- Welcome, everyone, to Wednesday Nite @ the Lab.
I'm Tom Zinnen.
I work here at the UW-Madison Biotechnology Center.
I also work for the Division of Extension Wisconsin 4-H.
And on behalf of those folks and our other co-organizers,
PBS Wisconsin, the Wisconsin Alumni Association,
and the UW-Madison Science Alliance,
thanks again for coming to Wednesday Nite @ the Lab.
We do this every Wednesday night, 50 times a year.
Tonight, it's my pleasure to introduce to you Jessica Hua.
She's a professor here
in the Department of Forest and Wildlife Ecology.
She was prompted on the five questions,
so hopefully she's had time to adjust.
[Jessica laughing]
Jessica, the rules are you get to answer
the questions in any way that you'd like.
Doesn't have to be true; just has to be believable.
Where were you born?
- I was born in Kingston, New York.
- And where'd you go to high school?
- Westwood High School in Austin, Texas.
- Whoa, and then where'd you go for your undergrad
and what did you study?
- I went to Southwestern University
and I studied biology and kinesiology.
- We lost our signal.
We have our signal.
Good. - Exciting.
- And I said the word kinesiology and it went away.
And then where'd you go for your advanced degrees
and what did you study?
- I went to the University of Pittsburgh for my PhD
and I studied ecology and evolution there.
- And then did you do any postdocs?
- I did; I spent about a year at Purdue University.
- And then where did you go after Purdue?
- After Purdue, I got my first assistant professor position
at Binghamton University.
- And that's part of the State University of New York.
- That is. - Way to go.
And then when did you come here?
- I came here this past fall, so, brand-new.
- Good timing. [Jessica chuckling]
It's a delight to have you here.
You're gonna talk with us about pollutants,
parasites, and you.
Would you please join me in welcoming Jessica Hua
to Wednesday Nite @ the Lab?
[audience applauding]
- Thank you all for being here.
I appreciate the invitation.
I am really excited to have this chance
to share a little bit more
about what my students and I have been doing
for the past few years.
So for today's talk, I have broken up these slides
into three themes.
The first will focus on pollutants
and the pollutants that we study.
Then I'll talk about emerging infectious diseases,
so the parasites.
And then I'll finish up with people.
So if you're interested in any of the work that we do,
how might you get involved in some of the work
we are working on
in the next few years here at UW-Madison.
So broadly, we are a global change biology lab.
We're interested in a wide range
of different global change factors,
from things like emerging infectious diseases,
changes in our climates, habitat shifts, pollutants,
how these various factors influence natural ecosystems.
And so under this broader umbrella
of global change biology,
today, what I'll focus this talk on
will be how do pollutants influence aquatic ecosystems?
And so to understand how pollutants
influence aquatic ecosystems,
a traditional approach is we can take a pollutant
and ask, "What is the direct toxicity
of this pollutant on model organisms?"
There are a wide range of different organisms,
a wide diversity of organisms that are in nature.
Trying to understand the toxicity of a chemical
or pollutant on each one of these organisms
just isn't feasible.
So we can focus on these models,
understand the toxicity of a pollutant on a fish,
a vertebrate model, then extrapolate
to how might this pollutant influence
more complex ecosystems.
So these short-term lab tests can help us
to predict pollutant toxicity in complex communities.
There are many benefits to this approach.
It's fast, it's simple, it's easy to replicate,
but also, there are limitations.
For instance, we're using these model organisms
to extrapolate risk to the rest of community,
which may be very different than the model organism.
Second, it's rare that you ever would find
an organism existing in a vacuum.
They're interacting with other organisms,
which may influence how toxic a chemical might be.
And so a central theme in my lab is to ask,
"How can we integrate ecological complexity
into our understanding of pollutants?"
And so that's what I'll focus the first part of this talk on.
I'll tell you about our tiered approach
and how we work to integrate in this complexity
into ecotoxicology.
In my lab, we work with a wide range of pollutants,
from microplastics to light pollution to pesticides.
Today, I'll tell you about the tiered approach
using road salts as an example.
So road salts are common pollutants
in freshwater ecosystems.
They're used to protect our roadways
or to protect drivers on our roadways,
but they can enter into freshwater ecosystems
and can cause negative consequences.
And so to understand the toxicity,
the effects of road salts, we can focus on model organisms
and then extrapolate out.
But are these model organisms, are they generalizable
to the wide diversity of organisms that are in nature?
In the first section,
I'll start simply at the species level.
Are the effects of these pollutants generalizable
across species that are similar to each other?
Next, I'll start building in that complexity.
We know that in nature, organisms are living
in habitats that differ from one location
to the next that might affect their susceptibility.
So even across individuals of the same species,
are the effects of salt generalizable?
Next, even more complexity.
We know that organisms are interacting
with a wide range of other organisms in their environment.
How do pollutants like salt influence these interactions?
So this is now at the community level.
Lastly, at the ecosystem level.
So we've talked about interactions
between living organisms.
What about the non-living components of the ecosystem?
So how do differences in environmental conditions
influence the toxicity of salt?
