This study aimed to identify genomic loci associated with metamorphosis rate in the copepod Tigriopus californicus. F1 hybrids were generated between two divergent populations: SD (from San Diego, CA), and SH (from Strawberry Hill, OR). Once F1 female developed egg sacs, the F2 larvae from each reciprocal cross (SDfemale x SHmale, and SHfemale x SDmale) were hatched in large plates and monitored daily. When each individual reached metamorphosis into a copepodid juvenile, the individual was scored for the date and frozen. After ~3000 individuals were scored for each cross, the 10% slowest and the 10% fastest were each pooled for library prep and sequencing.