The Lizard Log

The Langkilde Lab in Action


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Maternal glucocorticoid effects across life stages in fence lizards – new paper!

“Anthropogenic disturbance is a growing threat, and the physiological consequences of exposure to such stressors is gaining increasing attention. A recent paper published in the Journal of Animal Ecology explores the consequences of stress-relevant hormones for mothers and their offspring…”

Read more in David’s new paper, and featured blogpost on the Journal of Animal Ecology blog!

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Sex-dependent effects of maternal stress in lizards

Check out the second chapter of Dustin’s thesis on the “Sex‐dependent effects of maternal stress: Stressed moms invest less in sons than daughters”!

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Multigenerational effects can have important and sex‐dependent effects on offspring. Sex allocation theory predicts that females should differentially invest in sons and daughters depending on sex‐specific fitness returns and costs of investment. Maternal stress‐relevant (glucocorticoid) hormones may be one mechanism driving this effect. We investigated how maternal stress hormones differentially affected sons and daughters by manipulating levels of the glucocorticoid, corticosterone (CORT), in gravid female eastern fence lizards (Sceloporus undulatus) and quantifying reproductive investment and sex ratio of resulting clutches, and the mass, snout‐vent length, and body condition of sons versus daughters at hatching. We found no effect of maternal CORT‐treatment on the number or size of eggs laid or on the sex ratio of resulting offspring, but sons of CORT‐treated mothers were shorter, lighter, and of poorer body condition at hatching than were sons of control mothers. We found no difference in size or condition of daughters with maternal treatment. Our results suggest that maternal stress, mediated by elevations in maternal CORT concentrations, can have sex‐specific effects on offspring manifesting as lower investment in sons.


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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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The Natural State

Happy Memorial Day!

I am happy to report that the “uninvaded” team has returned to PA, lizards in hand–or bag as it were. Our team, consisting of Braulio,  Caty, and myself, traveled to Tennessee and Arkansas. Arkansas prides itself on being “The Natural State” for its “natural scenic beauty, clear lakes and streams, and abundant wildlife.” I can’t speak to most of that, but it does have lizards!

Fence lizard with a regenerating tail.

Fence lizard with a regenerating tail.

Rainy and overcast days slowed us down a bit. As ectotherms, lizards rely on external sources of heat, which means they like to bask in sunny spots in order to warm up. The thick clouds didn’t provide many good basking opportunities, but thankfully a few lizards made an appearance in the brief moments of sun.

Sometimes fence lizards like rocky habitat.

Sometimes fence lizards like rocky habitat.

2blendinMany other lizards like to bask on trees.

We did see a few sunny days, which gave Braulio and Caty the opportunity to catch their first lizards.

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Braulio with a Tennessee lizard.

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One of Caty’s first catches!

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Lizard selfies are the best selfies.

We even managed some “expert” catches, on more than one occasion slowly driving by a basking lizard and noosing it through the open car window.

Because we were looking for females, we of course became experts at catching males. One male lizard really hoped I was a tree. We tried to return him to his log, but on two separate occasions he ran up my leg. Sorry little guy!

Nope, not a tree.

Nope, not a tree.

Another male, pictured below, really surprised me. Lizards vary in coloration, but not usually by much. I’ve never seen a fence lizard so dark!

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A very dark fence lizard. His chest badges were impressive as well!

After two weeks of catching, we headed back to the lab. Our females are now happily housed in their nesting boxes, and one has laid her first clutch of the season. We’re all excited to see the resulting hatchlings!

Check back soon for more stories and photos from the field as well as updates on the specific research projects happening this summer.

We even spotted a fence lizard on a fence. So satisfying. A fence lizard on a fence. So satisfying.


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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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Starting the year with a bang!

2015 ended in style for the Langkilde Lab, and we are proud to report that thus far 2016 has been just as exciting! In the last few months, we have celebrated a number of lab accomplishments and enjoyed some attention from the media. Here’s a taste of what we have been celebrating:

 

Press:

LangkildeLizard 2Penn State News featured the lab’s work on adaptation to invasive species and anthropogenic noise in this great article by Matt Swayne, complete with disco references. It’s definitely worth the read!

 

Tracy1Penn State Science recently covered the lab’s research on the effects of stress, our collaborations, and Tracy’s mentoring style. The story quotes many lab members and also includes a “person-to-person” feature on graduate student Gail McCormick.

