Pandemic, novel, and hybrid genotypes of the amphibian pathogen Batrachochytrium dendrobatidis in the southern Atlantic Rainforest of Brazil
T. S. JENKINSON (1), C. M. Betancourt-Román (1), C. Lambertini (2), C. H. L. N. Almeida (3), J. Ruggeri-Gomes (4), D. Rodriguez (5), D. da Silva Leite (2), K. R. Zamudio (5), J. E. Longcore (6), L. F. Toledo (3), T. Y. James (1). (1) Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, MI, U.S.A.; (2) Departamento Genética, Evolução e Bioagentes, Instituto de Biologia, Universidade Estadual de Campinas, Campinas, Brazil; (3) Museu de Zoologia “Prof. A
Chytridiomycosis of amphibians, caused by the chytrid pathogen <i>Batrachochytrium dendrobatidis</i> (<i>Bd</i>), is the emerging infectious disease implicated in the recent population declines and extinction of amphibian species worldwide. Current data suggest that <i>Bd</i> has been recently introduced to naïve host populations by the intercontinental movement of amphibians. In the decade after its discovery in 1998, all isolated strains of <i>Bd</i> were shown to belong to a single, hyper-virulent clonal genotype. Recently however, multiple groups have reported the existence of novel <i>Bd</i> genotypes, including the existence of a hybrid genotype from the Atlantic Rainforest of Southeastern Brazil. In-depth sampling is needed to define the spatial distribution of the putative endemic and hybrid genotypes. To investigate the population structure of novel, pandemic and hybrid lineages in this putative hybrid zone, pure isolates of pathogen strains were collected from <i>Bd</i> infected anurans at six field sites along a 1400 Km transect of the historical range of the Atlantic Rainforest. Isolates of <i>Bd</i> strains were genotyped by multi-locus sequence typing to assess the effect of latitude, presence of invasive amphibian species, and anthropogenic habitat fragmentation on the spatial distribution of <i>Bd</i> genotypic diversity. Insights gained from this investigation will provide a future framework to test the hypothesis that the hyper-virulence of the pandemic lineage arose from past hybridization events.
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