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.

Public Health Relevance

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.

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Research Project (R01)
Project #
5R01GM114093-03
Application #
9211338
Study Section
Genetic Variation and Evolution Study Section (GVE)
Program Officer
Janes, Daniel E
Project Start
2015-05-01
Project End
2019-01-31
Budget Start
2017-02-01
Budget End
2018-01-31
Support Year
3
Fiscal Year
2017
Total Cost
$386,218
Indirect Cost
$91,574
Name
Princeton University
Department
Type
Organized Research Units
DUNS #
002484665
City
Princeton
State
NJ
Country
United States
Zip Code
08543
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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
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