So this is how, I'll show you how
we build in that complexity
from the species level all the way up
to the ecosystem level.
And so we're interested in integrating
ecological complexity,
but also evolutionary processes are fundamental.
There are many examples of evolutionary responses
to pollutants.
We have the evolution of antibiotic resistance,
we have the evolution of tolerance to pesticides.
In my lab, we're interested in integrating
an evolutionary perspective into our understanding
of host-parasite interactions.
So why host-parasite interactions?
Diseases, they're emerging at unprecedented rates.
So we're interested in understanding
how human activities might influence these outcomes.
Additionally, these host-parasite interactions
are at the forefront of public thought,
given the past few years of the COVID pandemic.
And so when it comes to host-parasite interactions,
one approach is to ask, "What are factors
"that influence a host's ability
to defend itself against parasites?"
Or you could look at the parasite perspective.
What are factors that influence
the parasite's ability to infect the host?
Now, building upon this model,
the field of disease ecology has increasingly recognized
the importance of the environment
in shaping these interactions.
In my lab, we're interested in the effects of pollutants.
So how do pollutants affect hosts and parasites?
So on the screen, this is the disease triangle framework.
It's a really useful framework
for breaking down the effects of pollutants on hosts,
on parasites, and then their interactions.
But in today's talk, what I'd like to advocate for
is integrating in an evolutionary perspective
to this disease triangle framework.
We know that pollutants can cause selection,
host and parasites can evolve tolerance
to pollutants like pesticides.
This can be costly.
How does it then affect their ability
to defend themselves against parasites?
And so how do evolutionary responses, EVO,
what are the consequences, the ecological consequences
on host-parasite interactions?
So EVO-ECO.
And so in this second section,
I'll tell you about some of our work with pesticides
and focusing on EVO-ECO dynamics.
Lastly, global change biology.
This is a field that is intimately linked
with humans and also conservation.
And so it's important to me and also members of my lab
that we find ways of more effectively communicating
our research to broader audiences
and also making science accessible
to more people in the public.
And so in the final section,
I'll tell you about our science communication
and outreach work,
specifically how we've used non-traditional approaches
like art and visual narratives
to try to facilitate understanding
and perception of science.
So this is the outline for today.
I'll spend 20 minutes on the first section,
about 10 minutes on the EVO-ECO section,
and the remainder of the time
on the science communication and outreach section.
So jumping right in, what are the effects of road salts?
We can start by focusing on these model organisms,
but are the effects of these model organisms,
are the effects of salt on these model organisms,
are they generalizable to the diversity
of organisms in nature?
At the species level, we can ask,
"Are the effects of sodium chloride
generalizable across similar wetland species?"
And so throughout the talk,
I'll highlight the students that were responsible
for leading the project.
So this is Dr. Nick Buss, a former PhD student.
So to address this question,
a common approach might be to use an LC50 test,
a lethal concentration 50 test.
This is simply the concentration that is lethal
to 50% of an organism, of your test organism.
So the way that a study like this can work
is you can expose your model organism
to increasing concentrations of a pollutant.
We might expect that you have lower survival
at the highest concentration,
so something that looks like this.
We can then graph this response.
On the x-axis, we have the concentration,
on the y-axis, we have response.
We'll probably get a curve that looks like this.
The LC50 value is then the concentration
at which there is 50% mortality.
So what's really nice about these assays
is that they're easy to replicate across species.
Then you get an LC50 value
that you can then compare relative tolerance.
So what are the model organisms we work with?
In my lab, oftentimes, it's amphibians.
And there are many reasons for this,
one of which is amphibians are incredibly neat.
There are over 8,000 species worldwide.
However, over a third of them are threatened.
And they're threatened for a wide variety of reasons,
including pollutants.
And so understanding what pollutants do
to these amphibians also has broad conservation implications.
When it comes to the toxicology aspect
of using amphibians, amphibians are great models
because they have highly permeable skin.
This makes them susceptible to many pollutants,
and so they're often called an indicator species,
oftentimes the first warning
that something might be wrong with the community.
So using amphibians as our model, what did we do?
We conducted LC50 tests for four common amphibian larvae.
We focused on wood frogs, spring peepers,
leopard frogs, and also American toads.
So on the x-axis, that's the species.
On the y-axis, this is that LC50 value.
A higher LC50 value would indicate
that the tadpole is more tolerant,
so they can tolerate a higher concentration
before experiencing 50% mortality.
So right off the bat,
perhaps one thing that you notice
is that there is wide variation
in the LC50 value across even species
that are similar to each other, that live in similar habitats.
From the most to the least susceptible tadpole species,
there's about a 50% difference.
Now, as you're looking at this,
one thing that you might be wondering
is what do these numbers mean relative to,
say, concentrations of salt found in nature?
So for reference, the highest concentration
in freshwater was in runoff;
this is about 18 grams per liter.
The highest concentration found in a wetland
was about 4.6 grams per liter.
And this was a worst-case scenario situation.
And so you see that this line overlaps
with the wood frog and the spring peeper.
So if there were a contamination event at this level,
then wood frogs and spring peepers might be vulnerable.
