1st Place: Uncovering the genetic architecture of locust phase polyphenism using the locust Schistocerca piceifrons and grasshopper Schistocerca serialis cubense

Locusts display a remarkable form of phenotypic plasticity, known as locust phase polyphenism, in which one genotype produces different phenotypes in response to crowded and isolated environments. Crowded conditions facilitate a transition to the gregarious (more locust-like) phase, while isolation leads to a shift towards the solitarious (more grasshopper-like) phase. Within the genus Schistocerca, certain quantifiable traits, such as color, morphology, and behavior, exhibit various density-dependent plastic reaction norms. With this in mind, we chose two closely related species that can hybridize to produce viable offspring, Schistocerca piceifrons (a locust with high plasticity) and Schistocerca serialis cubense (a grasshopper with reduced plasticity), to study the genetic architecture of locust phase polyphenism via quantitative trait loci (QTL) mapping. Since backcrossing F1 hybrid females with males of both parental species generates variation in the form of single nucleotide polymorphism (SNP) markers, we can perform QTL mapping and analysis to locate significant QTL regions for behavior, color, and morphology. So far, we have reared backcrossed hybrid individuals in both crowded and isolated conditions and quantified the traits of interest. We can infer that locust phase polyphenism involves complex multigenic traits, each with a small number of impactful genes that are located at different genomic regions. Future work will use SNP data and the reference genomes of each species to produce high-quality genetic linkage maps. These linkage maps, in conjunction with the quantified phenotypic trait data, will allow us to pin-point significant QTL regions.