Toxin-resistant garter snakes in MBE

My paper on toxin-resistance evolution in garter snakes with Butch Brodie was published in Molecular Biology and Evolution. Thanks to help from VT libraries, we were able to publish this Open Access. The paper was also honored as a “Fast Track” article by the editors of MBE.

In this paper, we show that garter snakes, which have long been known to be predators of highly toxic newts, have evolved toxin resistance in three voltage-gated sodium channels found in different tissues. These channels are normally blocked by the toxin, leading to paralysis and even death in many organisms. In 2004, Shana Geffeney and colleagues showed that the muscle channel Nav1.4 has evolved resistance to the toxin via amino acid substitutions in the channel’s pore. We looked at five other channels in this paper, and found that two of them that are expressed in peripheral nerves, Nav1.6 and 1.7, had also evolved resistance in very similar ways in garter snakes. Three other channels only found in the brain had not evolved resistance, probably because they are protected by the blood-brain barrier. These results tell us that the interaction between garter snakes and newts is a lot more complex than we originally thought.

Amino acid changes in three sodium channels.

This work wouldn’t have been possible without hard work from Dan Janes, who conducted BAC library scans of garter snake DNA while I visited Scott Edwards’s lab at Harvard back in 2010.

The project has been a long time coming together, and it will be really exciting to see where it goes next!

Evolution meetings in Raleigh, NC

Tamara, Eric, and I all presented posters at Evolution 2014 in Raleigh, NC. Both Tamara’s and Eric’s posters included contributions from undergraduate co-authors Prabh Dhillon, Anastasia Arkhipova, Chris Noble-Molnar, Andy Schurtz, and Thomas Wood. These posters contained some early data obtained our lizard colony. My poster was based on some prelimary analyses of voltage-gated sodium channels in bird genomes, which builds off our soon-to-be published work on garter snake sodium channel evolution. Stay tuned for more from all these projects!

Lizard collecting on San Salvador

Graduate student Tamara Fetters, VT colleague Ignacio Moore, and I have just returned from a collecting trip to Gerace Research Centre in San Salvador, The Bahamas. The lizards we collected will allow us to begin work on the VT half of a long-term collaborative project we are working on with Bob Cox at UVA. We collected over 200 brown anoles (Anolis sagrei), which we will use to start the lab’s breeding colony in Blacksburg.

The collecting trip was a success in the end, despite several setbacks along the way. First, the hot, dry conditions and the scrubby vegetation in San Salvador made the anoles almost impossible to catch during the day. Consequently, we did almost all of our catching at night, plucking the lizards from the tips of branches where they slept.

We very nearly lost all our specimens on the way home. Despite filing all the appropriate paperwork with the Bahamian government and the US Fish & Wildlife service, we were detained by US Customs in Nassau for over two hours, causing us to miss our plane. After the customs agents were finally able to reach Miami FWS on the phone, we were finally free to go, and we had to spend an unplanned night in Miami. Thankfully, all the lizards are now safe in their new homes!

Hamilton’s rule and quantitative genetics

My paper on Hamilton’s Rule with Jason Wolf, Butch Brodie, and Allen Moore was published in Philosophical Transactions of the Royal Society B as part of a special issue on inclusive fitness. We review several different ways that Hamilton’s rule, which predicts whether altruism should evolve, has been incorporated into the standard quantitative genetic model of evolution. We distill a lot of mathematical theory down into what I hope is a fairly readable account of some pretty complex models!

Maternal effects in Evolution

My paper on maternal effects with Laura Galloway was just published in Evolution. We compared the fit of multiple quantitative genetic models of maternal effects to data from a greenhouse selection experiment in Campanulastrum americanum. We showed that these models differ in subtle ways and that the best predictions are made from a fairly complex model that includes effects that cascade across generations.