However, the majority of ponds that we work with
have concentrations ranging from 0 to 1.1 grams per liter.
So put all together, what are some of the take-homes
that you should take from this first section?
First, sodium chloride can cause mortality
for the more susceptible species,
wood frogs and spring peepers,
but only in worst-case scenarios.
In fact, of the ponds that we work in,
most of them have low environment, like these
low environmentally-relevant concentrations
that do not cause direct mortality.
By taking a step back,
the main take-home that I'd like to communicate here
is that considering species-level variation
is important.
We focus on these model organisms
to make predictions about,
sometimes very different organisms.
In this case, we see that even across organisms
that are similar to each other,
the effects of the toxicity of sodium chloride
are not generalizable.
Now, of course, there are limitations
to these LC50 tests.
First of which, these tests are designed
to facilitate repeatability.
So we often use a single population of organisms,
so very low genetic variation.
This is important because in nature,
we have populations that live in very different habitats.
You might have a population that live in a pond
right next to a roadway.
They're exposed to a number of different contaminants
that might affect how they respond to pollutants.
Alternatively, you might have a population
that live in an environment that, such as this.
This is in northwestern Pennsylvania.
It is about a thousand meters from the closest road.
And this closest road is a dirt path,
so unlikely to be experiencing as much human activity.
And so integrating in this variation,
this population level variation is important
because even among individuals of the same species,
we need to know, are the effects of salt generalizable?
And so moving on, now adding in that complexity
at the population level,
we can ask how generalizable is sodium chloride
across toxicity across populations?
To do this, we went out and we collected eggs
of wood frogs from a number of different populations.
And these populations vary
in how close they are to human activity.
Once we collected these individuals or these egg masses,
we raised them in common garden environments.
So they were all raised in pollutant-free environments.
And then once they reached the tadpole stage,
we asked, "How tolerant were these tadpoles
from the different populations?"
We exposed them all to a single concentration of salt
and measured their survival over time.
And this is what you'll see here in this figure.
On the x-axis is time,
on the y-axis is percent survival.
What will pop up will be different lines,
and each of these lines represents
a different population.
So likely what you see again
is there is, even within individuals of the same species,
there is wide variation.
In fact, from the most to the least susceptible population,
it's about a 61% difference in susceptibility.
This was more than for the variation
in susceptibility across species.
And so taking a step back, what does this mean
and what should you take away from this study?
First, there is high variation
in susceptibility to sodium chloride across populations.
Even across individuals of the same species,
there is this variation.
This matters because we need to take care
in making conclusions based on single population studies.
In other words, let's say we're conducting
an LC50 test and we just so happen to use
a highly-tolerant population.
This might lead to a complete underestimation
of how toxic that chemical or that pollutant is.
Whereas if you use a population that is highly susceptible,
you may overestimate that toxicity.
So again, I hope that sort of these studies
have shown why it's so useful
to have an ecological perspective
when thinking about the effects of pollutants
on aquatic ecosystems.
Similar to before, there are limitations.
Thus far, I've talked to you only
about the lethal effects of pollutants.
I showed earlier that the ponds that we work in,
the majority of them have really low concentrations.
And so I think what's important to consider here is these
low environmentally-relevant concentrations,
they may not cause direct lethal effects,
but can they still have effects that harm organisms
by modifying how these organisms
are interacting with other organisms in their environment?
And so what I mean by this is in my lab,
we study ecological interactions; for instance,
the interaction between prey and their predators,
or the interaction between competitors,
so tadpoles competing with each other,
and also the interaction between hosts and their parasites.
And so the question in this section
now at the community level, now integrating in
this living component is can low levels,
environmentally-relevant levels of sodium chloride,
modify the way species interact with each other?
For the sake of time, I'll focus just on our work with parasites.
In my lab, we work with a number of different parasites.
Ranavirus, which is an emerging infectious disease
that influences amphibians, turtles, fish, trematodes,
very common in ponds and wetlands,
and also a fungal pathogen Chytrid or Bd.
For this section, I'll focus on the trematode.
Trematodes are a really interesting parasite species.
They have multiple hosts.
So what I'm showing on the screen,
this is the free swimming stage,
one of the free swimming stages, the cercaria form.
This cercaria will swim through the water column
and find a larval amphibian as a host.
They'll swim up the cloaca of the tadpole
and insist in the kidney.
And so one thing that is important about this parasite
is it is a dose-dependent parasite,
meaning the pathology of the disease
depends on how many of these parasites get in.
So once these parasites get into the larval amphibian,
they insist and they're called metacercaria.
In order for these parasites
to make it to the next stage of their life cycle,
it has to be consumed by a bird or a mammal.
In the bird or mammal, in the gut,
they reproduce and produce eggs.
These eggs are then deposited back into the wetland
where you then get the second free swimming stage.
This is the miracidia stage.
This miracidia will then swim and find a snail host,
insist in the snail, and then the snail will be the host
that produces the cercaria, and the cycle will begin again.
So to address this question, can sodium chloride,
or does sodium chloride modify host-parasite interactions?
