Schino, G. | bioRxiv Science

bioRxiv2019

Monitoring of group mates in relation to their activity in mandrills

Primates are known to have considerable knowledge about the social relationships that link their group mates, and are likely to derive this information from observing the social interactions that occur in their social group. They may therefore be hypothesized to pay particular attention to the social interactions involving group mates. In this study, we evaluated how the attention captive mandrills (Mandrillus sphinx) devote to their group mates was modulated by the behavior of the latter. Mandrills looked most frequently at foraging individuals and least frequently at sleeping invividuals. Mandrills also looked at grooming individuals more than at individuals that were simply sitting in contact. Grooming dyads were looked at regardless of the social rank and kinship of the individuals involved. These results contribute to our understanding of how primates obtain their social knowledge.

animal behavior and cognition↗

bioRxiv2018

Nepotism masks evidence for reciprocity in cooperation networks

Nepotism and reciprocity are not mutually exclusive explanations for cooperation, because helping decisions can depend on both kinship cues and past reciprocal help. The importance of these two factors can therefore be difficult to disentangle using observational data. We developed a resampling procedure for inferring the statistical power to detect observational evidence of nepotism and reciprocity. We first applied this procedure to simulated datasets resulting from perfect reciprocity, where the probability and duration of helping events from individual A to B equaled that from B to A. We then assessed how the probability of detecting correlational evidence of reciprocity was influenced by (1) the number of helping observations and (2) varying degrees of simultaneous nepotism. Last, we applied the same analysis to empirical data on food sharing in vampire bats and allogrooming in mandrills and Japanese macaques. We show that at smaller sample sizes, the effect of kinship was easier to detect and the relative role of kinship was overestimated compared to the effect of reciprocal help in both simulated and empirical data, even with data simulating perfect reciprocity and imperfect nepotism. We explain the causes and consequences of this difference in power for detecting the roles of kinship versus reciprocal help. To compare the relative importance of genetic and social relationships, we therefore suggest that researchers measure the relative reliability of both coefficients in the model by plotting these coefficients and their detection probability as a function of sampling effort. We provide R scripts to allow others to do this power analysis with their own datasets.

animal behavior and cognition↗