Intraspecific trait variation of a generalist herbivore in multiple dimensions: associations between personality, individual dietary specialisation and parasites

Abstract

Intraspecific variation in traits, such as animal behaviour, has important ecological consequences. This variation may affect an animal’s diet, space use and the risks they face from predators and parasites. Individual dietary specialisation recognises the intraspecific variation in realised dietary niche. Whether individual specialists and generalists consume diets differing in quality as well as breadth is unclear. Animal personality (consistent individual variation in behaviour) may influence dietary specialisation by altering how individuals perceive and react to external stimuli. Animal personality and personality-driven urban space use may affect variation in parasite occurrence among animals at the human-wildlife interface. I tested the association between behavioural and dietary phenotypes by quantifying animal personality, and diet in multiple dimensions, using free-ranging common brushtail possums (Trichosurus vulpecula). I also tested variation in parasite (protozoan Cryptosporidium) occurrence as linked to animal personality and space use of possums at the urban-natural interface. I found that dietary specialists ate a narrow set of low-quality resources while generalists consumed a broad, high-quality diet. My study demonstrates the important link between animal personality and individual dietary specialization for the first time. I identified three Cryptosporidium species — C. hominis, C. muris and C. parvum — in possums. Personality and urban space use affected the likelihood of individual possums carrying Cryptosporidium. My results highlight the importance of individual variation in behaviour to identify individual phenotypes that may disproportionately affect both food-web and disease dynamics: proactive – generalists likely to be pests and proactive – greater users of urban space likely to carry pathogens. Understanding these relationships provides a key basis for improving biodiversity conservation, pest, and disease management.