| Symposium proposal |
| Organizer: | Qi Xiao-Guang (Northwest University) |
| Co-organizer: | Zhang Guo-Jie (University of Copenhagen) |
Behavioral mechanisms mediate individual fitness and hence are the drivers of evolutionary change. Primate social complexity has been proposed to increase in a stepwise fashion from solitary individuals, through small groups to large, socially complex groups. For social systems to evolve, these varied behavior strategies facilitated animal fitness, successful radiation, and resulted into a lineage of social systems from small family groups to large modular societies characterized by high levels of social complexity.
In recent, the researches about social evolution mainly focused on three aspects: (1) The diversity of social systems, include spacing, grouping and mating patterns, as well as variability in individuals affiliation, cooperation and competition relationships; (2) Social ecology, it provide a model that relates fitness-relevant behavior of individuals. The underlying behavior of individuals towards conspecifics, is probably largely shaped by ecological factors, such as the distribution of risks and resources in the environment and their interactions. Socio-ecological models have documented social evolution in response to environmental conditions that both resource competition and cooperation regulate their behavior tactics, and played important roles in shaping primate sociality; (3) Genetic basis of social evolution, social behavior shows strong evidence for phylogenetic inertia, their contrast social systems are likely inherited from their respective ancestor, not only the adaptation to environment.
In previous work, researchers have been working on examining the evolutionary forces that have generated and shaped it. Considering that social grouping patterns are inheritable, and highly conservative with phylogenetic position, there is a growing consensus that primate social evolution are phylogenetic traits. However, the potential genetic mechanisms that constrain or promote the expression of primate social system variability remain poorly understood. Generally, discovering the cellular and molecular substrates for the social evolution, should lead to a better understanding about how the genome and nervous system can be transformed. Here, we provide 3 topics for discussion in this Symposia: (1) Evolution of social and mating systems; (2) Evolution of Social phenotypes; (3) Genetic basis of social evolution.
This conference intends to invite 3 experts who have made achievements in the area of social evolution to discuss this topic in-depth.
Prof. Christopher Opie from the Anthropology and Archaeology Department at the University of Bristol. His research interests are in the evolution of social systems in humans and other primates. He uses Bayesian phylogenetic methods to explore the evolution of social and mating systems, marriage and kinship and investigate the causes of changes in those traits. He will start the topic "Reconstructing Sociality in Extinct Primate Species" at this conference;
Prof. Cyril Grueter from University of Western Australia. His primary research interests lie at the interface of behavioral ecology and evolutionary anthropology and include the evolution of primate/human sociality and the mechanisms underlying social cohesion. He will bring a hot topic about "Secondary Sexual Traits and Complex Sociality in Primates";
Prof. Ikki Matsuda from Academy of Emerging Sciences, Chubu University. His main research direction is primate behavioral ecology and conservation biology. He will share his research about "Large Male Proboscis Monkeys Have Larger Noses But Smaller Canines" with you.
Prof Qi Xiao-Guang College of Life Sciences, Northwest University. His research interests span the fields of behavioral ecology, evolutionary ecology, molecular ecology and conservation of social primates. He will give a report about “Genomic basis of social evolution in Asian primates”. |
S7-1
Reconstructing sociality in extinct primate species
Christopher Opie1
1University of Bristol
Group living is fundamental to the lives of the majority of primate species, including humans. The switch to sociality impacted crucially on other social and behavioural traits as well as life history trade-offs. The social brain hypothesis suggests that group living brought about an increase in brain size across primate species, while the socioecological model predicts that primates from social species face fundamentally different choices in foraging and reproduction as well as life history. Despite a good understanding of how social behaviour might have evolved across the primate order, how and when group living first evolved is unclear. Here we use Bayesian phylogenetic methods to show for the first time that it is possible to reconstruct sociality in extinct fossil primate species and pinpoint where and when this crucial change took place. Our results suggest that the earliest group-living species came from two families of late-middle Eocene stem anthropoid primates, the Eosomiids and Amphipithecids. The fossils of these species were found predominantly in the Pondaung Formation in Myanmar, South East Asia, dating from 40 million years ago. This suggests that the shift to group living may have been due to a change in diet that allowed for an increase in body size, and a shift from nocturnal to diurnal living. Increased frontation in the skulls of these fossil primates might, in part, be the first indication of increased frontal lobe sizes due to the complexities of group living.
S7-2
SECONDARY SEXUAL TRAITS AND COMPLEX SOCIALITY IN PRIMATES
Cyril C. Grueter1
1The University of Western Australia
Primates exhibit two kinds of sexually dimorphic secondary sexual traits: ornaments and weaponry. Ornaments are conspicuous decorative features that can signal male quality to prospective female mating partners or act as badges of intrinsic male viability. Weaponry includes body mass and canine dimorphism, phenotypic traits that enhance success in male-male contest. While links between secondary sexual traits and mating systems are well known, the role a species’ wider social environment exerts on the evolution of secondary sexual traits requires further study. Here we place particular emphasis on the adaptive signalling function of ornaments and weaponry in primate species with supra-group social organization (the existence of tolerant relationships between social groups) and multilevel societies (the organization of core social units into a larger collective encompassing multiple nested social levels). Lastly, we also examine whether investments in traits that promote access to females (i.e. ornaments and weaponry) come at the expense of investments in traits that enhance fertilization success (i.e. testis size).
