Fighting Batrachochytrium dendrobatidis: Seeking for the Mechanism Allowing Bd and Host Co-Existence in Two Andean Frogs from Colombia

Sandra Victoria Flechas


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22 Aug 2017

The Role of the Skin Fungal Community as a Barrier Defense against the Pathogen Batrachochytrium dendrobatidis

We aim to compare Bd infection rates and determine whether frog’s microbiome or behaviour affects disease dynamics in two Andean frogs.

© Laura A. Escobar.

© Laura A. Escobar.

In effort to understand the ecology of disease resistance, we will study two sympatric species of frogs from the Colombian Andes; the high-Andean frog (Dendropsophus labialis) and the rocket frog (Rheobates palmatus). Our preliminary research on Bd in these two species revealed differences in infection rates among individuals, among life stages (larvae/metamorph/adult) and between species. We therefore hypothesize that this observed variation in infection prevalence might be due to differences in the microbiome composition, and that the diversity and abundance of bacterial species will vary by life stage and host species also may vary according to the ecology of each frog species. I aim to compare Bd infection rates and determine whether an individual frog’s microbial community composition is correlated with disease dynamics.

The main goals of this proposal are:

i) to estimate Bd infection levels among life stages within species and between species;

ii) to describe and compare variation in the whole microbiome across life stages and species using massively parallel sequencing and correlate the abundance and diversity of symbiotic bacteria with Bd intensity;

iii) to identify through antagonism assays which bacterial species confer antifungal activity and highlight possible candidates for probiotic therapy.

This research will provide much needed information on the ecology of the skin-associated bacteria and the dynamics of host-pathogen interactions helping the scientific community to better understand the basic ecology of the system. Recognizing how microbial communities change among life stages as well as between species with contrasting ecology (in this particular case, one which perform basking behaviour, and other which spend most of the time submerged in the pond), will give us more information and tools to implement management strategies to accurately treat each particular case.

Moreover, since the two study species appear to be stable, despite the prevalence of the pathogen, this high-Andean system offers an ideal scenario to understand how natural populations cope with this fungal pathogen. If we find the processes or mechanisms involved in conferring better resistance to Bd, we will be able to extrapolate our findings to other tropical species, which are in general understudied. Lastly, we will propose candidate bacteria to be tested in bioaugmentation experiments, in order to find good candidates to be used as potential probiotic therapy.

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