Experimental evolution alters the rate and temporal pattern of population growth in Batrachochytrium dendrobatidis, a lethal fungal pathogen of amphibians

Ecology and Evolution

Jamie Voyles³  Leah R. Johnson⁴  Cheryl J. Briggs²  Scott D. Cashins⁵  Ross A. Alford¹  Lee Berger⁵  Lee F. Skerratt⁵  Rick Speare⁵ 

[1] School of Marine and Tropical Biology, Amphibian Disease Ecology Group, James Cook University, Townsville, Queensland, Australia;Department of Ecology, Evolution and Marine Biology, University of California, Santa Barbara, California;Department of Biology, New Mexico Tech, Socorro, New Mexico;Department of Integrative Biology, University of South Florida, Tampa, Florida;School of Public Health, Tropical Medicine and Rehabilitation Sciences, Amphibian Disease Ecology Group, James Cook University, Townsville, Queensland, Australia

关键词: Amphibian chytridiomycosis;    amphibian declines;    Batrachochytrium dendrobatidis;    evolution of virulence;    experimental evolution;    host–pathogen interactions;    serial passage experiments;   

DOI  :  10.1002/ece3.1199

来源: Wiley

【 摘 要 】

Abstract

Virulence of infectious pathogens can be unstable and evolve rapidly depending on the evolutionary dynamics of the organism. Experimental evolution can be used to characterize pathogen evolution, often with the underlying objective of understanding evolution of virulence. We used experimental evolution techniques (serial transfer experiments) to investigate differential growth and virulence of Batrachochytrium dendrobatidis (Bd), a fungal pathogen that causes amphibian chytridiomycosis. We tested two lineages of Bd that were derived from a single cryo-archived isolate; one lineage (P10) was passaged 10 times, whereas the second lineage (P50) was passaged 50 times. We quantified time to zoospore release, maximum zoospore densities, and timing of zoospore activity and then modeled population growth rates. We also conducted exposure experiments with a susceptible amphibian species, the common green tree frog (Litoria caerulea) to test the differential pathogenicity. We found that the P50 lineage had shorter time to zoospore production (T_min), faster rate of sporangia death (d_s), and an overall greater intrinsic population growth rate (λ). These patterns of population growth in vitro corresponded with higher prevalence and intensities of infection in exposed Litoria caerulea, although the differences were not significant. Our results corroborate studies that suggest that Bd may be able to evolve relatively rapidly. Our findings also challenge the general assumption that pathogens will always attenuate in culture because shifts in Bd virulence may depend on laboratory culturing practices. These findings have practical implications for the laboratory maintenance of Bd isolates and underscore the importance of understanding the evolution of virulence in amphibian chytridiomycosis.

【 授权许可】

CC BY   
© 2014 The Authors. Ecology and Evolution published by John Wiley & Sons Ltd.

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