Description
Antarctic pinnipeds exhibit specialized thermoregulatory adaptations, with Antarctic fur seals (AFS; otariids) relying on dense fur, while Leopard (LS) and Weddell seals (WS; phocids) having thick blubber. To investigate the underlying molecular mechanisms of Antarctic pinniped adaptation, we analyzed microRNA expression from 18 flipper skin samples (n=6 per species). We extracted microRNAs utilizing the mirVana™ Isolation Kit and sent aliquots for sequencing by Illumina NovaSeq X plus. We identified known microRNAs with miRDeep2 and detected differentially expressed miRNAs using DESeq2 through pairwise species comparisons (AFS vs. LS, WS vs AFS, WS vs. LS). Numbers of differentially expressed microRNAs partially recovered family-level phylogenetic relationships (104 in WS vs AFS, 91 in AFS vs. LS, and 65 in WS vs. LS). Notably, hsa-miR-214 (known to regulate hair follicle formation via β-catenin) was differentially expressed between the otariid and phocid species, particularly in the WS vs AFS pairwise differential test. Enrichment analysis also identified microRNA gene targets associated with hair follicle development and adipose tissue regulation. Our findings support the hypothesis that microRNAs may facilitate divergent evolutionary adaptations among Antarctic otariids and phocids. Furthermore, these results establish baseline biomarkers for monitoring the potential impacts of environmental stressors on the physical adaptations of these sentinel species.