I'll focus on just this part of the life cycle.
So the model host will be a wood frog.
The model parasite will be the trematode
or Echinostoma trivolvis.
So to do this work, what Nick did
was he took wood frog tadpoles and he exposed them
to four environmentally-relevant concentrations of salt.
So these are lower levels that are meant to be sublethal.
These are the concentrations that we would find in nature.
After exposure, he then exposed them to,
the tadpoles to 50 trematodes
and asked, "How does exposure to the salt
influence their susceptibility to a very common parasite?"
And as a reminder, these parasites are dose-dependent,
so the more parasites, the more severe the disease.
So here we see some of the results.
On the x-axis is sodium chloride concentration.
On the y-axis is the average number of cysts.
And what you can see compared to when tadpoles
are not exposed to salt,
exposure to all three sublethal concentrations of salt
led to an increase in their susceptibility to trematodes.
And so with that, similar to the other sections,
what should you take away?
First, sodium chloride can modify
host-parasite interactions.
In the field of toxicology, we tend to focus
on what are these lethal effects of pollutants.
But I think studies like these underscore
the importance of also considering these
lower environmentally-relevant concentrations
because while they may not cause direct mortality,
they can still have harmful consequences
by changing how organisms interact with each other.
So with that, where have we been?
We talked about the effects of sodium chloride across species
and how it's not always generalizable across species.
We talked about the effects of sodium chloride
across individuals of the same species across populations.
There is variation there, underscoring the importance
of considering the population you work with
when assessing toxicity.
Next, we talked about low levels of salt
and why it's important to also consider
these concentrations, as they can have harmful effects
by influencing ecological interactions.
In this final section in the ecological theme,
I'll talk about and acknowledge that
from one location to the next,
we know that environmental conditions differ.
And this is important because these differences
in environmental conditions may exacerbate
or even dampen the effects of a pollutant.
And so how might environmental conditions differ
in aquatic ecosystems?
And what we're interested in is one way
that water chemistry in aquatic ecosystems can differ
is through the input of leaf litter.
So we have terrestrial systems
where there are different species of trees.
These trees have leaves that vary in their chemistry.
When these leaves drop into aquatic ecosystems
and break down, that can also change the water chemistry.
And so we're interested in how changes
in water chemistry due to leaf litter input
can modify sodium chloride.
Specifically, we're interested in this shift
from native plants to invasive plants.
Many invasive plants have chemicals and compounds
in their leaf litter that are meant to help protect them,
to help them outcompete native species.
When they drop this leaf litter into wetlands
and it decomposes, how does it influence
the susceptibility of organisms to sodium chloride?
And so this work is done by Dr. Devin DiGiacopo
in collaboration with Dr. George Meindl.
What's unique about this project
is it's part of a core space undergraduate
research experience, meaning all of this work
was done by undergraduates that were enrolled
in a plant ecology class.
This is important to us because one of the priorities
in my lab is to again, ask, "How can we broaden science
and make science accessible to more people?"
And by allowing undergraduates to participate
in authentic research experiences,
this is one way that we try to do this.
And so these students enrolled in classes.
What they were able to do is they went out
and they collected leaf litter
from six different plant species.
Highlighted in white, these are the native species,
in red, the invasive species.
And so they're paired by where they're found
in the wetland.
So once they had the leaf litter,
they soaked the leaf litter in water for 28 days.
Then they collected the leaches, the water from these pools,
and placed them in these beakers.
In each of these beakers, there's also a single embryo.
And there is an embryo of the leopard frog,
which is native to our area,
and then there's an embryo of an African clawed frog,
which is non-native and also invasive
in some parts of the U.S.
And so again, the question here is
how does being raised
in different environmental conditions,
different water chemistries influence
these tadpoles' susceptibility to salt?
So what we did was we measured their tolerance of salt.
Once they hit the tadpole stage,
they were raised in different leaf litter leachates,
native versus invasive.
On this data slide, on the x-axis,
you have the plant species, either native or invasive.
On the y-axis, you have average time to death.
You may notice that I condensed the x-axis,
the plant species.
We worked with six species,
but I condensed it to native and invasive
just for the sake of time.
And also, because we know that native leaf litter,
they're more similar to each other
than invasive leaf litter and vice versa.
So what did we find?
I'll start first with the native amphibian.
So what we found was that leopard frogs
raised in invasive plant leaf litter
were less tolerant to sodium chloride.
In other words, something about being raised
in invasive leaf litter leachates
made them more susceptible to salt
than when they were raised in native leaf litter leachates.
In contrast, when we looked at the African clawed frogs,
we found the exact opposite response.
So something about this invasive leaf litter leachate
made these African clawed frogs, these non-native amphibians
more tolerant to the pollutant.
And so these results stood out to us
because they were consistent with the idea
of invasional meltdown.
In other words, an invasive species
facilitating another invasive species.
And so the class, the next iteration of the class
became interested in trying to understand
why does invasive leaf litter
make leopard frogs more susceptible to sodium chloride,
but African clawed frogs less susceptible?
So what they began with is they took the leachates
and they conducted a wide range of measurements
from water quality to the various metals.
