Meeting Abstract
The copepod Calanus finmarchicus, an important primary consumer in North Atlantic ecosystems, has a flexible life history in which individuals may either delay maturation during the last juvenile stage (C5) and enter into diapause or skip diapause and molt directly into adults. Researchers are currently unable to induce C. finmarchicus diapause in the lab. We have combined morphological and transcriptomic approaches to understand the physiological changes that occur during progression of C. finmarchicus along each of these two paths by sampling lab-reared and field populations in which individuals molt directly into adults and enter diapause, respectively. We conducted Illumina-based RNA-seq to identify a large pool of differentially expressed genes during early and late stages of the C5 molt cycle in the lab-reared population. We found that progression through the stage was associated with substantial accumulation of lipids within the oil sac and changes in many genes necessary for the synthesis of storage lipids. By comparing lab-reared and field-collected copepods, we have compiled a list of candidate genes that are differentially expressed prior to entry into diapause. Homologs of many of these genes, including heat shock proteins, phosphoenolpyruvate carboxylase kinase, and RAS-related protein Rab-10, are associated with diapause preparation in other animals. These candidate genes may serve as biomarkers to distinguish C. finmarchicus that are preparing to initiate or skip diapause. Robust markers will enable laboratory and field studies to understand the factors that influence the decision to enter diapause.
