Postdoctoral Fellowship: PRFB: Using community coalescence theory to measure feedback between animal hosts and ecosystem function via the meta-gut system

This action funds an NSF Postdoctoral Research Fellowship in Biology for FY 2024, Integrative Research Investigating the Rules of Life Governing Interactions Between Genomes, Environment, and Phenotypes. The fellowship supports the research and training of the fellow who will contribute to the area of Rules of Life in innovative ways. Hippotamus (Hippos) are crucial members of the rivers they live in.

Hippos spend their days wallowing in pools, adding large amounts of nutrients from their urine and feces. During the dry season, water levels drop, and some pools become more isolated than others. When hippos defecate into isolated pools, bacteria from hippo feces dominate the community of bacteria in pools.

When the rains return, stagnant water is flushed out, and the bacterial community in the pools becomes more similar to the river. While the effects of flushing on pools are known, how hippos are affected remains un-studied. The bacteria in animal guts affect their health and social behavior, so the rapid turnover in pool microbiomes during the rainy season may affect hippo well-being and sociality.

This research will study connections scaling from bacteria up to rivers to understand hippos’ health better.

This project will investigate two main mechanisms that could affect hippo gut microbial communities (microbiomes): the hydrologic connectivity of pools and hippo grouping behavior. Aim 1 tests how hydrological connectivity affects the hippo microbiome. Hippo density and pool size interact to shape the biogeochemistry of pools and rivers.

Hippo gut microbiomes affect ecosystem health by making pools more toxic. Whether changes in the pool microbiome affect hippos' guts, in turn, remains un-studied. Aim 2 tests the impact of hippo behavior on hippo guts.

Hippos live in stable home ranges for years. Females and young overlap dominant males, who exclude bachelor males. Aim 2 will test how these grouping patterns affect hippo density and how density affects the hippo gut.

Aim 3 tests how these two mechanisms affect hippo health. Gut microbial diversity is an important indicator of gut health, with more diverse gut microbiomes providing more host benefits. While pool size and hippo density may affect the gut microbiome of hippos, whether these changes are important for hippo health remains to be studied.

This project will measure whether changes in hippo microbiomes affect body condition. Hippos are ecosystem engineers, so measuring the links between environmental factors and hippo health is crucial for understanding the health of rivers as a whole.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.