An emerging viral pathogen truncates population age structure in a European amphibian and may reduce population viability

• Published in: PeerJ preprints 2018-07
• Main Authors: Campbell, Lewis J, Garner, Trenton W J, Giulia Tessa, Scheele, Benjamin C, Griffiths, Amber G F, Wilfert, Lena, Harrison, Xavier A
• Format: Article
• Language: English
• Subjects: Age; Age composition; Demography; Infectious diseases; Life history; Mortality; Population; Population viability; Rana temporaria; Stochasticity
• ISSN: 2167-9843
• DOI: 10.7287/peerj.preprints.27056v1

Infectious diseases can alter the demography of their host populations, reducing their viability even in the absence of mass mortality. Amphibians are the most threatened group of vertebrates globally, and emerging infectious diseases play a large role in their continued population declines. Viruses belonging to the genus Ranavirus are responsible for one of the deadliest and most widespread of these diseases. To date, no work has used individual level data to investigate how ranaviruses affect population demographic structure. We used skeletochronology and morphology to evaluate the impact of ranaviruses on the age structure of populations of the European common frog (Rana temporaria) in the United Kingdom. We compared ecologically similar populations that differed only in their historical presence or absence of ranavirosis (the acute syndrome caused by ranavirus infection). Our results suggest that ranavirosis may truncate the age structure of R. temporaria populations. One potential explanation for such a shift might be increased adult mortality and subsequent shifts in the life history of younger age classes that increase reproductive output earlier in life. Additionally we constructed population projection models which indicated that such increased adult mortality could heighten the vulnerability of frog populations to stochastic environmental challenges.