Today, I'll focus on just one, general hardness,
and I'll focus on general hardness for two reasons.
First, we know that general hardness
varies between native leaf litter leachates
and invasive leaf litter leachates.
Invasive leaf litter leachates
had a higher general hardness value
than native leaf litter.
Additionally, this is important
because we also know that our native amphibian
and our invasive amphibian, non-native amphibian,
have different preferences for hardness.
Leopard frogs tend to prefer a lower general hardness
compared to African clawed frogs.
So the students hypothesized
that for the leopard frogs raised
in invasive leaf litter leachates,
this is a condition that is not preferable.
And so they were already stressed
prior to being exposed to the pollutant.
So that might be one reason
why they were more susceptible to salt.
So what they did was they conducted another experiment.
So the figure on your left, that's data you've already seen.
The figure on the right,
what the students did was they manipulated hardness
and they mimicked native
versus invasive leaf litter leachate hardness.
And what they found, as you can see,
is consistent with that first study, which gives us,
which suggests that one mechanism
for why leopard frogs do poorly
after being raised in invasive leaf litter leachates
might be associated with general hardness.
So altogether, those are our findings.
But the main take-home consistent with the theme today
is that the toxicity of sodium chloride
is influenced by shifts in these non-living conditions,
shifts in environmental conditions and water chemistry.
This highlights the importance of considering
not just what these pollutants do to organisms,
but where these organisms are found
and how this history, this legacy of their environment
can influence their toxicity,
their responses to pollutants in the environment.
So to sum up this entire section,
we looked at the effects of pollutants across species,
across populations, and found that
there is high variation.
Understanding this variation with an ecological lens
is important to understanding the effects of pollutants.
We then looked at sublethal effects,
these low levels of pollutants
and how they may not cause lethal consequences,
but understanding their sublethal consequences
and how they influence interactions is important.
Lastly, we looked at how variation in water chemistry
can dampen the toxicity of salt for some species,
but exacerbate the toxicity for others.
So understanding ecosystem-level variation
in water chemistry is also important
in understanding the effects of pollutants.
So altogether, I hope that this past section
sort of gives you a snapshot of how we approach
integrating in this ecological complexity into toxicology.
We try to do this with all the pollutants
that we work with.
So with that, what I will do now is switch gears to talking more
about emerging infectious diseases,
and importantly, how evolutionary processes
can shape the disease outcome of these organisms,
so EVO-ECO.
To do this, I'll tell you about some of our work
with the evolution of tolerance to pesticides.
Specifically, we know that pesticides
can cause selection on organisms.
These organisms can evolve tolerance to pesticides.
This might be great in that they can persist,
but what are the costs associated
with pesticide tolerance?
And that's what we'll be focusing on in this section.
So across the landscape, we know that agricultural activities
can have many effects on natural ecosystems.
One way that we have been tracking this
for over 17 years now is to study tadpole tolerance
across a pesticide agricultural gradient.
So from areas that have more agriculture
to areas that have less agriculture.
And so we study this in wood frog tadpoles.
And in this figure, as you go from left to right,
you have for more agriculture to less agriculture.
On the y-axis, you have less tolerant to pesticide,
more tolerant to pesticide.
And what we have found consistently
is that wood frog populations living closer to agriculture
are more tolerant to common pesticides.
And this can be extremely optimistic
in that these populations,
they're evolving tolerance to pesticides,
they're able to persist
even in the face of pollutants.
But again, oftentimes, tolerance to one stressor
can come at a cost to responding to other stressors
like diseases.
So in this section, the question that I'll talk about
is does the evolution of pesticide tolerance
influence host-parasite outcomes?
And this is work that was started
by Dr. Vanessa Wuerthner, a former PhD student in my lab.
So she went out to 15 populations of wood frogs.
These wood frog populations vary in their distance to agriculture
and also their susceptibility to pesticides.
And so she was curious,
does tolerance to pesticide influence susceptibility
to a very common pathogen, FV3 or frog virus 3.
Another name for this is ranavirus.
This is a pathogen that is highly transmissible.
It is transmitted via direct contact between amphibians,
and it can cause mortality in about 10 days,
an almost complete mortality of population.
So what Vanessa did was she looked along this gradient
of wood frogs.
So on the x-axis, this is less tolerant to pesticides,
all the way to more tolerant to pesticides.
On the y-axis is ranavirus load.
So one thing I wanted to point out,
what I'll show here, these are all survivors.
And so I bring this up
because the y-axis can be counterintuitive.
So a higher viral load actually means
that they're more tolerant to FV3.
So they survived despite having a higher load of the virus.
So what did Vanessa find?
She found that there was a clear relationship
between tolerance to pesticides and also tolerance to ranavirus.
So selection for pesticides
can influence susceptibility to disease,
but in the opposite direction that we thought.
We thought that if you're tolerant to pesticides,
there would be a cost in responding to this virus.
But that was not what we found.
Pesticide-tolerant tadpoles were more tolerant to the ranavirus.
And so this was a really interesting finding for us.
