1a. Objectives (from AD-416):
The goals of the proposed research are to develop new functional genomic resources for the fire ant Solenopsis invicta and to employ these resources to examine biological traits that are simultaneously important for understanding its basic biology and identifying genes and gene networks that are potential targets for its biological control.
1b. Approach (from AD-416):
1) Large-scale EST studies will be performed to significantly increase the breadth and depth of transcriptome coverage using both 454 pyrosequencing as well as traditional Sanger sequencing technology. 2) An oligo microarray platform (Agilent) will be developed for gene expression studies using the EST sequence data. 3) A platform for screening SNPs will be developed using Illumina technology for population genomic and linkage studies. 4) Integrated physical and genetic maps will be generated for S. invicta, which are essential for linking phenotypic traits to the responsible genetic variation. 5) A web-based platform will be developed integrating these data in an easily accessible format.
3. Progress Report:
This project is related to Objective 1 of this in-house project: Develop functional genomic resources and employ these resources to examine the genetic basis of biological traits that can potentially be used for biologically based control, including implications for the geographic origins of infestations. The goal of this project is to develop new functional genomic resources for fire ants. A comparative study of ants of the two social forms of fire ants revealed the genomic region responsible for two divergent forms of colony social organization in fire ants. The results demonstrate that show that this genomic region is part of a pair of heteromorphic chromosomes having many of the key properties of sex chromosomes. Importantly, the non-recombining region comprises most of the genes with demonstrated expression differences between individuals of the two social forms. These findings highlight how genomic rearrangements can maintain divergent adaptive social phenotypes involving many genes acting in concert by locally limiting recombination. A second study was completed that employed newly developed whole-genome microarrays to characterize the gene expression patterns underpinning different behavioral phenotypes of foundress fire ant queens. The results demonstrate that in fire ants, social environment (colonies started by single-queen vs. multiple-queens) plays a major role in the determination of the patterns of gene expression, while the physiological state and the social rank of founding queens are only secondary. These results highlight the powerful influence of social environment on regulation of gene expression patterns, physiology and, ultimately, social behavior of animals. Monitoring: Progress was continuously monitored through direct interactions with staff.