S7-3
Interaction between natural and sexual selection during the evolution of the sexually selected male masculine trait in proboscis monkeys
Ikki Matsuda1
1Chubu University Academy of Emerging Sciences
2Wildlife Research Center of Kyoto University
3Japan Monkey Centre
4Institute for Tropical Biology & Conservation, Universiti Malaysia
The uniquely enlarged noses of male proboscis monkeys (Nasalis larvatus) are prominent adornments and a sexually selected male masculine trait, as demonstrated by the significant correlations among nose, body, and testis sizes and the clear association between nose size and the number of females in a male’s harem and between nose sizes and nasalized acoustic signals. However, till date, analyses of other common male traits, i.e., canines, are lacking. Male nose size was positively correlated with body size, whereas body size was negatively correlated with canine size. Similar relationship between nose and body size was observed in females, whereas only a weak correlation was noted between canine and body size. We explain this by an interaction between sexual and natural selection. Larger noses in males may interfere with the use of canines, thereby reducing their effectiveness as weapons. However, longer canines are opposed by natural selection because they impose a larger gape upon its bearer and reduce foraging efficiency, particularly in folivores. The difference between the sexes regarding the regression intercept for body size vs. canine size was significant, although the difference of the slopes was insignificant, consistent with the hypothesis that the nose interferes with the effectiveness of canines as weapons in males but not in females. Moreover, a mathematical simulation supported our prediction. This unique case of decoupling of body and canine size reveals that large canines carry an ecological cost. It also raises interesting questions regarding the developmental mechanism that produces a negative correlation among adult body, nose size, and canine size.
S7-4
Social enhancer PAS1 modulates social hierarchy in amniotes
Yuting Wang1,2, Guangyi Dai1, Zhili Gu1, Guopeng Liu1,2
1Shanghai Institute of Nutrition and Health, Chinese Academy of Sciences
2University of Chinese Academy of Sciences
Social hierarchies emerged during evolution, and social rank influences behavior and health of individuals. However, the evolutionary mechanisms of social hierarchy are still unknown in amniotes. Here we developed a new method and performed a genome-wide screening for identifying regions with accelerated evolution in the ancestral lineage of placental mammals, where mammalian social hierarchies might have initially evolved. Then functional analyses were conducted for the most accelerated region designated as placental-accelerated sequence 1 (PAS1, P=3.15×10^(-18)). Multiple pieces of evidence show that PAS1 is an enhancer of the transcription factor gene Lhx2 involved in brain development. PAS1s isolated from various amniotes showed different cis-regulatory activity in vitro, and affected the expression of Lhx2 differently in the nervous system of mouse embryos. PAS1 knock-out mice lack social stratification. PAS1 knock-in mouse models demonstrate that PAS1s determine the social dominance and subordinate of adult mice, and social ranks could even be turned over by mutated PAS1. All homozygous mutant mice had normal huddled sleeping behavior, motor coordination and strength. Therefore, PAS1-Lhx2 modulates social hierarchies and is essential to establish social stratification in amniotes, and positive Darwinian selection on PAS1 plays pivotal roles in the occurrence of mammalian social hierarchies.
S7-5
Genomic basis of social evolution in Asian primates
Jinwei Wu1, Lan Zhao1, Cheng Deng2, Qiang Qiu3, Christopher Opie4, Guojie Zhang5, Cyril C. Grueter6, Dongdong Wu7, Baoguo Li1, Xiao-Guang Qi1
1Shaanxi Key Laboratory for Animal Conservation, College of Life Sciences, Northwest University, Xi’an, China.
2College of Life Sciences, Nanjing Normal University, Nanjing, China.
3College of Ecological and Environmental Sciences, Northwestern Polytechnical University, Xi’an, China.
4Department of Anthropology and Archaeology, University of Bristol, Bristol, United Kingdom
5BGI-Shenzhen, Shenzhen, China.
6School of Human Sciences, The University of Western Australia, Perth, Australia.
7Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming, China.
Primates evolved diverse sets of social system that have facilitated their successful radiation. Although ecological adaptations play a critical role in shaping primate social organization, recently there is a growing consensus that social evolution is highly correlated with phylogeny and regulated by genetic mechanisms. However, these genetic mechanisms remain poorly understood. To address this, we newly sequenced and de novo assembly the genomic data for all seven genera of Asian colobines, a subfamily of primates characterized by a wide range of social systems. By integrating paleogeology, paleoclimate, the fossil record, ancient ecological niche modeling, and comparative behavioral analysis, we reconstructed the origin, natural history, and changing environmental adaptations of Asian colobines over the past 8 million years, we found that cold contribute to the species differentiation and social system evolution in Asian colobines. Genomic analysis revealed that in response to glacial cold pressures, more efficient neuro-hormonal pathways have evolved and resulted in increased levels of social affiliation. This led to odd-nosed monkeys (one clade of Asian colobines) exhibit more male tolerance, cooperation, and enhanced social aggregation with a high complexity social system of multilevel society like our human being. The results provide novel insights into the phylogenomic basis of behavioral regulation and the social evolution in primates.
