potential prey partition the activity period. [ABSTRACT FROM AUTHOR]

Many questions in comparative biology require that new data be collected, either to build a comparative database for the first time or to augment existing data. Given resource limitations in collecting data, the question arises as to which species should be studied to increase the size of comparative data sets. By taking hypotheses, existing data relevant to the hypotheses, and a phylogeny, we show that a method of "phylogenetic targeting" can systematically guide data collection while taking into account potentially confounding variables and competing hypotheses. Phylogenetic targeting selects potential candidates for future data collection, using a flexible scoring system based on differences in pairwise comparisons. We used simulations to assess the performance of phylogenetic targeting, as compared with the less systematic approach of randomly selecting species (as might occur when data have been collected without regard to phylogeny and variation in the traits of interest). The simulations revealed that phylogenetic targeting increased the statistical power to detect correlations and that power increased with the number of species in the tree, even when the number of species studied was held constant. We also developed a Web-based computer program called PhyloTargeting to implement the approach (http:// phylotargeting.fas.harvard.edu). [ABSTRACT FROM AUTHOR]

Experiments in captivity have provided evidence for social learning, but it remains challenging to demonstrate social learning in the wild. Recently, we developed network-based diffusion analysis (NBDA; 2009) as a new approach to inferring social learning from observational data. NBDA fits alternative models of asocial and social learning to the diffusion of a behavior through time, where the potential for social learning is related to a social network. Here, we investigate the performance of NBDA in relation to variation in group size, network heterogeneity, observer sampling errors, and duration of trait diffusion. We find that observation errors, when severe enough, can lead to increased Type I error rates in detecting social learning. However, elevated Type I error rates can be prevented by coding the observed times of trait acquisition into larger time units. Collectively, our results provide further guidance to applying NBDA and demonstrate that the method is more robust to sampling error than initially expected. Supplemental materials for this article may be downloaded from http:// lb.psychonomic-journals.orglcontent/supplemental. [ABSTRACT FROM AUTHOR]

Cultural traits spread via multiple mechanisms among individuals within social groups, including via transmission biases that occur when subordinates copy from dominants (prestige transmission), or via common cultural trait variants that are favoured over rare ones (consensus transmission). Most animal populations are subdivided into social groups where cultural learning occurs, yet theoretical studies of cultural trait transmission have tended to focus on within-group transmission dynamics. We developed an agent-based model of cultural transmission in socially structured populations in which a trait arises in one individual and either persists until a stable population equilibrium is reached, or goes extinct. With this model, we systematically varied group size, rates of dispersal among groups, mortality rates, transmission characteristics, the benefit of the cultural trait (including possibly negative benefits), and whether individuals disperse locally or randomly. We used generalized linear models to examine how changes in these parameters influence trait extinction, equilibrium prevalence and time to equilibrium. Four traits increased the probability of extinction: smaller group size, higher background mortality, lower transmission rate and more costly traits (although costly traits sometimes reached an equilibrium). Local dispersal and biased transmission mechanisms (prestige and consensus) had no significant effects on extinction probability, and similar patterns were found for equilibrium prevalence. We found that a lower dispersal rate and local dispersal slowed the time required for a trait to reach equilibrium, as did smaller groups, lower transmission rates and lower costs. Collectively, these analyses reveal that prestige and consensus transmission have weaker effects than other factors associated with demographic and social conditions. [Copyright &y& Elsevier]

Statistical inference based on stepwise model selection is applied regularly in ecological, evolutionary, and behavioral research. In addition to fundamental shortcomings with regard to finding the "best" model, stepwise procedures are known to suffer from a multiple-testing problem, yet the method is still widely used. As an illustration of this problem, we present results of a simulation study of artificial data sets of uncorrelated variables, with two to 10 predictor variables and one dependent variable. We then compared results from stepwise regression with a regression model in which all predictor variables were entered simultaneously. These analyses clearly demonstrate that significance tests based on stepwise procedures lead to greatly inflated Type I error rates (i.e., the probability of erroneously rejecting a true null hypothesis). By using a simple simulation design, our study amplifies previous warnings about using stepwise procedures, and we follow others in recommending that biologists refrain from applying these methods. [ABSTRACT FROM AUTHOR]

The article focuses on the close phylogenetic relationship between humans and primates which resulted in high potential for pathogen exchange. It features the integration of empirical data, diagnostics, and comparative approaches which offer patterns of infections in primates, and explains the role of disease and how anthropogenic effects alter zoonotic potential of pathogenic organisms. It also presents the aspect of disease researches and approaches biodiversity and disease risk in primates.

