The Lizard Log

The Langkilde Lab in Action


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Solon Dixon!

Hey everyone!

Even though I am continuing the same project from last year (how maternal stress affects the offspring in fence lizards), there are still some striking differences. One of the biggest is that there are fellow grad students and a post doc this summer!

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From left to right: Cameron (PhD), myself (PhD), Kirsty (post-doc), and Dustin (PhD).

Also, last year we made the drive in one day, however this year we broke the drive up over 2 days. This gave us an excellent opportunity to experience different parts of the USA on our drive. For the night we stopped in Knoxville, TN and had dinner at an amazing place called Calhoun’s On The River. True to its namesake, it had a beautiful view of the Tennessee River!

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After all the driving, we finally made it back to Solon Dixon and started catching lizards. As usual, the lizards’ personalities were very evident.

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Male fence lizard unamused with our attempts to catch him

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Apparently the female lizards found that corner of the tub to be very interesting.

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As I went to put this female back in her tub, she refused to let go of my fingers!

On top of finding many fence lizards, we were also about to see many other reptiles and amphibians!

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A barking tree frog tightly hugging my finger.

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An American alligator, at a very reasonable size to handle.

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A yellow bellied slider who found a little bit of water to sit in.

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A glass lizard!

As I spend more time down here, I find it rubbing off on me more and more.

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Very tempted to get a cowboy hat.

After catching the females, our first trip came to an end. However, we were quickly back down to release the females and run experiments with the hatchlings. With us this time we had an undergraduate researcher, Jen!

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The Bayfront Park, overlooking Mobile Bay. Located right next to one of our field sites, Blakeley State Park.

As we wait for more hatchlings to emerge, we have been focusing on removing fire ants from some of the enclosures we built. As fire ants are highest in the mounds earlier in the day, this means some early mornings. On the up side, it also means we always get to see the sunrise.

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Sunrise right near the enclosures.

Most things have gone well, with only one piece of equipment starting to show signs of wear, but this just gave me an excuse to do some handywork!

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Used some steel epoxy to seal a leak in the pot we boil water in for fire ants.

Things have started to pick up in terms of hatchling, so soon you should be able to hear about how things are going with them. Until then, here is a pic from right here at Solon Dixon

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With the drier weather they are finally able to do prescribed burns.

Cheers,
David

 

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Word Clouds and Receptions

The end is near! I am happy to report that both Chris and I have submitted our final dissertations to the graduate school. What a relief!  Now that my dissertation is off to the printers, I decided to do some stats…

Unsurprisingly, the most used word in my dissertation (excluding common words), is “stress,” clocking in at a word count of 392 (out of 35K total words). Close behind were CORT (296), lizards (225), immune (201), and ants (144). Sounds about right! (The most used word was “of,” with a word count of 681. Fascinating!)

I couldn’t help but display this graphically, because who doesn’t love a word cloud?

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A word cloud featuring the most commonly used words in my dissertation. Note that “killing” applies to bacteria only! (Make your own at wordle.net)

For those of you keeping track, this is the “cleaned up” version–the original was quite overwhelming! I removed the citations and statistics as well as a number of prepositions,  less exciting words (“may” was a big one), and anything that occurred fewer than 20 times throughout my dissertation.

In other news, Tracy and I recently attended the 2016 Penn State Alumni Association Recognition Dinner, where I was presented with the Alumni Association Dissertation Award.

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Receiving the award. Thanks Penn State Alumni Association!

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Dave Eissenstat, head of the Ecology program, and Tracy helped celebrate at the recognition dinner.

The 13 graduate student winners were invited to talk about their research. I chose to highlight the last two chapters of my dissertation, which have been submitted to various journals. Here’s a sneak peak of the findings, as described in my short talk/acceptance speech:

My dissertation research addresses the circumstances under which stress produces negative consequences. Animals, including humans, have a way of dealing with stress, called the physiological stress response. This response involves a suite of changes in the body to help an animal deal with and recover from the stressor—these changes can mobilize energy and induce certain helpful behaviors to help deal with the stressor. Because of this stress response, experiencing a stressor isn’t always a “bad thing”.

