The Lizard Log

The Langkilde Lab in Action


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Racing baby lizards (for science)!

In the latest chapter of the “bearded lady” saga (female fence lizards bearing ornamentation that is typical of males), we continue to investigate what potential advantages these “unattractive” females could have that allow them to persist in high numbers.

We know that in many species, colorful, conspicuous ornaments have a tight relationship with levels of particular hormones (such as testosterone), which themselves are related to physical performance. One of our current guesses is that even though females bearing male-like ornamentation are not prime sexual partners in the lizard world, their offspring might be more physically competitive than offspring of the more desirable females (read more here). The costs and benefits of both strategies could be responsible for the coexistence of the two!

A good way of measuring the physical performance of an animal is by how fast they can run. With the help of two enthusiastic undergraduate students, Maggie Zemanek and Sean Dailey, I am recording slow-motion videos of juvenile lizards running on a race track. This will help us calculate how fast each of them can run, and compare that to what their moms looked like: are the faster runners offspring of ornamented females?

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Do your best!

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Body temperature greatly influences performance in reptiles, so Sean makes sure we record how warm each lizard is

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Maggie sets a contestant on its marks

Maggie, Sean and I still have a lot of juvenile lizards to race, but hopefully we’ll find some interesting patterns in our experiment. Stay tuned!


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The Lone Master’s Student

The first year of my MSc will be coming to a close in May! After a semester of my first graduate school classes and my first experiences as a teaching assistant I was just starting to get the hang of it and the semester ended. This semester has been filled with research planning and manuscript writing. Just coming from my undergraduate degree, the thought of not taking any classes for an entire semester sounded insane, but so far, I have been very productive. I have one field season down, one coming up this spring, and one manuscript started.

Writing my first manuscript has been interesting to say the least. I have learned so much about statistical analysis of data, and the dreaded R. I am having a difficult time with the introduction section but the results and methods were a breeze. I look forward to getting back out into the field, that is why I got into this field after all.

My upcoming field season will begin sometime in March as the vernal pools begin to thaw and the wood frogs return to them to lay their eggs. I will be doing a transplant study that will follow up on research that I did in the lab for the first chapter of my thesis. I used a 3×3 full factorial design to look at how pH and UV-B affected developmental rates, mass, body condition, survival, and baseline and stressed CORT levels in wood frog tadpoles. The second chapter will take place within local vernal pools. Stay tuned for the results from the upcoming season!

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Lizard poop and the parasites who love it

A lot of my work in the lab involves assessing the health and well-being of our fence lizards under different conditions, including their parasite burdens. Parasite infestation can vary with immune status, stress, or external factors such as predation (for example, lizards in fire ant invaded areas have fewer ectoparasites). Ectoparasite (ticks, mites, etc.) load is easy to assess, as we count them on each lizard shortly after capture. Internal parasites are a bit trickier, but one method commonly used in veterinary medicine is to collect their feces, and check it for intestinal parasites and eggs.

There are several different methods of testing for intestinal parasites, including direct smears, qualitative fecal flotations, and quantitative fecal egg counts. Direct smears are the simplest method, involving looking at fecal smears directly under a microscope, but they are also the least sensitive, and often don’t show any results. The most sensitive method is qualitative fecal flotations, the method of choice if you want to see all the possible parasites an organism may have in their feces.
The basic idea behind a fecal flotation is a feces sample is mixed with a solution denser than the parasite eggs you are looking for. The mixture is then spun in a swinging-bucket centrifuge. Due to the parasite eggs having a lower density than the solution, they float to the top of the tube while being centrifuged, and collect on a cover slip on the top of the tube. This results in most of the parasite eggs in the fecal sample being concentrated onto the cover slip for easy viewing.
Unfortunately, the fecal flotation method, while a great way to learn how many different types of parasites are in a fecal sample, does not tell you how many individual eggs are in each gram of feces. Such comparisons are important in veterinary medicine in order to tell if a treatment is working, and is important to us in the lab for comparing fecal egg loads between experimental groups. This is where quantitative fecal egg counts become useful. While less sensitive than fecal flotations (they may not identify lower-level infestations of parasites), fecal egg count methods can tell us how many eggs are in each gram of feces. To do this, we precisely dilute a set amount of feces into flotation solution, and mix it thoroughly. The mixture is then placed in a special slide, called a McMaster, and read after 5 minutes, using the grid on the slide.
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The McMaster slide we use

I’ve had some challenges adapting these methods to use in our fence lizards, as both fecal flotation and fecal egg counts require more feces than a lizard normally produces, but I have gotten some interesting results, mostly a variety of strongyle and coccidia eggs.