Social interactions generate complex selection patterns in virtual worlds

Understanding the influence of social interactions on individual fitness
is key to improving our predictions of phenotypic evolution. However, we
often overlook the different components of selection regimes arising from
interactions among organisms, including social, correlational, and
indirect selection. This is due to the challenging sampling efforts
required in natural populations to measure phenotypes expressed during
interactions and individual fitness. Furthermore, behaviours are crucial
in mediating social interactions, yet few studies have explicitly
quantified these selection components on behavioural traits. In this
study, we capitalize on an online multiplayer videogame as a source of
extensive data recording direct social interactions among prey, where prey
collaborate to escape a predator in realistic ecological settings. We
estimate natural and social selection and their contribution to total
selection on behavioural traits mediating competition, cooperation, and
predator-prey interactions. Behaviours of other prey in a group impact an
individual’s survival, and thus are under social selection. Depending on
whether selection pressures on behaviours are synergistic or conflicting,
social interactions enhance or mitigate the strength of natural selection,
although natural selection remains the main driving force. Indirect
selection through correlations among traits also contributed to the total
selection. Thus, failing to account for the effects of social interactions
and indirect selection would lead to a misestimation of the total
selection acting on traits. Dissecting the contribution of each component
to the total selection differential allowed us to investigate the causal
mechanisms relating behaviour to fitness and quantify the importance of
the behaviours of conspecifics as agents of selection. Our study
emphasizes that social interactions generate complex selective regimes
even in a relatively simple ecological environment.