Impact of Translocation,Provisioning and Range Restriction on a Group of Macaca thibetana

We examined the possible long-term impact of translocation and subsequent provisioning and range restriction on recruitment rates in a group of rare Tibetan macaques (Macaca thibetana) in Anhui Province, China. We compared demographic data recorded in the group (and in its fission products) during the 6 years before and after translocation and in a group with no history of management. We also compared preliminary data related to nutritional condition, habitat characteristics, and group activities. Infant losses markedly increased following translocation and management. Estimated measures of nutritional condition varied more among adults in the managed group than among those in the never managed group, suggesting that members of the managed group may have experienced higher levels of intragroup competition. We hypothesize that increased levels of intragroup competition for provisioned food may have put infants at increased risk.     

Group‐level competition influences urinary steroid hormones among wild red–tailed monkeys,indicating energetic costs

Various theories emphasize that intergroup competition should affect intragroup cooperation and social relationships, especially if the cost of intergroup competition outweighs that of intragroup competition. This cost of intergroup competition may be quantified by changes in physiological status, such as in the steroid hormones cortisol (C) and testosterone (T), which rise or are depressed during periods of energetic stress, respectively. Here we tested for changes in urinary C and T after intergroup encounters (IGEs) among wild red‐tailed monkeys (Cercopithecus ascanius), a species that experiences frequent intergroup feeding competition, at the Ngogo station in Kibale National Park, Uganda. We assayed 108 urine samples, of which 36 were collected after IGEs, from 23 individuals in four social groups. Bayesian multilevel models controlling for various confounds revealed that IGEs increased C and decreased T relative to baseline, consistent with an energetic cost to IGEs. The C change was more apparent in samples collected early after IGEs, suggesting an anticipatory increase, whereas the T change was stronger in later samples, suggesting sustained energetic trade‐offs. Hormone responses were not affected by the IGE outcome. This cost to intergroup competition, together with little evidence for intragroup competition in redtails and other guenons, establishes an interesting test case for theories emphasizing the effect of intergroup competition on intragroup cooperation.     

Natural genetic engineering of the bacterial genome

The term ‘natural genetic engineering’ means viewing genetic change as a coordinated cell biological process, the reorganization of discrete genomic modules, resulting in the formation of new DNA structures. Examples of natural genetic engineering continue to accumulate, and the concept can be used to integrate observations which demonstrate the similarity between in vitro genetic engineering and the action of in vivo agents of genetic change.     

Group fission among wild toque macaques as a consequence of female resource competition and environmental stress

At Polonnaruwa, Sri Lanka, four out of 29, groups of toque macaques, Macaca sinica, divided in a period of 16 years. Temporary peripheral subgroups of varying sizes and compositions preceded fission by 9–40 months. Fission crystallized within a month through an increase and stabilization of subgroup membership and permanent division. All members in the newly seceded groups had been frequent participants in pre-fission subgroups, and belonged to subordinate matrilineages. Subgroups, and hence group divisions, were initiated by cores of mutually loyal females and occurred mostly along kinship lines. In the year of fissions, the rate of change in female dominance relations was significantly greater among groups that divided than among those that did not. It is hypothesized that low-ranking females secede to form new groups when the costs, especially of intragroup competition for food resources, outweigh the benefits of group membership. Such seceding females were easily available and familiar mates for group males that had recently lost rank. Final division, therefore, resulted from a coalition of subordinate females and males acting according to their respective interests. It was triggered in this population by rapid growth of some groups to large size and by environmental stress (the reduction and fragmentation of food resources caused by drought and a cyclone), which accentuated the costs of resource competition. Male aggression, such as infanticide, which negatively affects female fitness, might also have contributed to one group fission.     

