My thesis work focused on the evolution of species in Dr. Ana Llopart's Lab at the University of Iowa using Drosophila (fruit fly) sister species. I investigated 1) the levels of gene flow that can occur between species while still maintaining separate species identities, 2) how gene expression evolution occurs at different rates on sex chromosomes compared to autosomes, and 3) how divergent expression can be inherited in hybrids. The complete dissertation published in December of 2016 can be accessed at: ir.uiowa.edu/etd/2222/
One of the main rules in speciation genetics is the large X-effect, which posits that the X chromosome has a disproportionately large effect on hybrid male sterility compared to autosomes. Whole-genome analyses of gene expression in the lab indicate that X-linked genes are more differentially expressed between species while autosomal genes are preferentially misexpressed in hybrids. One explanation for this apparent paradox is that rapidly evolving X-linked trans-regulatory elements (TREs) influence the expression of autosomal genes through interactions with autosomal cis-regulatory elements (CREs). I hypothesize that both the rapid evolution of X-linked trans-regulatory elements and their hemizygosity in males contribute to widespread autosomal misexpression in hybrids as a result of the preferential recognition of cis-regulatory elements by conspecific trans-regulatory elements.
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Gene Expression Divergence in DrosoPhila
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FASTER-X EVOLUTION of Male-Biased Genes in Drosophila
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INTROGRESSISON IN
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Danielle Herrig
[email protected]
[email protected]