And so we spent the last three years or so
really diving deep to try to understand
what is it about these populations
that make them tolerant to pesticide
and also tolerant to the virus.
So we've looked at a wide range of different factors
from things like immunogenetic factors,
things like major histocompatibility complex,
so MHC II B; this is important for the immune system.
We looked at how they respond to stress.
So we measured oxidative stress metrics, corticosterone,
across these populations to see whether the tolerant ones
differ than the non-tolerant ones.
We looked at the microbiota, diversity of microbiota.
The microbiota oftentimes is the first line of defense
against pathogens.
You have microbes on the skin
that produce compounds that are anti-pathogenic,
so it's thought that more diverse microbiotas
can protect amphibians from their pathogens.
We looked at even behavior.
Do these populations differ in how they behave
that might influence their susceptibility to the pathogen?
And so we've learned quite a bit
about immunogenetic factors, oxidative stress,
corticosterone, but none of these factors were related to,
there was no variation across the different populations
with these factors.
And so today, I'll focus on microbiota and behavior.
So for the microbiota, again,
the idea is this is the first line of defense.
It's hypothesized that the tadpoles
that are most tolerant to their disease
should have the highest microbiota diversity.
And so we sought out to test this.
We went up to 10 populations of wood frogs.
Again, the same ones that vary
in their tolerance to pesticides.
We collected these in these populations as eggs.
We brought them back and held them in filtered water
until they reached the tadpole stage.
At the tadpole stage, we swabbed their skin
to sample their microbiota diversity.
We measured a wide range of different types of diversity.
Today, I'll focus on just alpha diversity
or the number of bacterial species on the skin.
So this is work done by my current PhD student, Isabela,
and also in collaboration with Dr. Obed Hernandez Gomez.
So on the x-axis, this is percent agriculture.
As a reminder, those that are far from agriculture,
these are less tolerant to pesticides
and also to the pathogen.
Those that are closer to agriculture
are also more tolerant
and tolerant to pesticides and the virus.
The y-axis is Shannon diversity index.
So a higher index means there are more bacterial species.
So what we have found thus far is that there is a relationship
between tolerance to pesticides and FV3
and also diversity of the microbiota.
Tadpoles that are more tolerant to pesticides
and the virus also have a higher diversity
of microbes on their microbiota, their skin microbiota.
And so this is just the first step
in sort of digging deep into the contribution
of the microbiota, but it suggests
that this is a direction that might be promising
to continue pursuing.
Along with the microbiota,
we're also interested in behavior.
Do these populations vary in how they behave
that might influence whether the disease
gets transmitted more often or not?
And so specifically, we're interested
in this behavior called necrophagy.
So necrophagy is the consumption of dead conspecifics,
and tadpoles do this.
Every so often, they will feed upon tadpoles,
other tadpoles that have died.
And as I mentioned before,
ranavirus is transmitted via direct contact,
and so necrophagy is a really easy way
of transmitting the virus.
So Mary Campbell, a future PhD student in my lab,
she was interested in asking,
"Do these different populations differ
in their necrophagy behavior?"
And so the first thing she had to do
is she wanted to confirm that indeed, yes,
the tadpole populations that are tolerant to pesticides
are also tolerant to FV3 'cause it had been a few years
since we were able to confirm that.
So in this figure, we have two populations,
those with lower pesticide tolerance
and those with higher pesticide tolerance.
She exposed them to ranavirus again
and she was able to confirm that yes,
those that were tolerant to pesticides
were still tolerant to the ranavirus.
So now we have these two populations;
we can look at their behavior.
That's what I'm showing in this pie chart here.
The solid part, that represents necrophagy behavior.
The hashed part represents no necrophagy.
So for the populations with lower pesticide tolerance,
57% of them were exhibiting this necrophagy behavior.
So let's compare this to the populations
that were more tolerant to both FV3 and pesticides.
Only 11% we detected of necrophagy.
So there was more necrophagy in the populations
that were more susceptible to the virus.
There's variation in behavior, and this variation in behavior
was consistent with the tolerance
of these tadpoles to ranavirus.
More necrophagy, we think, led to more transmission,
which led to increased susceptibility to the virus.
So with that, tadpoles with higher pesticide
and FV3 tolerance exhibited less necrophagy
than tadpoles with low pesticide and FV3 tolerance.
So to summarize this section,
we know that pollutants in the environment like pesticides
can cause selection on hosts.
We have these hosts that can evolve tolerance to pesticides.
And we know that
evolution of tolerance to pesticides
is important in patterns of disease susceptibility.
Those that are tolerant to pesticides
are also tolerant to these parasites.
And we've dug deep into a few mechanisms
trying to understand what might be driving these patterns.
But all in all, what I hope that this section conveys
is why we think it is so important
to integrate in this evolutionary perspective
into this disease triangle framework.
Because evolutionary processes, they're a cryptic factor
that can influence disease outcome.
And so trying to understand why is it
that some populations, some communities
are susceptible to disease and some aren't,
evolutionary factors may be a cryptic component
contributing to that variation.
So with that, I'll transition to the final part of this talk,
the science communication outreach part.
