University of Pittsburgh Department of Biological Sciences Presents:
Friday Noon Seminar Series 2017-2018
Graduate Student: Yang Liu
Changes to a Hox gene and its downstream regulatory network drive microevolution
A major objective of evolutionary biology is to derive a realistic understanding of how traits arose in the distant past through the genetic examination of recent phenotypic change. Hox genes play highly conserved roles in the organization of animal body plans, yet it has been difficult to measure their relative contribution to the evolution of body plan phenotypes. Here, we describe how mutations in a Hox gene and its downstream network generated differences in abdominal pigmentation between Drosophila yakuba and D. santomea. In D. santomea, regulatory mutations in the Hox gene Abd-B shifted its expression along the body axis. In parallel, regulatory changes at pdm3, encoding a pigment-repressing transcription factor, temporally extended its expression during pupal development. In two pigment-producing enzymes, we attribute the loss of yellow primarily to upstream changes, while the gain of ebony resulted from a transposon insertion that disabled a silencer element. We have confirmed the contributions of these loci by CRISPR-Cas9 induced mutations in hybrid animals. Our results highlight how the dissection of a microevolutionary trait regulated by these body plan genes uncovers a much more complex genetic composition of Hox genes and their downstream networks. Thus, by extension we envision that our findings set a precedent for anticipating such complexity when small changes are compounded over hundreds of millions of years.
Friday, April 6, 2018
A219B Langley Hall
12:00 PM Seminar