Evidence for increased stress resistance due to polyploidy from synthetic autotetraploid Caenorhabditis elegans

Abstract

Whole genome duplication (WGD) is a well-studied yet enigmatic phenomenon. While it has long been recognised as contributing numerous genes to many eukaryotic lineages and often implicated in evolutionary radiations, how these lineages overcome the known burdens of polyploidy is poorly understood. Circumstantial evidence of many WGD events coinciding with periods of otherwise mass extinction is consistent with the hypothesis that polyploidy is conditionally advantageous under stress conditions. While support for this comes from both theoretical work and field studies, direct evidence is lacking, especially in animals. Here we compare diploid and neo-tetraploid Caenorhabditis elegans and show that tetraploid animals exhibit increased resilience under specific stress conditions related to temperature changes. Most notably, under severe cold stress gravid neo-tetraploids massively escape cold-induced death, and generate more progeny, of similar quality, than diploid animals. This is the first demonstration of the effects of polyploidy on stress resistance and physiology in animals.