Here, we've done a lot of work
trying to understand how non-traditional resources
like art and visual narratives
can improve understanding and perception of science.
There are three questions that we're interested in asking.
First, can art improve the way
that the public perceives science?
In addition to public perception of science,
can art contribute to improving public understanding
of science?
And then lastly, we know that there are many benefits
of participating in the scientific process.
Can art improve willingness
or excitement in participating in science?
So these are the three questions
that I'll talk about in this section.
So to start off, can art improve public perception of science?
This is work done by an artist, Benjamin McLauchlin, in my lab.
What he did is he took two publications
about wetland disease ecology,
and he's an incredibly talented individual;
he produced all of these original art pieces.
And the goal of this was to communicate
the findings of these publications.
And so he invited members of the campus community
to the art show.
These visitors took a survey before entering the art show
and also after entering the art show.
And in total, there were 188 total participants.
After filtering through these surveys
for those that only completed one
or the other of the survey,
we ended up with 155 total participants.
And so what Ben and Kyra, the lead on this paper,
what they did was they separated out
the interest in research scores,
which is on the y-axis here before and after the exhibit
based off of STEM background.
So for those participants that didn't have
a STEM background, after going through the exhibit,
you can see that their interest in science
increased dramatically and significantly.
This was encouraging for us as these art shows,
it was a lot of work.
And so seeing this was encouraging and exciting.
What about for those in general STEM?
So these, we also saw an increase
in their perception of research, though not quite as dramatic.
And then we were also curious, what about people
that were already interested in this type of research,
for those in the ecology field?
And so here we have the,
those that already have interest in ecology.
We see no increase.
In fact, what this shows is that there's likely a ceiling
as to how interested you can be in research.
But what's exciting about these findings
is that before the exhibit, you see
this dramatic variation across these groups
from ecologists to all the way to non-STEM.
But after going through the exhibit,
you see that it sort of levels the playing field.
At the end of it, all three groups
had similar interest in research scores.
So can art improve public perception of science?
The answer is yes, and it depends on STEM background.
And so this is important for us.
We learned a lot.
This art show was a lot of work to put together.
And what it taught us is that
we need to know our audience well.
These art shows are great for those
that may not have much experience in STEM fields,
but maybe not so great if they're already interested
in the research.
Well, what about public understanding of science?
And so this was sort of the next phase of Ben's project.
And we talked about this,
and we wanted to choose a topic in science
that we thought that maybe the public
wouldn't be as interested in.
So we didn't wanna choose something that was charismatic,
that people might already love and be interested in.
And so what we landed on
was we wanted to teach the public about parasites.
And so we thought that parasites,
they're such important components
of natural ecosystems, but are less appreciated.
And so we developed sort of a three-phase approach
to teaching the public about parasites.
In step one, we wanted to generate resources
that would communicate the material.
So we used art to teach about parasites.
And our vision for this was a children's book.
So this is the first iteration of the children's book.
This was done by me.
I am clearly not an artist.
And in fact, looking at this image,
I am so surprised that Ben got anything from,
this is the full story in one page.
But Ben was able to translate it to a storyboard.
And this is what the book looks like now.
This is called Gemma Jones Visits Nuthatch Hollow.
And what it does is it follows Gemma Jones
as she makes friends with a trematode.
So you met the trematode life cycle early on in this talk,
and it takes kids through the life cycle
and communicates parasite biology
as well as the important role that these parasites have
in natural ecosystems.
We paired this children's book with a lesson plan
on wetlands and parasite biology.
And we designed this lesson plan to meet educational standards
so that it would be easily used by teachers.
So the next step after generating these resources
was to train our educators.
So we invited educators from around the state
to come to a workshop, where we taught them
how to use these resources.
And then once these educators were trained,
we transported these educators and their students
to a local museum, where they implemented the lesson.
And so after implementing the lesson
and before implementing the lesson,
we ended up reaching about 593 third graders.
And then we also surveyed
and gave them quizzes about what they learned.
So in this slide, these are just the questions
that are associated with the parasites.
So we asked them, could they identify what a parasite is?
Are parasites bad?
And this actually, this question was a last-minute addition.
And the reason we have this question is
in the middle of our program, a school actually pulled out
because the principal was concerned
that parents would not like that their students
were learning about parasites because parasites are bad.
And so we were curious to sort of understand
if that was, how that perception changed
throughout our program.
And so the last question is
"Are parasites important in the ecosystem?"
And the y-axis, is proportion correct
before and after going through the program.
In all cases, we see an increase,
a significant increase in the proportion correct,
which again, was encouraging.
So can art associated with this program,
can it improve public understanding of science?
We found that yes, we saw a consistent increase
in scores as these third graders went through this program.
So lastly, now that we have some proof of concept
that art and visual narrative can be effective,
we started thinking more about using this program
to improve participation in science.
Again, there are many benefits of participating in science.
The public gets a deeper understanding of a topic,
they contribute to the scientific community,
things that scientists couldn't do on our own.
And so community citizen science is often called,
is often described as a win-win situation.