That said, in order for these changes to occur, an animal temporarily pulls energy away from other systems that aren’t immediately important—like growth and reproduction. That means when stress is frequent, when it doesn’t go away, there can be negative consequences on these traits—on growth, reproduction, and immune function.

The immediate consequences of stress are fairly well studied, but we know less about how stress experienced during development or in previous generations can affect adult traits.

To investigate this, I took advantage of populations of eastern fence lizards that co-evolved with different levels of stress in the environment. Some populations co-occur with invasive fire ants, which bite and sting lizards. These encounters are stressful for the lizards, and if you’ve been stung by a fire ant, I’m sure you can relate. So this study system gives us a unique opportunity to look at populations that have long history—many generations—of high–stress and compare to populations that do not have history with this kind of stress.

My research reveals that ancestral history with stress is actually really important. If a lizard’s ancestors experienced high-stress, that affects how it responds to stress as an adult—regardless of its personal experience with stress within its lifetime. So it’s not what it went through, but what its ancestors went through, that determines how robustly it responds to stress.

But it turns out the combination of a lizard’s personal experience and its ancestors’ experience that determines the immune consequences of stress. Researchers don’t usually consider how stress in previous generations can affect physiology, but my research indicates this should not be overlooked

Understanding when stress will become beneficial and when it becomes harmful will allows us to better predict how animals will be affected by the increasing amounts of stress due to global change, and to better allocate resources to manage these effects.

I would like to thank the Penn State Ecology Program and my advisor, Tracy Langkilde, without whom I could not have completed my degree. I would also like to thank my boyfriend, Rich, for his support and the Alumni Association for the recognition. It is a privilege to have your support, and I am excited to join the thriving community of Penn State alumni. Thank you.

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Major thanks to my boyfriend, Rich, who supported me not only at the dinner, but throughout my graduate studies. You’re the best!

 


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Gearing up for SICB!

Happy New Year!

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New year, new beginnings. And hats. Lots of hats.

As we start to wrap up our holiday break, Chris T. and I are preparing for a trip to Portland, Oregon for the 2016 annual meeting of the Society for Integrative and Comparative Biology (SICB). We will both be presenting talks on Monday.

I will be expanding on results I presented at ESA in August, which address how stress (fire ants) experienced in early life or in previous generations affect adult physiology and immune function in lizards. My talk is Monday, January 4th at 11:15 in room B110/111.

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Chris will be sharing his results from SSAR with a new audience. He will discuss how invasive fire ants have reversed geographical patterns in fence lizard ecology, including their behavior, stress responses, and morphology, across their range in less than 75 years. Chris’s talk is also on Monday, January 4th at 11:30 in room B114. A determined Langkilde Lab follower could attend both talks back to back in nearby rooms! 🙂

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Come say hello if you will be there!


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Science Communication and Art!

In addition to answering herp- and stress-related research questions, the members of the Langkilde are also very interested in outreach and science communication. I am personally quite interested communicating science and recently exercised my scicomm skills by interning with Penn State Research Communications. I wrote two stories over the summer and hope to write a few more later this year.

The first story covers the use of drones in research and conservation by recent Penn State Ecology graduate Jeff Kerby. Jeff does great work across the globe and is a photographer himself. Check out the story, entitled “Ecology on the Wing,” for more on his research and some of his photos. (For more of Jeff’s amazing photos, check out his flickr and instagram.)

