Postdoctoral Fellowship: PRFB: Behavioral and physiological mechanisms of buoyancy regulation in bony fishes

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 research and training of the fellow that will contribute to the area of Rules of Life in innovative ways. One of the most surprising facts about lungs is that they first evolved in fish hundreds of millions of years ago.

The origin of lungs was crucial to the evolutionary success of vertebrates—lungs enabled fish to later venture onto land and diversify and enabled active buoyancy control in fishes. Fundamental questions remain about how fish regulate their buoyancy and how these mechanisms evolved. The fellow will study the anatomy, physiology, and behaviors used for buoyancy regulation across a broad range of fish species and model the evolutionary history of these traits.

This research will reveal fundamental information about how fishes maintain homeostasis and interact with their environment, as well as reveal how changes in ecology and anatomy drive evolutionary changes in behavior and physiology. The fellow will develop educational STEM workshops for underserved high school students in Washington, DC, and mentor undergraduate students in the development of independent research projects related to the proposed work.

The original mechanism of buoyancy regulation was the use of air breaths to modify lung or gas bladder volume. While some extant fishes use this behavioral mechanism, other fishes use a specialized gas gland to physiologically regulate buoyancy. Little is known about the evolutionary transitions between these mechanisms and how their phylogenetic distributions relate to patterns in fish ecology.

The fellow will integrate histological techniques, pressure manipulation experiments, and phylogenetic comparative methods to investigate diversity in 1) the morphology of the pneumatic duct (which permits or restricts the use of air breaths), 2) the presence and density of gas gland cells (which physiologically regulate buoyancy), and 3) the use of air breaths to restore buoyancy. The fellow will synthesize these data to develop a predictive model of buoyancy regulation mechanisms based on ecological traits.

This research will result in the first comprehensive picture of the evolution of and relationships among gas bladder morphology, gas gland physiology, gas bladder ventilation, and ecology. The fellow will gain experience with histological techniques and phylogenetic comparative methods and will strengthen mentorship and science communication skills by working with undergraduate and high school students.

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.