Predicting Amphibian Survival of Chytridiomycosis (batrachochytrium dendrobatidis)

Allie Smith

Examining Key Enviromental, Ecological, and Biological Traits and their Relationship to Chytridiomycosis Susceptiabilty

Looking at the novel fungal disease Chytridiomycosis, caused by batrachochytrium dendrobatidis

Problem Statement & Background

Amphibian species are dying at an alarming rate, particularly due to a skin disease called chytridiomycosis, which is caused by the fungus batrachochytrium dendrobatidis (Bd). Though it is a novel disease, part of the reason it is so wide spread and devastating is because of carrier species. So, I am researching what factors cause a species to be susceptible or tolerant. Scientists working in the field do not have the time to sort through the large data base of disconnected factors, so I sought to create a generalized criterion to aid conservation efforts.

Research Queston

“What main environmental, biological, and genetic factors predict whether anurans will be Bd tolerant, and how can these commonalities be utilized to aid the scientific and general public in the conservation of at-risk species?”

Hypothesis

Based on three primary factors (environmental, biological, and genetic), utilizing multiple facets of information, it is possible to predict amphibian population declines from Bd based on certain criteria, and then use that in application of conservation purposes

Proposed Method of Study

I used the method data triangulation, which uses multiple sources to synthesize a conclusion, utilizing overlap as a way to strengthen evidence. It is crucial to assessing occurrences of specific traits to create a criteria to be applied to greater data sets. This is the method I chose because it was unrealistic to do population surveys and genome analysis at a high school level. However, it was feasible to use multiple sources as data points to formulate my own conclusion. I collected both qualitative and quanitative data, making my research mixed method.

Significance and Value of Study

Since amphibians breathe partially through their skin and are in both aqueous and terrestrial environments, they are more susceptible to extinction. Thus, they serve as a good indicator of the progression of the sixth extinction, similar to a canary in a mine. Bd specifically has affected so many amphibian species that obvious attention needs to be dedicated to it.
Scientists can have an easily discernible checklist to use in the field to test whether amphibians are more at risk or not based on primary factors that can be found in the field. This enables them to make quick snap decisions instead of taking months and months, which many species don't have
Conservation efforts can be more focused. Instead of spending months doing hard research about what species to dedicate efforts and resources to, which many species don't have the time for, they can utilize this checklist to pinpoint exact species that need help.

Gap

No collection of multiple different factors to formulate a generalized criterion understandable by scientists and the general population alike. While there is a lot of prior research, it is disconnected

Limitations

Little genetic info available
Varying levels of information on different species
Cannot process thousands of articles

Assumptions

First, I am assuming there are actual correlations between different environmental and biological factors and Bd tolerance, which is a fact my research relies on. I'm also assuming these are quantifiable traits. With regards to the six Bd-Tolerant species that I used as my main comparison group, I am assuming that they are in fact Bd-Tolerant.

Definitions

Amphibian: a class of cold-blooded vertebrate animals that includes frogs and toads, for the use of this experiment, that typically live both on land and in water

Anura: an order in the amphibian class that specifically includes frogs and toads

Tolerance: a mechanism that host organisms use to fight pathogens (Bd zoospores) and infections

Bd Zoospores: an asexual spore that is capable of movement, created by fungi to propagate themselves, or reproduce

Genome: the complete set of genes or genetic material present in an organism

Variables

Elevational Range
Occupied Elevations (meters)
Temperature Range
Primary Habitat Temperature (degrees Celsius)
Primarily Aquatic or Terrestrial Environment:
Snout-Vent Length (mm)
Interaction with Carrier Species:
Direct Development or Metamorphosis:
Exhibits Bd Tolerant / Resistant Traits:

Results

The most important data is that Bd-tolerant species and Least Concern species had wide elevational ranges, whereas endangered and extinct species had limited elevational ranges. Endangered and extinct species also had a higher amount of species that live at higher elevations. While the actual temperature that each species typically lives at widely varied across the different groups, there was a clear distinction between the species with a wide tolerance versus a limited tolerance. Only four endangered and extinct species had wide temperature tolerances, whereas the other nine did not. This proved the opposite for the Bd-tolerant and least concern species.

Implications

From my data, I found that conservation efforts should prioritize amphibians that are:

Small
Terrestrial
High Elevations
Limited Temperature Range
Non-adaptable
Interactions with Carrier Species

With these specific factors that I found, scientists should be able to use them as a checklist in the field to determine whether a species needs resources and efforts dedicated to their survival

Data table of Bd-tolerant Species

Data table of Least Concern and Endangered / Extinct Species

Conclusion

I concluded that it was possible to create a generalized criterion that accounted for a wide variety of factors, and when help up against actual sample data sets, the majority of expected results were found. The primary takeaway is that Bd-tolerant species were adaptable, specifically being able to occupy high and low elevations and temperatures. They also were medium or large. Because multiple factors, occupied elevation, temperature tolerance range, and interactions with carrier species, were shown in data to indicate Bd susceptibility, my hypothesis was confirmed. However, there were a few factors that did not lead to any clear indications, which thus causes my hypothesis to only be partially accepted.

Next Steps

Gather, map, and analysis genetic material and genomes
Create localized criteria for specific regions
Locate specific genomes that induce Bd tolerance / traits and genetically modify at-risk species

Researcher

Allie Smith

Class of 2023

alliesmith.research@gmail.com

Link to Presentation with Photo Citations

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