Thursday, 24 November 2011
Sunday, 6 November 2011
Farrer et al describe in PNAS the first whole-genome resequencing of Bd from isolates worldwide. This study has provided a wealth of new data, including the unexpected discovery of three divergent lineages of Bd. One lineage has only been recovered from Switzerland (BdCH) and another from South Africa and the Mediterranean island of Mallorca (BdCAPE). The third lineage, BdGPL, occurs worldwide and is the only lineage associated with declines in Europe (Pyrenees & Iberia), Central America, North America (Sierra Nevadas) and Australia. Laboratory tests show that BdGPL is hypervirulent when compared to BdCAPE, and emerged some time in the 20th Century. Genomic patterns in BdGPL shows that it arose only once and is likely a hybrid. So, what is this data telling us? Firstly, the intercontinental spread of Bd is clearly owing to human movement of amphibians: that is how BdCAPE came 'jump' from the African Cape to Mallorca. Secondly, BdGPL is a recombinant offspring resulting from mating between two lineages of Bd. Whether these were brought together by the trade in amphibians resulting in the creation of a 'fungal superbug' remains to be determined.