Disease and the endangered Litoria verreauxii alpina: what we know and how we can assist management

Amphibians are currently experiencing the greatest biodiversity decline of all vertebrate taxa, and disease is a major culprit. We studied the pathogen-host dynamics of the fungal pathogen, Bd, and the declining alpine frog... [ view full abstract ]

Amphibians are currently experiencing the greatest biodiversity decline of all vertebrate taxa, and disease is a major culprit. We studied the pathogen-host dynamics of the fungal pathogen, Bd, and the declining alpine frog species, Litoria verreauxii alpina, through field and lab experiments in order to improve our understanding of how remnant populations persist with endemic infection, and to inform disease management.
In the lab, we assessed how infection affected individuals from different exposure histories of the pathogen, and found that while individuals, populations and clutches varied in susceptibility, variations were not strongly correlated with population exposure history. We monitored infection in populations during the breeding season, and found that even in disease endemic populations, infection prevalence is high and there is a low chance of individual recovery from infection, causing near complete population turnover every year. However, the impact of Bd on larval and juvenile stages is less severe, and thus high recruitment facilitates population persistence in this species.
Because recruitment is important for persistence, we explored how disease may affect reproductive output in the lab. We found that both males and females increased gamete production when infected with disease. If infected animals are increasing reproductive efforts and producing more offspring before succumbing to disease, it is possible that population level selection for disease resistance or tolerance is minimised. In the absence of population level disease resistance or tolerance, conservation and management efforts for endangered species should focus on habitat management to support recruitment.