The goal of this research is to dissect the causative genes and mutations underlying a complex trait, and trace the stepwise process by which the identified causative alleles arose and spread through an isolated population to generate a fixed morphological phenotype. The species Drosophila santomea exhibits a recently evolved, drastic shift in its pigment patterns that represents an optimal model system in which to dissect complex polygenic traits. Our previous work identified the gene underlying one of four major QTL contributing to this trait. Analysis of multiple individuals in the population revealed that causative alleles of this gene arose several times in parallel in the D. santomea population (i.e. a soft sweep). Here, we propose to employ molecular genetic techniques (introgression mapping and transgenic complementation) to identify causative genes and mutations responsible for two additional QTL. Using a combination of molecular and genomic techniques (in situ hybridization, RNA-seq), we will then assess how these loci interact with each other, as well as how they impact the genome-wide profile of expression. Finally, we will survey population variation at these additional causative loci to assess whether a similar soft sweep occurred, and determine whether these genes exhibit signs of positive selection. This study will provide a rare vista of a complex morphological trait that integrates molecular studies of gene function with processes occurring at the population level.
The vast majority life's variation in phenotype (size, shape, color, behavior, morphology) is genetically encoded in the DNA as multiple mutations in genes scattered throughout the genome. The goal of this research is to dissect one such 'complex trait' down to its major genes and mutations, and trace how these mutations spread through the population to generate differences unique to a species. Understanding how this phenotype arose will provide a unique perspective of complex trait formation, impacting our understanding of complex traits in the human population.
| Grover, Sumant; Williams, Melissa E; Kaiser, Rebecca et al. (2018) Augmentation of a wound response element accompanies the origin of a Hox-regulated Drosophila abdominal pigmentation trait. Dev Biol 441:159-175 |
| Roeske, Maxwell J; Camino, Eric M; Grover, Sumant et al. (2018) Cis-regulatory evolution integrated the Bric-à-brac transcription factors into a novel fruit fly gene regulatory network. Elife 7: |
| Rebeiz, Mark; Williams, Thomas M (2017) Using Drosophila pigmentation traits to study the mechanisms of cis-regulatory evolution. Curr Opin Insect Sci 19:1-7 |
