Effects of overwintering on the transcriptome and fitness traits in a damselfly with variable voltinism across two latitudes

TL;DR

This study examines how winter diapause affects the damselfly's traits and gene activity, finding consistent effects across different latitudes.

Contribution

The study reveals a shared transcriptomic basis for diapause at the intraspecific level in damselflies.

Findings

Post-winter diapause led to larger and heavier damselfly cohorts with no survival differences.

Gene expression changes were observed, with some overlap across latitudes, especially in morphogenesis-related genes.

Results support evolutionary convergence in diapause responses across organisms.

Abstract

Winter diapause consists of cessation of development that allows individuals to survive unfavourable conditions. Winter diapause may bear various costs and questions have been raised about the evolutionary mechanisms maintaining facultative diapause. Here, we explored to what extent a facultative winter diapause affects life-history traits and the transcriptome in the damselfly Ischnura elegans, and whether these effects were latitude-specific. We collected adult females at central and high latitudes and raised their larvae in growth chambers. Larvae were split into a non-diapausing and post-winter (diapausing) cohort, were phenotyped and collected for a gene expression analysis. At the phenotypic level, we found no difference in survival between the two cohorts, and the post-winter cohort was larger and heavier than the non-winter cohort. These effects were mostly independent of the latitude of origin. At the transcriptomic level, wintering affected gene expression with a small fraction of genes significantly overlapping across latitudes, especially those related to morphogenesis. In conclusion, we found clear effects of diapause on the phenotype but little evidence for latitudinal-specific effects of diapause. Our results showed a shared transcriptomic basis underpinning diapause demonstrated, here, at the intraspecific level and supported the idea of evolutionary convergence of the response to diapause across organisms.

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