Lifespan after desiccation stress is genetically variable and partially associated to head traits in a set of recombinant lines in Drosophila melanogaster

Desiccation stress is one of the most critical stress forms in terrestrial environments under climate change and global warming. To search for genetic variation and any possible associations between lifespan after desiccation and two morphometric traits of head in flies, we used two sets of recombinant inbred lines (RIL) of Drosophila melanogaster. Desiccation survival was measured as lifespan at 25 °C by exposing flies to a desiccation environment for 1.5 h at 2, 4, and 6 days of age. This desiccation treatment decreased dramatically (2.5 times, in average) lifespan in treated flies as compared to control flies. There was high variation in desiccation survival across lines within each of two RIL panels, with mean survival ranging between 5 and 27 days across RIL. Composite interval mapping revealed 5 QTLs, all of them on chromosome 2 in females. The genetic basis of survival after desiccation episodes was found to be partially different from the genetic basis of survival under permanent desiccation studied previously in these RIL. Desiccation survival (lifespan after desiccation stress) was significantly correlated not to body size but rather to two parts of the head capsule that are well known to be related in a trade-off in Drosophila: frons and eye size. These associations between lifespan and head morphology appeared after non-lethal desiccation episodes rather than under permanent desiccation stress.