A number of infectious diseases have emerged as threats to humans and wildlife. Despite the growing importance of georeferenced data for mitigating disease risk, information on parasite threat is patchily distributed at a global scale. In this paper, we explore the utility of gap analysis techniques to investigate the global geographical distribution of parasite sampling in non-human primates. Specifically, we identify geographical areas that are undersampled for parasites in relation to primate geographical distributions, primate taxonomic sampling, primate threat status, and parasite taxonomy. Our results reveal that East Asia (particularly China), South-East Asia, and the South American Amazon are the most deficient in sampling effort with respect to all criteria. We also identify sampling gaps based on several criteria in West and Central Africa. Future research aimed at filling these gaps is needed for both human health and primate conservation purposes. [ABSTRACT FROM AUTHOR]

Aim Comparative studies have revealed strong links between ecological factors and the number of parasite species harboured by different hosts, but studies of different taxonomic host groups have produced inconsistent results. As a step towards understanding the general patterns of parasite species richness, we present results from a new comprehensive data base of over 7000 host–parasite combinations representing 146 species of carnivores (Mammalia: Carnivora) and 980 species of parasites. Methods We used both phylogenetic and non-phylogenetic comparative methods while controlling for unequal sampling effort within a multivariate framework to ascertain the main determinants of parasite species richness in carnivores. Results We found that body mass, population density, geographical range size and distance from the equator are correlated with overall parasite species richness in fissiped carnivores. When parasites are classified by transmission mode, body mass and home range area are the main determinants of the richness of parasites spread by close contact between hosts, and population density, geographical range size and distance from the equator account for the diversity of parasites that are not dependent on close contact. For generalist parasites, population density, geographical range size and latitude are the primary predictors of parasite species richness. We found no significant ecological correlates for the richness of specialist or vector-borne parasites. Main conclusions Although we found that parasite species richness increases instead of decreases with distance from the equator, other comparative patterns in carnivores support previous findings in primates, suggesting that similar ecological factors operate in both these independent evolutionary lineages. [ABSTRACT FROM AUTHOR]

1. Parasites and infectious diseases have become a major concern in conservation biology, in part because they can trigger or accelerate species or population declines. Focusing on primates as a well-studied host clade, we tested whether the species richness and prevalence of parasites differed between threatened and non-threatened host species. 2. We collated data on 386 species of parasites (including viruses, bacteria, protozoa, helminths and arthropods) reported to infect wild populations of 36 threatened and 81 non-threatened primate species. Analyses controlled for uneven sampling effort and host phylogeny. 3. Results showed that total parasite species richness was lower among threatened primates, supporting the prediction that small, isolated host populations harbour fewer parasite species. This trend was consistent across three major parasite groups found in primates (helminths, protozoa and viruses). Counter to our predictions, patterns of parasite species richness were independent of parasite transmission mode and the degree of host specificity. 4. We also examined the prevalence of selected parasite genera among primate sister-taxa that differed in their ranked threat categories, but found no significant differences in prevalence between threatened and non-threatened hosts. 5. This study is the first to demonstrate differences in parasite richness relative to host threat status. Results indicate that human activities and host characteristics that increase the extinction risk of wild animal species may lead simultaneously to the loss of parasites. Lower average parasite richness in threatened host taxa also points to the need for a better understanding of the cascading effects of host biodiversity loss for affiliated parasite species. [ABSTRACT FROM AUTHOR]

Background: Social and competitive demands often differ between the sexes in mammals. These differing demands should be expected to produce variation in the relative sizes of various brain structures. Sexual selection on males can be predicted to influence brain components handling sensory-motor skills that are important for physical competition or neural pathways involving aggression. Conversely, because female fitness is more closely linked to ecological factors and social interactions that enable better acquisition of resources, social selection on females should select for brain components important for navigating social networks. Sexual and social selection acting on one sex could produce sexual dimorphism in brain structures, which would result in larger species averages for those same brain structures. Alternatively, sex-specific selection pressures could produce correlated effects in the other sex, resulting in larger brain structures for both males and females of a species. Data are presently unavailable for the sex-specific sizes of brain structures for anthropoid primates, but under either scenario, the effects of sexual and social selection should leave a detectable signal in average sizes of brain structures for different species. Results: The degree of male intra-sexual selection was positively correlated with several structures involved in autonomic functions and sensory-motor skills, and in pathways relating to aggression and aggression control. The degree of male intra-sexual selection was not correlated with relative neocortex size, which instead was significantly positively correlated with female social group size, but negatively correlated with male group size. Conclusion: Sexual selection on males and social selection on females have exerted different effects on primate brain architecture. Species with a higher degree of male intra-sexual selection carry a neural signature of an evolutionary history centered on physical conflicts, but no traces of increased demands on sociocognitive tasks. Conversely, female sociality is indicated to have driven the evolution of socio-cognitive skills. Primate brain architecture is therefore likely to be a product of ecological and species-specific social factors as well as different sex-specific selection pressures. Our results also highlight the need for acquisition and analysis of sex-specific brain components in mammals. [ABSTRACT FROM AUTHOR]

