Is there any intron sliding in mammals?

Background Eukaryotic protein-coding genes consist of exons and introns. Exon–intron borders are conserved between species and thus their changes might be observed only on quite long evolutionary distances. One of the rarest types of change, in which intron relocates over a short distance, is called "intron sliding", but the reality of this event has been debated for a long time. The main idea of a search for intron sliding is to use the most accurate genome annotation and genome sequence, as well as high-quality transcriptome data. We applied them in a search for sliding introns in mammals in order to widen knowledge about the presence or absence of such phenomena in this group. Results We didn’t find any significant evidence of intron sliding in the primate group (human, chimpanzee, rhesus macaque, crab-eating macaque, green monkey, marmoset). Only one possible intron sliding event supported by a set of high quality transcriptomes was observed between EIF1AX human and sheep gene orthologs. Also, we checked a list of previously observed intron sliding events in mammals and showed that most likely they are artifacts of genome annotations and are not shown in subsequent annotation versions as well as are not supported by transcriptomic data. Conclusions We assume that intron sliding is indeed a very rare evolutionary event if it exists at all. Every case of intron sliding needs a lot of supportive data for detection and confirmation.

Assessing the reliability of an automated method for measuring dominance hierarchy in nonhuman primates

Among animals’ societies, dominance is an important social factor that influences inter-individual relationships. However, assessing dominance hierarchy can be a time-consuming activity which is potentially impeded by environmental factors, difficulties in the recognition of animals, or through the disturbance of animals during data collection. Here we took advantage of novel devices, Machines for Automated Learning and Testing (MALT), designed primarily to study nonhuman primates’ cognition - to additionally measure the social structure of a primate group. When working on a MALT, an animal can be replaced by another; which could reflect an asymmetric dominance relationship (or could happen by chance). To assess the reliability of our automated method, we analysed a sample of the automated conflicts with video scoring and found that 75% of these replacements include genuine forms of social displacements. We thus first designed a data filtering procedure to exclude events that should not be taken into account when automatically assessing social hierarchies in monkeys. Then, we analysed months of daily use of MALT by 25 semi-free ranging Tonkean macaques (Macaca tonkeana) and found that dominance relationships inferred from these interactions strongly correlate with the ones derived from observations of spontaneous agonistic interactions collected during the same time period. We demonstrate that this method can be used to assess the evolution of individual social status, as well as group-wide hierarchical stability longitudinally with minimal research labour. Further, it facilitates a continuous assessment of dominance hierarchies, even during unpredictable environmental or challenging social events. Altogether, this study supports the use of MALT as a reliable tool to automatically and dynamically assess social status within groups of nonhuman primates, including juveniles.

Recruitment and monitoring behaviors by leaders predict following in wild Barbary macaques (Macaca sylvanus)

For group-living animals it is essential to maintain the cohesiveness of the group when traveling. Individuals have to make an accurate decision about where and when to move. Communication before and during the departure of the first individual may play a crucial role in synchronizing a collective movement. We hypothesized that individuals in a wild primate group use signals or cues prior to and after departure to achieve collective movements. With two observers we used all-occurrences behavior sampling of collective movements in a group of wild Barbary macaques (Macaca sylvanus) in the Middle Atlas, Morocco. The number of individuals displaying pre-departure behavior predicted the success of an initiation of a collective movement. Pauses of the first departing individual after departure enhanced following behavior and might have served as recruitment signal. However, the opposite was the case for back-glancing, which functions as a monitoring signal in other species. Because in our study frequently back-glancing individuals were also less socially integrated, back glances may better be interpreted as indicators of hesitation and insecurity. To successfully initiate a collective movement, it seemed to be sufficient for a socially integrated group member to take action when other group members signal their willingness prior to departure and to occasionally wait for the group while moving.

Social Networks and Social Complexity in Female-bonded Primates

Most primates are intensely social and spend a large amount of time servicing social relationships. The social brain hypothesis suggests that the evolution of the primate brain has been driven by the necessity of dealing with increased social complexity. This chapter uses social network analysis to analyse the relationship between primate group size, neocortex ratio and several social network metrics. Findings suggest that social complexity may derive from managing indirect social relationships, i.e. relationships in which a female is not directly involved, which may pose high cognitive demands on primates. The discussion notes that a large neocortex allows individuals to form intense social bonds with some group members while at the same time enabling them to manage and monitor less intense indirect relationships without frequent direct involvement with each individual of the social group.