Dispersal patterns exhibited by group-living animals play an important role in individual reproductive success and survival,as well as population and social dynamics(Greenwood,1980;Isbell and van Vuren,1996;Kappeler and van Schaik,2002).Dispersing individuals may emigrate voluntarily,or they may be forcibly evicted by other individuals(Pusey and Packer,1987;Clobert et al.,2001).One cause of individual dispersal is when an extra-group male compels another male to leave a group of females.This phenomenon has been well documented in primates,especially Old World monkey species(e.g.Colobus vellerosus:Saj and Sicotte,2005;Erythrocebus patas:Ohsawa,2003;Macaca fascicularis:van Noordwijk and van Schaik,2001).
Food distribution and predation pressure are considered to be the main ecological factors that influence the use of forest strata(basically arboreality vs.terrestriality)in non-human primates.Here,we investigate ground use of wild,unprovisioned black-and-white snub-nosed monkeys Rhinopithecus bieti by means of the scan sampling method.The results show that the monkeys spent 15.0% of the day time on the ground;16.6%,12.7%,and 15.6% for adult males,adult females and juveniles,respectively.Adult males and juveniles of both sexes showed significantly higher rates of terrestrial time than adult females.Females without clinging infants spent significantly more time on the ground than expected,while females with clinging infants spent significantly less time on the ground than expected.These results suggest that the higher degree of terrestrial behavior for males and juveniles may be due to their higher agility in comparison with females.Our study showed that the monkeys fed more on lichens relative to other food items when in the trees,but more on buds/leaves,flowers,fruits/nuts,resin/bark,and herbs when on the ground.According to our investigation,the ecological significance of the species' terrestriality lies mainly in the utilization of terrestrial food
Since the birth of molecular evolutionary analysis,primates have been a central focus of study and mitochondrial DNA is well suited to these endeavors because of its unique features.Surprisingly,to date no comprehensive evaluation of the nucleotide substitution patterns has been conducted on the mitochondrial genome of primates.Here,we analyzed the evolutionary patterns and evaluated selection and recombination in the mitochondrial genomes of 44 Primates species downloaded from GenBank.The results revealed that a strong rate heterogeneity occurred among sites and genes in all comparisons.Likewise,an obvious decline in primate nucleotide diversity was noted in the subunit rRNAs and tRNAs as compared to the protein-coding genes.Within 13 protein-coding genes,the pattern of nonsynonymous divergence was similar to that of overall nucleotide divergence,while synonymous changes differed only for individual genes,indicating that the rate heterogeneity may result from the rate of change at nonsynonymous sites.Codon usage analysis revealed that there was intermediate codon usage bias in primate protein-coding genes,and supported the idea that GC mutation pressure might determine codon usage and that positive selection is not the driving force for the codon usage bias.Neutrality tests using site-specific positive selection from a Bayesian framework indicated no sites were under positive selection for any gene,consistent with near neutrality.Recombination tests based on the pairwise homoplasy test statistic supported complete linkage even for much older divergent primate species.Thus,with the exception of rate heterogeneity among mitochondrial genes,evaluating the validity assumed complete linkage and selective neutrality in primates prior to phylogenetic or phylogeographic analysis seems unnecessary.
Liang ZHAOXingtao ZHANGXingkui TAOWeiwei WANGMing LI
Most extant nonhuman primates occasionally prey on fast-moving, warm-blooded animals; however, Indriidae, Lepilemuridae,and Colobinae either scavenged for meat or did not eat meat at all. Here we report six cases of animal consumptionby the snub-nosed monkey Rhinopithecus bieti in a wild, habituated group between 2004 and 2009 in Yunnan, China. At present,only males in an all-male unit within the study group were involved in active hunting. Such a male-biased activity may be relatedto the group structure and spatial spread of R. bieti. Two females were observed eating freshly killed birds. The findings confirmedthat R. bieti engaged in scavenging and, when hunting, employed a cranio-cervical bite to kill their prey. Meat eating islikely a nutrient maximization feeding strategy in R. bieti, especially in males. A begging behavior occurred after successful preycapture. Although begging was observed, no sharing of the meat was seen. The present findings illuminate the dietary diversity ofR. bieti and their ability to expand their dietary
Baoping RENDayong LIZhijin LIUBaoguo LIFuwen WEIMing LI
Although there are some reports that have described primates eating animals,it is unknown whether predation on vertebrates exists in herbivorous leaf-eating primates.We have witnessed firsthand wild Sichuan snub-nosed monkeys(Rhinopithecus roxellana)preying on and consuming Eurasian blackbirds(Turdus merula)in the Qinling Mountains of China.This event suggests that R.roxellana,which has previously been described as a herbivorous leaf-eating primate,may be partially carnivorous and the correct classification of this species would be omnivorous.Furthermore,food-share behavior among higher-ranked members occurs in a one-male unit when vertebrate prey is hunted by this species.