Anthropologists and archaeologists increasingly use phylogenetic methods to test hypotheses involving cross-cultural traits, but the appropriateness of applying tree-based methods to analyze cultural traits is unclear. The authors developed a spatially explicit computer simulation model to investigate trait evolution in relation to phylogeny and geography and used the simulation to assess the sensitivity of two comparative methods (independent contrasts and partial Mantel tests) to different degrees of horizontal transmission. Simulation results show that (a) the method of independent contrasts is sensitive to even small amounts of horizontal transmission in cultural data sets, (b) Mantel tests fail to cleanly discriminate between datasets characterized by different levels of horizontal and vertical trait transmission, and (c) partial Mantel tests do not produce markedly improved statistical performance when testing for associations among traits (as compared to independent contrasts). The results highlight the need for empirical estimates of horizontal transmission and extinction rates in cross-cultural datasets. [ABSTRACT FROM AUTHOR]

Infectious disease risk is thought to increase in the tropics, but little is known about latitudinal gradients of parasite diversity. We used a comparative data set encompassing 330 parasite species reported from 119 primate hosts to examine latitudinal gradients in the diversity of micro and macroparasites per primate host species. Analyses conducted with and without controlling for host phylogeny showed that parasite species richness increased closer to the equator for protozoan parasites, but not for viruses or helminths. Relative to other major parasite groups, protozoa reported from wild primates were transmitted disproportionately by arthropod vectors. Within the protozoa, our results revealed that vector-borne parasites showed a highly significant latitudinal gradient in species richness. This higher diversity of vector-borne protozoa near the tropics could be influenced by a greater abundance or diversity of biting arthropods in the tropics, or by climatic effects on vector behaviour and parasite development. Many vector-borne diseases, such as leishmaniasis, trypanosomiasis, and malaria pose risks to both humans and wildlife, and nearly one-third of the protozoan parasites from free-living primates in our data set have been reported to infect humans. Because the geographical distribution and prevalence of many vector-borne parasites are expected to increase because of global warming, these results are important for predicting future parasite-mediated threats to biodiversity and human health. [ABSTRACT FROM AUTHOR]

Coevolutionary interactions such as those between hosts and parasites have been regarded as an underlying cause of evolutionary diversification, but evidence from natural populations is limited. Among primates and other mammalian groups, measures of host diversification rates vary widely among lineages, but comparative studies have not yet identified a reliable explanation for this variation. In this study, we used a comprehensive data set of disease-causing organisms from free-living primates to illustrate how phylogenetic comparative methods can be used to examine mammalian lineage diversity in relation to parasite species richness. Our results provide evidence that the phylogenetic diversity of primate clades is correlated positively with the number of parasite species harbored by each host and that this pattern is largely independent of other host traits that have been shown to influence diversification rates and parasite species richness in primates. We investigated two possible mechanisms that could explain this association, namely that parasites themselves drive host evolutionary diversification through processes linked with sexual selection and that host shifts or host sharing increases parasite species richness among diverse primate clades. Neither parasite species richness nor host diversification is related to measures of sexual selection in primates. Further, we found only partial evidence that more rapidly diversifying host lineages produced increased opportunities for host sharing or host shifting by parasites through mechanisms involving species' geographic range overlap. Thus, our analyses provide evidence for an important link between the evolutionary diversification of primates and the richness of their parasite communities, but other mechanisms, particularly those related to reciprocal selection or coextinction of hosts and parasites, require further investigation. [ABSTRACT FROM AUTHOR]

