Arianna Kuhn, PhD Candidate, City University of New York, American Museum of Natural History
Arianna posing with a juvinile flap-necked chameleon (Chamaeleo dilepis) seen crossing the road on her first field excursion in Gauteng, South Africa.
As a PhD candidate at the City University of New York, my current work aims to understand the evolutionary events that cause new species to form, but my career in herpetology actually began with geckos from Africa! As an undergraduate at Villanova University, I knew that I wanted to do research in a lab, but I knew little about the diverse fields of biological research active on my own campus. After doing research on the faculty of the biology department, I eventually found the labs of Dr. Todd Jackman and Dr. Aaron Bauer, where I began a project sequencing DNA from gecko tissues collected from sub-Saharan Africa. This project really clicked for me. Running analyses on my own study system that contributed to discovering and describing nine new species was more interesting and fun than I could have ever imagined! Being surrounded by a group of supportive graduate students, postdocs, and advisors that also loved to spend time outdoors catching local herps motivated me to delve deeper into my studies of herpetology and evolutionary biology. These experiences led to additional lizard projects and eventually a Master’s degree, where I spent multiple seasons in the field collecting snakes, geckos, and skinks in Angola.
A tiny Namib day gecko (Rhoptropus barnardi) in Namibe, Angola. This was my first time seeing my study organism in person after doing genetic work on tissues in the lab, so I was very excited!
Fast forward to where I am today—in a doctoral program advised by head Curator of Herpetology at the American Museum of Natural History, Dr. Frank Burbrink. Funded by the National Science Foundation, our team set out to generate the first comprehensive evolutionary history of Madagascar’s Gemsnakes (subfamily: Pseudoxyrhophiinae) to examine how ecology and morphology coevolved to produce this spectacularly diverse group of snakes.
One of my favorite snakes to find in the field is the Malgasy leaf-nosed snake (Langaha madagascariensis). The individual pictured here is a male, and the female snake of this species looks completely different! Scientists are still trying to figure out what exactly the weird projection on the nose of this snake is used for.
A quick recap on why Madagascar is one of the most fascinating biological hotspots on the planet Earth: located off the coast of East Africa, Madagascar is home to a massive assemblage of unique and bizarre animals that have been evolving in complete geographic isolation for more than 80 million years (Noonan & Chippindale, 2006). Madagascar is famous for having incredibly high species richness (number of species) and endemism (animals found nowhere else on earth). For example, more than 350 different species of frog can be found on Madagascar, giving this island the highest frog diversity per square kilometer of any country in the world (Vietes et al. 2009). Researchers have been intrigued by what ecological and historical factors have contributed to this exceptional faunal and floral composition for decades. Many of these species are currently at risk due to extreme habitat loss from deforestation and future climate change (Alnutt et al. 2008). With our research, we hope to uncover how species responded to changes in climate and vegetation in the past to better predict how they might respond in the future, and identify important genetic and landscape attributes that contribute to positive adaptive responses.
A Malagasy blonde hog-nosed snake (Leioheterodon modestus) photographed in Beanka Reserve, Western Madagascar. This species is not closely related to the hog-nosed snakes of North America – the noses of both species are upturned to aid in digging up eggs, but both evolved the trait independently.
Because snakes are one of the most widespread and ecologically significant groups of vertebrates that can be found across the island, they make a perfect study system for understanding diversification in the tropics (Nagy et al 2003). Unlike the more iconic residents of the island, such as lemurs, snakes have received comparably little attention with respect to biodiversity assessment and landscape genetics (Yoder et al. 2016).
Dr. Phillip Skipwith and I capturing a Malgasy giant hog nosed snake (Leioheterodon madagascariensis) we saw crossing the road on our way to Kirindy Forest.
My current project uses the genetic information encoded in the DNA of snakes to understand how they got to the island, why there are so many species, and how these new species formed. This means that I get to travel to Madagascar to undersampled habitats and catch snakes! What a field season looks like in real time is a team of biologists out in the forest flipping over every single rock and log they can find, hoping that one of these structures will have a snake underneath to catch and bring back to the campsite for sampling. During the day, we might stumble across diurnal snakes out basking in the sun, or we might get lucky enough to spot one crossing the road while driving to new survey sites. At night, our team heads out with powerful headlamps, this time looking for nocturnal animals that are hunting on the ground or in the trees.
There are only four species of boa on Madagascar. Here, I am holding the Malagasy ground boa (Acrantophis madagascariensis) – females can grow up to 10 feet long!
When I find a snake, I can catch it with my hands because there are no lethally venomous snakes on Madagascar. Back at the campsite, I take a small tissue sample from the animal that I will bring back to my lab at the American Museum of Natural History. In the lab, I can extract and sequence a huge amount of DNA from this tiny piece of tissue, and this genetic information is the primary data I use to answer questions about how these snakes evolved and adapted to specialized habitats on Madagascar. I can also examine this genetic information to identify new species previously unknown to science. In fact, last year my colleagues discovered as many as 38 potentially new species of gemsnake (Burbrink et al 2019). Looking thousands of years into the past, I am able to identify particular genes that may have helped snakes to adapt to new environments in response to historical climate change events. Once I know this information, I can use future climate projections to better understand how populations of snakes might respond to climate and land use change in the future.
Although it is sad to see a snake that has been killed by a car on the road, we are still able to take tissue samples from these individuals, which make up an important portion of my geographic samples for population genetic studies.
Lycodryas citrinus is a stunning arboreal gemsnake that I have spotted several times cruising through foliage at night in arid regions of western Madagascar. This species is known to give birth to live young rather than laying eggs.
Check out my website to learn more about my research!
By Arianna Kuhn, PhD student in the lab of Dr. Sara Ruane, Assistant Professor, Department of Biological Sciences, Rutgers University-Newark; Lisa Rothenburger, Somerset County 4-H Agent, Rutgers Cooperative Extension