Life‐History, Stress‐Resistance, and Transcriptomic Variation Among a Mexican Caenorhabditis elegans Isolate and Contemporary and Ancestral N2 Lineages

ABSTRACT Long‐term laboratory propagation can be associated with phenotypic and transcriptional differences in model organisms, but comparisons with recently isolated strains and earlier laboratory lineages remain limited. Here, we compared a recently isolated Caenorhabditis elegans strain from Mexico City (VJV2) with the contemporary N2 Bristol strain. To contextualize laboratory propagation history, we also included the N2 Ancestral strain, a cryopreserved lineage from 1969 derived from early laboratory stocks. Phenotypic assays showed that, under standard laboratory conditions, the VJV2 strain exhibited reduced lifespan and fertility but increased survival following Pseudomonas aeruginosa exposure, whereas the Ancestral strain showed higher oxidative stress tolerance but reduced thermotolerance. RNA‐seq analyses showed that transcriptomic profiles of the VJV2 and Ancestral strains were more similar to each other than to the contemporary N2 Bristol strain, suggesting expression differences associated with strain history and laboratory propagation. Differential gene expression analyses identified strain‐specific expression patterns involving stress‐, immune‐, and collagen‐related genes. Under acute heat stress, only a small set of canonical heat shock genes was commonly upregulated across the three strains, whereas the VJV2, Ancestral, and contemporary N2 Bristol strains exhibited distinct strain‐specific expression patterns. Together, these findings provide a comparative phenotypic and transcriptomic characterization of three C. elegans strains with distinct laboratory histories and highlight the importance of strain background when interpreting experimental outcomes.