Meeting Abstract
The subarctic Pacific is home to the lipid-rich copepod Neocalanus flemingeri. With a one-year life cycle, this copepod depends on a short annual spring phytoplankton bloom for growth and accumulation of capital to fuel both diapause and reproduction. This species is highly resilient: its distribution spans the northern Gulf of Alaska, a region where spring food resources vary by one to two orders of magnitude. RNA-Seq was used to profile global gene expression of pre-adult N. flemingeri collected across the shelf and in Prince William Sound. t-Distributed Stochastic Neighbor Embedding (t-SNE) analysis of gene expression profiles followed by group identification using the DBSCAN algorithm identified three phenomic clusters. With one exception, these corresponded to three distinct collection regions. Functional analysis of differentially expressed genes identified lipid metabolism as a key biological process contributing to regional differences in transcription. Genes involved in lipid synthesis were up regulated in individuals from Prince William Sound, while genes involved in lipid catabolism were up-regulated in individuals collected in high-nutrient low-chlorophyll (HNLC) gulf waters. Gene expression divergence in N. flemingeri indicated acclimatization to local conditions, and a capacity to persist in a habitat with steep resource gradients. We hypothesize that the observed resilience of these copepods stems from a combination of acclimatizion to low food conditions and the ability to exploit pulses of high food to build lipids to fuel diapause and reproduction.
