A história de vida do hospedeiro pode intermediar respostas adaptativas a um patógeno emergente em anfíbios?

• Autor(a) principal: Mesquita, Andréa Ferreira Cussolim [UNESP]
• Data de Publicação: 2016
• Tipo de documento: Trabalho de conclusão de curso
• Idioma: por
• Título da fonte: Repositório Institucional da UNESP
• Texto Completo: http://hdl.handle.net/11449/156057; http://www.athena.biblioteca.unesp.br/exlibris/bd/capelo/2017-09-28/000890198.pdf
• topic: Anfíbio; Tolerancia; Diatese; Amphibians

Host-generalist pathogens sporadically infect naïve hosts, potentially triggering epizootics. The frog killing-fungus Batrachochytrium dendrobatidis (Bd), which is linked to amphibian declines globally, is described as a host-generalist pathogen, infecting host species with varying life histories. Bd is a waterborne pathogen and has caused disproportionate population declines and extinctions of amphibians breeding in aquatic environments. Conversely, terrestrial amphibian species undergoing direct development in the forest leaf-litter are only sporadically exposed to Bd in the wild, and thus they may lack evolutionary responses against the pathogen. Here we tested whether terrestrial amphibian species show (i) higher infection loads and (ii) higher mortality rates than aquatic amphibians when experimentally exposed to Bd. We exposed three terrestrial and three aquatic amphibian host species to Bd (or clean water for the control group) in the laboratory. We swabbed individual frogs before and after the experimental infection and used qPCR analyses to quantify Bd infection loads from each individual host. We used a combination of Generalized Linear Mixed Models (GLMMs) and Parametric Survival Models (PSMs) to test for the effect of host developmental mode (aquatic vs. terrestrial) on both Bd loads and host mortality. We found that terrestrial amphibian species exposed to Bd showed higher infection loads than aquatic amphibian species. Terrestrial amphibians exposed to Bd also showed higher mortality rates than aquatic amphibian species. Our study shows a clear pattern of host life history triggering strong evolutionary responses against a widespread pathogen. Combined, our results provide novel information about the evolution of host responses to chytridiomycosis and contribute to the conservation of the globally endangered amphibians...