Corresponding Authors: Léa Briard
Summary by Ethan Hackmeyer, edited by Léa Briard
Social behavior is an important driving factor in the spread of parasites between animals. Group size has traditionally been the dominant measure for the impact of social behavior on parasite transmission. However, advances in Social Network Analysis (SNA) have allowed researchers to investigate how subtle, more fine-grain, differences in behavior shape infection risk in unique ways. SNA takes into account the amount, duration and type of social interaction that individuals had with one another to compute multiple metrics that help determine how individuals are connected to one another. A new meta-analysis by Drs. Léa Briard and Vanessa Ezenwa finds that SNA is significantly better at detecting the relationship between social behavior and parasite infection, compared to group size alone. They also identify future research directions that will help us better understand the mechanisms underpinning parasite transmission between social hosts.
To conduct their meta-analysis Briard and Ezenwa examined 18 studies that utilized Social Networking Analysis (SNA) and identified general insights about social behavior and parasitism. They were first interested in quantifying, across host and parasite species, the overall effect of individual social behaviour, measured by SNA, on parasitism. Then, they were interested in identifying any attributes of the host and parasite that might help explain observed variation across studies, in terms of magnitude or direction of said effect. The attributes they consider were 1) SNA metrics 2) host behaviour used to build the social network (e.g. contact versus distance) 3) host social organization (solitary versus stable group), 4) the measure used to quantify parasite infection (richness versus presence/absence) and 5) parasite transmission mode.
The results of the meta-analysis indicate that SNA may be a better tool for measuring the relationship between social behavior and parasite infection risk than group size. It was also found that there was a significant amount of variability in effect sizes across the 18 studies that were analysed, with this phenomena unable to be attributed to SNA metrics or host and parasite attributes. This indicates that further research will be necessary to determine why effects seem to vary across different groups of social animals. Additionally, it was noted that a majority of the studies analyzed were focused on mammalian hosts and helminth parasites, with there being a possibility that parasite dynamics could act differently with non-mammalian hosts and a wider array of parasites.
Briad, L., Ezenwa, V.O. (2021). Parasitism and host social behavior: a meta-analysis of insights derived from social network analysis. Animal Behavior. https://doi.org/10.1016/j.anbehav.2020.11.010