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Multidirectional interactions between amphibian hosts, the gut microbiome, and environmental temperature

Fontaine, Samantha S. (2023) Multidirectional interactions between amphibian hosts, the gut microbiome, and environmental temperature. Doctoral Dissertation, University of Pittsburgh. (Unpublished)

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All vertebrate species harbor dense and diverse microbial communities living in their gastrointestinal tract, called the gut microbiome, that profoundly influence their physiology, ecology, and potentially evolution. These communities are shaped by both the internal and external environment of their host, and in turn, influence how hosts respond to the environment through provisioning of numerous physiological services. Although the gut microbiome benefits all vertebrate groups, the majority of studies have focused on mammalian microbial communities, likely due to their similarities to humans. However, extending study to a wider variety of animals will aid our understanding of the role microbes play in the ecological and evolutionary trajectories of vertebrates. For my dissertation, I have focused on investigating relationships between amphibians, a particularly understudied group in the microbiome literature, their gut microbes, and their external environment. I focus specifically on temperature as an environmental variable because temperature impacts all aspects of amphibian physiology, and rising global temperatures threaten amphibian persistence. Throughout my dissertation, I’ve investigated these relationships from multiple directions. First, I explored how environmental temperature alters amphibian gut microbial communities, with the potential to impact host physiological function. Specifically, I showed that increasing environmental temperatures alters the composition and diversity of salamander gut microbiota, which is associated with deleterious outcomes for host digestive performance. Additionally, I showed that increases in environmental temperature can cause significant changes to the tadpole gut microbiome on the timescale of hours, indicating that expected increases in temperature variability could rapidly affect amphibian physiology. Second, I focused on how the microbial community itself could influence amphibian responses to environmental temperature. Here, I found that disrupting the natural microbiome of tadpoles resulted in reductions of the host’s acute thermal tolerance, physiological performance at high temperatures, and ultimately survival under prolonged heat stress. Subsequently, using a hologenomic approach, I identified potential interactions between host and microbial functional pathways that could be driving these effects. Ultimately, my dissertation has highlighted the importance of gut microbial communities in shaping interactions between amphibians and their environment, and that these interactions should be considered when assessing amphibian responses to global climate change.


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Item Type: University of Pittsburgh ETD
Status: Unpublished
CreatorsEmailPitt UsernameORCID
Fontaine, Samantha S.ssf20@pitt.edussf200000-0002-2448-8800
ETD Committee:
TitleMemberEmail AddressPitt UsernameORCID
Committee ChairKohl, Kevin D.kkohl@pitt.edukkohl
Committee MemberRichards-Zawacki, Corinnecori.zawacki@pitt.educori.zawacki
Committee MemberAshman, Tia-Lynntia1@pitt.edutia1
Committee MemberBoyle, Jonboylej@pitt.eduboylej
Committee MemberWoodley,
Date: 25 January 2023
Date Type: Publication
Defense Date: 28 July 2022
Approval Date: 25 January 2023
Submission Date: 6 September 2022
Access Restriction: No restriction; Release the ETD for access worldwide immediately.
Number of Pages: 212
Institution: University of Pittsburgh
Schools and Programs: Dietrich School of Arts and Sciences > Biological Sciences
Degree: PhD - Doctor of Philosophy
Thesis Type: Doctoral Dissertation
Refereed: Yes
Uncontrolled Keywords: Gut microbiome, host-microbe interactions, physiology, temperature, heat, climate change, amphibians, tadpoles
Date Deposited: 25 Jan 2023 15:33
Last Modified: 25 Jan 2023 15:33


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