Abstract
Chytridiomycosis, a disease caused by the emerging fungus Batrachochytrium dendrobatidis (Bd), has been implicated in the decline of over 500 amphibian species. Population declines could have important genetic consequences, including reduced genetic diversity. We contrasted genetic diversity among both long-Bd-exposed and unexposed populations of the south-east Australian alpine tree frog (Litoria verreauxii alpina) across its range. At the population level, we found no significant differences in genetic diversity between Bd-exposed and unexposed populations. Encouragingly, even Bd-infected remnant populations that are now highly isolated maintain genetic diversity comparable to populations in which Bd is absent. Spatial genetic structure among populations followed an isolation-by-distance pattern, suggesting restricted movement among remnant populations. At the individual level, greater heterozygosity was associated with reduced probability of infection. Loss of genetic diversity in remnant populations that survived chytridiomycosis epidemics does not appear to be a threat to L. v. alpina. We suggest several factors underpinning maintenance of genetic diversity: (1) remnant populations have remained large enough to avoid losses of genetic diversity; (2) many individuals in the population are able to breed once before succumbing to disease; and (3) juveniles in the terrestrial environment have low exposure to Bd, providing an annual ‘reservoir’ of genetic diversity. The association between individual heterozygosity and infection status suggests that, while other work has shown all breeding adults are typically killed by Bd, males with greater heterozygosity may survive longer and obtain fitness benefits through extended breeding opportunities. Our results highlight the critical role of life history in mitigating the impacts of Bd infection for some amphibian species, but we infer that increased isolation as a result of disease-induced population extirpations will enhance population differentiation and thus biogeographic structure.
| Original language | English |
|---|---|
| Article number | e43875 |
| Pages (from-to) | 1-14 |
| Number of pages | 14 |
| Journal | Frontiers of Biogeography |
| Volume | 12 |
| Issue number | 1 |
| Early online date | 2019 |
| DOIs | |
| Publication status | Published - 2020 |
Bibliographical note
Funding Information:We thank the National Parks Association of the ACT for an Honours scholarship for AM; S. Kearney, C. Portway and C. Scheele for assistance with field work; Aaron Chuah for bioinformatic work (initial processing of raw data and quality control); Niccy Aitken for laboratory assistance; Don Driscoll for initial advice on the project. Sampling methods were approved by the ANU Ethics Committee (permit numbers A2011/51 and A2013/32) and carried out under scientific licences SL100411 (NSW), T2011501 (ACT) and 10006052 (Vic). The research was partly funded by an Australian Research Council Future Fellowship to S Banks (FT130100043).
Funding Information:
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