Rate of evolutionary change in cranial morphology of the marsupial genus Monodelphis is constrained by the availability of additive genetic variation

We tested the hypothesis that the rate of marsupial cranial evolution is dependent on the distribution of genetic variation in multivariate space. To do so, we carried out a genetic analysis of cranial morphological variation in laboratory strains of Monodelphis domestica and used estimates of genetic covariation to analyse the morphological diversification of the Monodelphis brevicaudata species group. We found that within‐species genetic variation is concentrated in only a few axes of the morphospace and that this strong genetic covariation influenced the rate of morphological diversification of the brevicaudata group, with between‐species divergence occurring fastest when occurring along the genetic line of least resistance. Accounting for the geometric distribution of genetic variation also increased our ability to detect the selective regimen underlying species diversification, with several instances of selection only being detected when genetic covariances were taken into account. Therefore, this work directly links patterns of genetic covariation among traits to macroevolutionary patterns of morphological divergence. Our findings also suggest that the limited distribution of Monodelphis species in morphospace is the result of a complex interplay between the limited dimensionality of available genetic variation and strong stabilizing selection along two major axes of genetic variation.     

Intergroup affiliative interactions and intergroup transfer of young male Japanese macaques (Macaca fuscata)

The social interactions between young male Japanese macaques (Macaca fuscata) and members of two adjacent groups were studied. Young males usually associated with members of a single group. Although some young males occasionally interacted with members of the neighboring group, the frequency of their intergroup affiliative interactions was much lower than that of their intragroup interactions. The intergroup affiliative interactions were less symmetrical than the intragroup interactions. Three- or four-year-old males who remained in their natal group interacted with males of the neighboring group, whereas males over 5 years old did not. Young males revealed a dramatic change in their association partners from males in one group to those in another during the course of their intergroup transfer. Males who remained in their natal group did not attempt to interact with females of the neighboring group. In contrast, males who had transferred to a non-natal group interacted with females in their natal group. It is suggested that intergroup affiliative interactions and intergroup transfer of young male macaques are influenced by close associations between males. The immediate motivation for transfer of young natal macaques may be some attraction to males outside their group rather than sexual attraction to unfamiliar females.     

Cranial growth and growth dimorphism in Ateles geoffroyi

With the exception of the work of Schultz (1960), cranial growth in Ateles is not well documented. This paper describes the results of a detailed quantitative study of cranial ontogeny in male and female Ateles geoffroyi. Using Euclidean Distance Matrix Analysis (EDMA), local areas of form change due to growth within spider monkey crania are identified. We found substantial change local to the zygomatic region in the face, identified mediolaterally directed changes in the palate, detected relatively larger amounts of change local to the anterior neurocranium compared to the posterior neurocranium, and demonstrate a greater amount of basicranial growth along a mediolateral axis than previously reported. Cranial sexual dimorphism is also examined. A. geoffroyi is noted for being monomorphic, and we found a general similarity between male and female cranial forms at all developmental ages. However, differences in overall cranial size between the sexes were found in the oldest subadult age group but not between male and female adults. This difference suggests that A. geoffroyi females attain their adult cranial form slightly before males and implies a pattern of earlier onset of female maturity relative to males. © 1993 Wiley-Liss, Inc.     

Robertsonian fusion and centric fission in karyotype evolution of higher plants

Robertsonian fusion and centric fission are uniquely detectable in comparative studies of karyotype patterns. They are the most important types of karyotype change in animals but seem to be relatively uncommon in higher plants. Both modify intra- and interchromosomal recombination and linkage relationships and consequently patterns of genetic variation. When differentiating populations or species they can produce postulating barriers to gene flow. The number of reported cases of fusion or fission in higher plants has increased over the years but remains low, and most of these are casual comparisons of karyotypes without any follow-up investigation. This review focuses on more adequate studies made in a few groups. Studies in the Tradescantieae produce the strongest evidence for fusion as a type of orthoselection in the subfamily. Some species ofLycoris are also considered to have evolved their karyotypes in that way. Some genera of slipper orchids and the cycad genusZamia have populations where atypical chromosome number increase can be attributed to fission probably as a result of stressful influences. It is suggested that fusion may have been involved in the evolution of many stable karyotypes and that fission is generally a secondary destabilizing mechanism which may lead to refusion in the long term. Their proven incidence remains making it unwise to suggest that they have been major influences in karyotype evolution in higher plants.     

