Evolution of the Gut Microbiota though Adaptive Radiation of Hosts
Depiction of multidirectional selection experiment (by January Weiner)
Comparative studies have shown that host evolutionary history determines gut microbial communities in mammals. However, it is unclear how selection at the host-level may be influencing these relationships. I am collaborating with Dr. Pawel Koteja at Jagiellonian University in Krakow, Poland on an artificial selection experiment. Wild field voles (Myodes glareolus) have been selected for 13 generations for high aerobic capacity, predatory behavior, or tolerance of a low-quality diet [Link]. We have demonstrated that voles selected for the ability to thrive on a high-fiber diet have more diverse cecal microbial communities, even when they are not feeding on high fiber diets [Link].
Avian Gut Microbiota
A majority of the research conducted on the gut microbial communities of has been conducted on mammals. Birds represent a diverse and unique group of vertebrates that remain to be thoroughly studied. I have written a review article on the diversity and function of the avian gut microbiota, and highlighted areas for future research [PDF].
Amphibian Gut Microbiota
Photo by T. Cary
Amphibians represent another understudied group of vertebrates in terms of gut microbiology. I am collaborating with Dr. William Karasov and his student, Tawnya Cary to investigate how the amphibian microbiota changes over development, as well as in response to environmental conditions. We have shown [here] that the microbiota undergoes significant changes between tadpoles and adults. Additionally, we have shown [here] that larval exposure to an environmental pollutant (polychlorinated biphenyl 126) causes persistent alteration of the amphibian microbiota.We have also demonstrated that environmental temperature yields distinct microbial community structures in the tadpole gut [Link].
Fasting and the Microbiota
Many wild animals undergo times of fasting and starvation. The effects of of undernourishment on the gut microbiota are poorly understood, especially across vertebrates. I am collaborating with Dr. Marshall McCue to investigate the effect of food shortages on gut microbial communities of various vertebrate classes (fish, amphibians, reptiles, birds, mammals). We have shown here that the responses to fasting vary widely across vertebrate hosts.
I am collaborating with Johanna Varner to study the microbiota of the American Pika (Ochotona princeps). Pikas are small, herbivorous mammals that are closely related to rabbits. We are investigating the microbial diversity of the pika gut in relation to geography and dietary habits. We are particularly interested in atypical habitats where pikas consume high amounts of moss, which is especially high in fiber.
Physiological Effects of Fruit Toxins on Rodents
Photo by M. Samuni-Blank
This work is largely performed in collaboration with Dr. Michal Samuni-Blank at the Technion-Israel Institute of Technology. She has recently discovered that a group of rodents have evolved to behaviorally avoid glucosinolates (a.k.a. the "mustard oil bomb") present in fruits [Link]. This behavior may be driven by physiological tolerance to toxins, and may ultimately drive ecological interactions (seed predation or seed dispersal). While the physiological effects and adaptations to glucosinolates have been well studied in insects, the effects on vertebrates are much less understood. We have shown that seed predators exhibit higher physiological tolerance to fruit toxins compared to seed dispersers. [PDF]. We have also demonstrated that these rodents regulate activities of intestinal and microbial β-glucosidases in order to prevent activating glucosinolates [Link]