This action funds an NSF Postdoctoral Research Fellowship in Biology for FY 2025. The fellowship supports research and training of the fellow that will contribute to biology in innovative ways. Soil animals, such as nematodes (small roundworms), play a critical role in ecosystem functions, including decomposition, which influences carbon and nutrient cycling. However, environmental changes, such as soil warming, may disrupt nematode characteristics (traits) and, in turn, alter the essential functions they perform. Understanding how nematode traits and their associated gene expression respond to warming is key to predicting shifts in soil processes that regulate ecosystem health. This project investigates how long-term soil warming affects the traits and gene expression of fungal-feeding nematodes (fungivores) and aims to establish predictive links between nematode traits and decomposition. By identifying these relationships, this research will improve our ability to anticipate how environmental change influences soil biological processes, with broader implications for soil fertility, carbon storage, and ecosystem resilience. The project has three primary objectives: (1) determine how long-term soil warming alters key fungivore nematode traits, including body size, lifespan, and reproductive rates; (2) assess how warming influences the expression of genes corresponding to these traits; and (3) examine how nematode phenotypic variation affects decomposition, a key ecosystem