Incorporating habitat distribution in wildlife disease models: conservation implications for the threat of squirrelpox on the Isle of Arran

Abstract

Emerging infectious diseases are a substantial threat to native populations. The spread of disease through naive native populations will depend on both demographic and disease parameters, as well as on habitat suitability and connectivity. Using the potential spread of squirrelpox virus (SQPV) on the Isle of Arran as a case study, we develop mathematical models to examine the impact of an emerging disease on a population in a complex landscape of dierent habitat types. Furthermore, by considering a range of disease parameters, we infer more generally how complex landscapes interact with disease characteristics to determine the spread and persistence of disease. Specic ndings indicate that a SQPV outbreak on Arran is likely to be short lived and localised to the point of introduction allowing recovery of red squirrels to pre-infection densities; this has important consequences for the conservation of red squirrels. More generally, we nd the extent of disease spread is dependent on the rare passage of infection through poor quality corridors connecting good quality habitats. Acute, highly transmissible infectious diseases are predicted to spread rapidly causing high mortality. Nonetheless the disease typically fades out following local epidemics and is not supported in the long-term. A chronic infectious disease is predicted to spread more slowly but can remain endemic in the population. This allows the disease to spread more extensively in the long-term as it increases the chance of spread between poorly connected populations. Our results highlight how a detailed understanding of landscape connectivity is crucial when considering conservation strategies to protect native species from disease threats.

An assessment of conflict areas between alien and native species richness of terrestrial vertebrates on a macro‐ecological scale in a Mediterranean hotspot

“…Biological invasions have emerged as a major component of human‐induced global change and are one of the five major pressures driving biodiversity loss, and ultimately the extinction of native species (Lövei, ; Brook, Sodhi & Bradshaw, ; Roy et al ., ). Alien species may affect the invaded ecosystems to varying degrees (Hobbs et al ., ), some resulting in substantial economic and health costs to human societies (Pejchar & Mooney, ), along with causing the progressive substitution and elimination of native species through predation, hybridization, the introduction of disease, habitat alteration and competition for resources or space (Gurevitch & Padilla, ; Kumschick et al ., ; Macpherson et al ., ). Known examples of these negative impacts are, among others, the zebra mussel Dreissena polymorpha , which have invaded fresh waters in North America (Ricciardi, ), and amphibian chytrid fungus Batrachochytrium dendrobatidis , which are responsible for the recent worldwide outbreaks of amphibian chytridiomycosis (Fisher, Garner & Walker, ).…”

“…In this respect, although alien species are the second most common threat associated with native species extinction (Bellard, Cassey & Blackburn, ), large‐scale studies with which to explicitly guide decisions relating to the management of alien species risk assessments are not frequent (but see Rodríguez et al ., ; Guisan et al ., ; Thalmann et al ., ). This is, however, not exclusive to invasion biology, since <1% of the currently published papers that employ a macro‐ecological perspective are specifically targeted toward conservation decisions (Guisan et al ., ; Acevedo et al ., ; Macpherson et al ., ). In this scenario, it is necessary to disentangle the aspects which drive alien species distribution patterns that can be attributed to different factors (namely, native species richness, human activity and abiotic characteristics) in order to establish solid and efficient alien species management plans.…”

Disease, invasions and conservation: no evidence of squirrelpox virus in grey squirrels introduced to Italy

“…Where SQPV is present, the grey squirrel replaces red squirrels up to 25 times faster than in areas without the infection, where only competition for resources occurs (Rushton et al ., ). SQPV in the UK appears thus as a crucial driver in the interaction between the alien and the native species and collecting data on its presence is fundamental in order to plan adequate management and conservation strategies (Gurnell et al ., ; Schuchert et al ., ; Macpherson et al ., ; Bertolino et al ., ; White et al ., ).…”

Modelling seasonal habitat suitability and connectivity for feral pigs in northern Australia: towards risk-based management of infectious animal diseases with wildlife hosts

“…Deeper, dynamic insights into disease-host interactions and the spread of epidemics for better incursion preparedness could be gained through epidemiological simulation models (Ostfeld et al 2005;Riley 2007;Milne et al 2008). Our data on patch and matrix connectivity could be integrated to realistically constrain pathways of spread or the extent of epidemiologically connected zones (Cowled & Garner 2008;Rees et al 2013, Macpherson et al 2016. Epidemiological models could also elucidate the relationship between connectivity and disease transmission or persistence in wildlife hosts.…”

“…We focused on understanding habitat connectivity for the wildlife host, as such knowledge gaps have impeded epidemiological models and disease management in Australia and elsewhere (Ostfeld et al 2005;Cowled & Garner 2008;Rees et al 2013;Macpherson et al 2016). …”