Penn State graduate student Jeff Kerby used drones for his ecological research in Greenland and is sharing his expertise to enhance research and conservation efforts worldwide. Image: Martin Holdrege

Penn State graduate student Jeff Kerby used drones for his ecological research in Greenland and is sharing his expertise to enhance research and conservation efforts worldwide. Read the story at Penn State NewsImage: Martin Holdrege

The second story I wrote was a news story, which, unlike the “feature” story highlighted above, is written in AP (“news”) style and focuses on the results of a recently published paper. I summarized a study by Penn State Ecology and Neuroscience grad student Lauren Chaby, which was recently published in Animal Behavior. Lauren investigated whether stress in adolescence affects problem solving in adult rats. Read the story, entitled “Stress in adolescence prepares rats for future challenges,” for more information.

"Unpredictable stress can have dramatic and lasting consequences, both for humans and for free-living animals," said Chaby. Image: Lauren Chaby/Penn State

“Unpredictable stress can have dramatic and lasting consequences, both for humans and for free-living animals,” said Chaby. Read the story at Penn State News.
Image: Lauren Chaby

Thanks to my new connections at Research Communications, I was also able to revisit one of my other hobbies–paper cutting! As you may have guessed by our herp-flake holiday door, I am also a paper artist. I was commissioned to create three paper cut illustrations for a story about the evolution of skin color in the Penn State Research magazine.

Paper cut portrait of Nina Jablonski; Research at Penn State Magazine 35(2) Fall 2015

Paper cut portrait of Nina Jablonski, printed in Research at Penn State Magazine 35(2) Fall 2015

The story is based on the work of Penn State anthropologist Nina Jablonski. The first illustration is a portrait of Nina, based on a photo by Patrick Mansell. This is probably the most complicated portrait I have made to date!

Paper cut portrait of Nina Jablonski, created for the Research at Penn State Magazine.

Paper cut portrait of Nina Jablonski, created for the Research at Penn State Magazine.

Curious how this was made? Check out this work-in-progress video:

As part of Nina’s research, she and her colleagues created a map predicting skin colors of indigenous peoples based on ultraviolet radiation. I converted this map to paper for the story’s opening spread.

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The opening spread for the story, written by David Pacchioli.

Both the portrait and the third piece posed quite a challenge, as the black shadows blended into the background in one seamless piece. The third piece in particular was quite stubborn, but it turned out all right in the end.

Paper cut hands created for the Penn State Research Magazine. Based on a photo by Patrick Mansell.

Paper cut hands created for the Penn State Research Magazine. Based on a photo by Patrick Mansell.

I am very pleased with how these illustrations turned out! Pick up a copy of the magazine on campus to see them for yourself.

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Research | Penn State – Fall 2015. My illustrations can be found on pages 12-17.

You can learn more about my paper art on my website and facebook. I also take commissions–or at least, I will after defending!

 

Modified from a post originally at gailmccormick.wordpress.com.


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What Makes Stress Stressful?

Stress is a familiar concept to most people. Paying the bills on time, entering a week of exams, caring for a sick loved one, or even sitting in heavy traffic on the way to work. When you get stressed out, your body goes through a series of changes to help you deal with that stress. This stress response includes both physiological and behavioral changes and is generally a good thing! For animals, the physiological stress response can mobilize energy and trigger important behavior, perhaps to get away from a predator. It can also enhance immune function in the short term to prepare for wounding or infection that might occur as a result of that stressful encounter.  Short term stress is typically called “acute,” and the resulting stress response is very similar across vertebrates—because it works!

Stressors come in a variety of forms.

Stressors come in a variety of forms.

If stress lasts for a long time, however, there can be costs to using so much energy on the stress response. If you have ever become sick after a week of exams or a particularly challenging week at work, you know what I’m talking about. Long term stress—typically called “chronic” stress—can suppress immune function as well as growth and reproduction.

Sometimes, however, these generalizations don’t hold up—short term acute stress may produce negative consequences or long term chronic stress may produce positive outcomes. This got us wondering—just what is it about stress that might lead to negative consequences? We discuss just that in our latest paper published in General & Comparative Endocrinology, which is now available online.

Now published in GCE!