Mammals are exposed to a diverse array of parasites and infectious diseases, many of which affect host survival and reproduction. Species that live in dense populations, large social groups, or with promiscuous mating systems may be especially vulnerable to infectious diseases owing to the close proximity and higher contact rates among individuals. We review the effects of host density and social contacts on parasite spread and the importance of promiscuity and mating structure for the spread and evolution of sexually transmitted diseases. Host social organization and mating system should influence not only parasite diversity and prevalence but may also determine the fitness advantages of different transmission strategies to parasites. Because host behavior and immune defenses may have evolved to reduce the spread and pathogenicity of infectious diseases, we also consider selective pressures that parasites may exert on host social and mating behavior and the evolutionary responses of hosts at both the immunological and behavioral levels. In examining these issues, we relate modeling results to observations from wild populations, highlighting the similarities and differences among theoretical and empirical approaches. Finally, the epidemiological consequences of host sociality are very relevant to the practical issues of conserving mammalian biodiversity and understanding the interactions between extinction risk and infectious diseases. [ABSTRACT FROM AUTHOR]

Presents a comparative tests of parasite species richness in primates. Association of host population density was associated with total parasite richness and the diversity of helminths, protozoa and viruses tested separately.

Sexually transmitted diseases (STDs) are known to exist in wild and domesticated animals, but little is know about behavioural defences that animals use to reduce the risk of acquiring STDs. Using comparative data and a phylogeny of primates, I investigated whether behaviours hypothesized to reduce STD transmission are correlated with measures of STD risk involving mating promiscuity and life-history traits. Comparative tests revealed no support for genital inspection as a means to identify and avoid infected individuals with genital inspection was performed more commonly by males than females and uncorrelated with mating promiscuity. Primate species characterized by increased promiscuity were not more likely to display genital self-grooming following mating. Similarly, males and females of these species were not more likely to urinate immediately after mating, counter to suggestions that urination flushes microorganisms from the urethra and surrounding genital areas. Finally, monogamy was not correlated with a slow life history, which differs from predictions that monogamy is a response to increased STD risk in long-lived animals. Tests involving monogamy remained unsupported after controlling for potentially confounding variables, and all tests yielded similar results in phylogenetic and nonphylogenetic tests. Few results were significant even before controlling statistically for multiple comparisons, but nonsignificance was unlikely due to low statistical power or poor data quality in all tests. Instead, the comparative patterns were consistent with theoretical models showing that precopulatory behavioural defences to STDs, such as mate choice, are unlikely to be fully effective. In addition, many putative behavioural defences to STDs in primates entail substantial fitness costs in terms of reproductive output, offspring quality and infanticide avoidance. Copyright 2003 Published by Elsevier Ltd on behalf of The Association for the Study of Animal Behaviour. [Copyright &y& Elsevier]

Focuses on a study which the examined the correlates of baseline white blood cell (WBC) counts using the larger International Species Information System database. Data on WBC counts and correlations with phylogeny; Discussion on comparative data on primate socioecological variables; Absence of behavioral counterstrategies to sexually transmitted diseases; Transmission mode and host-parasite interactions.

Focuses on a study which investigated the relationship between the energetic needs and ranging patterns in primates. Methods; Results and discussion; Conclusions.

Although early comparative studies supported hypotheses that ecological demands selected for primate cognition, later work indicated that social demands were more important. One difference between earlier and later studies is that earlier studies scaled brain structures by (A) taking residuals from an interspecific regression of the brain structure in question on body mass, whereas later studies scaled them by (B) taking residuals from an interspecific regression of the brain structure in question on another brain structure or by (C) taking ratios of the brain structure in question to another brain structure. We conducted a series of comparative tests to explore the possibility that the different methods are responsible for the discrepancy between earlier and later studies. Specifically, we tested the ability of a social variable – group size – and an ecological variable – home range size – to explain variation in the non-V1 isocortex (isocortex minus primary visual cortex) when this structure was scaled with the three different methods. In multiple regression analysis, group size was a better predictor of the non-V1 isocortex with method (B). With methods (A) and (C), however, results were ambiguous: either home range size or group size explained more of the variation, depending on the inclusion of outliers, the use of independent contrasts, and whether home range size was scaled relative to body mass. We examine the three scaling methods and find no reasonable basis for preferring any of them. Hence, our results do not allow a distinction between social and ecological hypotheses. The general implications of our study are that (1) previous comparative studies are inconclusive and (2) further research is needed to develop a scaling method where relative measures of brain structure size are demonstrated to correspond with behavioral performance.Copyright ® 2000 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]

