Research
Current Research
Our lab is currently working to better understand the physiological constraints of TTX production. Further, we are working to understand anti-predator behavior in newts, and the factors that influence those behaviors. See my Publications page for a full list of publications.
PhD Research
My PhD research focused on further understanding the function of tetrodotoxin (TTX) in various systems. First, however, I modified previous methodology to develop an assay for quantifying TTX. This method allows us to quantify TTX at a fraction of the cost associated with other methods such as HPLC or LCMS.
Tetrodotoxin in Bipalium adventitium and Bipalium kewense. Tetrodotoxin in terrestrial ecosystems has up until recently only been described in terrestrial vertebrates. No terrestrial invertebrate was ever described with this toxin. However, we found that the terrestrial flatworms B. adventitium and B. kewense have TTX. We also found that TTX is distributed evenly throughout the body. However, when mass of body segments are taken into account both species have much higher amounts of TTX in the head. This indicates that TTX may be used to subdue large prey items, however, does not rule out the use of TTX in defense for Bipalium species.
Novel predation on Taricha newts. These newts have long been studied, but most commonly are thought to only have one main predator-garter snakes. However, we observed and documented predation by river otters in Oregon. We found that the newts in this location had very low levels of TTX. We also looked at trends in TTX levels over different elevations. We found that newts at low elevations <300 m had significantly higher levels of TTX than those at higher elevations >700 m.
Stokes et al. Northwestern Naturalist. 2015.
MS Research
My research for my Master's degree focused on sex-biased predation by a novel predator in Annadel State Park in Santa Rosa, CA. Newts of the genus Taricha have tetrodotoxin (TTX) in their skin glands. Up until this work their only known predator was garter snakes of the genus Thamnophis. However, surveys in the area indicated that there was a novel predator that was eviscerating newts, presumably in order to avoid the toxic skin. Furthermore, predation was male biased. We documented 10 years worth of predation data as well as quantified TTX in males and females of the two Taricha species found in the park.