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.

Background: Many amphibian species are negatively affected by habitat change due to anthropogenic activities. Populations distributed over modified landscapes may be subject to local extinction or may be relegated to the remaining—likely isolated and possibly degraded—patches of available habitat. Isolation without gene flow could lead to variability in phenotypic traits owing to differences in local selective pressures such as environmental structure, microclimate, or site-specific species assemblages.Methods: Here, we tested the microevolution hypothesis by evaluating the acoustic parameters of 349 advertisement calls from 15 males from six populations of the endangered amphibian species Proceratophrys moratoi. In addition, we analyzed the genetic distances among populations and the genetic diversity with a haplotype network analysis. We performed cluster analysis on acoustic data based on the Bray-Curtis index of similarity, using the UPGMA method. We correlated acoustic dissimilarities (calculated by Euclidean distance) with geographical and genetic distances among populations.Results: Spectral traits of the advertisement call of P. moratoi presented lower coefficients of variation than did temporal traits, both within and among males. Cluster analyses placed individuals without congruence in population or geographical distance, but recovered the species topology in relation to sister species. The genetic distance among populations was low; it did not exceed 0.4% for the most distant populations, and was not correlated with acoustic distance.Discussion: Both acoustic features and genetic sequences are highly conserved, suggesting that populations could be connected by recent migrations, and that they are subject to stabilizing selective forces. Although further studies are required, these findings add to a growing body of literature suggesting that this species would be a good candidate for a reintroduction program without negative effects on communication or genetic impact.

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Background. Many amphibian species are negatively affected by anthropogenic habitat change. Populations distributed over modified landscapes may be subject to local extinction or may be relegated to remaining, likely isolated and possibly degraded, patches of available habitat. Isolation without gene flow can lead to variability in phenotypic traits due to differences in local selective pressures, such as environmental structure, microclimate or site-specific species assemblages. Methods. Here we tested this microevolution hypothesis by evaluating the acoustic parameters of 349 advertisement calls from 15 males representing six populations of the endangered species Proceratophrys moratoi. In addition, we analyzed the genetic distance between populations and the genetic diversity by haplotype network. We carried out a cluster analysis by Bray-Curtis index of similarity using acoustic data by UPGMA method. We correlated acoustic dissimilarities (calculated by Euclidean distance) with geographic and genetic distances among populations. Results. Spectral traits of the advertisement call of P. moratoi presented lower coefficients of variation than did temporal traits both within and among males. Cluster analyses placed individuals without population and geographical distance congruence, but recovered the species topology in relation to sister species. The genetic distance was low among populations: it did not exceed 0.4% for the most distant populations, and was not correlated with acoustic distance. Discussion. Both acoustic features and genetic sequences are highly conserved, suggesting that populations may be connected by recent migrations or that they are subject to stabilizing selective forces. Although future studies are needed, these findings contribute to a growing body of literature suggesting that this species would be a good candidate for a reintroduction program without negative effects on communication or even genetic heritage.