Brief Communication: Quantitative‐ and molecular‐genetic differentiation in humans and chimpanzees: Implications for the evolutionary processes underlying cranial diversification

Estimates of the amount of genetic differentiation in humans among major geographic regions (e.g., Eastern Asia vs. Europe) from quantitative‐genetic analyses of cranial measurements closely match those from classical‐ and molecular‐genetic markers. Typically, among‐region differences account for ～10% of the total variation. This correspondence is generally interpreted as evidence for the importance of neutral evolutionary processes (e.g., genetic drift) in generating among‐region differences in human cranial form, but it was initially surprising because human cranial diversity was frequently assumed to show a strong signature of natural selection. Is the human degree of similarity of cranial and DNA‐sequence estimates of among‐region genetic differentiation unusual? How do comparisons with other taxa illuminate the evolutionary processes underlying cranial diversification? Chimpanzees provide a useful starting point for placing the human results in a broader comparative context, because common chimpanzees (Pan troglodytes) and bonobos (Pan paniscus) are the extant species most closely related to humans. To address these questions, I used 27 cranial measurements collected on a sample of 861 humans and 263 chimpanzees to estimate the amount of genetic differentiation between pairs of groups (between regions for humans and between species or subspecies for chimpanzees). Consistent with previous results, the human cranial estimates are quite similar to published DNA‐sequence estimates. In contrast, the chimpanzee cranial estimates are much smaller than published DNA‐sequence estimates. It appears that cranial differentiation has been limited in chimpanzees relative to humans. Am J Phys Anthropol 154:615–620, 2014. © 2014 Wiley Periodicals, Inc.     

Successional loss of two key food tree species best explains decline in group size of Panamanian howler monkeys (Alouatta palliata)

Negative impacts of discrete, short‐term disturbances to wildlife populations are well‐documented. The consequences of more gradual environmental change are less apparent and harder to study because they play out over longer periods and are often indirect in their action. Yet, they can drive the decline of wildlife populations even in seemingly pristine and currently well‐protected habitats. One such environmental change is a successional shift in a community's species composition as it regenerates from disturbance caused by past human land use. Early and middle successional tree species often provide key foods to folivores and frugivores, but the abundance of these resources drops as the forest matures, with adverse repercussions for these consumers. Our 44‐year record (1974–2018) of howler monkey (Alouatta palliata) group sizes and demographic composition from Barro Colorado Island, Panama, a protected reserve, documents an example of this phenomenon. After 70 years of relative stability, the mean size of howler monkey groups exhibited a marked decline, beginning in 2003. This downward trajectory in group size has continued through the most recent census in 2018. The composition of howler groups also changed significantly during the study period, with the patterns of decline differing among age/sex classes. There is no evidence that these changes were caused by increased rates of emigration, group fission, predation, parasitism, or disease. Rather, they are best explained by an island‐wide, succession‐driven decline in the densities of two species of free‐standing fig trees, Ficus yoponensis and F. insipida, which together were providing ~36% of BCI howlers’ annual diet. Abstract in Spanish is available with online material.     

The evolution of hominoid cranial diversity: A quantitative genetic approach

Hominoid cranial evolution is characterized by substantial phenotypic diversity, yet the cause of this variability has rarely been explored. Quantitative genetic techniques for investigating evolutionary processes underlying morphological divergence are dependent on the availability of good ancestral models, a problem in hominoids where the fossil record is fragmentary and poorly understood. Here, we use a maximum likelihood approach based on a Brownian motion model of evolutionary change to estimate nested hypothetical ancestral forms from 15 extant hominoid taxa. These ancestors were then used to calculate rates of evolution along each branch of a phylogenetic tree using Lande's generalized genetic distance. Our results show that hominoid cranial evolution is characterized by strong stabilizing selection. Only two instances of directional selection were detected; the divergence of Homo from its last common ancestor with Pan, and the divergence of the lesser apes from their last common ancestor with the great apes. In these two cases, selection gradients reconstructed to identify the specific traits undergoing selection indicated that selection on basicranial flexion, cranial vault expansion, and facial retraction characterizes the divergence of Homo, whereas the divergence of the lesser apes was defined by selection on neurocranial size reduction.     

