Population declines and extinctions of amphibians have been attributed to the chytrid fungus Batrachochytrium dendrobatidis (Bd), especially one globally emerging recombinant lineage (‘Bd-GPL’). We used PCR assays that target the ribosomal internal transcribed spacer region (ITS) of Bd to determine the prevalence and genetic diversity of Bd in South Korea, where Bd is widely distributed but is not known to cause morbidity or mortality in wild populations. We isolated Korean Bd strains from native amphibians with low infection loads and compared them to known worldwide Bd strains using 19 polymorphic SNP and microsatellite loci. Bd prevalence ranged between 12.5 and 48.0%, in 11 of 17 native Korean species, and 24.7% in the introduced bullfrog Lithobates catesbeianus . Based on ITS sequence variation, 47 of the 50 identified Korean haplotypes formed a group closely associated with a native Brazilian Bd lineage, separated from the Bd-GPL lineage. However, multilocus genotyping of three Korean Bd isolates revealed strong divergence from both Bd-GPL and the native Brazilian Bd lineages. Thus, the ITS region resolves genotypes that diverge from Bd-GPL but otherwise generates ambiguous phylogenies. Our results point to the presence of highly diversified endemic strains of Bd across Asian amphibian species. The rarity of Bd-GPL-associated haplotypes suggests that either this lineage was introduced into Korea only recently or Bd-GPL has been outcompeted by native Bd strains. Our results highlight the need to consider possible complex interactions among native Bd lineages, Bd-GPL and their associated amphibian hosts when assessing the spread and impact of Bd-GPL on worldwide amphibian populations.
Bibliographical noteThe research was supported by the National Research Foundation of Korea (NRF), funded by the government of the Republic of Korea (MSIP) (grants 2010‐0002767, 2012R1A1A2044449 and 2012K1A2B1A03000496 to B.W., and KRF‐2007‐313‐C00503 and 2009‐0067686 to M.S.M.) and by Seoul National University (Brain Fusion Program, Brain Korea 21 Program, and New Faculty Resettlement Fund grants to B.W.).
- chytrid fungus
- emerging infectious disease
- host–parasite co-evolution
- invasive species
- population declines
BATAILLE, A., FONG, J. J., CHA, M., WOGAN, G. O. U., BAEK, H. J., LEE, H., MIN, M-S., & WALDMAN, B. (2013). Genetic evidence for a high diversity and wide distribution of endemic strains of the pathogenic chytrid fungus Batrachochytrium dendrobatidis in wild Asian amphibians. Molecular Ecology, 22(16), 4196-4209. https://doi.org/10.1111/mec.12385