Joel Atallah

email: jatallah [at] ucdavis [dot] edu

In my research I seek to understand how changes at the cellular and molecular levels have led to the origin and diversification of complex traits. I use tools such as RNA-Seq, genomic analysis and 4D confocal imaging to study the evolution of novelty. I am particularly interested in cases of closely related species that are similar in most respects but have diverged markedly in specific characters.

I have worked on a number of systems, including a variety of Drosophila fruit fly species, and aculeate Hymenoptera (ants, bees and stinging wasps). I have recently participated in a Drosophila Model Organism Encyclopedia of DNA Elements (modENCODE) project that has involved the sequencing and analysis of 8 Drosophila genomes.  In order to study the changes in cellular processes that have led to evolutionary diversification, I have conducted extensive research on a male-specific Drosophila trait, an elaborate and diverse bristle structure known as the sex comb that forms through complex cellular rearrangements during fruit fly metamorphosis. I am also interested in a female trait, the egg-laying organ or ovipositor. The evolution of a sharp, enlarged, serrated ovipositor in the lineage leading to Drosophila suzukii has allowed this species to colonize ripening fruit. As an invasive pest, D. suzukii has caused massive agricultural damage. In contrast, the vast majority of Drosophila species have blunt ovipositors, feed on rotting fruit, and do not typically puncture intact fruit skin. Analyzing the genomic underpinnings of this evolutionary change can shed light on the molecular basis of the origin of an adaptive trait.

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