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United States Department of Agriculture

Agricultural Research Service

Research Project: Evolutionary Genomics of a Sociality Supergene

Location: Imported Fire Ant and Household Insects

Project Number: 6615-32000-044-26
Project Type: Reimbursable

Start Date: Mar 15, 2014
End Date: Feb 28, 2015

Objective:
1. Identify genes in the Gp-9 non-recombining region in native fire ants. 2. Determine which of these genes exhibit complete LD with Gp-9 and with colony social form in the native species. 3. Infer the gene products and functional roles of the supergene genes. 4. Reconstruct the evolutionary history of the supergene. 5. Identify the forms and strength of selection acting on supergene genes.

Approach:
Targeted sequence data will be generated to increase breadth of coverage and fill in gaps in existing supergene scaffolds. Sequences of the supergene region from a sample of 48 fire ant males will allow detailed description of the haplotype architectures of the two Gp-9 allele classes, with multiple data sources and computational tools employed to estimate gene number and content within the region. Multiple sequence alignments will be compared to infer routes and mechanisms of gene gain, loss, and silencing in the Gp-9 block, and a molecular phylogeny of fire ants will serve as a framework to reconstruct the sequence of specific architectural changes that occurred during supergene evolution. Formal recombination analyses will further test the hypothesis that the Gp-9 region is non-recombining. Sequences of genes located in the Gp-9 supergene will be compared to those of reference genes to detect differences in codon bias, GC (gas chromatographic) content, and rate of molecular evolution. Evidence of selection acting on supergene loci will be obtained by calculating dN/dS statistics and conducting site-frequency and haplotype-frequency spectrum tests.

Last Modified: 7/25/2014
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