title: Amphibian-killing chytrid in Brazil comprises both locally endemic and globally expanding populations.
abstract: Chytridiomycosis, caused by the fungus Batrachochytrium dendrobatidis (Bd), is the emerging infectious disease implicated in recent population declines and extinctions of amphibian species worldwide. Bd strains from regions of disease-associated amphibian decline to date have all belonged to a single, hypervirulent clonal genotype (Bd-GPL). However, earlier studies in the Atlantic Forest of southeastern Brazil detected a novel, putatively enzootic lineage (Bd-Brazil), and indicated hybridization between Bd-GPL and Bd-Brazil. Here, we characterize the spatial distribution and population history of these sympatric lineages in the Brazilian Atlantic Forest. To investigate the genetic structure of Bd in this region, we collected and genotyped Bd strains along a 2400-km transect of the Atlantic Forest. Bd-Brazil genotypes were restricted to a narrow geographic range in the southern Atlantic Forest, while Bd-GPL strains were widespread and largely geographically unstructured. Bd population genetics in this region support the hypothesis that the recently discovered Brazilian lineage is enzootic in the Atlantic Forest of Brazil and that Bd-GPL is a more recently expanded invasive. We collected additional hybrid isolates that demonstrate the recurrence of hybridization between panzootic and enzootic lineages, thereby confirming the existence of a hybrid zone in the Serra da Graciosa mountain range of Paraná State. Our field observations suggest that Bd-GPL may be more infective towards native Brazilian amphibians, and potentially more effective at dispersing across a fragmented landscape. We also provide further evidence of pathogen translocations mediated by the Brazilian ranaculture industry with implications for regulations and policies on global amphibian trade.
authors.affiliation: Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, MI, 48109, USA.
authors.forename: T S
authors.initials: TS
authors.lastname: Jenkinson
authors.affiliation: Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, MI, 48109, USA.
authors.forename: C M
authors.initials: CM
authors.lastname: Betancourt Román
authors.affiliation: Laboratório de História Natural de Anfíbios Brasileiros (LaHNAB), Departamento de Biologia Animal, Instituto de Biologia, Universidade Estadual de Campinas, Campinas, SP, 13083-862, Brasil.
authors.forename: C
authors.initials: C
authors.lastname: Lambertini
authors.affiliation: Programa de Pós-Graduação em Diversidade Biológica e Conservação nos Trópicos, Instituto de Ciências Biológicas e da Saúde, Universidade Federal de Alagoas, Maceió, AL, 57052-970, Brasil.
authors.forename: A
authors.initials: A
authors.lastname: Valencia-Aguilar
authors.affiliation: Department of Biology, Texas State University, San Marcos, TX, 78666, USA.
authors.forename: D
authors.initials: D
authors.lastname: Rodriguez
authors.affiliation: Laboratório de História Natural de Anfíbios Brasileiros (LaHNAB), Departamento de Biologia Animal, Instituto de Biologia, Universidade Estadual de Campinas, Campinas, SP, 13083-862, Brasil.
authors.forename: C H L
authors.initials: CH
authors.lastname: Nunes-de-Almeida
authors.affiliation: Laboratório de Anfíbios e Répteis, Departamento de Zoologia, Instituto de Biologia, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, 21941-902, Brasil.
authors.forename: J
authors.initials: J
authors.lastname: Ruggeri
authors.affiliation: Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, MI, 48109, USA.
authors.forename: A M
authors.initials: AM
authors.lastname: Belasen
authors.affiliation: Laboratório de Antígenos Bacterianos, Departamento de Genética, Evolução e Bioagentes, Instituto de Biologia, Universidade Estadual de Campinas, Campinas, SP, 13083-862, Brasil.
authors.forename: D
authors.initials: D
authors.lastname: da Silva Leite
authors.affiliation: Department of Ecology and Evolutionary Biology, Cornell University, Ithaca, NY, 14853, USA.
authors.forename: K R
authors.identifier: http://orcid.org/0000-0001-5107-6206
authors.initials: KR
authors.lastname: Zamudio
authors.affiliation: School of Biology and Ecology, University of Maine, Orono, ME, 04469, USA.
authors.forename: J E
authors.initials: JE
authors.lastname: Longcore
authors.affiliation: Laboratório de História Natural de Anfíbios Brasileiros (LaHNAB), Departamento de Biologia Animal, Instituto de Biologia, Universidade Estadual de Campinas, Campinas, SP, 13083-862, Brasil.
authors.forename: F L
authors.initials: FL
authors.lastname: Toledo
authors.affiliation: Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, MI, 48109, USA.
authors.forename: T Y
authors.initials: TY
authors.lastname: James
mesh_terms: D000663:Amphibians / Q000382:microbiology*; D000818:Animals; D001938:Brazil; D008411:Chytridiomycota / Q000235:genetics*; D005828:Genetics, Population; D005838:Genotype; D006824:Hybridization, Genetic; D058885:Multilocus Sequence Typing; D016533:Mycological Typing Techniques; D009181:Mycoses / Q000382:microbiology* / Q000662:veterinary
keywords: Batrachochytrium dendrobatidis; chytridiomycosis; emerging infectious disease; multilocus genotyping; population genetics