A naturally segregating polymorphism balancing semelparous reproduction versus reproductive diapause revealed via microfluidic assessment of starvation stress in Caenorhabditis elegans.

Abstract

Caenorhabditis elegans typically feeds on rotting fruit and plant material in a fluctuating natural habitat, a boom-and-bust lifestyle. Moreover, stage specific developmental responses to low food concentration suggest that starvation-like conditions are a regular occurrence. In order to assess variation in the C. elegans starvation response under precisely controlled conditions and simultaneously phenotype a large number of individuals with high precision, we have developed a microfluidic device that, when combined with image scanning technology, allows for high-throughput assessment at a temporal resolution not previously feasible and applied this to a large mapping panel of fully sequenced intercross lines. Under these conditions worms exhibit a markedly reduced adult lifespan with strain-dependent variation in starvation resistance, ranging from <24 hours to [~]120 hours. Genome-wide mapping of the responses of more than 7,855 individuals identified four quantitative trait loci (QTL) of large effects. Three of these loci are associated with single genes (ash-2, exc-6, and dpy-28) and the fourth is a [~]26 KB region on Chromosome V encompassing several genes. Backcross with selection confirmed the effect of the Chromosome V locus. Segregating natural variation for starvation response in this species suggests that different isolates may use different strategies (facultative vivipary versus reproductive diapause) for dealing with extreme food deprivation.