Evolutionary processes and its environmental correlates in the cranial morphology of western chipmunks (Tamias)

The importance of the environment in shaping phenotypic evolution lies at the core of evolutionary biology. Chipmunks of the genus Tamias (subgenus Neotamias) are part of a very recent radiation, occupying a wide range of environments with marked niche partitioning among species. One open question is if and how those differences in environments affected phenotypic evolution in this lineage. Herein we examine the relative importance of genetic drift versus natural selection in the origin of cranial diversity exhibited by clade members. We also explore the degree to which variation in potential selective agents (environmental variables) are correlated with the patterns of morphological variation presented. We found that genetic drift cannot explain morphological diversification in the group, thus supporting the potential role of natural selection as the predominant evolutionary force during Neotamias cranial diversification, although the strength of selection varied greatly among species. This morphological diversification, in turn, was correlated with environmental conditions, suggesting a possible causal relationship. These results underscore that extant Neotamias represent a radiation in which aspects of the environment might have acted as the selective force driving species’ divergence.     

Social group fission and the origin of intergroup genetic differentiation among the rhesus monkeys of Cayo Santiago.

The serum transferrin locus is used to investigate the roles of the lineal effect of fission, male migration effect of fission, and genetic drift in causing intergroup genetic differentiation among the rhesus macaques of Cayo Santiago. These three mechanisms prove sufficient to explain the degrees of differentiation between the newly formed social groups A, K, and L as of July 1, 1971. The lineal effect of fission provides a baseline of intergroup differentiation which is altered by forces leading to intragroup genetic change, the male migration effect and genetic drift. The importance of population dynamics for the distribution of alleles among subgroups of a population is recognized.     

Fatal intragroup kidnapping in yellow baboons

The fatal kidnapping of a 5-day-old baboon (Papio cynocephalus) in Amboseli National Park, Kenya, is described. Although pulling and rough handling of primate infants by nonmothers are frequently observed, records of fatal intragroup kidnappings are rare. In the instance described here, the mother, a healthy, primiparous female, did not retrieve the infant from the kidnapper, a higher-ranking juvenile female of the same group, until he died 3 days later, presumably from starvation or dehydration. This incident is compared with other fatal intragroup kidnappings in nonhuman primates and related to adaptive interpretations.     

Characterization of biological diversity through analysis of discrete cranial traits

In the present study, the frequency distributions of 20 discrete cranial traits in 70 major human populations from around the world were analyzed. The principal-coordinate and neighbor-joining analyses of Smith's mean measure of divergence (MMD), based on trait frequencies, indicate that 1). the clustering pattern is similar to those based on classic genetic markers, DNA polymorphisms, and craniometrics; 2). significant interregional separation and intraregional diversity are present in Subsaharan Africans; 3). clinal relationships exist among regional groups; 4). intraregional discontinuity exists in some populations inhabiting peripheral or isolated areas. For example, the Ainu are the most distinct outliers of the East Asian populations. These patterns suggest that founder effects, genetic drift, isolation, and population structure are the primary causes of regional variation in discrete cranial traits. Our results are compatible with a single origin for modern humans as well as the multiregional model, similar to the results of Relethford and Harpending ([1994] Am. J. Phys. Anthropol. 95:249-270). The results presented here provide additional measures of the morphological variation and diversification of modern human populations.     

Gis analysis of patch use and group cohesiveness of bearded sakis (chiropotes sagulatus) in the upper essequibo conservation concession,guyana

This study examines how northern bearded sakis (Chiropotes sagulatus) in Guyana adjust group cohesiveness according to the distribution and quality of food patches. I introduce a GIS based method for quantifying food patch quality and how it relates to bearded saki group spread and group size. While the concept of food patch is central to most models of primate socioecology, defining what constitutes a patch has been notoriously problematic in primate studies. In addition, researchers have struggled to quantify group spread and group cohesiveness. Advances in spatial analysis software in the last decade now allow primate researchers to better quantify these variables. Group spread in bearded sakis was not significantly greater in lower quality patches and sakis were not more spread out during feeding than during other activities. However, the study group was significantly less spread out during social behavior. Bearded saki group size was significantly correlated with both monthly fruit abundance and patch quality. In fact, mean daily patch quality explained ～40% of the variation in foraging party size. These results suggest that bearded sakis may rely on a highly fluid social structure to mitigate the effects of intragroup feeding competition while living in large groups. Sakis do not adjust group spread on a patch‐by‐patch basis but rather fission into smaller foraging parties when resources become scarce seasonally and patch quality is low. This study shows that GIS is a powerful tool for modeling the relationship between group cohesiveness and resource quality and distribution. Am J Phys Anthropol, 2013. © 2012 Wiley Periodicals, Inc.     