The scientific community gets to better understand
a pattern across broader areas.
The community gets the chance
to interact with scientists, to learn more
about something that they're interested in.
And so we are interested in community science
and how that might contribute to the research
that we do in our lab;
specifically, we are so interested in this idea
of biodiversity and disease relationship.
What this is is the idea that as you increase
in species diversity on the x-axis here,
you should get a decrease in overall infection,
overall diseases in that community.
This is called the dilution effect.
And this is really exciting to a lot of people
because it provides a clear benefit
for why we might want to protect biodiversity.
You protect biodiversity,
you get the benefit of reduced infection.
The problem is sometimes this happens,
and sometimes the opposite happens,
where you have higher species diversity and more disease.
And so in my lab, we think that pollutants
in the environment might be contributing
to why this relationship shifts.
And so what we wanna do is to measure diversity
across different natural populations
and overall infection, and how that differs in areas
that are polluted versus not.
The problem is we can't do this alone.
And so we asked, "Can the community help?"
And how can we convince the community
and engage with the community
that this is a really important question?
And so this is where we go back to art.
So this is Kyra; she's a PhD student in my lab.
And what she has been doing
is working with a group of artists
to develop a graphic novel.
This graphic novel is called Amphibian Adventures.
And what it does is it introduces third graders
to the biodiversity in wetland ecosystems.
So similar to before,
we're using this three-step program.
We have the resources with a lesson plan.
We teach teachers how to use these resources
at a teachers' workshop.
The teachers then go back to their classrooms,
teach them about biodiversity and disease.
And then once the third graders are trained
and understand this concept,
they are then transported to helping us
collect data on biodiversity.
And so how does this look?
They go out to different locations
that vary in human impact.
They help us to identify tadpole species.
And we've been able to do this with 26 classrooms,
and we have all the data on biodiversity.
So going back to this figure,
this is where the third graders are contributing.
They're helping us to understand species diversity
across different populations.
The next step is, what about infection
in these tadpoles across these populations?
This is where first-year undergraduate students
come into play.
Using the same tadpoles that the third graders worked on,
these undergraduates look at the amount of disease
in these tadpoles, and also they measure
water quality at the different sites.
So we're really excited in the next few months
to understand more of what they found.
And hoping to continue to build upon this,
I'm gonna transition in the next minute or so
to this last section.
If any of these topics in today's talk
sparked some interest,
and if you're thinking about, well,
how might you get involved,
in this section, what I'd like to talk about
is a recent project that my lab and I have been working on
that focuses on amphibian conservation in Wisconsin.
So to understand amphibian population declines,
an important data set that we need
is to understand how are amphibian populations doing
across space and time.
Again, this is not something that we can do alone.
There's so many different habitats in Wisconsin.
And so we've been so lucky to have met
and begun working with a number of individuals
across the city of Madison.
And these individuals are associated
with many of the natural areas,
the friends groups of natural areas in Madison.
And what we've decided to do
is to work together to help to track
and monitor amphibian populations
across space and time.
And so what does this look like?
We have standard protocols that are consistent
with the Wisconsin DNR Frog and Toad Call Surveys.
[frogs chirping] So these volunteers will go out,
listen to frog and toad call surveys across the summer,
and these data will get uploaded
into a public Google map that looks like this.
And over time, we can better understand
where the populations are,
why are frogs found in some places but not,
and over time, if climate changes, for instance,
does this change when these frogs are calling?
And so this is a project that we just got off the ground.
If anybody is interested in this project,
our central location at the moment
is at the website presented here at the bottom.
It's in the Friends of the Lakeshore Nature Preserve.
All of our information is there.
Or you can contact me if you wanna get involved.
In addition to this project,
we talked about emerging infectious diseases.
Emerging infectious diseases are occurring worldwide,
but again, we can't be everywhere
to detect these events.
And so one of the things that we need help with
is if people are out hiking
and they notice amphibian mortality events,
meaning mortality events with five or more individuals
that experience mortality, please help us out.
Contact the DNR; the wildlife hotline is here,
as well as a switchboard email address.
And you can also contact me.
My email is here.
And our social media is there.
Both places we check regularly and would appreciate any help
detecting these mortality events.
So all together, to conclude, who are we as the Hua Lab?
We're interested in understanding
how pollutants influence the environment.
We do this using a tiered approach.
We start off simply at the species level,
and we start to build in more and more complexity
at the population, community, and ecosystem level.
And so I hope that this talk demonstrates
why we think it's important to integrate
an ecological perspective to toxicology.
We're also interested in how pollutants
influence host-parasite interactions.
And we advocate for adding in this evolutionary perspective,
as this evolutionary perspective
is important to understanding host-parasite interactions.
Lastly, we're passionate and we care deeply
about science communication and outreach,
and we do this at different levels.
Overall, all of this work would not be possible
without the funding sources that have supported us,
but most importantly, none of this work
would be possible without the amazing team
that we have in the lab.
These are the people that do the work.
I just have the privilege of presenting it
to you all today.
So with that, thank you so much for your attention
and I'd be happy to take any questions
if there are any.
[audience applauding]