 

 

Other achievements:

  • PI Tracy Langkilde recently accepted the position as the Head of the Department of Biology.
  • Gail McCormick successfully defended her PhD dissertation and won the Alumni Association Dissertation Award. This award is among the most prestigious available to Penn State graduate students and recognizes outstanding achievement in scholarship and professional accomplishment.
  • Chris Thawley won the Intercollege Graduate Student Outreach Award, a university-level award that recognizes outstanding achievements related to bringing scholarship to the community. Chris will be defending in February and will be starting a post-doc with the Kolbe Lab in May, where he will be investigating the effects of urban light on anoles.
  • Kirsty MacLeod will be joining the Langkilde and Sheriff Labs as a post doc this spring. We are excited to have her!
  • Michaleia Mead will be staying on as a Masters student with Chris Howey. They will be investigating the effects of prescribed burns on amphibians and vernal pools.
Hooray!

Hooray!

Stay tuned throughout 2016 for more exciting research and updates from the Langkilde Lab!


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Winter Is Coming; Herp While You Can

Since my summer has been full of writing and conferences and decidedly empty of time spent working with reptiles and amphibians, I decided to take advantage of a recent family wedding (congrats Tanya!) and do some herping in North Carolina, a state I haven’t spent much time in since my undergraduate days in the Herpetology Lab at Davidson College.

Even before arrival at my final destination, I spotted a promising sign: a green anole (Anolis carolinensis) out basking in the afternoon sun near the Forest Service office.

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Ahhhh, sunlight.

I camped in the Uwharrie National Forest, a relatively small national forest with some nice campsites on Badin Lake.

Yep, pretty nice alright.

Yep, pretty nice alright.

While it’s been getting chilly here in State College, the climate in NC is still rather balmy with daytime temperatures in the 70’s and nighttime temps warm enough for a little reptile activity, at least on the roads. Unfortunately, warm roads with cars and cool weather are a pretty good recipe for snake deaths, and the first snake of the trip was a DOR (dead-on-road) scarlet kingsnake (Lampropeltis elapsoides). These gorgeous snakes are coral snake mimics and can be an unusual find.

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DOR snakes often look a little bug-eyed…:*(

A full day of hiking around Badin Lake, and through streams and backwoods resulted in a decent turnout, including many of the usual suspects:

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Bullfrogs (Lithobates catesbeiana) were common along the shoreline of the lake and in adjacent streams.

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The most surprising thing about finding this black racer (Coluber constrictor) was that it didn’t bite me….what?!?

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This little brown skink (Scincella lateralis), was moseying through the leaf litter in a sunny patch along the lakeshore. And yes, that is its “official” common name. Scientists are so creative!

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Northern cricket frogs (Acris crepitans) were abundant throughout the forest and easy to spot as they used their outrageously long jumps (> 3 ft for a frog <2 in!) to escape approaching humans (me).

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Northern dusky salamanders (Desmognathus fuscus) were holding out in a small spring seep in an area surrounded by muddy creeks and lots of horse poop.

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Upland chorus frogs (Pseudacris feriarum) were active, but not chorusing, on a cloudy day.

 

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This hatchling midland water snake (Nerodia sipedon pleuralis) was none to pleased to be removed from its natal creek (and bit me numerous times, as watersnakes are wont to do).

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However, it calmed down (a bit) when return to its aquatic environs.

On the way back to PA, I couldn’t resist targeting one specific species, the Peaks of Otter salamander (Plethodon hubrichti). This species is found only along a 13 mile stretch of the Blue Ridge Parkway near Peaks of Otter (surprise!) in southern Virginia and is under review to be considered federally threatened or endangered due to its very limited range. This salamander is named after the eminent citizen naturalist Leslie Hubricht (who also discovered the Red Hills salamander) and was so named after a bit of scientific skullduggery (you can read the story here). Finding this species was no problem thanks to a tip on a great locality from ex-Langkilde Lab member Sean Graham. I’d found a few, snapped a couple of pics, and was on my way home in under 15 minutes.

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These ‘manders were all dirty from their stay under the local rocks, but, as I didn’t want to disturb the population too much, I settled for some slightly less polished photos.

And of course, I couldn’t resist stopping at some of the awesome overlooks scattered along the Parkway.

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Even on a cloudy day, the fall colors were still very nice (even for a colorblind viewer!)

And with that, I’ll enter a long, dark winter of writing and working towards finishing my dissertation!