The timing of fission among free-ranging Rhesus monkeys

Behavioral observations were carried out on a large group of free-ranging rhesus monkeys (Macaca mulatta) on Cayo Santiago from January 1968 to December 1969 and from October through December 1970. During this period, social group A divided. The 24-month study period can be classified into five stages which represent the different phases in the process of group fission. Two criteria for fission were established: the cessation of grooming between adult females of different sub-groups of the main group and the stabilization of the adult female population. The criteria were based on established information on group dynamics and inter-group behavior on Cayo Santiago. Several points became clear from the chronological analysis. Group fission is a long process. The duration of the process of fission and the specification of the season in which fission begins and is completed depends upon the definition applied. For purposes of this analysis, fission was defined as beginning with the onset of spatial fragmentation and corresponded to the initial part of the breeding season. The fission was completed during the breeding season. The duration of the process of fission was 18 months.     

The Telomere-Binding Protein Taz1p as a Target for Modification by a SUMO-1 Homologue in Fission Yeast

In fission yeast (Schizosaccharomyces pombe) the homologue of the mammalian SUMO-1 ubiquitin-like modifier is encoded by the pmt3 gene. A two-hybrid screen using the telomere-binding protein Taz1p as bait identified Pmt3p as an interacting factor. In vitro experiments using purified components of the fission yeast Pmt3p modification system demonstrated that Taz1p could be modified directly by Pmt3p. The amino acid sequence of Taz1p contains a close match to the consensus modification site for SUMO-1, and a PEST sequence similar to those found in established SUMO-1 targets. Although previous experiments have identified an increase in telomere length as one consequence of the pmt3– genotype, we could not detect Pmt3p modification of Taz1p in protein extracts made from exponentially growing haploid cells or any effect of Pmt3p on the localization of GFP-Taz1p at discrete foci in the haploid cell nucleus.     

Intragroup Social Relationships of Male Alouatta palliata on Barro Colorado Island,Republic of Panama

We examined social and spatial relations of adult males in one group of mantled howling monkeys (Alouatta palliata) on Barro Colorado Island (BCI) in central Panama to document patterns of association. Beyond the existence of an alpha male, we could not distinguish any linear dominance hierarchy among the 6 study males. All males copulated with estrous females. Our findings contrast with reports of intragroup male behavior in Costa Rican howlers. Study males engaged in little or no affiliative or agonistic behavior with one another, but engaged in significantly more such interactions with females. The alpha male, the oldest male and a younger male were most frequently in association with females. Of group males, the oldest male associated significantly more with other males. Overall, male behavior in mantled howling monkeys on BCI generally followed the van Hooff and van Schaik (1994) model of male relationships. The low incidence of intragroup social interactions of any type in the focal males may reflect the energetic costs of social behavior. We suggest that intragroup social relationships among mantled howler males are structured by more subtle means than overt physical interactions, possibly including vocal communication, relationships with individual group females, and kinship.     

Has Predation Shaped the Social Systems of Arboreal Primates?

I studied antipredator behavior in two species of monkeys to elucidate the role of predation in shaping the social systems of arboreal primates. I compared the responses of monkeys to auditory and visual contact with predators to response elicited by sound playback experiments using the recorded calls of predators. Changes in vigilance and aggregation persisting up to 30 min after predator encounter occurred in both cases. Measures of vigilance shed light on individual perceptions of risk, while aggregation measures—intragroup spatial cohesion and polyspecific associations—permit direct inference about the protective benefits of grouping for the monkeys. They responded to real predator encounters and simulations in similar ways. Thus, sound playbacks of predator vocalizations are effective to simulate predator proximity. Contrary to predictions, predator encounters did not lead invariably to increased cohesion within groups or to increased time spent vigilant. Moreover, behavior in polyspecific associations was no different from that in single-species groups. Only red colobus encountering chimpanzees behaved as predicted by increasing vigilance and intragroup cohesion. The red colobus social system may have developed to protect against chimpanzee attack. In contrast, red-tailed monkey encounters with raptors and chimpanzees involved no change in time spent vigilant, coupled with decreases in intragroup cohesion. I conclude that predation is not a uniform selective pressure and patterns of social behavior within groups do not predict antipredator behavior.