The quantitative genetic basis of tolerance to environmental change during early embryogenesis in Drosophila melanogaster
Authors: Sumaetee Tangwancharoen; Brent Lockwood
Affiliation: University of Vermont
Keywords: Complex traits
Despite the paradigm of environmental robustness in developmental biology and decades of research into the genetics of developmental traits, relatively little is known about the genetic basis of tolerance to environmental change during embryonic development. We used introgression and selection to uncover the genomic basis of enhanced embryonic heat tolerance in neotropical lines of Drosophila melanogaster. After 16 generations of introgression and selection, we mapped embryonic heat tolerance with pooled whole-genome resequencing of 12 replicate crosses. This allowed us to map the genomic basis of embryonic heat tolerance to an average of 640 kb per quantitative trait locus (QTL). We found embryonic heat tolerance to have a complex genetic basis, with a total of 10 unique QTL that represented mapped regions on every chromosome. Two of these QTL were repeatedly selected in multiple crosses and mapped to adjacent regions on chromosome 2R. These two regions were non-overlapping and consisted of 54 genes known to be expressed in early embryos, notably genes involved in the electron transport chain and response to oxidative stress. Overall, our data suggest that while embryonic heat tolerance is influenced by loci across the genome, key genes involved in redox balance may be critical for the maintenance of embryogenesis in the face of environmental change. This result corroborates recent reports on the important role of redox biochemistry in embryogenesis. Further, our study extends previous work in developmental genetics in Drosophila by characterizing the quantitative genetics of an ecologically relevant developmental trait in natural populations.