The Lizard Log

The Langkilde Lab in Action


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Transformative Learning: Highschoolers Metamorphose into Scientists

Our next guest blog post is from Melissa O’Brien, a lab undergraduate student, who did a fantastic job this summer serving as a mentor in an education initiative for high school students, which she describes below:

This summer our lab had the opportunity to work with three fantastic Upward Bound Math and Science students through the SEECoS program (Summer Experience in the Eberly College of Science). Students selected for the program show a lot of potential in their high school science classes, but they come from inner city schools that may not give them the preparation they need for college. This is where SEECoS comes in. Once students have been accepted into the program, they come up to Penn State in the summer for six weeks of research and coursework. These courses are designed to prepare the students for high school classes they will have in the upcoming Fall. In addition, students have the opportunity to do a research project with Penn State faculty and students, for which they are required to write a research paper and, during the final week of the program, present to their classmates.

The three SEECoS students in the Langkilde Lab were:

Selena, who is entering her senior year at Reading High School and is interested in criminology and, after working with us this summer, herpetology.

Jermayne, who will be a junior at Olney Charter High School in Philadelphia, and wants to pursue a career in forensic science, and

Kiara, who is entering her freshman year at Reading High School and is interested in veterinary science.

This summer our students conducted an experiment to study tadpole behavior, titled: “City frogs versus country frogs: investigating the effects of urbanization.”

SEECoS-Group-Shot

A group photo from the first day of SEECoS. From left to right: Melissa (SEECOS undergraduate mentor), Selena, Jermayne, and Kiara.

Our students worked with wood frog (Lithobates sylvaticus) tadpoles lovingly raised by Jenny Tennesson, a graduate student in the Langkilde Lab. Jenny gave the students background information on her system before they designed their research project. She asked students to think about the differences between noisy and quiet environments and how these differences might influence animal behavior. Our students came up with some great ideas, and we decided to study differences in sociality and anti-predator behavior in tadpoles from noisy and quiet environments (ponds with different noise levels). Brad Carlson, another grad student in the lab, helped us develop an exciting project to investigate both sociality and anti-predator behavior over the course of three days.

Students set up 12 tubs that they would use for 6 different trials. The tubs contained two mesh dividers (one on each end), and the center of each tub was divided into four equal zones (numbered from 1 to 4).  A subject tadpole from a noisy or quiet environment was placed in the center of each of the tubs while a stimulus tadpole from a separate pond was placed behind one of the dividers. The tubs were numbered so that zone 1 was closest to the stimulus tadpole and focal tadpoles in this zone were likely more social, while zone 4 was the farthest away from the stimulus tadpole and should be used by less social focal tadpoles.

Tadpole tub

Tadpole tub complete with subject and stimulus tadpoles.

The tadpoles were given 30 minutes to acclimate to the tubs, after which the students added control or predator water to the center of the tubs. The control water consisted of tap water that had been treated with ReptiSafe to neutralize any chemicals that could harm the tadpoles. Predator water was obtained from water in which dragonfly nymphs had eaten tadpoles. These cues should make the subject tadpoles think there was a predator nearby. Our students were initially freaked out by the dragonfly nymphs (they do look like aliens with large protruding jaws), but we were able to convince Jermayne to pick one up!

Jermayne holding a dragonfly nymph.

Jermayne holding a dragonfly nymph.

A dragonfly nymph munching on a tadpole (photo taken by Tracy).

A dragonfly nymph munching on a tadpole (photo taken by Tracy).

After the tadpoles had adjusted to the predator cues, our students began collecting data. They took turns observing each tub every 30 seconds to record the location (zone #) and movement (moving/still) of the subject tadpoles for 15 minutes. The zone number gave us information about sociality, and taking notes on tadpole movement would help us study anti-predator behavior. After conducting their experiment, our students analyzed their data to see whether sociality and anti-predator behavior differed between tadpoles from noisy and quiet environments. Our students found that, regardless of the type of pond a tadpole came from, the tadpole tended to reduce its movement in the presence of a predator cue. Students also found that tadpoles didn’t show social behavior, although it might be possible that tadpoles from quiet ponds become less social in the presence of predators. Our students also discovered that treatment order matters. They used 36 different subject tadpoles over the course of three days, and each tadpole was used twice. The results showed that tadpoles that were exposed to predators first would stay still even when they were placed in a control tub a few days later. This may mean that tadpoles have better memories than we think they do, if they still associated the tubs with predators.

While our students didn’t see any significant differences between frogs from noisy and quiet environments in their results, they gained something much more important from this research experience. They had the opportunity to see how much fun science can be, and they learned that being a scientist doesn’t mean you have to sit in a lab all day. They had the opportunity to handle frogs, lizards, and even dragonfly nymphs! Our students also had the opportunity to go into the field and catch tadpoles and salamanders with Jenny, Lindsey, and Courtney. While they weren’t so fond of the waders right away, it wasn’t long before our students were competing with each other to see who could catch the most tadpoles with one scoop of the net.

Kiara, Selena, and Jermayne catching tadpoles.

Kiara, Selena, and Jermayne catching tadpoles.

