Parasite infection and host personality: Glugea-infected three-spined sticklebacks are more social

Abstract

The existence of animal personality is now well-documented, although the causes and consequences of this phenomenon are still largely unclear. Parasite infection can have pervasive effects on hosts, including altering host behaviour, and may thus contribute to differences in host personality. We investigated the relationship between the three-spined stickleback and its common parasite Glugea anomala, with focus on differences in host personality. Naturally infected and uninfected individuals were assayed for the five personality traits activity, exploration, boldness, sociability, and aggression. If infected fish behaved differently from uninfected, to benefit this parasite with horizontal transmission, we predicted behaviour increasing interactions with other sticklebacks to increase. Infection status explained differences in host personality. Specifically, Glugea-infected individuals were more social than uninfected fish. This confirms a link between parasite infection and host behaviour, and a relationship which may improve the horizontal transmission of Glugea. However, future studies need to establish the consequences of this for the parasite, and the causality of the parasite-host personality relationship.Significance statementParasite infection that alters host behaviour could be a possible avenue of research into the causes of animal personality. We studied the link between infection and personality using the three-spined stickleback and its parasite Glugea anomala. We predicted that infected individuals would be more prone to interact with other sticklebacks, since this would improve transmission of this parasite. The personality of uninfected and naturally infected fish was measured and we observed that Glugea-infected sticklebacks were more social. Our results confirm a link between parasitism and variation in host personality.Electronic supplementary materialThe online version of this article (10.1007/s00265-018-2586-3) contains supplementary material, which is available to authorized users.

Effects of monoamine manipulations on the personality and gene expression of three-spined sticklebacks

“…Our study confirms the importance of parasites in terms of animal behavior, matching previous findings particularly showing that infected sticklebacks are more sociable than uninfected fish (Ward et al, 2005;Barber and Scharsack, 2010;Petkova et al, 2018). Parasitism could thus be another contributing mechanism explaining variation in host personality (Poulin, 2010).…”

“…Thus, a subset of fish were sampled at each time point (day 0, day 6 and day 18) after the behavioral assay to collect brains to measure gene expression, providing us with both behavioral data and gene expression data from three time points, but for each individual fish we only have the brain data from one time point. At this point, fish length was measured and the presence of visible parasites (Glugea anomala) was noted (Petkova et al, 2018). Parasite infection, which was due to the fact that the fish were wildcaught, was monitored to account for potential inter-individual differences for statistical analysis; however, as it was impossible to experimentally control the infection, we did not investigate the interaction between pharmaceutical treatment and parasitic infection.…”

“…Type of manipulation (dopamine, serotonin, both, or control; categorical variable with four levels) and parasite status (binary, yes/no) were added as fixed effects. Parasite status was included to control for the fact that our fish were wild caught and some were parasitized, and previous studies show that parasite infection and personality can co-vary (Petkova et al, 2018), and that monoamine variation and parasite status can be linked (e.g. Øverli et al, 2001a,b).…”

Bidirectional interactions between host social behaviour and parasites arise through ecological and evolutionary processes

“…All four possibilities, whether parasite-or host-mediated, can lead to notable changes in social behaviours of hosts, with important consequences for parasite transmission. For example, three-spined sticklebacks (Gasterosteus aculeatus) infected with the socially transmitted parasite Glugea anomala are more likely than their uninfected counterparts to be attracted to conspecifics, a behaviour predicted to augment transmission (Petkova et al, 2018). Whether behavioural changes in that system are parasite-or host-mediated remains unclear, but in this section, we focus on changes in behaviour during infection that are likely host-mediated, and consider parasite-mediated behavioural changes in 'Host social behaviours influence parasite evolution (Arrow D)' section.…”

Personality affects dynamics of an experimental pathogen in little brown bats

“…For instance, sociability, defined as an individual's reaction to the presence or absence of conspecifics, could be particularly important [ 14 ] because sociable individuals with high contact rates should have more opportunities to spread infection [ 12 ]. However, despite theoretical models [ 11 , 15 ] and some observational data [ 13 , 16 , 17 ], experimental tests of this hypothesis are generally lacking.…”