When these lizards lay their eggs, they dig a little burrow, lay their eggs, camouflage the site, and then leave. Some of the work I was doing this summer was trying to understand how much time the eggs incubate in the nest before hatching. Q: Presumably the paint helps you keep track of them?Ī: Right. We also use high-throughput sequencing to identify all the microbes in the sample this requires advanced bioinformatics to give us measures of microbial diversity and composition. Then in the lab, we can culture the material from the swab in a petri dish, see what grows, isolate it, extract and sequence the DNA, and use databases to find its identity. Then we put a small dab of paint on their back and release them. While the lizard is in hand, we also take basic measurements-sex, mass, length-and one of our undergraduates, Alexi Ebersole, takes a little snip of their tail tissue, so we can learn about their diets using stable isotope analyses. Then we pull them out of the loop and take a swab and gently twirl it around in the cloaca to collect a microbial sample. To catch the lizards, we use a lasso slipknot-a fishing line at the end of an extendable fishing pole-and we get a loop around the lizards’ neck and flick up. Q: How does one measure bacteria and fungus on lizard eggs, anyway?Ī: It’s actually pretty fun. That aspect isn’t what drives my intellectually curiosity, but it’s the only time in my career when my research could have direct impacts on human health. Since we’re looking at antifungal properties of cloacal bacteria, our work could potentially identify new antifungal agents. Q: Is there conceivably any relevance to humans?Ī: Yes.
So even the basic descriptive components of our work are important. For instance, might females advertise their high quality, egg-protective microbiome to potential mates? It’s also critical to our field that we’re studying a diversity of host species, environmental pressures, and adaptations-and, so far, lizards tend to be underrepresented in microbial ecology. Since I’m trained as a behavioral ecologist, I’m very interested in investigating how my microbial work intersects with theory about the evolution of parental care-or lack thereof-and of female sexual signaling. The field of microbial ecology is rapidly advancing, and we’re learning so much about host-microbe coevolutionary relationships. If so, it will open up new ways to think about the role of microbes on their hosts. But this mechanism of egg-protection could potentially be very wide-spread among oviparous, or egg-laying, animals. We have good support for the evolution of egg-protective cloacal microbes in one lizard species.
Q: What’s the broader significance of all this?Ī: It’s multifold. My current research student McKenna Boulet is trying to figure out which bacteria are affecting which fungi, and what the underlying mechanism might be. These results are the focus of a recent open-access publication in Animal Microbiome that includes my wonderful technician, Marie Bunker, as lead author two undergraduate students, Grace Elliott and Helena Heyer-Gray and two colleagues, Mark Martin and Betsy Arnold (from University of Arizona) as co-authors. More bacteria resulted in less fungus, and more hatch success. Since then, we’ve learned that when an egg is laid naturally through the cloaca-the tube that’s the shared end of the digestive and reproductive tracts-it has more bacteria compared to the surgically removed eggs.
Why is that? It was my colleague Mark Martin who had the idea of cloacal microbes-it really was one of those hallway conversations with him that led to this work. When incubating eggs in the lab, I’ve found that if an egg is laid by the female, it has a very high hatch success, but if it’s surgically removed from the mother, it’s less likely to be successful. In reptiles, parental care is rare is there a way for the mother to protect her eggs in her absence? We developed this research based on an anecdotal observation. What are you hoping to discover?Ī: Our hypothesis is that maternal microbes coat the lizards’ eggs and protect them from fungal pathogens in the nest environment. Q: You received a $730,000 National Science Foundation grant to study the maternal and eggshell microbiome of striped plateau lizards.
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