Publication
Predation and parasitism as determinants of animal personalities
Publisher:
Wiley
Date:
31-07-2022
DOI:
10.1111/1365-2656.13781
Abstract: Within the same population, proactive (i.e. bolder, more exploratory, active and aggressive) and reactive (i.e. more timid, less exploratory, less active and more passive) in iduals could be hypothetically maintained due a trade‐off between foraging and vigilance behaviours, provided that both phenotypes differ in their state (e.g. metabolic rates, body condition or energetic needs). Yet, recent findings indicate that among‐in idual variation in intrinsic state can explain only a small proportion of variation in behaviour, meaning that other mechanisms, such as the presence of trophically transmitted parasites, might contribute to maintaining inter‐in idual behavioural differences. Empirical evidence, indeed, suggests strong relationships between certain animal personality traits and parasitic load within host populations. However, the direction of causation between these traits remains unclear: are different behaviours in infected hosts in contrast to uninfected ones the result of manipulation by parasites to increase host predation, or are some personalities inherently more susceptible to infection than others? To better understand the role of parasites in shaping behavioural differences within host populations and examine to what extent parasite manipulation and/or intrinsic differences in parasite susceptibility contribute to maintaining behavioural differences, we used a simulation approach and analysed the change in the frequencies of proactive and reactive in iduals over time under different predation and starvation scenarios, when in idual phenotype either affected a host's risk of infection or not. We found that in the absence of parasites, predation pressure strongly affected the expression of host personality, but the trade‐off between foraging and vigilance behaviours alone could not explain the maintenance of inter‐in idual behavioural differences without temporal variation in predation pressure. By contrast, in the presence of parasites, the two host phenotypes could coexist within populations even when in iduals experienced no temporal variations in predation risk, but only when proactive and reactive hosts were equally susceptible to parasitism. Our findings, thus, indicate that parasites can play an important role in maintaining genetic ersity in their host populations in addition to generating behavioural differences though manipulation.