Postdoctoral Fellowship: PRFB: Evolution of ion transporter function during salinity decline

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. As climate change alters ocean salinity, biodiversity and fisheries will be impacted worldwide.

Rising temperatures, polar ice melt, and altered precipitation decreases salinity in polar regions, while evaporation and reduced river flow increase salinity towards the equator. These shifts threaten ecosystem stability and fisheries, emphasizing urgency in understanding how organisms adapt to rapid habitat changes. The ability to regulate internal salt and fluid composition amidst the changing external environment will ultimately determine which populations survive.

This research explores how the proteins responsible for moving ions in and out of cells facilitate adaptation to shifting habitat salinities. By characterizing specific protein functions and their interactions with one another, the results from this study will help predict population responses to climate-induced salinity shifts.

The estuarine copepod Eurytemora affinis offers insights into the evolution of physiological mechanisms during salinity decline. This species has repeatedly colonized freshwater habitats across the Northern Hemisphere, undergoing shifts in ion regulation. Previous studies have identified selection on ion transport genes like Na+/H+ antiporter (NHA) during saline to freshwater transitions, which are likely crucial for ion uptake in dilute environments.

In this study, the research fellow will conduct electrophysiological assays in Xenopus oocytes to elucidate substrate specificity and transport modes of saline versus freshwater alleles of NHA and identify causal SNPs responsible for enhancing survival in low salinities. By characterizing NHA paralog functions and interactions with other proteins, this research helps us understand how genes cooperate in ion transport across membrane systems.

Furthermore, the research fellow will also investigate allele frequency shifts in response to salinity changes. Laboratory selection lines and wild population sampling across salinity gradients will reveal how natural selection acts on advantageous alleles. By integrating genetics, environment, and phenotype, the project aims to predict population responses to climate-induced salinity shifts via correlating allele dynamics with environmental salinity.

This project’s broader impacts extend beyond scientific communities. Engaging the public through educational exhibits and STEM initiatives will foster awareness of climate impacts on marine ecosystems. In summary, this research bridges physiology and evolution to understand how ion transporter alleles drive population responses to climate-driven salinity changes.

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.