What a salamander virus can tell us about the future of biodiversity
amid a changing climate

Date:
February 3, 2022
Source:
Northern Arizona University
Summary:
The 'Ebola virus of the amphibian world' is as unpleasant as it
sounds, but a species of salamander that lives in Arizona found
a way to live with the endemic disease. As the climate changes,
viruses change along with it, and this unpredictable virus could
have a more severe effect on different species in the future.



FULL STORY ==========================================================================
A new project from two NAU scientists aims to predict the future - - specifically, the future of different amphibian species in the face of
an unpredictable environment.


========================================================================== Principal investigator Joseph Mihaljevic, an assistant professor in
the School of Informatics, Computing, and Cyber Systems who studies
the ecology of infectious diseases, and co-PI Jason Ladner, assistant
professor in the Pathogen and Microbiome Institute who studies genomic epidemiology, received an $844,000 grant from the National Science
Foundation to study ectotherms -- a type of cold-blooded organism that
includes amphibians, fish, reptiles and insects. Their project will
create better, more predictive models to help scientists understand
how climate change and infectious diseases will likely interact in the
future to impact the health of wildlife species and predict how climate
and disease affect these species, including those at risk of extinction.

Ectotherms play a variety of diverse roles in the ecosystem; amphibians
eat many insects that are considered pests, and they are sources of food
for snakes, fish, birds and other animals. Because they have life stages
in the water and on land, they are a significant part of the food web
for multiple ecosystems.

"Our ultimate goal is to better understand and better predict how
climate change interacts with infectious diseases to affect whether some species might be at a higher or lower risk of extinction, particularly
for species that are ectotherms," Mihaljevic said. "For these types of
species, whose body temperature is regulated by the environment, the
climate determines how well they can cope with infectious disease, and
the climate also impacts how well these species survive and reproduce
in their habitats. We need better predictive models of when climate
and disease are expected to have the largest combined impacts on these
species in the future. This is important for conserving biodiversity,
as well as for agriculture and aquaculture." The research will focus
on ranaviruses, a naturally occurring group of viruses that infects
amphibians, and their effects on the tiger salamander population.

Mihaljevic called it the "Ebola virus of the amphibian world;" it causes systemic infection and organ failure among larval salamanders, but
adults are typically able to produce an effective immune response. Tiger salamanders can live for a decade or more, so even if a virus outbreak decimates one set of offspring, the animals have many years of
reproduction left. Historically, this has meant the overall population
of salamanders has been fairly stable.

That's good news for the tiger salamander, but not every amphibian lives
that long. Many species don't have as many opportunities for reproduction, which means their populations are at much greater risk from this and
other diseases - - diseases that are evolving in unpredictable ways as
the climate changes.

The researchers will survey natural populations of larval salamanders in
water bodies in Arizona. They test for the virus by swabbing the skin of
larvae and adults; the virus is shed from the skin back into the water,
so they can detect the virus molecularly on the swabs. They also will
monitor when adults breed and how many eggs they produce and can relate
these patterns to precipitation, temperature patterns and other climate indicators.

Using lab experiments, they will study how water temperature affects how
the virus transmits and build that knowledge into mathematical models,
which explain how the climate influences salamander breeding and the
severity of virus outbreaks. The next step is to look at long-term
effects on population sizes, simulating what climate will look like in
20, 30 or 50 years and attempt to predict the likelihood that salamander populations will decline over time.

What they learn from the salamanders will help create better models
that can be applied to predict whether other amphibian species are at
a higher or lower risk of extinction in the future.

It's a critical question to answer when we know the threat of climate
change is real but we don't know the specific forms that threat will take.

"Emerging infectious diseases are a serious concern for global
biodiversity, especially due to the movement of animals and pathogens
through anthropogenic activity, and future climate change has the
potential to exacerbate the impacts of infectious diseases, especially
for exothermic species that are not able to self-regulate their internal temperature," Ladner said. "This work is important because it will allow
us to link seasonal disease dynamics with temperature variability to
understand how the impacts of infectious disease might be affected by
climate change." As part of the project, the team also will sequence
up to 50 genomes of the Ambystoma tigrinum virus (a type of ranavirus)
isolated from various wildlife species, which will allow them to explore
basic questions about how this pathogen survives and circulates throughout
the Southwest.

Mihaljevic and Ladner also are partnering with Greg Dwyer at the
University of Chicago and scientists from Arizona Game and Fish. Several undergraduate students and a doctoral student will participate in
the research, which builds on work from master's students Kelsey
Banister and Kathryn Cooney, alumni Diego Olivo and Monica Long, and undergraduate students Braden Spencer and Zane Ondovcik. Olivo and
Spencer's collaborative project was funded by Urdea, Ondovcik's current
project is funded by the Hooper Undergraduate Research Award. It also
builds on efforts that were funded by a Heritage Grant from Arizona Game &
Fish and TRIF.

========================================================================== Story Source: Materials provided by Northern_Arizona_University. Note:
Content may be edited for style and length.


==========================================================================


Link to news story: https://www.sciencedaily.com/releases/2022/02/220203083622.htm

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