Poster presented at the 2015 Ecology & Evolution of Infectious Diseases conference @ Athens, Georgia.

1. Spatial and temporal dynamics of skin microbial communities
in a Neotropical frog persisting with chytridiomycosis
Ana V. Longo* and Kelly R. Zamudio
Department of Ecology and Evolutionary Biology, Cornell University, Ithaca, NY 14850 (*avl7@cornell.edu)
Introduction
Batrachochytrium dendrobatidis (Bd) is a pathogenic
skin fungus of amphibians. Bd infection disrupts the
stability of skin microbial communities (Jani and Briggs,
2014; Becker et al. 2015). However, we still lack a clear
understanding of how fine scale temporal variability can
alter microbial community structure and composition,
and whether the loss of beneficial microbes predisposes
hosts to subsequent infections.
Objectives
Goal: Test the resilience of skin microbial communities
under different regimes of natural infections and
seasonal temperature changes.
Objectives:
1. Measure frog body temperature as a proxy of
environmental fluctuations.
2. Quantify bacterial alpha and beta diversity in time
and space.
3. Compare and contrast microbial communities and Bd
infection dynamics.
Methods
Contrasting responses in frog body temperatures
25.0
22.5
20.0
17.5
15.0
West Central East
FrogBodyTemperature(°C)
Jan Apr Sep Nov Jan Apr Sep Nov Jan Apr Sep Nov
2012
a a b b a b c d a a b b
700
800
900
1000
1100
20
30
40
50
60
Jan Apr Sep Nov
PhylogeneticDiversityOTURichness
Locality
West
Central
East
Jan Apr Sep Nov
700
800
900
1000
1100
20
30
40
50
60
Jan Apr Sep Nov
PhylogeneticDiversityOTURichness
Locality
West
Central
East
Jan Apr Sep Nov
700
800
900
1000
1100
20
30
40
50
60
Jan Apr Sep Nov
PhylogeneticDiversityOTURichness
Locality
West
Central
East
Jan Apr Sep Nov
Body
Temperature
Bacteria
Bd
Skin
Swabs
PCR 16S V4 rRNA
(earthmicrobiome.org)
Infection intensity
MiSeq 250bpggplots,
vegan, betapart
OTU table,
alpha and
beta diversity
3 localities
4 time points (yr. 2012)
West & East –
seasonal patterns in
body temperatures
Central – steady
increase in body
temperatures
through time.
Intra-season cycles of Bd infection
Intensity
0
104
Prevalence:At the western and eastern localities, we
detected intra-seasonal cycles
characterized by months with low infection
prevalence and high infection intensity
(denoted by asterisks). The timing of these
cycles did not match expected changes in
temperature related to seasons.
Microbial diversity significantly increased through time
Temporal changes in α-diversity
were not concordant with Bd or body
temperatures. Bacteria were replaced
through time rather than represent a
subset of the communities from the
most biologically diverse time point.
Proportion
anti-Bd (*): 0.25 0.03 0.26
Prevalence: 0.70 0.44 0.64
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Anti-Bd bacteria absent or in low abundance in January
A high proportion of
indicator OTUs with
confirmed anti-Bd activity
(denoted by asterisks) were
highly associated with the
months of April, September,
and November. The central
locality had the lowest
proportion of these putatively
beneficial bacteria.
Funding and more…
Discussion
Scan the QR code with your
smartphone to access this
poster at slideshare.net
References
Becker MH, Walke JB, Cikanek S, Savage AE, Mattheus N, Santiago CN et al
(2015). Composition of symbiotic bacteria predicts survival in Panamanian golden
frogs infected with a lethal fungus. Proceedings of the Royal Society B-Biological
Sciences 282.
Jani AJ, Briggs CJ (2014). The pathogen Batrachochytrium dendrobatidis disturbs
the frog skin microbiome during a natural epidemic and experimental infection.
Proceedings of the National Academy of Sciences 111: E5049-E5058.
Seasonally-modulated dynamics of infection present
many interpretation challenges, in part, because causal
mechanisms are intertwined. Environmental changes
affect host behavior, immunity and physiology, as well
as pathogen growth, yet we have not been able to
quantify their relative contribution to pathogen and host
performance. Our findings contribute important links
between seasonal environmental changes, species
interactions, and host responses in wild amphibian
populations.
Our results underscore how natural fluctuations in
temperature and precipitation between months create
opportunities for microbial replacement, potentially
attenuate pathogen transmission, and contribute to host
persistence in E. coqui populations.
Eleutherodactylus coqui is a
terrestrial direct-developing frog.