Anthropogenic resource subsidies and host-parasite dynamics in wildlife.

Abstract

For a wide range of wildlife, anthropogenic change and human activities modify the abundance, distribution and timing of food resources [1,2]. Although activities such as deforestation and overfishing deplete resources for many wildlife species, in other cases, urbanization, agriculture and supplemental feeding can provide wildlife with abundant and predictable food [3–8]. As a result, many wildlife have adapted their foraging behaviour to capitalize on these resources [9,10], leading to subsidized populations that are often larger, more aggregated and better fed than their naturally foraging counterparts [11–13]. Importantly, novel assemblages of species can form around anthropogenic resources [14,15], which could facilitate the cross-species transmission of pathogens among wildlife, humans and domestic animals [16]. For example, bird feeders have been implicated in the emergence of virulent pathogens such as Mycoplasma gallisepticum and Trichomonas gallinae in songbirds [17,18]. The 2014 Ebola outbreak in West Africa and 1998 emergence of Nipah virus in Malaysia also underscore the importance of understanding how anthropogenic resources can bring wildlife reservoirs of zoonotic pathogens into close proximity with humans and domesticated species [19–21]. Predicting how anthropogenic resources will impact host–parasite interactions is challenging owing to multiple underlying mechanisms with potentially opposing effects [22,23]. Although energy and nutrients from supplemental food can support robust immune function needed to resist and recover from infections [24], anthropogenic food containing toxins or lacking nutrients could reduce host immunity and increase susceptibility to infection and pathogen shedding [25–27]. Moreover, aggregation around food sources can increase contact rates and facilitate pathogen transmission [28–30]. These individual-scale effects and local interactions are …