Results published in GCE.

Stress is typically defined by duration—as acute or chronic— in the scientific literature as well as in veterinary and medical practices. I wanted to investigate not only stressor duration, but also other characteristics of the stressor, like frequency and intensity. There is some evidence that frequency and intensity affect the outcomes of stress, but few studies have attempted to look at how they might interact with each other or duration.

To test these ideas, I exposed fence lizards to different stress regimes. I did not want to use a physical stressor, so we instead manipulated a stress relevant hormone. When the stress response is activated, the glucocorticoid hormone cortisol (in humans) or corticosterone (in lizards) is secreted by the adrenal glands. We often measure CORT as a proxy for stress, and we can give a lizard CORT to replicate the increase in CORT that occurs in response to a stressor. After dissolving CORT in oil, one simply drops the solution onto the back of a lizard and it is quickly absorbed. One can also put the CORT-oil solution into a hormone patch for a slower release. These work a lot like a nicotine patch in humans, just with CORT and on a lizard.

A fence lizard with a slow release CORT patch.

A fence lizard with a slow release CORT patch. Stylish!

We used different regimes of CORT application to help determine how duration, frequency, and intensity affect immune outcomes in lizards. After the 9 days, we measured the innate immune system in two ways [similiar to  this post], both of which roughly measure the ability of lizard blood to deal with foreign particles. One of these assess hemagglutination, which is the ability of plasma to hold sheep red blood cells in suspension. Higher scores indicate greater ability, or better immune function.

The completed hemagglutination assay.

A completed hemagglutination assay.

Some of our results were particularly interesting:

Two of our treatments would be considered “acute.”  Both were short in duration and differed only in the intensity of the dosage. Exposure to short duration low-doses of CORT  enhanced immune function (hemagglutination), while exposure to short duration high-doses suppressed immune function. This indicates that intensity is an an important factor when considering immune outcomes of stress.  This matches up with what we know about PTSD—short but intense stressors can have lasting effects in that context as well.

Additionally, while both of these treatments mimic “acute” stress, they produced opposite results. This demonstrates that the terms “acute” and “chronic” may not be enough to sufficiently characterize stress. These terms are also inconsistently used in the scientific literature, which only adds to the confusion.

Three of our treatments received the same average amount and total amount of CORT over each three day period and over the duration of the experiment but differed in how they were distributed–they varied in duration, intensity, and frequency. All three of these treatments, however, produced different outcomes—one enhanced immune function (frequent low doses), one suppressed immune function (infrequent high doses), and one was somewhere in the middle (slow release of the high dose). This suggests that average or total amount of stress (CORT) may not be comprehensive enough to characterize how the stress is experienced or accurately reflect its outcomes.

Although frequency and duration had lesser roles in this experiment, intensity was a major factor in altering the immune consequences of stress. We recommend that researchers consider and report aspects of stress other than duration, such as intensity and frequency, to aid our understanding of the consequences of stress. We should also move away from the terms “acute” and “chronic,” as they are inconsistency used and incompletely describe stress.

Because the environment is changing due to climate and human activities, wild animals will be exposed to new stressors or familiar ones more often. Determining what about stress leads to negative consequences is important to understand how species will respond to environmental change.

How will wild organisms respond to the stress of environmental change?

How will wild organisms respond to the stress of environmental change?

These results are published in General and Comparative Endocrinology. This research is also featured on the Penn State CIDD website, here.


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The Ants of Guana Island

As Chris mentioned in a recently post, we both had the wonderful opportunity to do some research on Guana Island. And it was BEAUTIFUL!

The amazing view from my porch.

The amazing view from my porch.

Such clear water!

Such clear water!

But it was also exhausting! Getting used to temperatures in the 80s and 90s and the incredible humidity was a challenge we were to happy to meet. And it’s hard to complain about doing fieldwork on a beach…

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North beach!

North beach!