Small terrestrial mammals are major hosts of infectious agents responsible for zoonotic diseases. Astroviruses (AstVs)–the cause of non-bacterial gastroenteritis mainly affecting young children–have been detected in a wide array of mammalian and avian host species. However, understanding the factors that influence AstV infection within and across hosts is limited. Here, we investigated the impact of land use changes on AstVs in terrestrial small mammals in rural northeastern Madagascar. We sampled 515 small mammals, representing seven endemic and four introduced species. Twenty-two positive samples were identified, all but one of which were found in the introduced species Mus musculus and Rattus rattus (family Muridae), with a positivity rate of 7.7% (6/78) and 5.6% (15/266), respectively. The non-introduced rodent case was from an endemic shrew-tenrec (family Tenrecidae). We found the highest positivity rate of AstVs infection in brushy regrowth (17.5%, 7/40) as compared to flooded rice fields (4.60%, 8/174), secondary forest (4.1%, 3/74), agroforest (3.6%, 1/28), village (2.61%, 3/115), and semi-intact forest (0%, 0/84). A phylogenetic analysis revealed an association between AstVs and their rodent host species. None of the viruses were phylogenetically related to AstVs previously described in Malagasy bats. This study supports AstV circulation in synanthropic animals in agricultural habitats of Madagascar and highlights the need to assess the spillover risk to human populations in rural areas. Author summary: This article describes the diversity of Astroviruses (AstVs) shed by Malagasy terrestrial small mammals and explores the impact of habitat degradation on positivity rate in animal reservoirs. Using a sample of 515 terrestrial small mammals from northeastern Madagascar, we show that AstV infection is almost exclusively restricted to rats and mice, suggesting that AstVs from terrestrial mammals were introduced to Madagascar. A phylogenetic analysis including AstVs sequences from Malagasy small mammals reveals a strong structuring of AstV sequences within host species, indicating limited host switching of these viruses among small mammals. Finally, positivity rates show that some habitat types are particularly conducive to AstV infection in reservoirs, such as rice fields where mice exhibit maximal infection. Altogether, presented data encourage the need for assessing the actual exposure of the local human population to the AstVs in small mammals, especially rice-field farmers. [ABSTRACT FROM AUTHOR]

Focuses on heterochrony in marsupial and placental mammals. Changes involved in heterochrony; Presentation of methods for the comparison of developmental sequences; Examination of the sequence of development events in the craniofacial region of marsupial and placental mammals; Listing of related studies.

Highlights research work on the phylogenetic distribution of exaggerated sexual swellings among primates. Correlation of morphology, physiology and behavior of species with the trait; Confusion of paternity certainty among males; Enabling of females to manipulate male behavior by altering the costs and benefits of mate guarding.

Presents a simulation test of Smith's `degrees of freedom' correction for comparative studies. Comparative methods; Phylogenetic constraint; Nonindependence; Computer simulation.

The behavioral and ecological factors involved in immune system evolution remain poorly explored. We present a phylogenetic analysis of white blood cell counts in primates to test three hypotheses related to disease risk: increases in risk are expected with group size or population density, exposure to soil-borne pathogens, and mating promiscuity. White blood cell counts were significantly greater in species where females have more mating partners, indicating that the risk of sexually transmitted disease is likely to be a major factor leading to systematic differences in the primate immune system. [ABSTRACT FROM AUTHOR]

Future biodiversity loss threatens the integrity of complex ecological associations, including among hosts and parasites. Almost half of primate species are threatened with extinction, and the loss of threatened hosts could negatively impact parasite associations and ecosystem functions. If endangered hosts are highly connected in host--parasite networks, then future host extinctions will also drive parasite extinctions, destabilizing ecological networks. If threatened hosts are not highly connected, however, then network structure should not be greatly affected by the loss of threatened hosts. Networks with high connectance, modularity, nestedness and robustness are more resilient to perturbations such as the loss of interactions than sparse, nonmodular and non-nested networks. We analysed the interaction network involving 213 primates and 763 parasites and removed threatened primates (114 species) to simulate the effects of extinction. Our analyses revealed that connections to 23% of primate parasites (176 species) may be lost if threatened primates go extinct. In addition, measures of network structure were affected, but in varying ways because threatened hosts have fewer parasite interactions than non-threatened hosts. These results reveal that host extinctions will perturb the host--parasite network and potentially lead to secondary extinctions of parasites. The ecological consequences of these extinctions remain unclear. This article is part of the theme issue 'Infectious disease macroecology: parasite diversity and dynamics across the globe'. [ABSTRACT FROM AUTHOR]