Kiara holding a wood frog metamorph, and Selena with freshly-caught salamander larvae

Kiara holding a wood frog metamorph, and Selena with freshly-caught salamander larvae

It was easy to see that Kiara, Selena, and Jermayne became much more confident in themselves over the course of the SEECoS program. We’re sure that they developed a love of slimy critters (you know you did!). They were able to design and carry out an experiment, analyze the data, and present their results to their peers. Their enthusiasm for and knowledge of their project earned them 4th place among SEECoS presentations and 6th place for overall best research project. Most importantly, our students learned that they are very capable scientists who can be anything they want to be. We feel so privileged to have had the opportunity to work with such great students, and we know that they will be successful no matter what field they choose! Thank you to everyone who made this experience possible, and we can’t wait for next year!

Group photo on the last day of SEECoS. From left to right: Mr. Licona (biology teacher), Melissa, Jermayne, Kiara, Selena, and Tracy.

Group photo on the last day of SEECoS. From left to right: Mr. Licona (biology teacher), Melissa, Jermayne, Kiara, Selena, and Tracy.


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Mark Measures Eggshells to See Who Has More

As the summer field season winds down and school begins to pick back up, we’re going to start featuring guest posts by our undergraduate researchers to give you an idea of the breadth of the projects going on in the lab. First up is Mark Goldy-Brown, a rising senior at PSU who will be starting his second year in the lab this fall:

This past fall I started as an undergraduate researcher in the Langkilde Lab, and so far I have enjoyed every minute of my time here.  The lab is well known for studying the interactions between the Eastern Fence Lizard (Sceloporus undulatus) and the Red Imported Fire ant (Solenopsis invicta), an invasive ant species that had been causing many problems in the United States since it was accidentally brought here from South America over 80 years ago.  These fire ants cause a great deal of agricultural damage each year in addition to affecting native plants and animals, which are not adapted to handle this invasive species.  Some of the lab’s work focuses on how the fire ants affect the fence lizards in the southern U.S. and has shown that fence lizards seem to be adapting to deal with these nasty little ants.

UninvVsInv

Map showing where the females who laid the eggs used in my study were collected from. Invaded sites have fire ants, while uninvaded sites have no fire ants.

Most research so far has been to see how the fire ants affect the hatchling, juvenile, and adult lizards, but my research over the last year examined how the fire ants could be affecting the fence lizard eggs.  Fire ants are extremely aggressive predators, capable of attacking and eating nearly anything that they come across when they are searching for food, including reptile eggs.  They have been shown to eat the eggs of sea turtles, painted turtles, chicken turtles and even yellow rat snakes.  Last summer and this past summer, our lab showed that the ants will also eat fence lizard eggs.  Wow!  So I wanted to see whether there were any differences between eggs from populations of fence lizards that had been living with fire ants for many years and eggs from populations of fence lizards that had never been exposed to fire ants.  You would think that if fire ants can eat through the eggs, then perhaps eggs that are laid where fire ants are also found should have some added protection so that they have a greater chance of surviving.  My two hypotheses for this experiment were that eggs from sites invaded by fire ants would 1) have thicker shells and 2) more Calcium Carbonate (a crystal compound that could make it harder for fire ants to penetrate the eggs) than those from sites where no fire ants were present.

Testing these hypotheses involved working with a ton of fence lizard eggs (collected after the baby lizards hatched, of course).  To test my first hypothesis, I cut each eggshell in half, cleaned out the inside and then used a biopsy punch to remove equally sized bits along the length of the eggshell that I called eggdiscs.  These eggdiscs were placed in between two glass microscope slides and left to dry out in a container filled with silica beads (the silica removes water and dries them out).  Once they had all dried, I measured each of the eggdiscs (there were quite a few) using a thickness gauge that could measure very thin things with high accuracy.  After analyzing the data collected, I found that eggshells from uninvaded sites (no fire ants) were actually thicker than those from invaded sites (fire ants), the complete opposite of what I was expecting.  I wasn’t really sure why this would be the case, but I thought that perhaps mother lizards who aren’t stressed by fire ants can put more energy into their eggs and therefore make thicker ones.  Interestingly, I also found that thickness also varies within the eggshell, meaning that the tips of the egg are not the same thickness as the middle of the egg.

Diagram showing the eggdiscs on a slide, and how I sampled them along the whole length of an eggshell.

Diagram showing the eggdiscs on a slide, and how I sampled them along the whole length of an eggshell.

So my second hypothesis was that fence lizard eggs from invaded sites would have more calcium carbonate than eggs from uninvaded sites.  To test this theory, I used whole eggshells that came from the same mothers as the eggs used for the thickness experiment.  Each eggshell was cut in half, placed into a test tube and then stuck in a dehydrator (the same kind of one you would use to make dried fruit) for 2 days.  After they dried out, I weighed each of them and then added hydrochloric acid (the acid dissolves all of the calcium carbonate) and then let the eggs “soak” for 24 hours.  After they had sat in the acid for a day, I poured out the remaining liquid, dehydrated the eggshells again and then weighed them once more.  The difference in weight from before and after the eggshells were dissolved in acid is equal to how much Calcium Carbonate was present in the eggshell.  When I analyzed my data for this part of my project, I didn’t find any significant results but it did show a trend that there was more calcium carbonate in eggs from uninvaded sites than invaded sites, which again was contrary to my hypothesis.

I was very excited to complete my first full research project this past spring and to be able to present my research at the annual undergraduate research symposium.  Performing all of the data collection took me several months and it required a lot of repetitive work, but it definitely paid off.  After completing this project, I began to create a project to work on over the summer and this project will be the subject of a future post.  Hope you enjoyed hearing about my research project and pose any questions in the comments section!