We had a number of projects to keep us busy. As Tracy described in a previous post, our lab and our collaborators are interested in how invasive fire ants (Solenopsis invicta) affect one of the world’s most endangered iguanas: the Stout Iguana (Cyclura pinguis).  (remember this guy?) This year, Chris and I wanted to address whether fire ants are capable of preying on iguana eggs while in the nest. Thanks to some of Chris’s previous research, we know that fire ants are potential threats to fence lizard eggs: they are capable of foraging at depths of fence lizard nests, can find artificial nests, and can get through the shell of the egg to obtain a meal.  We wanted to know if fire ants could get to depths approaching those of an Iguana nest, which are deeper than those of fence lizards. To do this, we installed fake “nests” next to clear plastic tubes in the beach and forested area nearby. This involved digging a hole roughly 16 inches into the soil (or sand!) and inserting a tube. We then placed slices of hot dogs (faux “eggs”) along the outside of the tube at a standard depth and filled in the hole with sand. Every afternoon, we checked our mock nests by sliding a small camera down the tube and taking video of the hot dogs through the tube wall. We immediately checked these videos to determine if any fire ants were present (or beetle larvae, as we observed in one case!).

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Chris digging a hole on the beach for our nesting experiment.

Tube in a hole before filling in.

Tube in place before we filled in the hole with sand.

During our stay, we also continued to survey the island for fire ant mounds. Our lab has collected this since we started working on Guana in 2010, and the resulting maps help us monitor the spread of fire ants on the island.

Looking for fire ant mounds...

Looking for fire ant mounds.

Crabs like peanut butter too!

Crabs like peanut butter too!

We also set up baits around the island to see which species of ants are actively foraging in the area. The fire ants love our peanut butter balls, but occasionally a crab would stake claim:

Chris and I had 6 days of hard work and amazing views, but we eventually had to return to the Pennsylvania fall. Next step: data analysis!

Taking in the view!

Taking in the view!

So incredible.

So incredible.

Goodnight Guana!

Goodnight Guana!


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The Riveting Life of Jumping Beans

by undergrad Cecilia Zemanek

Being placed in charge of my first independent research project my 3rd semester, I was very excited to get started. Maybe a little bit too excited, as I happily signed up to present a poster for Tracy’s Undergraduate Poster Exhibition that was less than two weeks away. Needless to say, I miraculously managed to pull something off in that time frame and was relieved to have something ready for the judges. While at the event, Tracy introduced me to freshman Greg Reiley, who apparently had a huge passion for jumping beans. Tracy told me how he was looking to get involved with some research, and asked if I would like some help with mine. After seeing how much work it took just to collect one round of initial data, I realized any help would be extremely beneficial.

bean1My project involves looking at why some jumping beans posses more of a propensity to jump than others. It was thought that maybe it had something to do with physical constraints, so Tracy and I devised an experiment that would test the number of jumps per bean versus larva and pod size, larva body condition, and larval activity outside of the pod.

Greg analyzing a grub's length, width, and area.

Greg analyzing a grub’s length, width, and area.

From the masses and dimensions of both, the size of the pod and the size of the grub were both compared to the number of jumps. Body condition of the grub was also taken into account, using the mass of the grub compared to its length and area.

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Cutting open the bean reveals the grub inside!

Grub activity trial.

Grub activity trial.

It was very cool extracting the larva from its pod. Grub activity was observed with video analysis. I looked at the number of head thrashes, the number of grub contractions and distensions, and the number of grid lines crossed.

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Measuring bean temperature.

 

One interesting thing I saw was that as the size of the Mexican jumping bean increased, the slower the temperature of the bean rose.

 

 

 

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Greg hard at work!

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Cecilia with jumping beans.

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Many jumping beans!

Greg and I have been working hard collecting all the data we need. This week, we will be sitting down with Tracy to discuss the results. I am so appreciative to have the opportunity to work in such an amazing lab with such amazing people!